Re: [Emc-users] How Exactly does a Mister Work

[Roland Jollivet]

This is quite informative.
As seen at the 1:50 min mark, it looks like there is no special nozzle used.

http://www.mmsonline.com/videos/video-getting-started-with-minimum-quantity-lubrication.aspx

Roland



2009/11/23 Gene Heskett 

> On Monday 23 November 2009, Kenneth Lerman wrote:
> >I have some ruby orifices measuring -- two sizes 11.5 and 26
> >thousandths. They are set in brass cylinders measuring .125 by .125 with
> >a slight tapered end. They also have stainless steel screens to keep
> >them from clogging. I usually press fit them into a reamed hole.
> >
> >I can spare a few if Gene or someone would like to try them.
> >
> >Ken
>
> Thanks for the offer, Kenneth.  But in my case, I think I'd settle for a
> quality needle valve.  The air flow takes care of the droplet generation
> quite well, and at my low pressures of 20-40 psi, doesn't really make an
> airborne nuisance or hazard. I just haven't hit all the gittin places. Yet.
> :)
>
> Thought exercises here have involved edm to be sure, but my prowling the
> net
> looking for suitable electrodes to use has been largely futile, as about
> 1mm
> seems to be the lower limit.  Deep holes with my passive fluid setup are
> another problem, I learned a lot about deep holes while removing those
> broken
> 6-32 taps. :)
>
> The bottom line is that it appears I now have something that works much
> better than tipping an 8oz bottle of cutting oil up and running some down
> the
> spinning bit.
>
> --
> Cheers, Gene
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> The NRA is offering FREE Associate memberships to anyone who wants them.
> 
>
> Quantum Mechanics is a lovely introduction to Hilbert Spaces!
>-- Overheard at last year's Archimedeans' Garden Party
>
>
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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Monday 23 November 2009, Kenneth Lerman wrote:
>I have some ruby orifices measuring -- two sizes 11.5 and 26
>thousandths. They are set in brass cylinders measuring .125 by .125 with
>a slight tapered end. They also have stainless steel screens to keep
>them from clogging. I usually press fit them into a reamed hole.
>
>I can spare a few if Gene or someone would like to try them.
>
>Ken

Thanks for the offer, Kenneth.  But in my case, I think I'd settle for a 
quality needle valve.  The air flow takes care of the droplet generation 
quite well, and at my low pressures of 20-40 psi, doesn't really make an 
airborne nuisance or hazard. I just haven't hit all the gittin places. Yet. 
:)

Thought exercises here have involved edm to be sure, but my prowling the net 
looking for suitable electrodes to use has been largely futile, as about 1mm 
seems to be the lower limit.  Deep holes with my passive fluid setup are 
another problem, I learned a lot about deep holes while removing those broken 
6-32 taps. :)

The bottom line is that it appears I now have something that works much 
better than tipping an 8oz bottle of cutting oil up and running some down the 
spinning bit.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


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Re: [Emc-users] How Exactly does a Mister Work

[Kenneth Lerman]

I have some ruby orifices measuring -- two sizes 11.5 and 26 
thousandths. They are set in brass cylinders measuring .125 by .125 with 
a slight tapered end. They also have stainless steel screens to keep 
them from clogging. I usually press fit them into a reamed hole.

I can spare a few if Gene or someone would like to try them.

Ken

dave wrote:
> On Fri, 2009-11-20 at 16:39 +, Andy Pugh wrote:
>   
>> 2009/11/20 Gene Heskett :
>>
>> 
>>> A cube of dry ice sitting on
>>> it would help, but would raise the available oxygen too.
>>>   
>> I am fairly sure it would displace the oxygen (being heavier) and so
>> would both cool and reduce oxide formation.
>>
>> You might have hit on a cunning plan, and it would look cool too.
>>
>> 
>
> Carbon Dioxide doesn't disassociate easily but will if pushed hard. 
> It cannot be used in heat-treating furnaces for that reason but for
> cooling/shielding Al machined parts I think it will work just fine.
>
> I'm not sure the kinetics of Al oxidation are as aggressive as Gene
> states but cannot find any evidence to support or disallow such a claim.
> The oxidation curve, at least at high temps (600 F), is parabolic so it
> limits fairly quickly. 
>
> A couple of alternatives for small orifices come to mind. Diesel rebuild
> shops should always have a supply of used injector nozzles. I understand
> the newer ones are carbide. 
>
> IIRC Gene had a tap remover (crude edm) running at one time. That should
> fab almost any small hole he wants. :-)
>
> Small volumes of oil/mist might be available by using model airplane
> engines as pumps. 
>
> Just thinking out loud. Usually dangerous. 
>
> Dave
>
>
>
>
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Re: [Emc-users] How Exactly does a Mister Work

[Dave]

I've spent quite a few days in a Chrysler transmission plant servicing 
CNC machines and as I recall every machine I worked on used regular 
flood coolant,  although some of them may have had high pressure systems 
- still flood coolant.   Some of the machines were cutting steel, but 
many where cutting the transmission case and case components which are 
primarily aluminum.

Dave

Gene Heskett wrote:
> On Saturday 21 November 2009, Jeshua Lacock wrote:
>   
>> On Nov 21, 2009, at 9:55 AM, Gene Heskett wrote:
>> 
 My first attempt was in olivine sand, and I had about 1/2 inch layer
 of black quartz fused around the casting!
 
>>> I'll bet that was NOT fun to remove without damaging the casting too
>>> much. :(
>>>   
>> Lets just say I wrote that one off as an experiment.
>>
>> ;)
>>
>> 
> :P
>
>   
>>> In graphite I'd think the cooling would be pretty slow, but the
>>> finish should
>>> show the machining marks in the graphite I'd think.  With thought &
>>> carefull
>>> design, that mold should be re-usable several times too.
>>>   
>> You got it!
>>
>> One of the main reasons I have been building a CNC machine is for
>> making patterns and molds...
>> 
>
> Which generally, means a larger machine, but it can work in easier to cut 
> materials too.  I wish I had the time and space to build a gantry with a 2x4 
> foot vacuum bed & at least a foot of z, two A's and whatever the ability to 
> swing it in both directions, the Z axis motions would be called.  I hate 
> hogging out the thumb holes in a gun stock by hand.  First time, its fun. 
> 2nd, a chore, 3rd and beyond tend to qualify for the PIMA description. ;)
>
> I'm contemplating a 4th pass since the 3rd one turned out to have been tried 
> on an explosive piece of fawncy Maple.  It was cooked, but it was far from 
> dry & took several ounces of superglue to keep in in one piece, and has now 
> had another decade for the other half of that plank to stabilize.  The gun 
> its holding, a TC Black Diamond 50 cal, has decided to shoot very well since 
> I pitched the 209 primer carrying breech plug and put a #11 nipple in it.  
> The 209's fire come hell or even high water, but are way too brutal and lift 
> the rammed bullet clear of the packed powder before the powder can get a 
> decent explosion going, and that lack of a solidly rammed load can make a 
> decent gun shoot a shotgun pattern at shotgun ranges.  With the #11 musket 
> cap, its doing 2" to 3" groups at 50 yards, not great but will put venison in 
> the freezer, and 3 feet smaller then the same load being lit by a 209 primer.
>
> I made a #11 carrying breech plug for my other coal burner, a TC Omega 50 cal 
> with the factory thumb hole stock, but the firing pin is so well centered it 
> goes right down the middle of the nipple, putting a very nice dent in the 
> cap, but with nothing under the middle of the cap for an anvil, it doesn't 
> fire.  I hit the first one about 6 times without cracking it off.  Gave up.  
> With the 209's lighting it, it is not reliably on the paper at 50 yards.  I 
> hear they are making a puny powered 209 these days, but none of them seem to 
> have filtered down to the gittin places of unwashed shooters of charcoal 
> burners yet.
>  
> Centerfire season opens here on Monday if you can't tell.  I think I have a 
> place to sit & let the dust settle on my eyeballs, till something wanders by. 
>  
> If I can keep my diabetic feet warm that is. :(
>
> Humm, not much left on topic in this here thread. ;)
>
>   
>> Best,
>>
>> Jeshua Lacock
>> Founder/Programmer
>> 3DTOPO Incorporated
>> 
>> Phone: 208.462.4171
>>
>> 
>
>   


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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Saturday 21 November 2009, Jeshua Lacock wrote:
>On Nov 21, 2009, at 9:55 AM, Gene Heskett wrote:
>>> My first attempt was in olivine sand, and I had about 1/2 inch layer
>>> of black quartz fused around the casting!
>>
>> I'll bet that was NOT fun to remove without damaging the casting too
>> much. :(
>
>Lets just say I wrote that one off as an experiment.
>
>;)
>
:P

>> In graphite I'd think the cooling would be pretty slow, but the
>> finish should
>> show the machining marks in the graphite I'd think.  With thought &
>> carefull
>> design, that mold should be re-usable several times too.
>
>You got it!
>
>One of the main reasons I have been building a CNC machine is for
>making patterns and molds...

Which generally, means a larger machine, but it can work in easier to cut 
materials too.  I wish I had the time and space to build a gantry with a 2x4 
foot vacuum bed & at least a foot of z, two A's and whatever the ability to 
swing it in both directions, the Z axis motions would be called.  I hate 
hogging out the thumb holes in a gun stock by hand.  First time, its fun. 
2nd, a chore, 3rd and beyond tend to qualify for the PIMA description. ;)

I'm contemplating a 4th pass since the 3rd one turned out to have been tried 
on an explosive piece of fawncy Maple.  It was cooked, but it was far from 
dry & took several ounces of superglue to keep in in one piece, and has now 
had another decade for the other half of that plank to stabilize.  The gun 
its holding, a TC Black Diamond 50 cal, has decided to shoot very well since 
I pitched the 209 primer carrying breech plug and put a #11 nipple in it.  
The 209's fire come hell or even high water, but are way too brutal and lift 
the rammed bullet clear of the packed powder before the powder can get a 
decent explosion going, and that lack of a solidly rammed load can make a 
decent gun shoot a shotgun pattern at shotgun ranges.  With the #11 musket 
cap, its doing 2" to 3" groups at 50 yards, not great but will put venison in 
the freezer, and 3 feet smaller then the same load being lit by a 209 primer.

I made a #11 carrying breech plug for my other coal burner, a TC Omega 50 cal 
with the factory thumb hole stock, but the firing pin is so well centered it 
goes right down the middle of the nipple, putting a very nice dent in the 
cap, but with nothing under the middle of the cap for an anvil, it doesn't 
fire.  I hit the first one about 6 times without cracking it off.  Gave up.  
With the 209's lighting it, it is not reliably on the paper at 50 yards.  I 
hear they are making a puny powered 209 these days, but none of them seem to 
have filtered down to the gittin places of unwashed shooters of charcoal 
burners yet.
 
Centerfire season opens here on Monday if you can't tell.  I think I have a 
place to sit & let the dust settle on my eyeballs, till something wanders by.  
If I can keep my diabetic feet warm that is. :(

Humm, not much left on topic in this here thread. ;)

>Best,
>
>Jeshua Lacock
>Founder/Programmer
>3DTOPO Incorporated
>
>Phone: 208.462.4171
>

-- 
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Re: [Emc-users] How Exactly does a Mister Work

[Jeshua Lacock]

On Nov 21, 2009, at 9:55 AM, Gene Heskett wrote:

>> My first attempt was in olivine sand, and I had about 1/2 inch layer
>> of black quartz fused around the casting!
>
> I'll bet that was NOT fun to remove without damaging the casting too  
> much. :(

Lets just say I wrote that one off as an experiment.

;)

> In graphite I'd think the cooling would be pretty slow, but the  
> finish should
> show the machining marks in the graphite I'd think.  With thought &  
> carefull
> design, that mold should be re-usable several times too.


You got it!

One of the main reasons I have been building a CNC machine is for  
making patterns and molds...


Best,

Jeshua Lacock
Founder/Programmer
3DTOPO Incorporated

Phone: 208.462.4171


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Re: [Emc-users] How Exactly does a Mister Work

[Jeshua Lacock]

On Nov 21, 2009, at 5:58 AM, Erik Christiansen wrote:

> On Sat, Nov 21, 2009 at 05:00:13AM -0700, Jeshua Lacock wrote:
>> One of the beauties of casting with aluminothermic reactions is there
>> is no crucible used (or furnace)!
>
> Would another beauty be that TiO2 is cheap enough to put in paint and
> plastic, but Ti metal costs a mozza?

Indeed.

> I can't quite get over that you're
> casually extracting the metal from a most recalcitrant oxide, while
> current industrial processes to do the same are horribly expensive.

A considerable percent of commercial titanium reduced uses a similar  
reaction.

The are several reasons why Ti costs "a mozza":

1. Marketing - they have you by the *alls - its Titanium!!! You know  
you want it!

2. It lasts forever - industries prefer you have to buy replacements -  
often!

3. Extremely difficult to machine and work with.

4. Raw materials still are not cheap. If you do the math for buying  
the TiO2, the aluminum powder, fluorite, etc, it would work out to  
around the going rate for raw titanium. Of course, if you order  
materials by the boat load, you can get the costs down.

>> You plug the sprue (entry) going to the mold cavity with a thin sheet
>> of metal (that is melted once the molten metal reaches it), and put
>> the chemical on top. The slag melts to the top and the metal drains
>> out into the mold
>
> Does it remain molten long enough to flow into a mould, if the  
> reaction
> takes 20 minutes?

The burning stage only lasts perhaps a couple minutes. But it keeps  
reacting for a good while afterwards. The burn rate is configurable by  
the size of the aluminum particle and the amount of flux used. Here is  
a pic of the actual combustion stage:



> Or was that just because you were melting a barrel of
> the stuff? Even so, that wouldn't give a sound casting, just a pig for
> remelting?


If the plug and reaction rate is properly chosen, then you can get  
sound castings as I have.

To get high purity Ti, one would have to re-melt the pig in an inert  
atmosphere (argon) and remove any slag that floats to top.

That being said, I have made usable parts directly from Ti  
aluminothermic reactions.


Cheers,

Jeshua Lacock
Founder/Programmer
3DTOPO Incorporated

Phone: 208.462.4171


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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Saturday 21 November 2009, Peter blodow wrote:
>Hello Gene,
>I take  this discussion about welding and combustibles as an oopportunity
>to clarify a few things.
>1. CO2 is used in arc welding only for old soft iron (mild steel) in order
>to maintain the percentage of carbon of the components also in the seam
>material. It's a balance reaction of consuming carbon by oxidation and
>returnig this amount by decomposing CO2. Without this, the properties of
>the material would be strongly affected, e.g. iron turning brittle
>jeopardizing constructions. Therefore, there are welding gases on the
>market containing different amounts of CO2 mixed with argon. Linde AG gave
>it the brand name of CORGON. For all other metals including stainless steel
>welding a pure inert gas is used, preferably argon because of the low
>price. It is obtained in the process of air liquefying as a byproduct. That
>means, it should cost nothing at all because air is actually liquefied to
>obtain liquid oxygen and nitrogen:-)

I am very well aware of the control one has over the finished weld that can 
be had by flame adjustments when using a smith wrench. I took welding lessons 
from the fellow that used a smith wrench to plug the con-rod hole in that big 
6 mercury block, which is Mag.  Admittedly that was 55 years ago, but not 
much has changed.  If I find myself working with scrap bed rail, use a hard, 
high oxygen flame to soften the brittleness, or on mill run steel, leave a 
bit of a feather on the flame to add carbon to the puddle.  Tools of the 
trade so to speak.

And I'm aware that the argon should be a throwaway, and what they don't sell 
probably is vented, but it seems outrageous to me that a little bottle, the 
same size your grandmother might carry over her shoulder with o2 in it for 
half an afternoons shopping or a league bowling session, should cost me $125.  
That is purely a case of what the traffic will bear pricing.  Of course these 
same folks are also charging about 90$ for a T2 sized bottle of dry nitrogen, 
something broadcasters use to keep the transmission lines pressurized to 
about 2 psi so any leaks won't suck in water when it rains as water=a line 
burnout & a few days off the air while you get a crew in to pull the lines 
off the tower, clean up the mess that burnt teflon leaves behind, and replace 
the burnt teflon.  I got tired of that and we did it ourselves the last time, 
finding about a pint of water sitting in an elbow at the tower top that a 
previous crew hadn't cleaned out after leaving it open overnight while it 
rained about 2" in the night.  Job security I guess.  We used an old gravely 
tractor/lawn mower for the lifter, and had 1k feet of 1/8" aircraft cable 
rigged over an 8" pully at the tower top to do the line lifting/lowering, 2, 
20' pieces at a time.  I might add that was a decade back, no repeats since.

That all boils down to "if you want the job done right, do it yourself".  And 
the tower company that did that to us has never gotten another dime from us, 
with the reason being carefully explained in 1 and 2 syllable words every 
time their sales force calls us looking to get a painting job or whatever. 

>2.) Thermite is a mixture or aluminium powder and iron oxides. When
>kindled, It develops temperatures above 3000 degrees C (5400 F) by burning
>(oxidizing) the Alu and in turn reducing the iron oxides to metallic iron
>with sufficient surplus energy to melt this iron at the instant and even
>melt the surrounding substances such as railway tracks. However, the
>thermite mix can't be started with a simple match, so a small strip of
>magnesium sheet is used as an iginiter. Alu is so reactive and, at the same
>time, safe, that today, it's the main component of rock blasting.

>3.) CO2 is a common fire extinguishing agent especially for strange and
>rare combustibles. It can't give off oxygen at the temperatures considered.
>It is, however, dangerous for alll personell around and, at least
>hereabouts, there must be a alarm time before the CO2 cylinders are fired.
>This delay might be detrimetal to the success of fire extinguishing. Some
>substances like thermite can't be extinguished because they carry their
>oxygen inside.

>4.) I don't think there is much use in applying mist to machine tools.
>There is way too little effect compared with flooding. Modern lathes and
>mills are capsuled and coolant is directed with high pressure from as many
>of 10 to 20 nozzles from all directions onto the tools. This makes it
>possible to mill stainless steel with, say, 15.000 rpm or Alu with up to
>100.000. I bought a CNC mill some years ago and all the elder statesmen in
>the shop shook their heads when they first saw what happened. Point is: the
>machine adjusts its speed automatically to tool diameter and material to be
>processed, and all the workers, with their lifetime experience, believed
>that the machine must be in error and the tools won't make it longer than
>an hour.

And you

Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Saturday 21 November 2009, Jeshua Lacock wrote:
>On Nov 21, 2009, at 4:40 AM, Gene Heskett wrote:
 s/infinity/affinity :)
>>>
>>> Doh! So much for trying to sound intelligent!
>>
>> Or ENOTENOUGHCAFFIENE, it is quite early here and the pot hasn't
>> been started
>> yet. Its purely accidental that I caught that this time of the
>> morning.
>> Diabetic, up to pee, and I don't care how old you are, its an
>> unwritten rule
>> that if you want to keep your geek credentials you have to check
>> your email
>> before going back to bed. ;-)
>
>Ahahahaah!
>
>>> :P
>>> :
> Note that titanium dioxide takes a great deal more energy to
> sustain
> an exothermic reaction compared to iron oxide, so the use of a
> catalyst is required.

 Interesting Jeshua, and the catalyst used was?
>>>
>>> Thanks Gene!
>>>
>>> I have used both potassium perchlorate (KClO4) and calcium sulphate
>>> (eg drywall, plaster of paris or gypsum). Drywall is much more
>>> readily
>>> available and safer to handle (KClO4 is a carcinogen).
>>
>> So is some chinese drywall ;)
>
>You're funny Gene!
>
>>> It is a really interesting reaction - it is like Thermite in slow
>>> motion. Here is what the alumina (slag) looked like about 20 minutes
>>> after starting the titanium reaction:
>>>
>>> 
>>
>> And it took 20 minutes to reach that state?  Wow!
>
>Exactly!
>
>> And I assume the titanium
>> was suitably 'cast' once the reaction was used up & things cooled.
>
>Yes, that was actually the end of the reaction so it had slowed down
>quite a bit (but it was still going) than the actual burning stage.
>When a titanium reaction is going, you get white sparks flying - a lot
>like sparklers.
>
>Note that you also add fluorite to make the titanium flow better. Here
>are percents to use by weight:
>
>Titanium dioxide 30.0%
>Drywall 25.5%
>Aluminium powder 27.0%
>Ground fluorite 17.5%
>
>> What does
>> one use for a casting mold/crucible material at those sorts of temps?
>
>Graphite and water cooled copper molds work great. Copper molds are
>pretty easy to cast using lost foam or machined. Graphite is easy to
>machine (messy though!).

I haven't tried either of those.  Wood, alu, hdpe, brass & assorted 
indeterminate grades of steel from the metals salvage people.  Some of that 
old coal mine shafting plays hell with carbide tools though. The sliding fin 
motor couplings I use on the mill were made from it, as was the steel nut 
holder in the heart of the Z drive, and its cost me about $100 in broken 
inserts and 1/4" mills to make them.  I still have a few chunks of that 
tossed in the corner.  Its like its case hardened, all the way through.  A 
fresh Valenite insert, if not cutting .006" deep & .004" per turn, something 
my little 7x12 lathe doesn't have the spindle power to do at diameters over 
3/4", will just slide off it, so you pull the tool and take a look with a 
high powered glass, and its not chipped, its smoothly worn as if that steel 
was diamond coated.  So you tune it up with a diamond wheel and try again.  I 
used up a whole box of those inserts just on those 4 couplings.  Now I get my 
steel from the cold rolled bin at TSC, much easier stuff to work, but often 
not big enough as 1" rod is their largest.

>My first attempt was in olivine sand, and I had about 1/2 inch layer
>of black quartz fused around the casting!

I'll bet that was NOT fun to remove without damaging the casting too much. :(

In graphite I'd think the cooling would be pretty slow, but the finish should 
show the machining marks in the graphite I'd think.  With thought & carefull 
design, that mold should be re-usable several times too.

>Best,
>
An interesting conversation Jeshua, thanks.

>Jeshua Lacock
>Founder/Programmer
>3DTOPO Incorporated
>
>Phone: 208.462.4171

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 soap, ballot, jury, and ammo. Please use in that order."
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Re: [Emc-users] How Exactly does a Mister Work

[Rainer Schmidt]

I don't want to rain onto this parade, but what has this to do with EMC?
Please visit a forum oriented towards the core of this discussion,
specially considering that the majority of information posted in this
thread is flawed to say the least. Actually it makes my brain hurt.
This might sound arrogant, but is not meant that way.
Happy EMC'ing
Rainer

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Re: [Emc-users] How Exactly does a Mister Work

[Mark Cason]

On 11/21/2009 04:03 AM, Erik Christiansen wrote:
> On Fri, Nov 20, 2009 at 05:10:18PM +, Leslie Newell wrote:
>> Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it will
>> strip oxygen out of the CO2. That is also the reason why you should
>> never use a CO2 fire extinguisher on magnesium fires.
>
> However, it is extensively used in fire extinguishers precisely because
> it does not give up its oxygen even at hundreds of degrees C. I'm not
> sure of how many thousand degrees magnesium burns at, but it is more
> than 1500, because thermite (magnesium and iron oxide) combustion melts
> the iron produced by the reduction of the iron oxide.
>
> If the cutting operation is hot enough to dissociate CO2, then there'd
> better not be any oil about, especially as mist, unless Gene has his
> detonation-deadening earmuffs on tight. ;-)
>
> Wikipedia appears to be self-contradicting:
>
> "Carbon dioxide also finds use as an atmosphere for welding, although in
> the welding arc, it reacts to oxidize most metals."
>
> The closest I've come in a quick search is:
>
> http://www.hitech-inst.co.uk/pdfs/technical/heat_treatment.pdf which
> says:
>
> "The graph shows cell output against carbon monoxide/carbon dioxide
> ratio. this is plotted at 634°C and 812°C, ..."
>
> i.e. CO2 is still so completely undissociated at 812°C that ratios can
> be measured for metallurgical analysis. So the aluminium would melt
> long before the CO2 dissociated to any measurable degree.
>
> Erik

   This may true in theory, but not in practice.  Welding Aluminum with 
a CO2 or AR/CO2 mix will give bad results.  Guess how I found that out.:)



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Re: [Emc-users] How Exactly does a Mister Work

[Andy Pugh]

2009/11/21 Jack :

> Knowing how much would be part of the art of using this method.  I would think
> that you would always want just a little more so as to overfill it to a bit 
> more
> than the sprue will hold.

but not so much that it overflows onto the kitchen worktop.

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Re: [Emc-users] How Exactly does a Mister Work

[Jack]

>>
>>One of the beauties of casting with aluminothermic reactions is there
>>is no crucible used (or furnace)!
>>
>>You plug the sprue (entry) going to the mold cavity with a thin sheet
>>of metal (that is melted once the molten metal reaches it), and put
>>the chemical on top. The slag melts to the top and the metal drains
>>out into the mold
>
> Kewl!  I take it the magic is in knowing how much you need to fill the mold.
> :)

Knowing how much would be part of the art of using this method.  I would think
that you would always want just a little more so as to overfill it to a bit more
than the sprue will hold.

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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Saturday 21 November 2009, Jeshua Lacock wrote:
>On Nov 21, 2009, at 4:40 AM, Gene Heskett wrote:
>> And it took 20 minutes to reach that state?  Wow!  And I assume the
>> titanium
>> was suitably 'cast' once the reaction was used up & things cooled.
>> What does
>> one use for a casting mold/crucible material at those sorts of temps?
>
>P.S.
>
>One of the beauties of casting with aluminothermic reactions is there
>is no crucible used (or furnace)!
>
>You plug the sprue (entry) going to the mold cavity with a thin sheet
>of metal (that is melted once the molten metal reaches it), and put
>the chemical on top. The slag melts to the top and the metal drains
>out into the mold

Kewl!  I take it the magic is in knowing how much you need to fill the mold. 
:)

Thanks Jeshua.

>Best,
>
>Jeshua Lacock
>Founder/Programmer
>3DTOPO Incorporated
>
>Phone: 208.462.4171

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 soap, ballot, jury, and ammo. Please use in that order."
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Worth seeing?  Yes, but not worth going to see.

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Re: [Emc-users] How Exactly does a Mister Work

[Erik Christiansen]

On Sat, Nov 21, 2009 at 05:00:13AM -0700, Jeshua Lacock wrote:
> One of the beauties of casting with aluminothermic reactions is there  
> is no crucible used (or furnace)!

Would another beauty be that TiO2 is cheap enough to put in paint and
plastic, but Ti metal costs a mozza? I can't quite get over that you're
casually extracting the metal from a most recalcitrant oxide, while
current industrial processes to do the same are horribly expensive.

> You plug the sprue (entry) going to the mold cavity with a thin sheet  
> of metal (that is melted once the molten metal reaches it), and put  
> the chemical on top. The slag melts to the top and the metal drains  
> out into the mold

Does it remain molten long enough to flow into a mould, if the reaction
takes 20 minutes? Or was that just because you were melting a barrel of
the stuff? Even so, that wouldn't give a sound casting, just a pig for
remelting?

Erik

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Re: [Emc-users] How Exactly does a Mister Work

[Peter blodow]

Hello Gene,
I take  this discussion about welding and combustibles as an oopportunity 
to clarify a few things.
1. CO2 is used in arc welding only for old soft iron (mild steel) in order 
to maintain the percentage of carbon of the components also in the seam 
material. It's a balance reaction of consuming carbon by oxidation and 
returnig this amount by decomposing CO2. Without this, the properties of 
the material would be strongly affected, e.g. iron turning brittle 
jeopardizing constructions. Therefore, there are welding gases on the 
market containing different amounts of CO2 mixed with argon. Linde AG gave 
it the brand name of CORGON. For all other metals including stainless steel 
welding a pure inert gas is used, preferably argon because of the low 
price. It is obtained in the process of air liquefying as a byproduct. That 
means, it should cost nothing at all because air is actually liquefied to 
obtain liquid oxygen and nitrogen:-)
2.) Thermite is a mixture or aluminium powder and iron oxides. When 
kindled, It develops temperatures above 3000 degrees C (5400 F) by burning 
(oxidizing) the Alu and in turn reducing the iron oxides to metallic iron 
with sufficient surplus energy to melt this iron at the instant and even 
melt the surrounding substances such as railway tracks. However, the 
thermite mix can't be started with a simple match, so a small strip of 
magnesium sheet is used as an iginiter. Alu is so reactive and, at the same 
time, safe, that today, it's the main component of rock blasting.
3.) CO2 is a common fire extinguishing agent especially for strange and 
rare combustibles. It can't give off oxygen at the temperatures considered. 
It is, however, dangerous for alll personell around and, at least 
hereabouts, there must be a alarm time before the CO2 cylinders are fired. 
This delay might be detrimetal to the success of fire extinguishing. Some 
substances like thermite can't be extinguished because they carry their 
oxygen inside.
4.) I don't think there is much use in applying mist to machine tools. 
There is way too little effect compared with flooding. Modern lathes and 
mills are capsuled and coolant is directed with high pressure from as many 
of 10 to 20 nozzles from all directions onto the tools. This makes it 
possible to mill stainless steel with, say, 15.000 rpm or Alu with up to 
100.000. I bought a CNC mill some years ago and all the elder statesmen in 
the shop shook their heads when they first saw what happened. Point is: the 
machine adjusts its speed automatically to tool diameter and material to be 
processed, and all the workers, with their lifetime experience, believed 
that the machine must be in error and the tools won't make it longer than 
an hour.
5.) I can't see what all this has to do with electronic machine control...:-)))

Greeting from Germany

Peter Blodow
Dipl.-Phys.

(and don't call me wise guy, I used to be the head of a rather special 
scientific work shop for more than 30 years)


At 12:04 21.11.2009, you wrote:
>On Saturday 21 November 2009, Erik Christiansen wrote:
> >On Fri, Nov 20, 2009 at 05:10:18PM +, Leslie Newell wrote:
> >> Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it will
> >> strip oxygen out of the CO2. That is also the reason why you should
> >> never use a CO2 fire extinguisher on magnesium fires.
> >
> >However, it is extensively used in fire extinguishers precisely because
> >it does not give up its oxygen even at hundreds of degrees C. I'm not
> >sure of how many thousand degrees magnesium burns at, but it is more
> >than 1500, because thermite (magnesium and iron oxide) combustion melts
> >the iron produced by the reduction of the iron oxide.
> >
> >If the cutting operation is hot enough to dissociate CO2, then there'd
> >better not be any oil about, especially as mist, unless Gene has his
> >detonation-deadening earmuffs on tight. ;-)
> >
> >Wikipedia appears to be self-contradicting:
> >
> >"Carbon dioxide also finds use as an atmosphere for welding, although in
> >the welding arc, it reacts to oxidize most metals."
> >
> >The closest I've come in a quick search is:
> >
> >http://www.hitech-inst.co.uk/pdfs/technical/heat_treatment.pdf which
> >says:
> >
> >"The graph shows cell output against carbon monoxide/carbon dioxide
> >ratio. this is plotted at 634°C and 812°C, ..."
> >
> >i.e. CO2 is still so completely undissociated at 812°C that ratios can
> >be measured for metallurgical analysis. So the aluminium would melt
> >long before the CO2 dissociated to any measurable degree.
> >
> >Erik
>
>True, but those temps are not the temps of the arc, by about a factor of 10.
>My single sample that was badly decomposed, blackened and porous, I blamed on
>the 75% argon/25% co2 in the shielding gas I had.  I theorized that the o2
>was used up by the alu's reaction, leaving the c to blacken and contaminate
>the alu puddle.  I resolved to get some purer argon, but locally it is not
>available.  The mixed b

Re: [Emc-users] How Exactly does a Mister Work

[Jeshua Lacock]

On Nov 21, 2009, at 4:40 AM, Gene Heskett wrote:

>>> s/infinity/affinity :)
>>
>> Doh! So much for trying to sound intelligent!
>
> Or ENOTENOUGHCAFFIENE, it is quite early here and the pot hasn't  
> been started
> yet. Its purely accidental that I caught that this time of the  
> morning.
> Diabetic, up to pee, and I don't care how old you are, its an  
> unwritten rule
> that if you want to keep your geek credentials you have to check  
> your email
> before going back to bed. ;-)

Ahahahaah!

>> :P
>> :
 Note that titanium dioxide takes a great deal more energy to  
 sustain
 an exothermic reaction compared to iron oxide, so the use of a
 catalyst is required.
>>>
>>> Interesting Jeshua, and the catalyst used was?
>>
>> Thanks Gene!
>>
>> I have used both potassium perchlorate (KClO4) and calcium sulphate
>> (eg drywall, plaster of paris or gypsum). Drywall is much more  
>> readily
>> available and safer to handle (KClO4 is a carcinogen).
>
> So is some chinese drywall ;)

You're funny Gene!

>> It is a really interesting reaction - it is like Thermite in slow
>> motion. Here is what the alumina (slag) looked like about 20 minutes
>> after starting the titanium reaction:
>>
>> 
>
> And it took 20 minutes to reach that state?  Wow!

Exactly!

> And I assume the titanium
> was suitably 'cast' once the reaction was used up & things cooled.

Yes, that was actually the end of the reaction so it had slowed down  
quite a bit (but it was still going) than the actual burning stage.  
When a titanium reaction is going, you get white sparks flying - a lot  
like sparklers.

Note that you also add fluorite to make the titanium flow better. Here  
are percents to use by weight:

Titanium dioxide 30.0%
Drywall 25.5%
Aluminium powder 27.0%
Ground fluorite 17.5%

> What does
> one use for a casting mold/crucible material at those sorts of temps?


Graphite and water cooled copper molds work great. Copper molds are  
pretty easy to cast using lost foam or machined. Graphite is easy to  
machine (messy though!).

My first attempt was in olivine sand, and I had about 1/2 inch layer  
of black quartz fused around the casting!


Best,

Jeshua Lacock
Founder/Programmer
3DTOPO Incorporated

Phone: 208.462.4171


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Re: [Emc-users] How Exactly does a Mister Work

[Jeshua Lacock]

On Nov 21, 2009, at 4:40 AM, Gene Heskett wrote:

> And it took 20 minutes to reach that state?  Wow!  And I assume the  
> titanium
> was suitably 'cast' once the reaction was used up & things cooled.   
> What does
> one use for a casting mold/crucible material at those sorts of temps?


P.S.

One of the beauties of casting with aluminothermic reactions is there  
is no crucible used (or furnace)!

You plug the sprue (entry) going to the mold cavity with a thin sheet  
of metal (that is melted once the molten metal reaches it), and put  
the chemical on top. The slag melts to the top and the metal drains  
out into the mold


Best,

Jeshua Lacock
Founder/Programmer
3DTOPO Incorporated

Phone: 208.462.4171


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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Saturday 21 November 2009, Jeshua Lacock wrote:
>On Nov 21, 2009, at 4:11 AM, Gene Heskett wrote:
>>> Generically speaking, Thermite is referred to an "aluminothermic"
>>> reaction. It is aluminum's high infinity for oxygen that strips the
>>> oxygen away from the iron oxide.
>>
>> s/infinity/affinity :)
>
>Doh! So much for trying to sound intelligent!

Or ENOTENOUGHCAFFIENE, it is quite early here and the pot hasn't been started 
yet. Its purely accidental that I caught that this time of the morning.  
Diabetic, up to pee, and I don't care how old you are, its an unwritten rule 
that if you want to keep your geek credentials you have to check your email 
before going back to bed. ;-)

>:P
>:
>>> Note that titanium dioxide takes a great deal more energy to sustain
>>> an exothermic reaction compared to iron oxide, so the use of a
>>> catalyst is required.
>>
>> Interesting Jeshua, and the catalyst used was?
>
>Thanks Gene!
>
>I have used both potassium perchlorate (KClO4) and calcium sulphate
>(eg drywall, plaster of paris or gypsum). Drywall is much more readily
>available and safer to handle (KClO4 is a carcinogen).

So is some chinese drywall ;)

>It is a really interesting reaction - it is like Thermite in slow
>motion. Here is what the alumina (slag) looked like about 20 minutes
>after starting the titanium reaction:
>
>

And it took 20 minutes to reach that state?  Wow!  And I assume the titanium 
was suitably 'cast' once the reaction was used up & things cooled.  What does 
one use for a casting mold/crucible material at those sorts of temps?

>Best,
>
>Jeshua Lacock
>Founder/Programmer
>3DTOPO Incorporated
>
>Phone: 208.462.4171
>
>
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Re: [Emc-users] How Exactly does a Mister Work

[Erik Christiansen]

On Sat, Nov 21, 2009 at 03:25:01AM -0700, Jeshua Lacock wrote:
> 
> On Nov 21, 2009, at 3:03 AM, Erik Christiansen wrote:
> 
> > On Fri, Nov 20, 2009 at 05:10:18PM +, Leslie Newell wrote:
> >> Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it  
> >> will
> >> strip oxygen out of the CO2. That is also the reason why you should
> >> never use a CO2 fire extinguisher on magnesium fires.
> >
> > However, it is extensively used in fire extinguishers precisely  
> > because
> > it does not give up its oxygen even at hundreds of degrees C. I'm not
> > sure of how many thousand degrees magnesium burns at, but it is more
> > than 1500, because thermite (magnesium and iron oxide) combustion  
> > melts
> > the iron produced by the reduction of the iron oxide.
> 
> 
> Correction: "Thermite" is actually a name brand which is a mixture of  
> aluminum and iron oxide.

You are so right. A bit of magnesium ribbon can be used to start the
reaction. Please forgive the typo.

> Generically speaking, Thermite is referred to an "aluminothermic"  
> reaction. It is aluminum's high infinity for oxygen that strips the  
> oxygen away from the iron oxide.
> 
> I am sure you could also burn (exothermic reaction) magnesium with  
> iron oxide, however, that would result in such rapid combustion it  
> would cause an explosion.

Your correction of the record is important in that light, and I don't
doubt the conclusion. (I've seen photographs of the severely burned arms
of a handyman who used a narrow belt sander on rusty iron after his son
had used it on aluminium/magnesium alloy. There was an instantaneous
incandescent flash, and the skin hung somewhat loosely from his arms.)

> I have actually casted iron, steel, nickel, chromium, ferrotitanium,  
> and even titanium using aluminothermic reactions (you use the oxide  
> for the metal that you want - like titanium dioxide for titanium). It  
> is fascinating stuff!

I've only seen it used to weld railway line lengths together. I like to
stand well back. The other uses are very intriguing.

Erik

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Re: [Emc-users] How Exactly does a Mister Work

[Jeshua Lacock]

On Nov 21, 2009, at 4:11 AM, Gene Heskett wrote:

>> Generically speaking, Thermite is referred to an "aluminothermic"
>> reaction. It is aluminum's high infinity for oxygen that strips the
>> oxygen away from the iron oxide.
>
> s/infinity/affinity :)

Doh! So much for trying to sound intelligent!

:P

>> Note that titanium dioxide takes a great deal more energy to sustain
>> an exothermic reaction compared to iron oxide, so the use of a
>> catalyst is required.
>
> Interesting Jeshua, and the catalyst used was?


Thanks Gene!

I have used both potassium perchlorate (KClO4) and calcium sulphate  
(eg drywall, plaster of paris or gypsum). Drywall is much more readily  
available and safer to handle (KClO4 is a carcinogen).

It is a really interesting reaction - it is like Thermite in slow  
motion. Here is what the alumina (slag) looked like about 20 minutes  
after starting the titanium reaction:




Best,

Jeshua Lacock
Founder/Programmer
3DTOPO Incorporated

Phone: 208.462.4171


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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Saturday 21 November 2009, Jeshua Lacock wrote:
>On Nov 21, 2009, at 3:03 AM, Erik Christiansen wrote:
>> On Fri, Nov 20, 2009 at 05:10:18PM +, Leslie Newell wrote:
>>> Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it
>>> will
>>> strip oxygen out of the CO2. That is also the reason why you should
>>> never use a CO2 fire extinguisher on magnesium fires.
>>
>> However, it is extensively used in fire extinguishers precisely
>> because
>> it does not give up its oxygen even at hundreds of degrees C. I'm not
>> sure of how many thousand degrees magnesium burns at, but it is more
>> than 1500, because thermite (magnesium and iron oxide) combustion
>> melts
>> the iron produced by the reduction of the iron oxide.
>
>Correction: "Thermite" is actually a name brand which is a mixture of
>aluminum and iron oxide.
>
>Generically speaking, Thermite is referred to an "aluminothermic"
>reaction. It is aluminum's high infinity for oxygen that strips the
>oxygen away from the iron oxide.

s/infinity/affinity :)

>I am sure you could also burn (exothermic reaction) magnesium with
>iron oxide, however, that would result in such rapid combustion it
>would cause an explosion.
>
>I have actually casted iron, steel, nickel, chromium, ferrotitanium,
>and even titanium using aluminothermic reactions (you use the oxide
>for the metal that you want - like titanium dioxide for titanium). It
>is fascinating stuff!
>
>Note that titanium dioxide takes a great deal more energy to sustain
>an exothermic reaction compared to iron oxide, so the use of a
>catalyst is required.

Interesting Jeshua, and the catalyst used was?

>
>Cheers,
>
>Jeshua Lacock
>Founder/Programmer
>3DTOPO Incorporated
>
>Phone: 208.462.4171

-- 
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 soap, ballot, jury, and ammo. Please use in that order."
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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Saturday 21 November 2009, Erik Christiansen wrote:
>On Fri, Nov 20, 2009 at 05:10:18PM +, Leslie Newell wrote:
>> Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it will
>> strip oxygen out of the CO2. That is also the reason why you should
>> never use a CO2 fire extinguisher on magnesium fires.
>
>However, it is extensively used in fire extinguishers precisely because
>it does not give up its oxygen even at hundreds of degrees C. I'm not
>sure of how many thousand degrees magnesium burns at, but it is more
>than 1500, because thermite (magnesium and iron oxide) combustion melts
>the iron produced by the reduction of the iron oxide.
>
>If the cutting operation is hot enough to dissociate CO2, then there'd
>better not be any oil about, especially as mist, unless Gene has his
>detonation-deadening earmuffs on tight. ;-)
>
>Wikipedia appears to be self-contradicting:
>
>"Carbon dioxide also finds use as an atmosphere for welding, although in
>the welding arc, it reacts to oxidize most metals."
>
>The closest I've come in a quick search is:
>
>http://www.hitech-inst.co.uk/pdfs/technical/heat_treatment.pdf which
>says:
>
>"The graph shows cell output against carbon monoxide/carbon dioxide
>ratio. this is plotted at 634°C and 812°C, ..."
>
>i.e. CO2 is still so completely undissociated at 812°C that ratios can
>be measured for metallurgical analysis. So the aluminium would melt
>long before the CO2 dissociated to any measurable degree.
>
>Erik

True, but those temps are not the temps of the arc, by about a factor of 10.  
My single sample that was badly decomposed, blackened and porous, I blamed on 
the 75% argon/25% co2 in the shielding gas I had.  I theorized that the o2 
was used up by the alu's reaction, leaving the c to blacken and contaminate 
the alu puddle.  I resolved to get some purer argon, but locally it is not 
available.  The mixed bottle, about 4" in diameter and maybe 18" tall, is 
$125 at TSC.  Samson's in Clarksburg are similarly priced.  And that makes it 
a very expensive toy for me.  One that I only drag out when there is no other 
choice.

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Re: [Emc-users] How Exactly does a Mister Work

[Michael Buesch]

On Saturday 21 November 2009 11:03:23 Erik Christiansen wrote:
> If the cutting operation is hot enough to dissociate CO2, then there'd
> better not be any oil about, especially as mist, unless Gene has his
> detonation-deadening earmuffs on tight. ;-)

If the heat produced by the cutting operation is able to dissociate CO2, you
have a freaking _serious_ problem anyway.
CO2 extinguishers are successfully used in Mg/Al cutting environments that use
oilmist. There is _no_ problem with that in practice. Yeah, you can say: But
if in theory the Mg fire is able to dissociate the O from the CO2, you're
screwed... . But in practice it doesn't happen. At least not that much that
it matters. Hell, the Mg-oil mist is burning. We don't care if a few CO2 
molecules
are broken up by that. A CO2-filled machining room is _way_ better in that
situation than an air-filled room (which has a _lot_ more free oxygen in it).
You could say that an inert-gas filled room would be even better, but it simply
does not matter that much in practice.

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Re: [Emc-users] How Exactly does a Mister Work

[Jeshua Lacock]

On Nov 21, 2009, at 3:03 AM, Erik Christiansen wrote:

> On Fri, Nov 20, 2009 at 05:10:18PM +, Leslie Newell wrote:
>> Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it  
>> will
>> strip oxygen out of the CO2. That is also the reason why you should
>> never use a CO2 fire extinguisher on magnesium fires.
>
> However, it is extensively used in fire extinguishers precisely  
> because
> it does not give up its oxygen even at hundreds of degrees C. I'm not
> sure of how many thousand degrees magnesium burns at, but it is more
> than 1500, because thermite (magnesium and iron oxide) combustion  
> melts
> the iron produced by the reduction of the iron oxide.


Correction: "Thermite" is actually a name brand which is a mixture of  
aluminum and iron oxide.

Generically speaking, Thermite is referred to an "aluminothermic"  
reaction. It is aluminum's high infinity for oxygen that strips the  
oxygen away from the iron oxide.

I am sure you could also burn (exothermic reaction) magnesium with  
iron oxide, however, that would result in such rapid combustion it  
would cause an explosion.

I have actually casted iron, steel, nickel, chromium, ferrotitanium,  
and even titanium using aluminothermic reactions (you use the oxide  
for the metal that you want - like titanium dioxide for titanium). It  
is fascinating stuff!

Note that titanium dioxide takes a great deal more energy to sustain  
an exothermic reaction compared to iron oxide, so the use of a  
catalyst is required.


Cheers,

Jeshua Lacock
Founder/Programmer
3DTOPO Incorporated

Phone: 208.462.4171


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Re: [Emc-users] How Exactly does a Mister Work

[Erik Christiansen]

On Fri, Nov 20, 2009 at 05:10:18PM +, Leslie Newell wrote:
> Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it will 
> strip oxygen out of the CO2. That is also the reason why you should 
> never use a CO2 fire extinguisher on magnesium fires.

However, it is extensively used in fire extinguishers precisely because
it does not give up its oxygen even at hundreds of degrees C. I'm not
sure of how many thousand degrees magnesium burns at, but it is more
than 1500, because thermite (magnesium and iron oxide) combustion melts
the iron produced by the reduction of the iron oxide.

If the cutting operation is hot enough to dissociate CO2, then there'd
better not be any oil about, especially as mist, unless Gene has his
detonation-deadening earmuffs on tight. ;-)

Wikipedia appears to be self-contradicting:

"Carbon dioxide also finds use as an atmosphere for welding, although in
the welding arc, it reacts to oxidize most metals."

The closest I've come in a quick search is:

http://www.hitech-inst.co.uk/pdfs/technical/heat_treatment.pdf which
says:

"The graph shows cell output against carbon monoxide/carbon dioxide
ratio. this is plotted at 634°C and 812°C, ..."

i.e. CO2 is still so completely undissociated at 812°C that ratios can
be measured for metallurgical analysis. So the aluminium would melt
long before the CO2 dissociated to any measurable degree. 

Erik

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Re: [Emc-users] How Exactly does a Mister Work

[Jack]

I agree that welding is part of the complete process of manufacturing
with metals,
and understanding the effects of the chemistry (whether or not you
understand the
chemistry itself) is needed to turn out the 'best' products we can.

Oh, on the prior post, my friend does MIG almost exclusively, with the
AR and AR/CO2 mix.

><> ... Jack

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Re: [Emc-users] How Exactly does a Mister Work

[Mark Cason]

On 11/20/2009 05:27 PM, Jack wrote:
> A friend does argon for Aluminum, and a argon/co2 mix for most other.  Only
> because
> argon is a pretty inert gas.  But it is significantly more costly than CO2
> or the mix.
>> <>  ... Jack

   I agree with the cost issue, my 80 CuFt argon bottles cost me around 
$40.00 each to refill the last time I took them in, and they last me 
between 8, and 12 hrs of use each.

   I'm currently renting a 25/75-C02/AR mix bottle, which I rarely use, 
but when it's empty, I will be buying a couple of CO2 bottles, and 
machining a custom mixer valve, to interface with my argon bottles. 
That way, I can precisely meter the percentage of mix being used, and, 
my overhead will be lower, as I won't need to rent/buy different ratio 
mix bottles.

   The type of gas used is determined by the type of material, it's 
thickness, the type of filler wire being used, and the welding process.

   GTAW (TIG) uses argon only, heliarc uses helium, GMAW (MIG) uses 
argon, AR/CO2, or CO2.

   FCAW (flux-cored MIG), and  SMAW (Stick) uses no external shielding 
gas, because the flux creates it's own.

   You don't use just any old gas available, strong welds are the 
cornerstone of good welding practices.  Your welding wire will state 
which type of shielding gas is preferred, but the entire welding 
practice needs to be looked at as a whole.

   Helium is mainly used for heliarc welding, and gives very good welds 
that stand proud of the surface, and gives good penetration.  It is 
rarely used these days, mainly because of the exorbitant costs.

   Argon causes a weld bead to flow out, and can stand slightly proud of 
the surface, lay flat, or even depressed slightly below the surface, 
with very good penetration.  It is the only shielding gas used for TIG, 
but is frequently used for MIG.

   CO2 causes a weld bead to stand proud, giving a good fill, and decent 
penetration, but suffers from porosity problems.  It is rarely used, but 
works ok on mild steel over 3/8".

   AR/CO2 mix is a good compromise, as it allows a good buildup of a 
weld, gives good penetration, and reduces the amount of porosity in the 
weld.  It is the most common shielding gas for MIG on mild steel over 1/4".

   Flux-cored MIG is the most popular type of welding these days, but 
TIG is the most versatile.  You can pretty much TIG weld any type of 
metal, including copper, brass, titanium, etc...  Even highly reactive 
metals like magnesium can be TIG'd with proper shielding.  TIG is very 
much similar to oxy-welding, only with a arc, instead of a flame, and it 
doesn't suffer from warpage any where near as bad as oxy-welding.

   There are several other welding procedures, and I've probably taken 
this too far OT, but I consider welding to be a essential part of 
machining, because I generally machine sub-assemblies, and then weld 
them into finished parts.


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Re: [Emc-users] How Exactly does a Mister Work

[Jack]

A friend does argon for Aluminum, and a argon/co2 mix for most other.  Only
because
argon is a pretty inert gas.  But it is significantly more costly than CO2
or the mix.
><> ... Jack


On Fri, Nov 20, 2009 at 4:06 PM, Andy Pugh wrote:

> 2009/11/20 Mark Cason :
> >
> >   In my experience, the only gas that should be used on aluminum is
> > argon.
>
> Don't misunderstand me, I am not advocating CO2 for mig welding
> aluminium. It worked poorly, but was all I had to hand at the time.
>
> --
> atp
>
>
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Re: [Emc-users] How Exactly does a Mister Work

[Andy Pugh]

2009/11/20 Mark Cason :
>
>   In my experience, the only gas that should be used on aluminum is
> argon.

Don't misunderstand me, I am not advocating CO2 for mig welding
aluminium. It worked poorly, but was all I had to hand at the time.

-- 
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Re: [Emc-users] How Exactly does a Mister Work

[Mark Cason]

On 11/20/2009 02:14 PM, Gene Heskett wrote:
> On Friday 20 November 2009, Andy Pugh wrote:
>> 2009/11/20 Leslie Newell:
>>> Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it will
>>> strip oxygen out of the CO2.
>>
>> The electronegativity of Al is 1.6, and that of iron is 1.8 (cf 2.5 for
>> Oxygen) CO2 works perfectly well as a shielding gas for MIG welding of
>> steel at molten temperatures, I would not anticipate it reacting strongly
>> with Al at machining temperatures.
>>
>> I have MIG welded aluminium with CO2 shielding gas, and it worked
>> (whilst being demonstrably non-ideal)
>
> My one pass seemed to have left a blackened, (using the 25% co2 supplied
> commonly in the teeny bottles for outrageous prices)&  rather porous looking
> weld that wasn't any stronger than it looked..  But I'm not a mig expert,
> don't even play one on tv. :)  All I have is a 125 amp farmhand with a mig
> kit added.
>

   In my experience, the only gas that should be used on aluminum is 
argon.  I use argon for all of my welding needs,  I have one bottle for 
my TIG/Stick welder, and another for my MIG welder.

   If you are going to go through all of the trouble of using a 
shielding gas, a good non-reactive gas would be better than CO2, and 
depending on where you live, argon should be easier to find than nitrogen.

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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Friday 20 November 2009, Michael Buesch wrote:
>On Friday 20 November 2009 18:10:18 Leslie Newell wrote:
>> Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it will
>> strip oxygen out of the CO2. That is also the reason why you should
>> never use a CO2 fire extinguisher on magnesium fires.
>
>Uhm, at work we machine about 80% magnesium and 20% Aluminum. All
>machines are equipped with CO2 extinguishers. This works very well.

I hope your insurance is paid up, your widow might need it. Those chips can 
be downright explosive.  And whose the insurance company that allows that?

 I have personally seen a 6 cyl mercury outboard block welded up where a con-
rod went through it, with a smith wrench yet.  But since the block was also 
so badly warped from overheating that it couldn't be line bored for a fresh 
crank, he after he had welded it very professionally and serviceable looking, 
proceeded to warm up his weld a little more to show us frogs what happens 
when you get cocky.  Good thing he was working on the sidewalk in front of 
the store for this particular demo, cuz he had to warn off the fire dept when 
they arrived.  So it just burned with lots of smoke and a very bright flame, 
leaving a 6' section of sidewalk that had to be back filled in and a new one 
poured the next day to placate the city, Iowa City IA to be exact.  This guy 
had welding certification cards in his billfold that when unfolded was about 
4 feet long.  Good teacher, and to this day my favorite stick em together 
tool is a smith wrench.  Nothing I've put together with it has ever come 
apart again unless I took it apart, usually with the same wrench but a 
cutting torch screwed in.

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"There are four boxes to be used in defense of liberty:
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I can't decide which WRONG TURN to make first!!  I wonder if BOB
GUCCIONE has these problems!

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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Friday 20 November 2009, Andy Pugh wrote:
>2009/11/20 Leslie Newell :
>> Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it will
>> strip oxygen out of the CO2.
>
>The electronegativity of Al is 1.6, and that of iron is 1.8 (cf 2.5 for
> Oxygen) CO2 works perfectly well as a shielding gas for MIG welding of
> steel at molten temperatures, I would not anticipate it reacting strongly
> with Al at machining temperatures.
>
>I have MIG welded aluminium with CO2 shielding gas, and it worked
>(whilst being demonstrably non-ideal)

My one pass seemed to have left a blackened, (using the 25% co2 supplied 
commonly in the teeny bottles for outrageous prices) & rather porous looking 
weld that wasn't any stronger than it looked..  But I'm not a mig expert, 
don't even play one on tv. :)  All I have is a 125 amp farmhand with a mig 
kit added.

-- 
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"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
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Why don't you ever enter any CONTESTS, Marvin??  Don't you know your
own ZIPCODE?

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Re: [Emc-users] How Exactly does a Mister Work

[Andy Pugh]

2009/11/20 Michael Buesch :
>
> Uhm, at work we machine about 80% magnesium and 20% Aluminum. All
> machines are equipped with CO2 extinguishers. This works very well.

Interesting demo here:
http://www.ilpi.com/genchem/demo/co2mg/index.html

However, there is a requirement to have the Mg actually burning before
there is any reaction, which is why I think that CO2 probably doesn't
react with aluminium at room temperature.

-- 
atp

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Re: [Emc-users] How Exactly does a Mister Work

[Michael Buesch]

On Friday 20 November 2009 18:10:18 Leslie Newell wrote:
> Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it will 
> strip oxygen out of the CO2. That is also the reason why you should 
> never use a CO2 fire extinguisher on magnesium fires.

Uhm, at work we machine about 80% magnesium and 20% Aluminum. All
machines are equipped with CO2 extinguishers. This works very well.

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Re: [Emc-users] How Exactly does a Mister Work

[Andy Pugh]

2009/11/20 Leslie Newell :

> Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it will
> strip oxygen out of the CO2.

The electronegativity of Al is 1.6, and that of iron is 1.8 (cf 2.5 for Oxygen)
CO2 works perfectly well as a shielding gas for MIG welding of steel
at molten temperatures, I would not anticipate it reacting strongly
with Al at machining temperatures.

I have MIG welded aluminium with CO2 shielding gas, and it worked
(whilst being demonstrably non-ideal)

-- 
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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Friday 20 November 2009, John Harris wrote:
>Hm. I don't think carbide bits were around in 58, so it looks like the
>foreman was not too far off.
>
>The fast oxidization of aluminum during cutting is an interesting effect.
>
>In the early 60s, we were making small electronic modules by soldering tiny
>Fairchild ICs to printed circuit cards, using locally made hot nitrogen
>soldering. There was a wall powered gadget that extracted nitrogen from the
>air, and a bell jar that held the nitrogen at 1/2 PSI. A plastic tube fed
>the nitrogen to something that looked like a normal soldering iron, except
>that the tip was a hypodermic needle with a blunt tip. The nitrogen came
> out of the needle tip hot enough to melt (reflow) the solder at the joint,
> but while doing so flooded the area around the joint with nitrogen to
> prevent oxidation.
>
>You do not need the heat but maybe a low flow of nitrogen to the cutting
>point may stop the oxidation long enough for the next cutting edge to get
>there. Anyone have any ideas on how the gadget running from wall power that
>made the nitrogen worked?
>
>John
>
No more chemistry than I've learned would tend to make me think there was a 
chemical in there that absorbed the oxygen as the air passed by, probably was 
either replenished by the night crew, or heated to reverse the process at 
some point in the unmanned day.  Something along the lines of the dehydrators 
we use for pressurizing transmission lines at broadcast facilities.  They run 
the air thru silica gel to dry it, then reverse the valves & dump the air 
being pulled in back to atmosphere and heat the tank of gel to drive the 
water back out of it about once a day, or in the better ones, every x hours 
of accumulated running time.  As for the chemical used to pull oxygen, I 
wouldn't have a clue, but common sense says that is going to generate heat 
just as a fire would.  All I know is that one isn't going to have an air 
reduction (compress to liquid and controlled evaporization of the liquid 
compressed air) system in a wall wart supply.  Possibly in a refrigerator 
sized compressor I suppose as we presently have a portable oxygen generator 
on site for the wife's use as she has COPD.  Given the pressures involved, I 
wouldn't expect to ever see that reduced to a wall wart sized device so it 
almost has to be chemical based.

>- Original Message -
>From: "Leslie Newell" 
>To: "Enhanced Machine Controller (EMC)" 
>Sent: Friday, November 20, 2009 8:43 AM
>Subject: Re: [Emc-users] How Exactly does a Mister Work
>
>> In general flood with a water based coolant will shift more heat than a
>> mist system. Flood also usually shifts the chips better. On the down
>> side it is very messy and can actually reduce the life of carbide
>> tooling.
>>
>> Carbide tooling can take a lot of heat but it hates thermal shock. The
>> cutting edges of a milling cutter operating in flood coolant will get
>> heated rapidly while they are actually cutting then suddenly cooled as
>> they hit the coolant. This can cause cracking and chipping. Oil has a
>> much lower thermal capacity and conductivity than water so it doesn't
>> cause as much thermal shock. To a large extent you can get around the
>> problem by using high pressure flood coolant to make sure the cutter
>> does not get a chance to heat up.
>>
>> So why are mist systems still fairly rare in industry? Two main reasons
>> spring to mind. 1) flood keeps the work and machine at an even
>> temperature so you don't need to allow for thermal expansion. 2) Flood
>> has always been used. If it works, why change it?
>>
>> In my experience carbide works well with oil misters, HSS needs flood or
>> a heavy mist of water based coolant.
>>
>> Les
>>
>> John Harris wrote:
>>> Hi All,
>>> Back in the late 50s when, as a young apprentice, I was
>>> turning knobs on a milling machine as part of my education, the shop
>>> foreman replaced the flood system on the mill with a new-fangled mister.
>>> The mister feed tank was filled with the same stuff that was used for
>>> the flood system. That is water with 15(?) percent soluble oil.
>>>
>>> The foreman told me that the mist cooled the part and the tool by
>>> evaporating the water, and the oil gave some lubrication to the cutting
>>> action. Also misting greatly aided the water evaporation compared to the
>>> flood system.
>>>
>>> As the foreman is by now no longer with us, I feel safe in raising the
>>> question, was what he told me true? If it was, why are you now using
>>> only oil that i

Re: [Emc-users] How Exactly does a Mister Work

[John Harris]

Hm. I don't think carbide bits were around in 58, so it looks like the 
foreman was not too far off.

The fast oxidization of aluminum during cutting is an interesting effect.

In the early 60s, we were making small electronic modules by soldering tiny 
Fairchild ICs to printed circuit cards, using locally made hot nitrogen 
soldering. There was a wall powered gadget that extracted nitrogen from the 
air, and a bell jar that held the nitrogen at 1/2 PSI. A plastic tube fed 
the nitrogen to something that looked like a normal soldering iron, except 
that the tip was a hypodermic needle with a blunt tip. The nitrogen came out 
of the needle tip hot enough to melt (reflow) the solder at the joint, but 
while doing so flooded the area around the joint with nitrogen to prevent 
oxidation.

You do not need the heat but maybe a low flow of nitrogen to the cutting 
point may stop the oxidation long enough for the next cutting edge to get 
there. Anyone have any ideas on how the gadget running from wall power that 
made the nitrogen worked?

John

- Original Message - 
From: "Leslie Newell" 
To: "Enhanced Machine Controller (EMC)" 
Sent: Friday, November 20, 2009 8:43 AM
Subject: Re: [Emc-users] How Exactly does a Mister Work


> In general flood with a water based coolant will shift more heat than a
> mist system. Flood also usually shifts the chips better. On the down
> side it is very messy and can actually reduce the life of carbide tooling.
>
> Carbide tooling can take a lot of heat but it hates thermal shock. The
> cutting edges of a milling cutter operating in flood coolant will get
> heated rapidly while they are actually cutting then suddenly cooled as
> they hit the coolant. This can cause cracking and chipping. Oil has a
> much lower thermal capacity and conductivity than water so it doesn't
> cause as much thermal shock. To a large extent you can get around the
> problem by using high pressure flood coolant to make sure the cutter
> does not get a chance to heat up.
>
> So why are mist systems still fairly rare in industry? Two main reasons
> spring to mind. 1) flood keeps the work and machine at an even
> temperature so you don't need to allow for thermal expansion. 2) Flood
> has always been used. If it works, why change it?
>
> In my experience carbide works well with oil misters, HSS needs flood or
> a heavy mist of water based coolant.
>
> Les
>
>
> John Harris wrote:
>> Hi All,
>> Back in the late 50s when, as a young apprentice, I was 
>> turning knobs on a milling machine as part of my education, the shop 
>> foreman replaced the flood system on the mill with a new-fangled mister. 
>> The mister feed tank was filled with the same stuff that was used for the 
>> flood system. That is water with 15(?) percent soluble oil.
>>
>> The foreman told me that the mist cooled the part and the tool by 
>> evaporating the water, and the oil gave some lubrication to the cutting 
>> action. Also misting greatly aided the water evaporation compared to the 
>> flood system.
>>
>> As the foreman is by now no longer with us, I feel safe in raising the 
>> question, was what he told me true? If it was, why are you now using only 
>> oil that is much less efficient in absorbing heat by evaporation than 
>> water?
>>
>> Regards all. I love reading the chat.
>>
>
>
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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Friday 20 November 2009, dave wrote:
>On Fri, 2009-11-20 at 16:39 +, Andy Pugh wrote:
>> 2009/11/20 Gene Heskett :
>> > A cube of dry ice sitting on
>> > it would help, but would raise the available oxygen too.
>>
>> I am fairly sure it would displace the oxygen (being heavier) and so
>> would both cool and reduce oxide formation.
>>
>> You might have hit on a cunning plan, and it would look cool too.
>
>Carbon Dioxide doesn't disassociate easily but will if pushed hard.
>It cannot be used in heat-treating furnaces for that reason but for
>cooling/shielding Al machined parts I think it will work just fine.
>
>I'm not sure the kinetics of Al oxidation are as aggressive as Gene
>states but cannot find any evidence to support or disallow such a claim.
>The oxidation curve, at least at high temps (600 F), is parabolic so it
>limits fairly quickly.
>
>A couple of alternatives for small orifices come to mind. Diesel rebuild
>shops should always have a supply of used injector nozzles. I understand
>the newer ones are carbide.
>
>IIRC Gene had a tap remover (crude edm) running at one time. That should
>fab almost any small hole he wants. :-)

But what to use for the electrode? That is the 64k$ question.  Even tag wire 
is too big for this.

I have since built a better power supply, but using the same idea. I needed 
to bore some holes in some 10" table saw blades so I could turn them on the 
table and sharpen them a wee bit.  With the new supply, 400 watts worth of 25 
ohm resistor, and about 80 volts charging a 10 uf oiled paper capacitor 
across the gap, I can set a tape spool ring into modeling clay for a dam, put 
1/2" of k1 in the ring and blow a nice clean hole through a saw blades .090" 
thick web in about 10 minutes.  But not without fishing a set of 32 db rated 
shooting muffs out of the range box in the pickup, it is that noisy.  It 
would obviously have to be scaled back considerably to do real teeny hole 
drilling.  And as I found out while tap removal was in progress, the 
inability to keep the gap flushed was a major problem, I had to back out of 
the hole, blow it as clean as my air compressor could, and put fresh k1 in 
the hole at about 1 minute intervals as it got so sludgy it shorted.

>Small volumes of oil/mist might be available by using model airplane
>engines as pumps.
>
>Just thinking out loud. Usually dangerous.

Chuckle, same here Dave, but so far I've managed to live through some pretty 
interesting times in my 75 years.

>Dave
>
>
>
>
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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Friday 20 November 2009, Leslie Newell wrote:
>Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it will
>strip oxygen out of the CO2. That is also the reason why you should
>never use a CO2 fire extinguisher on magnesium fires.
>
>Les
>
Thanks for confirming my suspicions, Les.  That reaction will no doubt also 
leave some co behind, a much more dangerous gas.

>Andy Pugh wrote:
>> I am fairly sure it would displace the oxygen (being heavier) and so
>> would both cool and reduce oxide formation.
>>
>> You might have hit on a cunning plan, and it would look cool too.
>
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 soap, ballot, jury, and ammo. Please use in that order."
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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Friday 20 November 2009, Andy Pugh wrote:
>2009/11/20 Gene Heskett :
>> A cube of dry ice sitting on
>> it would help, but would raise the available oxygen too.
>
>I am fairly sure it would displace the oxygen (being heavier) and so
>would both cool and reduce oxide formation.

That would depend on how easy it would be to obtain some oxygen from the co2 
vapors.  How active is carbon dioxide compared to say sulfur dioxide?  Sulfur 
dioxide is a very unstable gas, but its chemical reaction is the opposite as 
it will grab, by force, an oxygen molecule from any available src in its 
quest to convert itself to sulfur tri-oxide, which as some of us know it just 
another name for sulfuric acid.  This is why a leaking so2 refrigerant system 
(commonly used in household refrigerators back in the late 30 and mid-40's) 
is so deadly, the gas will steal the oxygen from the moisture in your lungs 
to make sulfuric acid and _that_ burns your lungs out.

 In the gas fired camper fridges, that is also the destruction mechanism for 
those as even one molecule of water sealed into that system will, over time, 
generate enough sulfuric acid to eat a hole in a thin spot someplace.  I 
don't believe you will ever see a 'Dometic" made unit that will ever have 
more than a 5 year warranty on its no moving parts refrigeration system for 
exactly that reason.  And if its gas fired, it IS a Dometic inside the brand 
name labels & has been so since the 1950's after Servel disappeared.  Today I 
think 12 volt versions of the little bitty fridges like wally sells for a bit 
over a hundred dollar bill have replaced those gas fired ones in 100% of the 
new weekend campers.  I have one in the basement that I carry with me when 
I'm going to be on the job someplace for more than 3 or 4 days. But it runs 
on wall power.

As for how active the carbon dioxide from the dry ice is, can it be broken 
down to supply the o in its o2?  I am not _that_ much of a chemist, hence the 
question. :(

 >You might have hit on a cunning plan, and it would look cool too.

I agree, but the expense of keeping one supplied with dry ice would also have 
to be a factor.  Locally, I believe its special order and several dollars a 
pound, weight measured at their end of the shipping of course. ;)

-- 
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 soap, ballot, jury, and ammo. Please use in that order."
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Re: [Emc-users] How Exactly does a Mister Work

[dave]

On Fri, 2009-11-20 at 16:39 +, Andy Pugh wrote:
> 2009/11/20 Gene Heskett :
> 
> > A cube of dry ice sitting on
> > it would help, but would raise the available oxygen too.
> 
> I am fairly sure it would displace the oxygen (being heavier) and so
> would both cool and reduce oxide formation.
> 
> You might have hit on a cunning plan, and it would look cool too.
> 

Carbon Dioxide doesn't disassociate easily but will if pushed hard. 
It cannot be used in heat-treating furnaces for that reason but for
cooling/shielding Al machined parts I think it will work just fine.

I'm not sure the kinetics of Al oxidation are as aggressive as Gene
states but cannot find any evidence to support or disallow such a claim.
The oxidation curve, at least at high temps (600 F), is parabolic so it
limits fairly quickly. 

A couple of alternatives for small orifices come to mind. Diesel rebuild
shops should always have a supply of used injector nozzles. I understand
the newer ones are carbide. 

IIRC Gene had a tap remover (crude edm) running at one time. That should
fab almost any small hole he wants. :-)

Small volumes of oil/mist might be available by using model airplane
engines as pumps. 

Just thinking out loud. Usually dangerous. 

Dave




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Re: [Emc-users] How Exactly does a Mister Work

[Leslie Newell]

Carbon dioxide is 66% oxygen (CO2). As aluminum is very active it will 
strip oxygen out of the CO2. That is also the reason why you should 
never use a CO2 fire extinguisher on magnesium fires.

Les

Andy Pugh wrote:
> I am fairly sure it would displace the oxygen (being heavier) and so
> would both cool and reduce oxide formation.
>
> You might have hit on a cunning plan, and it would look cool too.
>
>   


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Re: [Emc-users] How Exactly does a Mister Work

[Andy Pugh]

2009/11/20 Gene Heskett :

> A cube of dry ice sitting on
> it would help, but would raise the available oxygen too.

I am fairly sure it would displace the oxygen (being heavier) and so
would both cool and reduce oxide formation.

You might have hit on a cunning plan, and it would look cool too.

-- 
atp

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Re: [Emc-users] How Exactly does a Mister Work

[Gene Heskett]

On Friday 20 November 2009, John Harris wrote:
>Hi All,
>Back in the late 50s when, as a young apprentice, I was turning
> knobs on a milling machine as part of my education, the shop foreman
> replaced the flood system on the mill with a new-fangled mister. The
> mister feed tank was filled with the same stuff that was used for the
> flood system. That is water with 15(?) percent soluble oil.
>
>The foreman told me that the mist cooled the part and the tool by
> evaporating the water, and the oil gave some lubrication to the cutting
> action. Also misting greatly aided the water evaporation compared to the
> flood system.
>
>As the foreman is by now no longer with us, I feel safe in raising the
> question, was what he told me true? If it was, why are you now using only
> oil that is much less efficient in absorbing heat by evaporation than
> water?
>
>Regards all. I love reading the chat.

Warning:  This is personal opinion, subject to revision.

1. in this instance, I'm cutting alu.  This makes a huge diff in the 
chemistry involved.  If in the target operation I was cutting steel or cast, 
I would have a different idea, although the last cast iron I cut, cut very 
well with a squirt of ace cutting oil on the side of the mill while I was 
cutting 1.4" deep with a 1/4" 4 flute TiN mill whose flutes were only an inch 
long.  3 passes to get to full depth while widening the center clearance in a 
starter nose housing for an old Olds diesel, and whose starters are by now 
made out of pretty much pure unobtainium.

2. Alu is a VERY actively oxidizing metal when the bare metal is exposed to 
oxygen from any source, including both air and water.  The oxide film so 
formed then protects it from further "rusting" at that high (about .001 
seconds) rate, but does continue forever at ever slower rates.

3. This rapid oxidation can raise the temp of the part being machined if its 
a small part vs the area being machined.  In this case a 2" square of 1/8" 
thick alu is sitting on top of a block of sweet gum machined flat for a 
sacrificial substrate so I can cut a few thou below the bottom edge, so there 
is not the close contact with another block of metal to act as a heat sink.

4. Any rise in the temp of alu rather adversely effects machining as softer 
alu will tend to push out of the way of the mill as it moved, and it sticks 
in the flutes of the mill like it was welded.  A cube of dry ice sitting on 
it would help, but would raise the available oxygen too.  However the lower 
temps would slow the oxide formation so that particular item could possibly 
be a plus factor.  That of course isn't going to be compatible with the chip 
flushing air blast.  If one could afford it, dry nitrogen would work even 
better but a T2 bottle refill was about $100 the last time I filled ours at 
the tv station.  Not everyone has a Cardox in their back yard. :)

5. Oil contains much less free oxygen and very little in compound so it 
protects the cut surface from this oxidization IF the oil film can be made to 
cover the cut surface in a thousandth of a second or less.  This latter I'm 
not convinced can be done really effectively without an enclosure and 500+ 
psi pressures feeding the coolant. 

So for little machines like mine, it seems the idea to keep the cut surface 
wet, along with the mill so it tends to leave an oil film on the cut with the 
back side of the cutting edge, or as wet as I can get it, and not using a 
fluid with any free oxygen, can only be a plus.

Alu oxide is the 2nd hardest substance we have readily available, and is 
quite capable of eroding the edge off a carbide tool considerably faster then 
the average ferrous material can.

For this same reason, one uses all the rpm the spindle has in order to bring 
the next cutting edge to the work face before the oxide can form.  But my 
little toy mill can only do 2500 revs, so I have 2500/60 to get rps,then  *2 
for the number of flutes & take the reciprocal to get the time=0.012 seconds 
between flutes, many times longer than optimum so there is plenty of time for 
the oxide to form if left uncovered.

So that is the reason I use straight oil.  Vactra #2 since I have it, 
safflower when I get to the store.

-- 
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Re: [Emc-users] How Exactly does a Mister Work

[Leslie Newell]

In general flood with a water based coolant will shift more heat than a 
mist system. Flood also usually shifts the chips better. On the down 
side it is very messy and can actually reduce the life of carbide tooling.

Carbide tooling can take a lot of heat but it hates thermal shock. The 
cutting edges of a milling cutter operating in flood coolant will get 
heated rapidly while they are actually cutting then suddenly cooled as 
they hit the coolant. This can cause cracking and chipping. Oil has a 
much lower thermal capacity and conductivity than water so it doesn't 
cause as much thermal shock. To a large extent you can get around the 
problem by using high pressure flood coolant to make sure the cutter 
does not get a chance to heat up.

So why are mist systems still fairly rare in industry? Two main reasons 
spring to mind. 1) flood keeps the work and machine at an even 
temperature so you don't need to allow for thermal expansion. 2) Flood 
has always been used. If it works, why change it?

In my experience carbide works well with oil misters, HSS needs flood or 
a heavy mist of water based coolant.

Les


John Harris wrote:
> Hi All,
> Back in the late 50s when, as a young apprentice, I was turning 
> knobs on a milling machine as part of my education, the shop foreman replaced 
> the flood system on the mill with a new-fangled mister. The mister feed tank 
> was filled with the same stuff that was used for the flood system. That is 
> water with 15(?) percent soluble oil.
>
> The foreman told me that the mist cooled the part and the tool by evaporating 
> the water, and the oil gave some lubrication to the cutting action. Also 
> misting greatly aided the water evaporation compared to the flood system.
>
> As the foreman is by now no longer with us, I feel safe in raising the 
> question, was what he told me true? If it was, why are you now using only oil 
> that is much less efficient in absorbing heat by evaporation than water?
>
> Regards all. I love reading the chat.
>   


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[Emc-users] How Exactly does a Mister Work

[John Harris]

Hi All,
Back in the late 50s when, as a young apprentice, I was turning 
knobs on a milling machine as part of my education, the shop foreman replaced 
the flood system on the mill with a new-fangled mister. The mister feed tank 
was filled with the same stuff that was used for the flood system. That is 
water with 15(?) percent soluble oil.

The foreman told me that the mist cooled the part and the tool by evaporating 
the water, and the oil gave some lubrication to the cutting action. Also 
misting greatly aided the water evaporation compared to the flood system.

As the foreman is by now no longer with us, I feel safe in raising the 
question, was what he told me true? If it was, why are you now using only oil 
that is much less efficient in absorbing heat by evaporation than water?

Regards all. I love reading the chat.
__
John Harris
E-mail: jdhhar...@customstage.net
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