Re: [Emc-users] polyurethane resin casting

[dave]

On Sat, 2013-09-28 at 23:03 -0600, Gregg Eshelman wrote:
> On 9/28/2013 5:16 AM, Erik Friesen wrote:
> > For the high speed vacuum, why not just use an external tank, with plumbing
> > valve or equivalent to switch to whichever has highest vacuum?
> 
> That's fine if you have the space and funds for a big tank, and a good 
> vacuum pump. I bought an old but excellent condition Gast rotary vane 
> vacuum pump, but haven't used it in some years since for the mold making 
> and casting I do pressure has worked much better.
> 
> Pulling a vacuum in a large tank takes quite a bit of time, unless you 
> get a very high volume pump - and you'd best have a high volume bank 
> balance to get one. ;-)
> 
> Instead of one large tank some smaller ones can be ganged together with 
> a manifold. Propane tanks with the valves removed so they can be hooked 
> together with as large of pipe as possible will work, but getting the 
> smelly stuff out can be a problem. I tried it with one tank, with the 
> insides of the valve removed and opened up some with a drill to reduce 
> restriction as much as I could. The stink would draw right through the 
> vacuum pump and smell up the whole shop.

mercaptans are soluble in sodium hydroxide soln; don't know the ideal
concentration. Also Clorox should oxidize them but be careful about
using on concentrated mercaptans due to rapid reaction rate. Dissolving
them in sodium hydroxide and then oxidizing with hydrogen peroxide
should work but the commonly available 3% peroxide may be a little
wimpy. 30% works better but is hard to get and nasty to handle. 
YMMV
HTH
 
> 
> To sorta on-topic this, one of the tasks I plan to put my mill to is 
> making prototypes of things in metal to use as masters for RTV molds to 
> make plastic castings.
> 
> --
> October Webinars: Code for Performance
> Free Intel webinars can help you accelerate application performance.
> Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from 
> the latest Intel processors and coprocessors. See abstracts and register >
> http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users



--
October Webinars: Code for Performance
Free Intel webinars can help you accelerate application performance.
Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from 
the latest Intel processors and coprocessors. See abstracts and register >
http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] polyurethane resin casting

[Jack Coats]

30% hydrogen peroxide is normally available at hair dressers for bleaching
hair.


On Sun, Sep 29, 2013 at 11:30 AM, dave  wrote:

> On Sat, 2013-09-28 at 23:03 -0600, Gregg Eshelman wrote:
> > On 9/28/2013 5:16 AM, Erik Friesen wrote:
> > > For the high speed vacuum, why not just use an external tank, with
> plumbing
> > > valve or equivalent to switch to whichever has highest vacuum?
> >
> > That's fine if you have the space and funds for a big tank, and a good
> > vacuum pump. I bought an old but excellent condition Gast rotary vane
> > vacuum pump, but haven't used it in some years since for the mold making
> > and casting I do pressure has worked much better.
> >
> > Pulling a vacuum in a large tank takes quite a bit of time, unless you
> > get a very high volume pump - and you'd best have a high volume bank
> > balance to get one. ;-)
> >
> > Instead of one large tank some smaller ones can be ganged together with
> > a manifold. Propane tanks with the valves removed so they can be hooked
> > together with as large of pipe as possible will work, but getting the
> > smelly stuff out can be a problem. I tried it with one tank, with the
> > insides of the valve removed and opened up some with a drill to reduce
> > restriction as much as I could. The stink would draw right through the
> > vacuum pump and smell up the whole shop.
>
> mercaptans are soluble in sodium hydroxide soln; don't know the ideal
> concentration. Also Clorox should oxidize them but be careful about
> using on concentrated mercaptans due to rapid reaction rate. Dissolving
> them in sodium hydroxide and then oxidizing with hydrogen peroxide
> should work but the commonly available 3% peroxide may be a little
> wimpy. 30% works better but is hard to get and nasty to handle.
> YMMV
> HTH
>
> >
> > To sorta on-topic this, one of the tasks I plan to put my mill to is
> > making prototypes of things in metal to use as masters for RTV molds to
> > make plastic castings.
> >
> >
> --
> > October Webinars: Code for Performance
> > Free Intel webinars can help you accelerate application performance.
> > Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most
> from
> > the latest Intel processors and coprocessors. See abstracts and register
> >
> >
> http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
>
>
>
>
> --
> October Webinars: Code for Performance
> Free Intel webinars can help you accelerate application performance.
> Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most
> from
> the latest Intel processors and coprocessors. See abstracts and register >
> http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>



-- 
><> ... Jack

On today's episode of 'This Ol Geek'...
"Texas is the finest portion of the globe that has ever blessed my vision."
- Sam Houston
"Whatever you do, work at it with all your heart"... Colossians 3:23
"If you are not part of the solution, you are part of the precipitate" -
Henry J. Tillman
"Anyone who has never made a mistake, has never tried anything new." -
Albert Einstein
"You don't manage people; you manage things. You lead people." - Admiral
Grace Hopper, USN
"Life is complex: it has a real part and an imaginary part." - Martin Terma
--
October Webinars: Code for Performance
Free Intel webinars can help you accelerate application performance.
Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from 
the latest Intel processors and coprocessors. See abstracts and register >
http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users

Re: [Emc-users] polyurethane resin casting

[Erik Friesen]

I have looked at similar machines, but 1 oz is about 4 or 5 oz too little.

I tried some pressure casting, it seemed to work.  However, a day later
little surface bubbles are ruining some of the surface.  It probably
because the molds are platinum rtv, which caused inhibition in the ie-3075,
which is possible per datasheet.  The alternate 50 second gel time material
is not doable to get in the tank soon enough.

My vacuum system seemed like it was taking a long time to do its job, I was
using one of the dessicators from
bel-air.
 I realized that the valve has a 1/16" inlet, so a quick drill has
shortened the vacuum time about 2/3.

I think I will try some method of using static mix pressure to pressurize
the mold.


On Sun, Sep 29, 2013 at 1:14 PM, Jack Coats  wrote:

> 30% hydrogen peroxide is normally available at hair dressers for bleaching
> hair.
>
>
> On Sun, Sep 29, 2013 at 11:30 AM, dave  wrote:
>
> > On Sat, 2013-09-28 at 23:03 -0600, Gregg Eshelman wrote:
> > > On 9/28/2013 5:16 AM, Erik Friesen wrote:
> > > > For the high speed vacuum, why not just use an external tank, with
> > plumbing
> > > > valve or equivalent to switch to whichever has highest vacuum?
> > >
> > > That's fine if you have the space and funds for a big tank, and a good
> > > vacuum pump. I bought an old but excellent condition Gast rotary vane
> > > vacuum pump, but haven't used it in some years since for the mold
> making
> > > and casting I do pressure has worked much better.
> > >
> > > Pulling a vacuum in a large tank takes quite a bit of time, unless you
> > > get a very high volume pump - and you'd best have a high volume bank
> > > balance to get one. ;-)
> > >
> > > Instead of one large tank some smaller ones can be ganged together with
> > > a manifold. Propane tanks with the valves removed so they can be hooked
> > > together with as large of pipe as possible will work, but getting the
> > > smelly stuff out can be a problem. I tried it with one tank, with the
> > > insides of the valve removed and opened up some with a drill to reduce
> > > restriction as much as I could. The stink would draw right through the
> > > vacuum pump and smell up the whole shop.
> >
> > mercaptans are soluble in sodium hydroxide soln; don't know the ideal
> > concentration. Also Clorox should oxidize them but be careful about
> > using on concentrated mercaptans due to rapid reaction rate. Dissolving
> > them in sodium hydroxide and then oxidizing with hydrogen peroxide
> > should work but the commonly available 3% peroxide may be a little
> > wimpy. 30% works better but is hard to get and nasty to handle.
> > YMMV
> > HTH
> >
> > >
> > > To sorta on-topic this, one of the tasks I plan to put my mill to is
> > > making prototypes of things in metal to use as masters for RTV molds to
> > > make plastic castings.
> > >
> > >
> >
> --
> > > October Webinars: Code for Performance
> > > Free Intel webinars can help you accelerate application performance.
> > > Explore tips for MPI, OpenMP, advanced profiling, and more. Get the
> most
> > from
> > > the latest Intel processors and coprocessors. See abstracts and
> register
> > >
> > >
> >
> http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk
> > > ___
> > > Emc-users mailing list
> > > Emc-users@lists.sourceforge.net
> > > https://lists.sourceforge.net/lists/listinfo/emc-users
> >
> >
> >
> >
> >
> --
> > October Webinars: Code for Performance
> > Free Intel webinars can help you accelerate application performance.
> > Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most
> > from
> > the latest Intel processors and coprocessors. See abstracts and register
> >
> >
> http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
> >
>
>
>
> --
> ><> ... Jack
>
> On today's episode of 'This Ol Geek'...
> "Texas is the finest portion of the globe that has ever blessed my vision."
> - Sam Houston
> "Whatever you do, work at it with all your heart"... Colossians 3:23
> "If you are not part of the solution, you are part of the precipitate" -
> Henry J. Tillman
> "Anyone who has never made a mistake, has never tried anything new." -
> Albert Einstein
> "You don't manage people; you manage things. You lead people." - Admiral
> Grace Hopper, USN
> "Life is complex: it has a real part and an imaginary part." - Martin Terma
>
> --
> October Webinars: Code for Performance
> Free Intel webinars can help yo

Re: [Emc-users] Is this feasible: BBB running LinuxCNC to Gecko G540 stepper driver

[Dave Cole]

>>I have a feeling that there is an option to not use the charge pump?

Yes.  There is a slide switch on the faceplate of the G540 to enable/disable 
the charge pump input.

Dave



On 9/28/2013 11:18 AM, andy pugh wrote:
> On 28 September 2013 16:13, Kirk Wallace  wrote:
>
>> The charge pump signal is different.
>> http://www.wallacecompany.com/machine_shop/G540/G540_upper_bottom_z-1b.png
>>
>> The input charges a capacitor and diode bridge which needs a lot more
>> current and is more sensitive to voltage, frequency and duty.
> I have a feeling that there is an option to not use the charge pump?
> (Though clearly it would be good to)
>

--
October Webinars: Code for Performance
Free Intel webinars can help you accelerate application performance.
Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from 
the latest Intel processors and coprocessors. See abstracts and register >
http://pubads.g.doubleclick.net/gampad/clk?id=60133471&iu=/4140/ostg.clktrk
___
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users