Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Wednesday 26 September 2018 14:06:36 Gene Heskett wrote:

[...[

> After this mornings work, the major remaining error is the nearly 4
> thou the z screw moves endways because of a poorly fitted thrust
> bearing. Thats too much backlash to correct with lcnc. And 3x the x
> backlash. Its a bear to get off to fix the preload which does not now
> exist. But it will be a good project while I wait for the stuff I
> ordered last night. I'll have a week to entertain myself before that
> stuff arrives, by which time I'll have had a couple near beers to
> celebrate my 84th. :)

I did that today inserting short bits of 10 thou shim between the outer 
races of the twin AC ball bearings in the thrust bearing, which was 
about 5 thou too much, but the clamp nut driving the inner races has an 
excellent locking facility, so I took it up to to zero lash, and another 
5 degrees for preload. Z backlash is now about 2.0 thou.

But in double checking x, I found it up to about 4 thou, quite dependent 
on the location of the x table.  I dialed the pulley the motor drives, 
zero end play there. That leaves the screws in the end of the nut cage, 
driving a plate with a tapered bore at a 45 degree angle, compressing a 
felt ring into the screws threads to serve both as a swarf wiper, oiler 
AND the endplay adjuster in the shop made nut cage. The felts outer edge 
has a finite thickness, and the felt seems to be doing a final collapse. 
Pulling that out to get to those screws is a bigger project than I 
wanted to tackle yet today, so thats tomorrows chore. I /think/ they are 
on the back face of the nut cage, so uncovering the rear face of the 
well covered tunnel that screw turns in, might let me get to them w/o a 
full disassembly of the carriage.

I was attacked on the phone by a phisher today, so stopped the card and 
got a new one. I'll see if between the fuzz and the banks security they 
can stop him before he hurts somebody. If I find him first, the fuzz 
won't have to worry. Like Marion Morrison (aka John Wayne) once said, 
stupid should hurt. But not for long...

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 


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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Wednesday 26 September 2018 16:17:15 andy pugh wrote:

> On Wed, 26 Sep 2018 at 15:08, Gene Heskett  
wrote:
> > And the 2nd is axial alignment, combined with the beam spreading at
> > 30" out, gives a bar of light at full intensity that is around 2mm
> > wide by 4mm long, and describes a nearly 10 mm diameter circle on
> > the target as the spindle rotates.
>
> I think you need to mount the module in a tube, then mount that tube
> in a bigger tube with 4 x setscrews at the front and the back. Then
> you can adjust both the axis and the alignment to make the smallest
> possible circle both near the spindle and at the end of the bed. It's
> like a 4-jaw chuck only tedious.

These appear to have such an adjustment facility, one is a 38 spcl 
replica, the other is a 6.5 Creedmore but with the laser instead of a 
bullet.

The screwdriver or whatever is used to adjust them is smaller than the 
needle for a flu shot. The access hole might be 15 thou in diameter. 
It's there, 4 of them at 90 degree spacing, but veddy veddy small. 
Smaller than an 0-80 screw by quite a bit.  Tedious would be an 
understatement, Andy.

I'll get my solder crack finder lens out and see what I can see in the 
holes tomorrow.

Thanks Andy.

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
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Re: [Emc-users] More on bed wear fix

[andy pugh]

On Wed, 26 Sep 2018 at 15:08, Gene Heskett  wrote:

> And the 2nd is axial alignment, combined with the beam spreading at 30"
> out, gives a bar of light at full intensity that is around 2mm wide by
> 4mm long, and describes a nearly 10 mm diameter circle on the target as
> the spindle rotates.

I think you need to mount the module in a tube, then mount that tube
in a bigger tube with 4 x setscrews at the front and the back. Then
you can adjust both the axis and the alignment to make the smallest
possible circle both near the spindle and at the end of the bed. It's
like a 4-jaw chuck only tedious.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916


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Re: [Emc-users] More on bed wear fix

[Gregg Eshelman via Emc-users]

The one I have was made by Avenger Products, model 21400. Uses G13A batteries.
 The company appears to have been bought by Jewett-Cameron circa 2011 and this 
particular product discontinued.

Web archive! 
https://web.archive.org/web/*/http://www.avengerproducts.com:80/laser.asp
Focus is adjustable to get the smallest dot at the aligning distance. Shine it 
up close at something and it makes a short line. Huh.The laser pointer I bought 
back when they first dropped to $10 was better than that, no adjustable focus 
but that could be remedied by sufficiently motivated use of a lathe.

The thing to search for is a single emitter laser module.

On Wednesday, September 26, 2018, 8:08:57 AM MDT, Gene Heskett 
 wrote:  
 On Wednesday 26 September 2018 05:23:42 andy pugh wrote:

> On Wed, 26 Sep 2018 at 06:13, Chris Albertson 
 wrote:
> > On Tue, Sep 25, 2018 at 1:04 AM andy pugh  wrote:
> > > I can't help thinking that the way to determine the amount of
> > > correction needed is to actually machine a test bar and measure
> > > it.
> >
> > A laser beam is straighter than any bar.  and is quicker and costs
> > less.

It may be straighter, but the ones I just bought for this, at a combined 
$85 for the 2of them, have 3 problems:

The 1st being that it appears they are multiple emitter devices giveing 
an upclose beam that integrates to about a .5 by 1mm central image made 
up of individual beams a few microns apart.

And the 2nd is axial alignment, combined with the beam spreading at 30" 
out, gives a bar of light at full intensity that is around 2mm wide by 
4mm long, and describes a nearly 10 mm diameter circle on the target as 
the spindle rotates. Theres no way a 5mm square working area chip can 
work with that much off axis a beam.  Its going to be clear off the 
imaging chip. The only way would be to rotate the spindle until the 
pattern is vertical, and drive the crossfeed to center the beam on the 
imager. Then rotate the spindle 180 degrees and using the crossfeed 
drive to recenter the image on the imager then calculate the center, 
doing this every 1/2 inch near the spindle because thats where the 
majority of the wear is.  
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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Wednesday 26 September 2018 10:59:34 Greg Bentzinger via Emc-users 
wrote:

> Greg begin
>
> Am I going to be the 1st person to point out that the tailstock on
> most lathe designs does not use the same ways as the lathe carriage
> and therefore is not subject to the bed wear issue.
No that came to me last Monday night, and I made some measurements based 
on that yesterday.

> If the tailstock 
> is out it is mal-adjusted or the lathe is not leveled properly and you
> have bed twist / slope / rainbow etc. Greg end

Not terribly likely.

In this case several visible nicks in the inside edge of the front flat 
it slides on, guided by the back v-way. Judicious use of the dmt plate, 
wetted with paint thinner to knock off the resultant high spots reduced 
the error noticeably. I also took a nice whacks high spot off the back 
v-way itself, in about the middle of its travel. Something had hit the 
top of the v-way, upsetting the metal on both front and rear faces of 
it.

As far as the lathe bed leveling goes, the Sheldon's nearly all ride the 
right end of the bed on a simple ball joint, and when moved, its 
recommended that the preload nut, inside the bed at the right end, be 
loosened enough to let the ball joint re-adjust itself to the new floor. 
Thats been done at least twice since it was parked in its present 
location a bit over 2 years ago.  So I am not overly concerned with a 
poorly poured floor causing bed twist.

After this mornings work, the major remaining error is the nearly 4 thou 
the z screw moves endways because of a poorly fitted thrust bearing.  
Thats too much backlash to correct with lcnc. And 3x the x backlash.  
Its a bear to get off to fix the preload which does not now exist. But 
it will be a good project while I wait for the stuff I ordered last 
night. I'll have a week to entertain myself before that stuff arrives, 
by which time I'll have had a couple near beers to celebrate my 84th. :)

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 


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Re: [Emc-users] More on bed wear fix

[Greg Bentzinger via Emc-users]

Greg begin 

Am I going to be the 1st person to point out that the tailstock on most lathe 
designs does not use the same ways as the lathe carriage and therefore is not 
subject to the bed wear issue. If the tailstock is out it is mal-adjusted or 
the lathe is not leveled properly and you have bed twist / slope / rainbow etc.
Greg end

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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Wednesday 26 September 2018 05:23:42 andy pugh wrote:

> On Wed, 26 Sep 2018 at 06:13, Chris Albertson 
 wrote:
> > On Tue, Sep 25, 2018 at 1:04 AM andy pugh  wrote:
> > > I can't help thinking that the way to determine the amount of
> > > correction needed is to actually machine a test bar and measure
> > > it.
> >
> > A laser beam is straighter than any bar.  and is quicker and costs
> > less.

It may be straighter, but the ones I just bought for this, at a combined 
$85 for the 2of them, have 3 problems:

The 1st being that it appears they are multiple emitter devices giveing 
an upclose beam that integrates to about a .5 by 1mm central image made 
up of individual beams a few microns apart.

And the 2nd is axial alignment, combined with the beam spreading at 30" 
out, gives a bar of light at full intensity that is around 2mm wide by 
4mm long, and describes a nearly 10 mm diameter circle on the target as 
the spindle rotates. Theres no way a 5mm square working area chip can 
work with that much off axis a beam.  Its going to be clear off the 
imaging chip. The only way would be to rotate the spindle until the 
pattern is vertical, and drive the crossfeed to center the beam on the 
imager. Then rotate the spindle 180 degrees and using the crossfeed 
drive to recenter the image on the imager then calculate the center, 
doing this every 1/2 inch near the spindle because thats where the 
majority of the wear is.

The 3rd problem is the general lack of availability of the battery these 
need, 2 393's-394's I think it was. And the 38 cal model has no switch, 
you must remove the device from its mounting and remove the batteries by 
unscrewing the cartridge rim/plug, $14 a pair with an estimated life of 
less than an hour. The 6.5 Creedmoor version does have a switch of 
sorts, a nylon button in the rear cap, left handed thread, that screws 
in and lifts the + end of the battery stack (3 of them in that one) from 
its ground contact to turn it off.

> Yes, but there is more to making straight parts than having perfect
> alignment between the unloaded toolpost and the spindle axis.

Which is basically what I was doing by dialing the barrel of the 
tailstock, and pushing the loose tailstock along with the carriage 
holding the dial. No cutting forces there. I found quite easily, some 
dings in the inside edge of the front flat the tailstocks front rests on 
in the bed that had the effect of tipping the tailstock to the rear. 
Several places along the bed might have light dings, but they were quite 
obvious in their effect on the dial when the tailstock rode over them at 
the far end. I'll polish those away with a worn red DMT plate today. 
After I wash it, its pretty well dirt packed and in need of a good 
scrubbing.

> You seem to be assuming that _I_ am the one under-thinking this :-)

That is a Chuckle. We should all know better than that by now, Andy. :-)

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 


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Re: [Emc-users] More on bed wear fix

[andy pugh]

On Wed, 26 Sep 2018 at 06:13, Chris Albertson  wrote:
>
> On Tue, Sep 25, 2018 at 1:04 AM andy pugh  wrote:
>
> > I can't help thinking that the way to determine the amount of
> > correction needed is to actually machine a test bar and measure it.

> A laser beam is straighter than any bar.  and is quicker and costs less.

Yes, but there is more to making straight parts than having perfect
alignment between the unloaded toolpost and the spindle axis.

You seem to be assuming that _I_ am the one under-thinking this :-)

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916


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Re: [Emc-users] More on bed wear fix

[Gregg Eshelman via Emc-users]

The V2 8 megapixel camera for Raspberry Pi uses the Sony IMX219 sensor which is 
a bit over 5mm wide by a bit under 5mm tall. They call it 1/4" diagonal.
Should be able to hit that with a laser beam, if the pinhole lens can be 
removed.
The first model Pi camera used the (since discontinued) Omnivision OV5647 
sensor. Fewer pixels and image area was a bit over 4mm by a but under 4mm.

On Wednesday, September 26, 2018, 1:08:06 AM MDT, Gene Heskett 
 wrote:  
But finding a camera chip big enough to shine these laser's on so that 
the laser stays on the imaging chip cannot be found in an integrated 
package that will plug into the 15 pin connector on a pi. The laser 
beams are 10x the size of the imaging chips even if they're perfectly 
aligned. To get something usable I may have to buy a lensless digital 
camera for around a 100 dollar bill, which of course has a usb-2 output, 
and controlling it to get the image data is something I'll have to 
invent.  
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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Wednesday 26 September 2018 01:11:50 Chris Albertson wrote:

> On Tue, Sep 25, 2018 at 1:04 AM andy pugh  wrote:
> > I can't help thinking that the way to determine the amount of
> > correction needed is to actually machine a test bar and measure it.
>
> A laser beam is straighter than any bar.  and is quicker and costs
> less. What you do is place a camera in the tool holder and watch the
> beam move as you move the carriage.   You can measure at the
> micrometer level typically 1/10th  the pixel size.
>
> We live in a time when  "nuts" level measurements is easy and cheap.
> for example:  I just bought a pair of BMP280 barometer chips on eBay
> for $6.  I have a live graph on my iMac showing the air pressure vs.
> time.   The chip is simple, just an I2C serial output.   I can see the
> plot on the screen move as I move the chip up and down.  Clearly I see
> that the air is thinner 10 inches above my desk then it is 2 inches
> above my desk.   It is a sensitive altimeter for $3.   Upstairs I have
> an oscillator that runs at 10. Mhz and all 13 of those
> zeros are significant.I have about $100 invested it that if you
> count all the parts.
>
Thats all true. I can recall buying two custom made frequency srcs to 
replace the failing oven types in our old GE transmitter in the late 
80's, paying $750 each, and building them into double-sided pcb boxes I 
soldered up, getting power to run them from the heater supply for the 
old crystals. They were far more accurate than the frequency monitors of 
the day made by Arnold Belar. It got to be a private joke of mine that 
when the Belar said it was off frequency, I sent it in for repair. TV 
transmitters were allowed +- 1 likohertz for the visual, and the aural 
was allowed that same 1 kilohertz but was 4.50 hz above the visual.
Those two srcs kept it well within the tolerance of a $6000 hp counter, 
and were probably never more than 10 hz off the rest of the life of that 
transmitter.  Today that sort of accuracy can be had for under $100 for 
the pair.  The trick is finding where to buy them. 

But finding a camera chip big enough to shine these laser's on so that 
the laser stays on the imaging chip cannot be found in an integrated 
package that will plug into the 15 pin connector on a pi. The laser 
beams are 10x the size of the imaging chips even if they're perfectly 
aligned. To get something usable I may have to buy a lensless digital 
camera for around a 100 dollar bill, which of course has a usb-2 output, 
and controlling it to get the image data is something I'll have to 
invent. I've probably spent 20 hours online already looking for 
something I could use with a pi, or a rock64 since it also has the 15 
pin camera connector. I can probably get, from digikey, an imager chip 
big enough (and low enough resolution, 1 megapixel is a great plenty) 
but to actually make the supporting circuitry to make a working camera 
out of it will take more than this old man has left in him. These 
$15-$25 cameras for the pi all have image chips less than 1/8" square, 
with as high as 8 megapixels. Some are even microscopic sized pin holes, 
no lens at all!

Nevertheless, I've ordered some 3/8" brass tubing to put on the rear of 
the "cartridge" to extend a switchable, dimmable power supply out the 
other end of the spindle some 21" away, a cross polarizing adjustable 
from ND2 to ND400 filter, and another 12x24 sheet of half inch 6061 to 
make a new apron plate for the front of the carriage so I can re-arrange 
things a bit and move the z nut to the right by at least an inch, 
getting away from the forces from over compressing the left bellows when 
I'm right at the nose of the spindle. The plate I made was cut from the 
deck of an old Ampex VR-1200, and has quite a few holes I filled with 
permatex liquid metal and sanded flat and painted over, and a newly made 
one will only have holes where I put them. A bit less hacky looking I 
hope.  And I'll clean up that DMT plate and remove the dings that are 
tipping the tailstock to the back of the bed by several thou when the 
tailstock is sitting on them. As it sits. I now have around 20 inches of 
+- a thou. There may be more dings in the edge of that front flat to 
address.  Frankly, this lathe has been beat to hell in its 70 years and 
I, like a dummy, paid 4x what it was worth. But what's done is done, but 
I reserve the right to claim I was an idiot to buy it. ;-)

The technology, Chris, has run off and left us behind. 

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 


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Re: [Emc-users] More on bed wear fix

[Chris Albertson]

On Tue, Sep 25, 2018 at 1:04 AM andy pugh  wrote:

> I can't help thinking that the way to determine the amount of
> correction needed is to actually machine a test bar and measure it.
>


A laser beam is straighter than any bar.  and is quicker and costs less.
What you do is place a camera in the tool holder and watch the beam move as
you move the carriage.   You can measure at the micrometer level typically
1/10th  the pixel size.

We live in a time when  "nuts" level measurements is easy and cheap. for
example:  I just bought a pair of BMP280 barometer chips on eBay for $6.  I
have a live graph on my iMac showing the air pressure vs. time.   The chip
is simple, just an I2C serial output.   I can see the plot on the screen
move as I move the chip up and down.  Clearly I see that the air is thinner
10 inches above my desk then it is 2 inches above my desk.   It is a
sensitive altimeter for $3.   Upstairs I have an oscillator that runs at
10. Mhz and all 13 of those zeros are significant.I have
about $100 invested it that if you count all the parts.



> --
> atp
> "A motorcycle is a bicycle with a pandemonium attachment and is
> designed for the especial use of mechanical geniuses, daredevils and
> lunatics."
> — George Fitch, Atlanta Constitution Newspaper, 1916
>
>
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>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Tuesday 25 September 2018 18:18:06 jeremy youngs wrote:

> On Tue, Sep 25, 2018, 5:15 AM Gene Heskett  gibs works great on TLM because
>
> > its carriage is so narrow its nigh impossible to use a qctp on it
> > and keep the point of the tool within the carriages footprint on the
> > bed. But I have a vivid memory of the difficulty in getting the
> > brass, tapered gib dead straight with a file that wasn't straight so
> > there wasn't a spring effect in setting it. The first month I used
> > it, the final wear-in used up much of the adjustment range but its
> > now quite solid and hasn't been readjusted since.
>
> https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fu
>lk%2Fitm%2F123034789359 This is an excellent solution to the ways/Gibs
> problem. I f used just on the dovetail it will likely move your gib
> enough you will need to re scrape it, I did all sides of mine and had
> to narrow the Gib. I have a 12*34 belt surfacer so that was not a huge
> issue for me. Good luck Gene .
>
>
The 5 mill thick, if applied inside the v-way on the bottom the the 
Sheldon's carriage would take up a considerable amount of the gib 
clearance. And should just about nail it if a 2" piece was placed on 
each end of the brass bar. Theres a gib strip on the back of the 
carriage, looks original and shows no sign of the carriage ever lifting 
high enough to touch the underside of the bed lip.

I did note that the front flat at the right end of the bed, has what 
looks like quite a few hammer blows against the inside edge, upsetting 
the bed metal enough to give a 10 thou tip back as the tailstock slides 
over them. So I laid a worn out 1200 grit DMT plate on them and did some 
minor polishing, but its going to take more of that polishing to get it 
down to the surrounding metal's level.  No clue what might have taken a 
dozen or so whacks at it.  That was BG, Before Gene, so I'm just 
guessing. 8 or 10 of them, bookmatch sized bumps once polished enough to 
see them plainly.

Thanks Jeremy.

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 


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Re: [Emc-users] More on bed wear fix

[jeremy youngs]

On Tue, Sep 25, 2018, 5:15 AM Gene Heskett  its carriage is so narrow its nigh impossible to use a qctp on it and
> keep the point of the tool within the carriages footprint on the bed.
> But I have a vivid memory of the difficulty in getting the brass,
> tapered gib dead straight with a file that wasn't straight so there
> wasn't a spring effect in setting it. The first month I used it, the
> final wear-in used up much of the adjustment range but its now quite
> solid and hasn't been readjusted since.
>

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F123034789359
This is an excellent solution to the ways/Gibs problem. I f used just on
the dovetail it will likely move your gib enough you will need to re scrape
it, I did all sides of mine and had to narrow the Gib. I have a 12*34 belt
surfacer so that was not a huge issue for me. Good luck Gene .

>

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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Tuesday 25 September 2018 13:51:20 Les Newell wrote:

> Hi Gene,
>
> If I remember correctly the piece I used was only about 18" long but
> about 4" diameter. Delrin that size is pretty spendy. I just used what
> I had.

Thats why I started with the 22" piece of A2 .500".

But it did not turn out to be straight by about 20 thou, well beyond the 
range of my .0001" dial.

> I was setting head alignment so I didn't need it to be that much
> longer. If I can get the taper down to a gnat's over that distance I'm
> happy.
>
> The laser setup has a lot of potential. I think this is how I would go
> about it:
> First align the laser as close to center as possible at the furthest
> travel. Make two alignment marks on the spindle 180 degrees apart.
> Align the spindle on one of the marks.
> Zero all offsets so you are in machine coordinates.
> Start at Z home and center the camera on the dot by moving X. Make a
> note of the X and Z positions. Rotate 180 degrees, center the dot and
> make a note of the X.
> Add the two X coordinates together and divide by 2. Move X to this
> value and zero the axis. You should now be dead center.
>
> Rotate another 180 degrees, Move Z by whatever step size

Step size when using a lincurve is arbitrary, and from my measurements, 
most of the jumping around is in the first 7" away from the spindle.

But I mentioned measuring to the tailstock barrel while pushing the loose 
tailstock down the bed with the carriage, so I did, putting a 
lincurve "corner" into every peak motion that found. Put that into the 
setp tables for the lincurve, and re-enabled it. From about .2" right of 
the MIN_LIMIT, it was just under +- .001" full length of the bed until I 
ran out of lincurve. That looked pretty good, so I rezeroed the z by 
moveing the tool out of the QC holder about a quarter inch. Ran the mt-5 
carver over that painted for size 5c adapter I've been screwing with for 
a week. Got a fit pretty well dead on the money, so I put it all 
together with the ER-40 adapter, and measured its runout right behind 
the nut at .0003", which is about 7 thou better than it was, and 
definitely close enough for the girls I go with.

Looking at the apron to see if I could move the nut to the right, I can 
by around 2" which would be a huge help. But I'll have to figure out 
where to put the pushbutton that is used to adjust the distance per 
click of the dial since the nut would then occupy the space the switch 
is in. I need to replace that switch anyway as its not making a reliable 
contact with my usual thumb pressure. So I've a big grin and a big pork 
chop in the skillet for dinner, and the weather is getting wet and 
noisy. Tomorrow is another day. And I'll figure out how to move the nut 
then.

Progress has been made.

Thanks Les.

> you want in 
> your table and take two X measurements as above. Repeat until you run
> out of travel.
> For each Z position add the X values and divide by 2. You should now
> have the values that need to go in your lincurve offsets. Depending on
> how lincurve is set up you may have to invert the values.
>
> It is important to always try to keep the dot centered on the camera.
> That way you minimize the effect of any distortion in the camera.
>
> Les
>
> On 25/09/2018 17:07, Gene Heskett wrote:
> > That too sounds like a great idea, Les. Suggested OD of the Delrin
> > to get that stiffness? At about 30" between centers...
>
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--
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Re: [Emc-users] More on bed wear fix

[Les Newell]

Hi Gene,

If I remember correctly the piece I used was only about 18" long but 
about 4" diameter. Delrin that size is pretty spendy. I just used what I 
had.
I was setting head alignment so I didn't need it to be that much longer. 
If I can get the taper down to a gnat's over that distance I'm happy.


The laser setup has a lot of potential. I think this is how I would go 
about it:

First align the laser as close to center as possible at the furthest travel.
Make two alignment marks on the spindle 180 degrees apart. Align the 
spindle on one of the marks.

Zero all offsets so you are in machine coordinates.
Start at Z home and center the camera on the dot by moving X. Make a 
note of the X and Z positions. Rotate 180 degrees, center the dot and 
make a note of the X.
Add the two X coordinates together and divide by 2. Move X to this value 
and zero the axis. You should now be dead center.


Rotate another 180 degrees, Move Z by whatever step size you want in 
your table and take two X measurements as above. Repeat until you run 
out of travel.
For each Z position add the X values and divide by 2. You should now 
have the values that need to go in your lincurve offsets. Depending on 
how lincurve is set up you may have to invert the values.


It is important to always try to keep the dot centered on the camera. 
That way you minimize the effect of any distortion in the camera.


Les

On 25/09/2018 17:07, Gene Heskett wrote:


That too sounds like a great idea, Les. Suggested OD of the Delrin to get
that stiffness? At about 30" between centers...




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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Tuesday 25 September 2018 12:10:54 andy pugh wrote:

> On Tue, 25 Sep 2018 at 16:56, Jon Elson  wrote:
> > You can't turn between centers, or at least that adds a
> > whole new dimension to possible errors.
>
> That depends on the aim of the exercise. Is the aim to make straight
> parts or to have a perfectly aligned lathe?

Both? :(

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 


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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Tuesday 25 September 2018 11:35:18 Jon Elson wrote:

> On 09/25/2018 03:02 AM, andy pugh wrote:
> > I can't help thinking that the way to determine the amount of
> > correction needed is to actually machine a test bar and measure it.
>
> The problem here is that deflection of the bar, and also the
> lathe, will affect the accuracy of the result.
> You can't turn between centers, or at least that adds a
> whole new dimension to possible errors.
> If you know that you turn the same diameter at each end,
> then maybe turning the whole length will give a profile of
> the bed.  But, then, diameter errors on the test bar could
> be pure shift in the X axis, or some combination of that
> plus a rolling of the carriage due to height differences on
> the two ways.
>
> Having (painstakingly) redone a lathe bed, it is more
> complicated than at first glance.
>
Understatement of the year, Jon. :)

> My preference is to use a hardened and ground bar of known
> straightness, held just in the spindle, and a sensitive
> indicator to ride up and down the length of it.
>
> Jon
>
>
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--
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 soap, ballot, jury, and ammo. Please use in that order."
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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Tuesday 25 September 2018 11:27:42 andy pugh wrote:

> On Tue, 25 Sep 2018 at 16:15, Bengt Sjölund  wrote:
> > 6082 is a good candidate that machines well if you can get it to
> > fair price.
>
> 800mm (31") of 2.75" 6082 is < £50 on eBay.
> https://www.ebay.co.uk/itm/281404474552

And doesn't post to the US. Darn it. And ebays broken search for 6082 
aluminum rod finds a battery charger.


-- 
Cheers, Gene Heskett
--
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 


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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Tuesday 25 September 2018 10:56:44 Bengt Sjölund wrote:

> 6082 is a good candidate that machines well if you can get it to fair
> price.
>
6082 isn't available from onlinemetals.com. I haven't checked other 
sources.

Thanks Bengt.

-- 
Cheers, Gene Heskett
--
"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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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Tuesday 25 September 2018 09:30:53 andy pugh wrote:

> On Tue, 25 Sep 2018 at 12:48, Les Newell  
wrote:
> > That assumes your tailstock is dead nuts on. If not you're going to
> > be trying to compensate for a mix of tailstock + bed errors.
>
> Indeed. In fact the linear component of the error will tell you how
> far from the _bed_ axis the tailstock is.
> A dial indicator on a long bar clocking round the tailstock bore will
> then tell you something about the spindle axis to tailstock alignment.
> Ideally you would align the tailstock to the bed, and then the
> headstock to the tailstock
> I think. .

Makes perfect sense here. In my case, moving the tailstock up to the 
head, puts the tailstock sitting smack in the middle of the wear, so 
aligning it there doesn't mean squat. Or does it? The tailstock is 
located by the rear v-way, which barring being beaten by the chuck key 
too many times, (how many times has it been started in reverse with the 
key still plugged in?) should have damned close to factory accuracy even 
after 70 years.

And that gives me yet another idea on how to measure this bed wear. Put a 
dial in the tool holder, rest its finger on the side of the tailstock, 
and just push the tailstock back down the bed with the carriage. 
Unwanted carriage motions from wear will show up on the dial.  After 
cleaning the flats well and a drop or 3 of vactra on the flats and rear 
v-way. I can check that out as soon as I disconnect the offset modules 
input and setp it to zero. That should get me pretty close.  And its 
simple. That, and moving the nut to the right as far as I can on the 
back of the apron so I'm not crushing the left bellows so tightly.

News at 23:00 local?  Maybe.

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 


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Re: [Emc-users] More on bed wear fix

[andy pugh]

On Tue, 25 Sep 2018 at 16:56, Jon Elson  wrote:

> You can't turn between centers, or at least that adds a
> whole new dimension to possible errors.

That depends on the aim of the exercise. Is the aim to make straight
parts or to have a perfectly aligned lathe?

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916


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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Tuesday 25 September 2018 07:46:44 Les Newell wrote:

> > I am talking in terms of a
> > light cut on a stiff aluminium bar between centres.
>
> That assumes your tailstock is dead nuts on. If not you're going to be
> trying to compensate for a mix of tailstock + bed errors. If you use
> the bar unsupported there are flex issues. Having said that you always
> get some flex in the work so maybe it is a good thing that the test
> bar flexes slightly...
>
That too, Les. For long cuts, cut light and measure. That almost calls 
for a compensating file. Unforch I have not figured out how to use that 
as it seems to be intended as a per screw, screw compensator, with no 
way to cross couple the z location to the x offset that I could deduce.

Thinking out loud here:

Ideally, a pulldown menu item to select the file to reload a lincurve 
according to the material being worked would be handier than sliced 
bread or bottled beer.  Hint hint hint.

Or perhaps a slider to adjust the gain between the lincurve output and 
the offset module in could be used to compensate for machine flex under 
heavy cutting loads. Wear is consistent, where flex is dependant on 
cutting forces.

So that implies 2 lincurve modules whose outputs are summed together 
before being presented to the offset module. That way if we had the gain 
slider, one could even raise the comp on a dynamic basis to compensate 
for a dulling tool. Not useful for one offs like most of my stuff is, 
but production quantities where you are making thousands of an item, the 
out of tolerance scrap could be reduced. Heck, the gain slider could 
even be put over in the pyvcp portion of the screen, and that could be 
done right now.

I'll do that bit of gui stuff after I've actually matched the taper on 
the od of the 5c, with the id taper of the spindle. I am still 
increasing the taper per inch by about .0002 per pass right now. Getting 
closer, but not there yet. I should put a dial on the shoulder, and 
measure how far I can move in in the mouth of the spindle as it rocks on 
the small end, and add about 40% of what I measure to the ramp/inch in 
the gcode thats re-carving that taper.

Right now I need a way to turn off the comp so I am measuring the raw 
machine and this would be one way to do it without needing to edit the 
hal file and restart LCNC and rehome the machine.

> When I was playing with the head alignment on my Colchester I used a
> large chunk of Delrin bar and a very sharp cutter. The bar was pretty
> stiff and cutting forces were low.
>
> Les

That too sounds like a great idea, Les. Suggested OD of the Delrin to get 
that stiffness? At about 30" between centers...

Tailstock isn't deadnuts on. The last 4 or 5 thou seems very difficult to 
achieve as the tightening of the adjustment screws seems to move it in 
reverse. So I have been experimenting with less and less tension on 
those screws, depending on the central holddown to lock it. I think the 
adjusting screws are flexing the base, tipping it slightly as they are 
snugged up.  And I am not convinced the barrel is pointed dead at the 
center of the spindle, but perhaps a few thou above, so the rear of it 
needs some Reynolds Wrap shimming? Stuff Yet To Be Determined.

> On 25/09/2018 12:19, andy pugh wrote:
> > On Tue, 25 Sep 2018 at 11:15, Gene Heskett  
wrote:
> >> This is also true. But that test bar costs money too.
> >
> > It can stay in stock as useful material. I am talking in terms of a
> > light cut on a stiff aluminium bar between centres.

Thanks everybody.

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 


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Re: [Emc-users] More on bed wear fix

[Jon Elson]

On 09/25/2018 03:02 AM, andy pugh wrote:

I can't help thinking that the way to determine the amount of
correction needed is to actually machine a test bar and measure it.
The problem here is that deflection of the bar, and also the 
lathe, will affect the accuracy of the result.
You can't turn between centers, or at least that adds a 
whole new dimension to possible errors.
If you know that you turn the same diameter at each end, 
then maybe turning the whole length will give a profile of 
the bed.  But, then, diameter errors on the test bar could 
be pure shift in the X axis, or some combination of that 
plus a rolling of the carriage due to height differences on 
the two ways.


Having (painstakingly) redone a lathe bed, it is more 
complicated than at first glance.


My preference is to use a hardened and ground bar of known 
straightness, held just in the spindle, and a sensitive 
indicator to ride up and down the length of it.


Jon


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Re: [Emc-users] More on bed wear fix

[andy pugh]

On Tue, 25 Sep 2018 at 16:15, Bengt Sjölund  wrote:
>
> 6082 is a good candidate that machines well if you can get it to fair price.

800mm (31") of 2.75" 6082 is < £50 on eBay.
https://www.ebay.co.uk/itm/281404474552

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916


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Re: [Emc-users] More on bed wear fix

[Bengt Sjölund]

6082 is a good candidate that machines well if you can get it to fair price.


Den 2018-09-25 kl. 16:51, skrev Gene Heskett:

On Tuesday 25 September 2018 07:19:12 andy pugh wrote:


On Tue, 25 Sep 2018 at 11:15, Gene Heskett 

wrote:

This is also true. But that test bar costs money too.

It can stay in stock as useful material. I am talking in terms of a
light cut on a stiff aluminium bar between centres.

What diameter would you consider as being stiff enough, Andy, in say 7075
alloy? (example 3'of2.5"=172 USD)

In 6061?(3'of3"=117.48 USD)

2024?(3'of2.5"=172USD)

6061 is cheaper, but its machinability sucks. Like bubble gum, it must be
kept cold to machine well. Or even to saw.

And I'd likely buy a larger dia just so I could make bigger stuff out of
it later. A 3' piece of 6" is 682 USD and at 100 lbs plus packing would
have to come by freight truck. I'd absolutely have to rig coolant on
everything too. Including buying a power hacksaw I don't have room for.

I have less than a foot left of a 40" long, nominally 6.25"x7" bar I
found at a scrap yard 20 years ago and bought for 50 cents a lb.

I've made lots of stuff out of it, but its packed the flutes full and
broken several hundred dollars worth of cutting tools too. No clue what
alloy, but it sure is difficult stuff to work with as its gummy at room
temps, getting nearly impossible to work long before its too hot to
touch.





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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Tuesday 25 September 2018 07:19:12 andy pugh wrote:

> On Tue, 25 Sep 2018 at 11:15, Gene Heskett  
wrote:
> > This is also true. But that test bar costs money too.
>
> It can stay in stock as useful material. I am talking in terms of a
> light cut on a stiff aluminium bar between centres.

What diameter would you consider as being stiff enough, Andy, in say 7075 
alloy? (example 3'of2.5"=172 USD)

In 6061?(3'of3"=117.48 USD)

2024?(3'of2.5"=172USD)

6061 is cheaper, but its machinability sucks. Like bubble gum, it must be 
kept cold to machine well. Or even to saw.

And I'd likely buy a larger dia just so I could make bigger stuff out of 
it later. A 3' piece of 6" is 682 USD and at 100 lbs plus packing would 
have to come by freight truck. I'd absolutely have to rig coolant on 
everything too. Including buying a power hacksaw I don't have room for.

I have less than a foot left of a 40" long, nominally 6.25"x7" bar I 
found at a scrap yard 20 years ago and bought for 50 cents a lb.

I've made lots of stuff out of it, but its packed the flutes full and 
broken several hundred dollars worth of cutting tools too. No clue what 
alloy, but it sure is difficult stuff to work with as its gummy at room 
temps, getting nearly impossible to work long before its too hot to 
touch.

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 


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Re: [Emc-users] More on bed wear fix

[andy pugh]

On Tue, 25 Sep 2018 at 12:48, Les Newell  wrote:

> That assumes your tailstock is dead nuts on. If not you're going to be
> trying to compensate for a mix of tailstock + bed errors.

Indeed. In fact the linear component of the error will tell you how
far from the _bed_ axis the tailstock is.
A dial indicator on a long bar clocking round the tailstock bore will
then tell you something about the spindle axis to tailstock alignment.
Ideally you would align the tailstock to the bed, and then the
headstock to the tailstock
I think. .

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916


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Re: [Emc-users] More on bed wear fix

[Les Newell]

I am talking in terms of a
light cut on a stiff aluminium bar between centres.


That assumes your tailstock is dead nuts on. If not you're going to be 
trying to compensate for a mix of tailstock + bed errors. If you use the 
bar unsupported there are flex issues. Having said that you always get 
some flex in the work so maybe it is a good thing that the test bar 
flexes slightly...


When I was playing with the head alignment on my Colchester I used a 
large chunk of Delrin bar and a very sharp cutter. The bar was pretty 
stiff and cutting forces were low.


Les


On 25/09/2018 12:19, andy pugh wrote:

On Tue, 25 Sep 2018 at 11:15, Gene Heskett  wrote:


This is also true. But that test bar costs money too.

It can stay in stock as useful material. I am talking in terms of a
light cut on a stiff aluminium bar between centres.





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Re: [Emc-users] More on bed wear fix

[andy pugh]

On Tue, 25 Sep 2018 at 11:15, Gene Heskett  wrote:

> This is also true. But that test bar costs money too.

It can stay in stock as useful material. I am talking in terms of a
light cut on a stiff aluminium bar between centres.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916


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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Tuesday 25 September 2018 04:02:01 andy pugh wrote:

> I can't help thinking that the way to determine the amount of
> correction needed is to actually machine a test bar and measure it.

This is also true. But that test bar costs money too. ATM, I am 
considering a tapered gib setup on the front of the carriage because the 
compression of the bellows when working almost directly under the 
spindle nose seems to be lifting the left side of the carriage off the 
v-way. There is now a nearly full width gib in place of the original two 
tabs, both of which were so worn that someone in the past had moved the 
anti-spin dowel to the other side of the bolt to use it reversed. The 
one on the left was badly worn, the one on the right also served as the 
carriage lock but had been worn and over tightened so much that bolt was 
bent. So I put a full width brass bar there while I had the carriage 
turned over machining enough space for a pair of thin roller bearing 
thrust washers to support the X screw, installed into the ends of the 
original hand crank boss you can unscrew from the front. The brass bar's 
left end is also the home switch activator, tripping it about 6" out 
from the spindle. But this brass bar normally clears the bottom of the 
bed lip by around 20 thou.  The tapered gibs works great on TLM because 
its carriage is so narrow its nigh impossible to use a qctp on it and 
keep the point of the tool within the carriages footprint on the bed. 
But I have a vivid memory of the difficulty in getting the brass, 
tapered gib dead straight with a file that wasn't straight so there 
wasn't a spring effect in setting it. The first month I used it, the 
final wear-in used up much of the adjustment range but its now quite 
solid and hasn't been readjusted since. The difference in how TLM 
handles a 15 thou deep cut in steel 2" in diameter is amazing, no more 
tipping the whole carriage in the direction of the spindle allowing the 
tool to dig into the workpiece by 70 thou, bringing the spindle to a 
stop in 1 degree of rotation and breaking or stripping the teeth off the 
belt and timing pulleys between the 1 hp motor and the spindle. And 
usually breaking the carbide chip in the tool too.

But since the carriage on the Sheldon weighs 25 lbs, I didn't think it 
needed the holddown precision of a tapered gib. But the compression of 
the bellows on the left side of the nut seems sufficient to disturb it, 
cutting around 3 thou smaller moving right than when moving left for 
about the last inch to the spindle face. Thats something I didn't 
foresee when I covered the screw with a pair of bellows that will 
prevent swarf from getting into the nut. Relocation of the ball nut to 
the right on the back of the apron would be the only fix, leading to the 
same problem on the right, but which end of the bed are you usually 
working on? Losing 6" of travel at the right end due to fully 
compressing the bellows may have been the better choice, but that would 
also need the nut reversed on the screw if access to the greasing zerk 
was to be maintained. It can't be put in the middle of the apron because 
of the window and slider plate for the x motor mount. A new apron could 
be made I suppose, relocating the x motor left or right far enough to 
help, but removing the bellows covering the screw is not an option as 
its totally prevented any screw contamination. That of coarse would foul 
up the symmetry of the aprons front panel since the jog dials and such 
are on it.  Sigh.  I'll see how far to the right I can move it as the 
grease fitting is so close the grease gun can't get to it now, but 4 
bolts release it so a gun fitting can access it. A half an inch would 
help, a lot.  Needs more round tuits for sure... ;-)

Theres that old saw about hindsight always being 20-20 or better. :-)

Thanks Andy.

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 


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Re: [Emc-users] More on bed wear fix

[andy pugh]

I can't help thinking that the way to determine the amount of
correction needed is to actually machine a test bar and measure it.
-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is
designed for the especial use of mechanical geniuses, daredevils and
lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1916


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Re: [Emc-users] More on bed wear fix

[Gregg Eshelman via Emc-users]

RealD 3D glasses are 
inexpensive.https://www.amazon.com/gp/offer-listing/B005Q3HFB8/ref=dp_olp_all_mbc?ie=UTF8=all
 
How they workHow RealD 3D Works

| 
| 
| 
|  |  |

 |

 |
| 
|  | 
How RealD 3D Works

Follow us at: RealD.com Twitter.com/RealD3D Facebook.com/RealD3D Instagram: 
@RealD3D
 |

 |

 |




On Monday, September 24, 2018, 9:56:55 AM MDT, Gene Heskett 
 wrote:  
Asking the missus about the real3d polaroid glasses got shot down, so 
I'll have the troll thru fleabays poor search engine to find something 
usable. Finding a variable cell ready made would be ideal. OTOH turning 
down the current might suffice.  
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Re: [Emc-users] More on bed wear fix

[Greg Bentzinger via Emc-users]

Gene - Xray film exposed to light and processed makes for a very heavy filter. 
Perhaps a single dental xray would provide enough material.
Also if you know anyone who processes there own 35mm. Pan X or Plus X and maybe 
even Tri-X B film - the leader area will be fully blacked out.
Pan X would be the finest grain but Plus X wasn't far behind.
Greg

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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Monday 24 September 2018 09:55:45 Les Newell wrote:

> Hi Gene,
>
> I'd take the lens off of the camera so the beam directly hits the
> sensor. The laser beam is co-linear so you don't need to focus it and
> a lens just introduces distortion. Everything else will just be an
> even colour background so you should be able to fairly easily
> distinguish between the background and the beam. Maybe put a black
> tube in front of the camera to exclude extraneous light.
> I'd also suggest dropping the supply current to the laser diode. It's
> a while since I last played with lasers but I seem to remember getting
> a cleaner dot by reducing the power.
>
> Les

I have given that some thought, consisting of extending the rear of this 
thing about 15" and making a set of slip rings on the end so I can feed 
a current limited 5 volts into it from the back of the spindle. It takes 
2 ea 394 batteries which I suspect would not last the 2 hours or so of a 
recording session, and cost $7 a pop.

Asking the missus about the real3d polaroid glasses got shot down, so 
I'll have the troll thru fleabays poor search engine to find something 
usable. Finding a variable cell ready made would be ideal. OTOH turning 
down the current might suffice.

Right now I'm baking rattle-gun rustoleum self-etching primer onto the 
mt5-5c adapter, and carving the paint back off with a mitsubishi chip 
which is much sharper than the banggood version. Hopefully I can get it 
hard enough it won't stick into the spindles mt5. The idea is to find 
the magic taper that matches.

When I first made it, it fit well, but 2 months later I re-assembled it 
to find a wobble of about 1/16" 2" out of a collet. That was good enough 
to cut the brass rod for the "tap hats", but not much else. And the 
spindle is still true +- .0003, which is essentially the internal 
surface roughness. Plugged in the mt5 to 5c, and get 7 thou runout at 
the mouth of it, and its riding with most of that at the mouth because 
the small end is in-adequately tapered. So I'm painting it and diddling 
the taper about half a thou per inch at a time. And I'll continue until 
I get a good fit. Tempted to run a mig bead all around at both ends of 
the taper but don't want to run the mig current thru the bronze spindle 
bearings. Plus its thin enough to muck up the 5c fit from the heat.  One 
of those damned if you do, and damned if you don't things, so I'm 
punting with paint, baking it with a hair drier. ;-)

> On 23/09/2018 20:13, Gene Heskett wrote:
> > Greetings all;
> >
> > I seem to have carved, polished whatever, that mt5 to 5c adaptor
> > pretty much in error, despite my last attempt to reduce the small
> > end of it to fit the spindle taper, its still at least 10 thou small
> > at the shoulder, and I am running out of shoulder as I keep pushing
> > it to try making the big end of the taper actually fit the spindle.
> >
> > But before I make a last pass to true that up, I am going to put
> > this 38 spcl laser in a TTS holder with a 3/8" collet, in the 3 jaw,
> > and see how much wobble it has as thats fairly well corrected for
> > the spindle nose bend now.

And its beam wobbles about 1/2" at 30" out, intolerable. I've not tried 
the 4 jaw yet.

> > Looking at cameras, thinking of putting the camera and a rock64, and
> > possibly a small tft screen all in a nice compact qctp tool holder,
> > I'm still trying to figure out how to arrive at an image that:
> >
> > A: is ND filtered enough so as to not overload the camera, so
> > do I put the camera module inline with the beam but with an
> > nd-10 in front of it, in which case the camera has nothing to focus
> > on or put an nd-10 as a 90 degree mirror, using a 45 degree angle to
> > point the reflection at the camera looking across the bed, or
> > put a frosted glass so the camera has something to focus on, and an
> > nd-10 to keep from overloading the camera, mounted inline.
> >
> > Then we have the problem of averaging the image over several turns
> > of the spindle, and finding the centroid of the pattern that
> > results.  Do we have some (probably python) code to do that?
> >
> > I'll take this latter question to the python list too.
> >
And got a link to some simple python that does that centroid thing. But 
I'd like to future-proof it by making it run on python 3.5, however it 
appears that numpy and cv2 are both python-2 yet. So we'll see in due 
time.

> > But camera and filter mounting, I have a piece of nd-10 for a
> > dimming filter, and if dim enough, it might be possible to use the
> > camera as the integrator by taking a time exposure, that should work
> > well if the spindle turns an even integer of turns while the
> > "shutter" is open.
> >
I have a handy index signal from the spindle encoder that might serve as 
the "shutter". If the camera has that sort of control ability... One 
might even switch the laser on and off in synch with the index. Either 
way, there's the quantizing error of the 1 

Re: [Emc-users] More on bed wear fix

[Les Newell]

Hi Gene,

I'd take the lens off of the camera so the beam directly hits the 
sensor. The laser beam is co-linear so you don't need to focus it and a 
lens just introduces distortion. Everything else will just be an even 
colour background so you should be able to fairly easily distinguish 
between the background and the beam. Maybe put a black tube in front of 
the camera to exclude extraneous light.
I'd also suggest dropping the supply current to the laser diode. It's a 
while since I last played with lasers but I seem to remember getting a 
cleaner dot by reducing the power.


Les

On 23/09/2018 20:13, Gene Heskett wrote:

Greetings all;

I seem to have carved, polished whatever, that mt5 to 5c adaptor pretty
much in error, despite my last attempt to reduce the small end of it to
fit the spindle taper, its still at least 10 thou small at the shoulder,
and I am running out of shoulder as I keep pushing it to try making the
big end of the taper actually fit the spindle.

But before I make a last pass to true that up, I am going to put this 38
spcl laser in a TTS holder with a 3/8" collet, in the 3 jaw, and see how
much wobble it has as thats fairly well corrected for the spindle nose
bend now.

Looking at cameras, thinking of putting the camera and a rock64, and
possibly a small tft screen all in a nice compact qctp tool holder, I'm
still trying to figure out how to arrive at an image that:

A: is ND filtered enough so as to not overload the camera, so
do I put the camera module inline with the beam but with an
nd-10 in front of it, in which case the camera has nothing to focus on
or put an nd-10 as a 90 degree mirror, using a 45 degree angle to point
the reflection at the camera looking across the bed, or
put a frosted glass so the camera has something to focus on, and an
nd-10 to keep from overloading the camera, mounted inline.

Then we have the problem of averaging the image over several turns of the
spindle, and finding the centroid of the pattern that results.  Do we
have some (probably python) code to do that?

I'll take this latter question to the python list too.

But camera and filter mounting, I have a piece of nd-10 for a dimming
filter, and if dim enough, it might be possible to use the camera as the
integrator by taking a time exposure, that should work well if the
spindle turns an even integer of turns while the "shutter" is open.

Any thoughts are welcomed at this point before I start carving a mount.





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Re: [Emc-users] More on bed wear fix

[Gene Heskett]

On Sunday 23 September 2018 19:55:21 Gregg Eshelman via Emc-users wrote:

> A circular polarizing filter, like from a pair of RealD 3D movie
> glasses, seems to both dim and 'sharpen' a LASER beam somewhat. What
> it doesn't do is make the beam split into a row of dots like a linear
> polarizing filter does.
>
I hadn't thought of that Gregg, shame on me. I'll have to ask the missus 
if she has a pair (or a box of them) of those squirreled away someplace 
in this midden heap.

She's a retired school teacher.

But the array of dots is plenty visible right now.

Thanks for the reminder.

-- 
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 


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Re: [Emc-users] More on bed wear fix

[Gregg Eshelman via Emc-users]

A circular polarizing filter, like from a pair of RealD 3D movie glasses, seems 
to both dim and 'sharpen' a LASER beam somewhat. What it doesn't do is make the 
beam split into a row of dots like a linear polarizing filter does.

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