[walter]

Nope. I finished the castings but didn't think it was good enough, so I shelved it. Frankly, I don't really care anymore.

[ckelloug]

Walter,

Are you talking about the little mini-mill base or your grand router?

[Eson]

Found this, nothing new but still: http://cmpnd.org/content/view/92/

[jstransky]

Can you take a look at the quarz sand in the link. It is 98% SiO2 sand used for water filtering in pools. Size up to 4 mm.

http://www.kerkosand.sk/files/KA_PP_CZ05.pdf

They make a sand for casting too, but the size is just up to 1.4 mm.

http://www.kerkosand.sk/files/KA_KS_SK03.pdf

Regards jstransky

[jhudler]

jstransky,

Sand filters for pools use a specific size of sand so that is does not pass through the screens and also to minimize hydraulic friction.

This is why pool sands have a large quantity of one size or a narrow range of aggregates. Any fines in the sange will be picked up by the pool cleaner and filtered out.
Pool sand has many contaminates that should be acid washed to remove.

The Kerkosand is a much better material for EG. It also has better grading (sizing) data and very clean.

Jack

[jstransky]

What do you think about the maximal grade size - 1.4 mm. Isn't it too small ?

jstransky

[jhudler]

jstransky,

If that is all you have on hand then go with it. If you can find some larger aggregate such as crushed granite or whatever is in your area.

Jack

[jhudler]

Ok I lapped it last night.
Some of those scratches are 2 micron and smaller. Going to fast and not practicing good cleanliness between grits.
Cool part's in the video.

It's 100% 3M Zeeospheres 200 and US Composites 635 2:1 Epoxy. 24 cure, then 2 hours at 50C.

Diamater is 100mm, ~35mm thick and the surface is flat to within +-.0005 or ~12 microns over 80mm.

[Eson]

That's sick! Unbelievable cool.

[magick_man]

Walter your picture reminded me of E-bay listing #320203796630
The blocks are sr-20 rails 460mm long.One rail and one block is$25.00
The guy only has 250 of them.Remember SR's are for horizontal use.
Larry

I just wanted to thank you for posting this auction.
I ended up scoring 14 sets of them for use in my machine.
And if you hadn't have posted this I would have never known about them.
I would have just sent you a PM but your box is full.

Joseph K.

[Zumba]

Very nice work, Jack. No de-airing agent?

Where did you get your Zeospheres? Same place as Walter? How much did you guys pay?

[jhudler]

Walter purchased his at Cary Co. Mine was from Ribelin Supply in Garland, TX.
The 800/850 run about $25-$30 a 50 lbs bag, the 200 from $35-$50 bag.
If they quote you a ridiculous price per bag or pound, then don't hesitate to call them on it. They might send you to another sales department or salesperson, but you will get the lower price. If not move on to the next distributer or call 3M.

Oh, you do! want to pick this up.

Jack

[ckelloug]

Jack,

Your video of lapping the E/G block and wringing it to a gage block is remarkable. Do you have a story on the process behind creating the E/G block? How level did the E/G get on it's own and how much lapping was required to get the surface into that state?

Regards all,
Cameron

[jhudler]

About a little over an hour.
I had originally cast it upon a black granite surface plate, but the release agent was visible in the cured flat. I used a release agent because I didn't want to trust micro-crystalline wax on its own.
So I ended up reverting to using sandpaper for the first few steps.
Something this small is easy to do with sandpaper up to 800 grit.
I then switched to diamond paste on flat glass down to 1 micron.

That was before... I never really mentioned it online because it was such a small thing.

I then used it as a coaster on my desk.

When Walter wanted to see pictures I re-poured a new 1/4 inch top and just used sand paper from 150 - 1500.

Something larger than this would require flat glass on a surface plate, or some serious time on surface grinder, or laser interferometer with the optics to calibrate a surface plate, or an autocollimator. Latter two requiring some serious patience.

Where is it now? Locked to my surface plate... need to get the air hose on it and pop it off! Make an excellent vacuum preloaded air bearing mount for a indicator on a surface plate .

Jack

[Gizmot]

Where is it now? Locked to my surface plate... need to get the air hose on it and pop it off! Make an excellent vacuum preloaded air bearing mount for a indicator on a surface plate .

Jack

funny that you mention that. I have been lurking in the back of this thread for a few months and that is what I'm currently researching.

[Eson]

Does anyone know any price for moglice? I really want to try to make my own hydrostatic bearings. Besides does anyone know of the minimum amount of space required for moglice to fit, i hope you understand what i mean.

[lerman]

Does anyone know any price for moglice? I really want to try to make my own hydrostatic bearings. Besides does anyone know of the minimum amount of space required for moglice to fit, i hope you understand what i mean.

Please let me know what you find out. I'm interested in using moglice as part of a DIY low friction, low backlash leadscrew. The idea is to take a plain old acme screw, lap it against a brass nut until it is uniform and then make a nut lined in moglice.

The moglice site claims that it is usual to have clearances of .0002 inches on an accurate screw and that this can be polished to .00005. So, if we could lap a screw to be consistent to 50 millionths, we could build one with a backlash of a tenth (twice 50 millionths).

That's not bad for DIY.

Ken

[harryn]

Please let me know what you find out. I'm interested in using moglice as part of a DIY low friction, low backlash leadscrew. The idea is to take a plain old acme screw, lap it against a brass nut until it is uniform and then make a nut lined in moglice.

The moglice site claims that it is usual to have clearances of .0002 inches on an accurate screw and that this can be polished to .00005. So, if we could lap a screw to be consistent to 50 millionths, we could build one with a backlash of a tenth (twice 50 millionths).

That's not bad for DIY.

Ken

Hi Ken, I had no idea you could hand lap a thread to that kind of accuracy. Pretty amazing.

[USMCPOP]

I haven't seen most of this thread, so pardon me if it had been discussed. Has anyone given any thought to using some ground fillers like slate flour, fly ash, rottenstone, floated silica or the like? Just noticed that some of these materials are not unlike granite in their composition and should be dirt cheap as a fine filler. The old "Keystone filler" was used many years ago as a filler/finish for cast iron machine tools.

[harryn]

I haven't seen most of this thread, so pardon me if it had been discussed. Has anyone given any thought to using some ground fillers like slate flour, fly ash, rottenstone, floated silica or the like? Just noticed that some of these materials are not unlike granite in their composition and should be dirt cheap as a fine filler. The old "Keystone filler" was used many years ago as a filler/finish for cast iron machine tools.

Hi - Thanks for joining into this thread. It takes a bit of digging, but the general idea has been around obtaining "high end" performance in an epoxy / filler mixture. The short story, is that this entails mixing well known / sized fillers with specific size ratios and minimizing the epoxy content, as well as finding ways to minimize air bubbles and enhance the bonding to the filler.

There still is room for improvement in the mix, especially if you start to move into tensile strength areas. The trade off has been increasing cost and ability to obtain the right size materials.