Grinding glass rods.

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dkemppai

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This one is maybe way out there... But with this group, you never know.

I have some unusual low CTE, lithium-aluminosilicate ceramic glass, and I'm wondering what equipment might be available to OD grind (centerless grinding???) this to a smaller diameter.

Would need to take a 40" long rod from ~1" down to say 5/8" or so. Have been thinking about building a grinder to grind other materials similarly, but haven't gotten serous about that yet. Also thinking about grinding threads and other features into this material... ;)

Any ideas? Concerns? Suggestions? Questions?
 
dkemppai said:
This one is maybe way out there... But with this group, you never know.

I have some unusual low CTE, lithium-aluminosilicate ceramic glass, and I'm wondering what equipment might be available to OD grind (centerless grinding???) this to a smaller diameter.

Would need to take a 40" long rod from ~1" down to say 5/8" or so. Have been thinking about building a grinder to grind other materials similarly, but haven't gotten serous about that yet. Also thinking about grinding threads and other features into this material... ;)

Any ideas? Concerns? Suggestions? Questions?
Click to expand...

First: Serious PPE

On to the reply: back in the mid-90’s the composites company had to produce a odd sized rod from material that contained fiberglass, carbon black and resin; we found a local shop that was willing to run rods (probably 12” long) through their centerless grinder at a reasonable cost. We then just needed to cut to length which wasn’t a big deal.

If they could handle that material they probably could do glass, but don’t know what their length limitations were, and don’t ask me who they were (may even have had to ship the stock to them). Point is, someone is set up that can do it for you.
 
It feels like wet diamond centerless grinding might be able to do it. That's a LOT of material to remove, and a long part for brittle materials.

Thread grinding is really getting out there... you likely don't want regular v threads. Radius root feels important. Or threads kind of like a light bulb.
Glass threads tend to be funny looking.

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This is a long term back burner project.

The first thing was getting my hands on this rod. It's basically unobtainium. Been trying for years with no luck. And finally managed to find something. Would have preferred something closer to size, but that just isn't going to happen. Not unless I win the lotto! So, took what I could find.

Was considering a purpose build machine to wet grind it. Stepper to rotate the rod, and a stepper to advance it or the grinding tool. Resin bond diamond wheels are pretty cheap now.

Tried a custom glass shop. They do similar things, but declined. I think they could do it, but are afraid of breaking it.

Still considering options here. Plenty of time to ponder this problem. Any input or suggestions are certainly welcome.
 
I'm tempted to say use a belt sanding attachment.
Uniformity might be an issue but you can swap out you grain size on the belt to achieve you finish then hunt with an indicator any high spots to polish even further. I would think you would be buying several grinding wheel, but may get away with just one depending how you dress it to achieve the final finish. I think though you'll be hand polishing for the final finish.

 
This needs the be ground with diamond, so not sure the belts would do the trick. (Although that looks like a handy attachment!)

This stuff is pretty hard, on the order of borosilicate glass from what I'm told. Normal applications are scientific optics, and extremely expensive telescopes.

The big property that everyone likes is the coefficient of linear expansion. Fused quartz is good, and this stuff is two orders of magnitude better (also two orders of magnitude better than invar36).

I wish I would have been able to find raw stock closer to size. Even getting this was a miracle.

So, if it takes a week or a month to grind it doesn't matter. It's hobby stuff anyway.
 
dkemppai said:
This needs the be ground with diamond, so not sure the belts would do the trick. (Although that looks like a handy attachment!)

This stuff is pretty hard, on the order of borosilicate glass from what I'm told. Normal applications are scientific optics, and extremely expensive telescopes.

The big property that everyone likes is the coefficient of linear expansion. Fused quartz is good, and this stuff is two orders of magnitude better (also two orders of magnitude better than invar36).

I wish I would have been able to find raw stock closer to size. Even getting this was a miracle.

So, if it takes a week or a month to grind it doesn't matter. It's hobby stuff anyway.
Click to expand...
Diamond grit sanding belts are available, McMaster Carr has them.
 
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