View Full Version : Ground Glass Grinding Tool

15-Mar-2011, 14:10
I've made a few pieces of ground glass for my camera over the years and today I needed to make a larger one for a new camera. I've only used the 5 micron powder to grind it and it can take some time with that fine a powder so I came up with an idea I'd like to share.

I have a round Dynabrade Orbital Air Sander. I took an old pad and scraped the foam off the plastic mount. Next I made a square blank out of MDF and screwed the plastic mount to it. Next I took a scrap piece of 2mm glass that I cut slightly smaller than the blank and epoxied it to the blank. Once set up I mixed more epoxy and spread it around the edges of the blank to keep water from soaking into the MDF.

My dad use to have a saying about the tireless arm of electricity and it sure worked well today. The sander did all the work and did it well. I ran the rpm's very slowly. I suppose if I were to get some coarser grit and run the sander at a higher rpm it might move along a little quicker but since I'm not making these to sell I see no reason to rush it. I just needed a method to make it easier. I didn't keep exact time for grinding but I think it was around 25 - 30 minutes for a 6 1/2 x 8 1/2" piece of Schott Borofloat glass.

I was thinking whether this idea could be adapted to a cheap electric orbital sander but it might become a bit dangerous if the speed can't be controlled.

Drew Wiley
15-Mar-2011, 14:18
How much are you willing to spend? (that is, in the hundreds, not thousands). I'm
testing some pretty interesting new German gear right now, but a bit at time. I'd think
the Dyanbrade or a conventional orbital sander would be too fast an orbit and suffer
from regrinding the dust due to poor pickup. I deal with some pretty specialized trades
including custom glass polishing. I also have some very specialized abrasives on hand.

Jim C.
15-Mar-2011, 20:33
testing some pretty interesting new German gear right now, but a bit at time.

Festool ?

Drew Wiley
15-Mar-2011, 20:39
Jim - I don't like mixing photog talk with potential promo of my day job, but yes, among numerous other things I am a Festool dealer with the entire line in stock, yeah, the whole damn catalog, including every abrasive they make. Also carry Fein. I've been fiddling with some scraps of tempered glass out in the shop before I turn things loose on the real deal. Always testing.

15-Mar-2011, 20:50
I'll have to remember this. I can see trying to use my drill next time I have a GG to polish.

They gave me a glass desktop award thing at work, and I used it as a grinding blank to freshen my GG. Is that bad?

Brad Rippe
15-Mar-2011, 21:06
Hey Bettersense, It's called re-purposing, excellent use of a trophy.
You might try black emery paper with water as the lubricant, works fast, and the water removes the grit very efficiently.

Drew Wiley
16-Mar-2011, 08:49
Glycerin and PEG are also effective lubricants which stay in place a little better than

Drew Wiley
16-Mar-2011, 09:01
Ordinary drills work quite poorly. They're apt to overheat and have an uneven swirl
pattern. But if you have a decent mini-grinder with variable speed, and can get the
speed way down to 2000 RPM or so, then you can find the appropriate polishing
attachmets, including diamond-coated discs. Just be careful with lubricants. True
water-fed polishing gear on this pattern is actually tested by UL underwater for shock
hazard, and is comparatively expensive. I've got some of those machines on hand to test too.

17-Mar-2011, 14:10
try getting an old variac-it will allow you to change the speed of and tool that doesn't use a synchronous motor.
so pretty much every tool with a motor will be slowed by it.
I use mine for slowing down a drill press occasionally when the slow speed on it is still too fast.

20-Mar-2011, 11:06
Be very careful not to breathe the dust from glass grinding. You don't want to end up a pulmonary cripple from silicosis.