Disc grinder.

Joined
Oct 5, 2001
Messages
108
I am about to buy a disc grinder for my bench grinder. I am looking at the one on Koval knives.My question is they sell 7" and 9" round sand paper that cost $3-$4 each, this seems very expensive, could I just but sheets for 75 cents each, cut out the 8" circle and use spray adhesive? I wonder if the Koval $3 sand paper will hold out much longer or not. So basically would I be better off buying sheets and making them fit my disc grinder? Thanks a lot for all the help.
 
Howdy There mpj13..!
Here's my two cents, us the cheaper sandpaper and use the spray glue to put it on the disk. Also you can get intouch with Rob Frink at his website "Beaumont Metal Work", have seen Rob's work and he does a great job.
Good Luck..!
"Possum" :cool:
 
9 x 11 sheets, and adhesive. Around here we put 3/32 rubberized cork gasket material on the face of the disk. I gives you a little better usage of the paper.
 
I mounted a rubber disk to my disk grinder. I use wet/dry sandpaper and spray adhesive. The rubber disk gives a very smooth finish and NO chatter. Hand sanding time is drastically cut using this method.
 
While I've been a firm believer and follower of the sheet and spray adhesive method, recently I've been wondering about the alternative.

I've talked with other makers that swear by the psa discs since they last longer...and I've gotta say that they're tougher and more resilient to water. Since I'm always dipping everything in water while grinding it...

But the sheets are waaaaaaay cheaper. I have to do some more experimenting though. Because with 2X72" belts, the ceramics are 3 times as much money as the aluminum oxide belts...but they last 5 times as long.

We'll see if that's the case with the discs :)

Good luck,
Nick
 
Are all of you guys using a side mounted disc sander? I'm thinking I want a horizontal disc like the one Tom Anderson had, with a speed reducer. That way I can just lay the piece on top while it's turning:

tom1.jpg
 
I think I will start out with the cheaper paper and buy one PSA piece and test it out to see what works the best. For price of one PSA disc I could buy 4-5 sheets. I will also try to get either a wood or rubber disc of some sort to put on my disc grinder.

I bought a simple bench grinder, I am at work now and I can't check it out myself but I wanted to go ahead and order the flat disc grinder soon, is there a standard size shaft on most grinders? I could buy a 1/2 or (I can't remember the other size) I just don't want to get the wrong size, I hate returning anything I buy on the internet.
 
I use 3 disc sanders (3 sizes of sandpaper) two operate at 1725 r.p.m.and one at approx. 1000 r.p.m. I sure like the slower one the best. The slower one is horizontal the others are vertical. I can't say that one system is better than another. What I have also found is that having a 3/4 plywood with an arborite overlay will dampen vibration and make the surface easy to clean. I found that the cork or rubber thing was hard to clean and did not produce good flat surfaces in preparation for hand sanding. Just what I have found. Frank
 
You know, I'm thinking that the disc sander at Tom Anderson's was going at a speed of no more than 100-200 RPM. It was very slow. Which is why you see him holding the piece so calmly in the pic above. We all took turns on the thing and it wasn't spinning a whole lot faster than a record player. It did a fine job too, BTW and the work didn't get overheated. Tom uses only 100 grit discs.

From my workshop notes:

Dayton Gear Reducer, Model 23.4:1

9" disc, 100 grit paper.

I believe the motor was a 1/3 or 1/2 horse motor.
 
Yes, slower is better. Mine runs around 150 RPM. I had the same problem as Frank when using the faster disks. The surface didn't seem as flat. Drag makes the blade rock. Under 200RPM, you can feel better what is happening, and control the process better.

The stock does not get as hot either.
 
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