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Disc Sander (Stumpy Jig Contest)

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Project by Quietflyer posted 03-31-2012 02:26 AM 4582 views 31 times favorited 20 comments Add to Favorites Watch

I picked up a couple of these 1 hp treadmill motors from Princess Auto (a Canadian discount auto parts/tool/surplus/everything store) on sale for $20 each and figured I should do something with them, so here we are.

I designed this sander, stealing ideas from the sander built by John Heisz (ibuildit.ca). His is a little more complex than mine in a few ways.

The disc on my sander is made from an Ikea shelf I picked out of the scratch and dent pile for a dollar or two. It is then mounted onto a split bushing, which is then mounted onto the treadmill motor. I had to drill and tap a hole in it for a set screw, since the bushing is designed to use a keyed shaft, and the motor was designed to use a set screw. Not a big deal, except that on the first few test runs, the set screw would back off the slightest bit and the disc would start “migrating” on the shaft. A few drops of superglue on the set screw solved this problem.

Other than the motor cover, the rest of the sander is made from baltic birch ply, a mixture of 12 and 18 mm.

I made the table rather huge, just because I could. Its 18 mm birch ply, and I put a stiffener along the bottom. By gluing up the whole thing while it was clamped firmly to my table saw table, I managed to get a pretty flat and true surface. The table is mounted to the body of the sander using a piano hinge. Several disc sanders I’ve seen online (including John Heisz’s) use complicated trunnions to keep the edge of the table close to the disc at all table angles. I didn’t bother with this, since I figured probably 90% of my sanding would be with the table at 90 degrees to the disc. I also didn’t add a mitre slot, figuring most of the sanding would probably be freehand. If I need one, I can always add it later.

The trunnions are 12 mm ply. I cut the slots using a spiral bit on the router. I made the handles out of some scrap cherry and some carriage bolts.

I added a curved MDF “ramp” in the base on the downward side of the disc to improve dust collection. With the guard and ramp installed, this machine moves quite a lot of air on its own. I was surprised! With a shop vac attached to the collection port, there’s virtually no dust put into the air.

The guard over the disc is made from many segments of 12 mm birch ply, glued to a 12 mm ply back panel.

I put two coats of water based poly on the whole sander, and two extra coats on the table top (figuring it would see hard use).

The switch is a standard household light switch. I’m proud of having wired this thing up without burning/shocking/melting anything, since my electrical skills are poor at best!

I’m quite pleased with the performance of this sander, and I figure I spent about $100 in total, for a tool that would cost $250-300 if purchased new from a store.

The second motor may or may not be reserved for a band saw ;)

UPDATE: I never thought I’d get this much interest in my disc sander! If people would like, I can try to clean up my CAD drawings a little, and I can post them somewhere. They won’t be complete step-by-step plans by any means, but they might be useful to someone trying to build a sander.





20 comments so far

View SuburbanDon's profile

SuburbanDon

486 posts in 1679 days


#1 posted 03-31-2012 03:47 AM

Crazy man. As a kid I had a neighbor who made an electric lawn mower this way. It’s amazing what can be done.

-- --- Measure twice, mis-cut, start over, repeat ---

View Rick's profile

Rick

6454 posts in 1718 days


#2 posted 03-31-2012 08:14 AM

Excellent Idea!!

-- COMMON SENSE Is Like Deodorant. The People Who need It Most, Never Use It.

View stefang's profile

stefang

13251 posts in 2020 days


#3 posted 03-31-2012 08:34 AM

Great work! I would suggest you cut a miter gauge slot in the table. Mine is very useful.

-- Mike, an American living in Norway.

View Belg1960's profile

Belg1960

808 posts in 1751 days


#4 posted 03-31-2012 11:37 AM

Flyer like your project very much. Can’t seem to locate a keyed or split flange, where did you get yours?

-- ***Pat*** Rookie woodworker looking for an education!!!

View Quietflyer's profile

Quietflyer

36 posts in 972 days


#5 posted 03-31-2012 01:45 PM

The split flange came from Princess Auto as well. I don’t know if you’re in Canada or not, but give them a shot.

View Belg1960's profile

Belg1960

808 posts in 1751 days


#6 posted 03-31-2012 02:19 PM

Im in the states so my search continues, thanks for the reply though.

-- ***Pat*** Rookie woodworker looking for an education!!!

View Woodwrecker's profile

Woodwrecker

3632 posts in 2261 days


#7 posted 03-31-2012 02:21 PM

I want a large disc sander and I actually think I have all these parts laying around.
Thanks for your version of this machine.
Time to start collecting parts!

-- All glory comes from daring to begin.

View Belg1960's profile

Belg1960

808 posts in 1751 days


#8 posted 03-31-2012 02:25 PM

Woodwrecker pm sent

-- ***Pat*** Rookie woodworker looking for an education!!!

View doncutlip's profile

doncutlip

2832 posts in 2242 days


#9 posted 03-31-2012 02:46 PM

Cool design, nice build

-- Don, Royersford, PA

View DaveTPilot's profile

DaveTPilot

271 posts in 1984 days


#10 posted 03-31-2012 08:23 PM

I LIKE it!

-- How valuable is time to a person who spends his disparaging the beliefs of others? --David Berthelette www.pilotwoodworks.com

View kiefer's profile

kiefer

3162 posts in 1352 days


#11 posted 04-02-2012 02:29 AM

Great sander design and resourceful use of inexpensive components ,I like the dust chute design .

Belg 1960 look at a store that sells chain and sprockets, like a farm supply .

Kiefer

-- Kiefer 松

View Enoelf's profile

Enoelf

192 posts in 949 days


#12 posted 04-02-2012 02:45 PM

Oh, that’s cool! I have a treadmill motor that I removed from an old treadmill just laying in the shop. This might be a nifty use for it!
I have been wondering about using the motor with a belt/pulley system of some kind that could be used to power several different hand-made machines.
Thanks for sharing.
Well done.

-- Central Ohio, Still got 9 and 15/16 fingers!

View bushmaster's profile

bushmaster

185 posts in 968 days


#13 posted 04-04-2012 09:46 PM

I also bought a couple of those motors, using one for a v drum sander. could you give me what numbers to hook the wires too thanks.

-- Brian - Hazelton, British Columbia

View Quietflyer's profile

Quietflyer

36 posts in 972 days


#14 posted 04-04-2012 11:22 PM

bushmaster,

DISCLAIMER: I am not an electrician, and I’m convinced it is just luck that kept me from setting my shop on fire in wiring up this sander. Use my advice at your own risk

I have the white and black wires attached to poles 2 and 5. It doesn’t seem to matter which goes onto which, the motor appears to run just fine regardless.

I attached the ground wire to the motor case with a screw.

View bushmaster's profile

bushmaster

185 posts in 968 days


#15 posted 04-05-2012 03:20 AM

Quietflyer

Thanks, the electrican for the school district thought that was how it should be wired. will try it tomorrow, I paid 15 dollars on their last sale. Your sander looks like a professional job. Thanks for sharing the information.

-- Brian - Hazelton, British Columbia

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