homebuilt disc sander

Greetings, I want to build a simple 12 inch disc sander. I have a motor, and know what I want to build. BUT, what can I use for the disc? Speed wll be 1725 RPM utilizing a 1/2 horse motor or alternately 3450 RPM using a 1.5 horse motor. I don't want to make something that might fly apart. Looking at some of the cheap (grizzly, harbor freight) disc sanders, they seem to use aluminum for the disc to which an adhesive sanding disc attaches. I don't have access to a 12 inch aluminun disc. Would a plywood or MDF or for that matter a solid wood disc be acceptable? Any suggestions for a backing material that would be safe to use? Something already round and 12 inches in diameter would be ideal. I can drill a center hole to adapt to the motor shaft. I have considered an abrasive cut--off disc but can't fine one in a 12 inch size. Obviously, the material needs to be ridged enough not to flex when pressure is applied to it's face. Ideas? suggestions? TIA Mike in Arkansas
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"JMWEBER987" writes:

Fred Bingham to the rescue.
Go to the library and get a copy of Fred's book, "Practical Yacht Joinery".
You will find sketches, drawings, the whole works, It how I built mine.
If you wonder why a boat building book for a disk sander, you haven't tried to finish a boat, there is simply no more important tool, IMHO.
HTH
--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
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Hell of a boat Lew. What did you use for the disc on your sander? Mike
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"JMWEBER987" writes:

Thank you. Those pictures on that site are way out of date. May get around to updating them someday.

I had a commercial 12" aluminum disk available; however, it would be NBD to use a sink cutout trimmed to size with a router with a circle jig and a small plywood block added on the backside to increase the bearing area for the motor shaft.
Not only are sink cut outs low cost, they will also have a laminate on one side to provide a smooth surface for the sandpaper.
Don't like a sink cutout, use a piece of 13 ply Birch and add laminate.
HTH
--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
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On 23 Apr 2004 23:24:39 GMT, snipped-for-privacy@aol.com (JMWEBER987) wrote:

go larger then 12" as you don't get to use much of the disc.
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Knight-Toolworks & Custom Planes
Custom made wooden planes at reasonable prices
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Plans for one here, it has 9" disk could be modified for 12": http://benchnotes.com/DISK%20SANDER%20/Disk_Sander.html
Frank C.
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http://doit101.com

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wrote:

The Shopsmith disc mounts on a 5/8" shaft. http://www.shopsmith.com/ownersite/catalog/SandingPromo04/sn_sandingdisc.htm Check ebay for used ones.
Paul.
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"Scarfinger" writes:

SFWIW, That's the one I used.
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Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
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