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I just finished my powered dish sander and am happy to not have to "drive the bus" with manual steering! I used a 1/4 HP gear motor with 72 RPM output, flexible coupling and flange bearing which drives a sprocket that I modified as a drive plate with 3/4" spindle and a 1/4" drive pin. The radius dishes have a corresponding 3/4" center hole and 1/4" drive pin hole and the whole mess rides on 8 ball bearing casters. I added a foot switch for start/stop.

I couldn't be more pleased with the smooth, quiet operation of the machine and the 278 inch/pound torque rating of the gearmotor is very powerful and does not slow down with even the hardest of sanding. I have sanded ukuleles and jumbo size guitar frames and it sure beats manual sanding.

I purchased all of the mechanical components on good old eBay and was happy with the quality of everything that I received.

Mike Franks
mjfranksguitars.com
http://www.facebook.com/mjfranksguitars

Very nice! We've been thinking of building one, but vertical to save space...

That is a great machine
Good job

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Joe Beaver
Maker of Sawdust

I like your caster support system, simple but practical.

Bob

Like it. Creative!

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Pat

That is a great machine
Good job

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Joe Beaver
Maker of Sawdust

Nice work. Do you have a list of the parts on EBay? I want to build one of these.


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I have a slightly different design, and mine works well, but you have given me some upgrade ideas. Thanks!

Dust control?

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Ken Cierp

http://www.kennethmichaelguitars.com/

This has given me an idea. My wife has an industrial pottery wheel that has been gathering dust for long enough!

Thanks!

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Wish I had the space, even for a vertical.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I never would have thought of using casters!

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Yeah... the casters are a nice idea... at first I had to laugh over the simple practicality of it. They will align nicely as the wheel is turning. Pretty darn clever!

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"I want to know what kind of pickups Vince Gill uses in his Tele, because if I had those, as good of a player as I am, I'm sure I could make it sound like that.
Only badly."

I like it, but I don't understand the gear mechanism. Can you show a picture of the underside of the dish?


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Think its being driven by the offset pin.

Nice simple design. Wish I had he room for something like that

Mike could explain in detail, since he built it, but it looks like the choice of the sprocket on top is just a matter of convenience, because it is round and flat and it fits securely on the end of a drive shaft. The teeth on the sprocket don't do anything. There is an offset pin on the outer edge of the face of the sprocket, and that pin inserted into an offset hole in the bottom of the dish provides rotational movement. Is that right, Mike? Like Tim said, that's a simple and effective design. I do something similar with a pulley instead of a sprocket, but I like the sprocket idea better. I also like the idea of having the drive shaft fit up into a centered hole in the dish; it helps keep the movement of the dish strictly rotational. I have been using two equidistant offset pins in my pulley, and it can shimmy around a little too much. Mike's way is better.

Who else wants to see an action video?

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

I think seeing such a video without the dish on top would explain how it works better than having the dish in place. We'll see the sprocket rotating, and the offset pin spinning in a circle. But it would also be cool to hear how the casters sound with the dish in place. I bet they are pretty quiet, compared to the noisy Lazy Susan I currently use.

Thanks to all who have commented on my dish sander. I will try to address some of your questions. After contemplating the design for some time, I purchased all of the components on eBay, at one sitting. The mechanical components are as follows:

Marathon/Bison Gearmotor, parallel 3/4" output shaft with keyway. 1/4 HP, 110/220vac, 27.82:1 ratio with 62 RPM output at 238 inch/pounds torque
Lovejoy Flexible Coupling, 3/4" X 3/4" keyed
3/4" I.D. Flange Bearing
3/4" X 12" Keyed shaft
7" X 1/4" flanged sprocket
(8) Ball Bearing Casters
Foot Switch

I was fortunate to find the gearmotor new in the box for about $250. The 62 RPM speed is perfect and allows good control of the workpiece. I was uncertain of the ideal rotational speed but considered that manual sanding at 1 rev per second was that speed that I worked at. Don is correct in that I chose a sprocket because that is what was handy for the drive plate. The steel is soft enough (apart from the teeth) to drill and tap for the 1/4" drive pin which I made from a cut off bolt. The table top is 3/4" plywood and I made it large enough to catch the sanding dust. I thought about dust collection but the dust when sanding is not airborne and is easy to vacuum off of the top of the machine after sanding, much like I did when manually sanding.
I screwed a 3/4" thick plywood backing plate to each of my radius dishes and drilled the center hole at 3/4" with the 1/4" drive pin hole. I used the actual drive plate as a drill guide after locating the center of the disc.
The casters are self-aligning, very quiet and work very well. The soft rubber tires are kind to the disc.
I pre-cut all of the wood frame pieces and used carriage bolts to assemble. I probably over-built the frame but it is solid as a rock.

I took a quick look on eBay and there is a good selection of 1/4 HP gearmotors to choose from. Many of them are rated for 90 VDC but I see a few that are similar to mine.
I'm not quite sure of how to upload a video but will give it a try if it would be of help to anyone considering building a dish sander.

Best,
Mike Franks
www.mjfranksguitars.com
www.facebook.com/mjfranksguitars

I get tired of "driving the bus" too. I'm thinking about how I could modify a used washing machine.

You must have bigger washing machines in the States, no way could I get even a parlour into mine

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I am unable to find the link, but the simplest power rim contour sander set up I ever saw, used a 1/2" variable speed drill with a small sanding drum (2"?) in the chuck. The drum rubbed against the turn table (two layers of MDF) with a center bearing. Instead of casters, the thrust bearings were pieces of Teflon fastened to the base. All kind of like the old phonograph record turn table worked.

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Ken Cierp

http://www.kennethmichaelguitars.com/

Happy hour must start early on Fridays, Colin!

Alex

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"Indecision is the key to flexibility" .... Bumper sticker

No kidding! Obviously you have to put it in there without the neck attached.

I use the wringer to thickness my plates too. I just run billets through until they are smashed down thin enough but sometimes my arm gets tired (especially if I start with 4/4 stock).

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

Cheers!

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.