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I want to make a power rim sander that I can use to radius the sides for the top and back. I am curious on motor size (I have a new 3/4 hp motor), rpm suggestions for the sander and any general pics.

Thanks!

Laurie

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Time you enjoy wasting is not wasted time.

I haven't made one (yet) but Bruce Sexauer has what I think is the best/easiest set up. He's got a lazy susan bearing on the bottom of his dish, mounted to a piece of plywood that's big enough to clamp on his drill press table. He clamps in on the drill press table, and uses a rubber sanding drum, with no sanding sleeve against the dish to turn it.

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So far I've decided not to make one since doing this step by hand is one of the few ways I get some exercise in the shop. I know that doesn't help.

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Randy Muth
RS Muth Guitars Website
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Laurie, Here's mine, really simple. You can build one in an hour or less. 1/2 hp 1725 rpm motor with an arbor to mount the 1 1/2" diameter freeze plug (wheel). The table has a lazy susan mounted and a 3/8" dia. bolt in the center to put the dish on. I use a bushing in the dish to keep the center hole from wearing.

Chuck

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I would have thought that a sanding dish operated from above, with the sides held in the mold, and the mold fixed to the bench, would be a more efficient and accurate way to sand the required radius.

I could well be wrong however, and would be interested to hear the reasons why.

Here's mine...a knock down version I use to flatten plate backs.
Starts with a 1/4hp buffer, (which I convert to drive motor with a hockey puck), mounted in a leg vise. The benchtop disc rotates into it.

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Dave
Milton, ON

Hey Chuck, love your design! Crude and simple, just the way I like it!

Could you give a little more info on the "freeze plug"? What is a freeze plug and where did you get it?

Thanks!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Alain, they may have another name, but basically are used when winterizing plumbing for swimming pools or trailers. Just a rubber disc with a hole in it for a bolt, with washers on each side. Tighten the bolt and expand the plug. Used to seal pipes that are not in use so water does not get in and freeze during winter. They are available at hardware stores...may be called simply expandable plugs. Just put the rubber and washers (may have to drill both out) on the arbor and tighten...makes a great drive wheel.

Sorry for the confusion,

Chuck

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Ok, I see now.

Thanks a lot for the clarifications! I've been wanting to make a design quite similar to yours for quite some time and was still wondering what to use as a drive wheel. Now I know!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Look for the thread on Brad Way's dish sander. I am going to rebuild mine and am going to start with 90 degree gear reduction plate from Princess Auto (they are about $200 I think). A 20:1 reduction and some pulley sizing from the motor to the gear reduction will get to the 110 to 120 final rpm I am after. If I can get 15:1 reduction with a 1750 rpm motor I am right around 116 rpm which is just perfect. Using one of these you should not need a lazy susan bearing which is what I am trying to get rid of. (worn out two already!)

Shane

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Canada

Barry Daniels built one with some heavy duty lazy suzan bearing (from McMaster-Carr) that seem to work well for him.

Here is the catalogue link: http://www.mcmaster.com/#18635a22/=alun7p

That's what I'll be trying.

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Here is the link to Brad's earlier thread. Even though I have a sander that works fine I will be following his lead and will be re-building mine next year because I want mine to be really smooth and it is only "OK" right now but probably more than adequate with the bearings.

http://www.luthiersforum.com/forum/viewtopic.php?f=10102&t=9836&hilit=rim+sander

Shane

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Canada

Here's a picture of mine. I was feeling very cheap at the time and found a 1/6 hp motor on craigslist that I picked up locally. It is really old though so maybe the 1/6 horse is stronger than today's horse.

I designed it to fit over my bench but miscalculated the v-belt length some so it's a bit longer than it has to be (by like almost a foot) but that's not necessarily that bad as it makes it easier to put it on the bench top. I'm using a lazy suzan as a bearing and at first I had a pin with a bushing in the center as I felt that the LS was too sloppy but I've since changed my mind as I thought the bushing was sucking too much power.

1/6hp is a little weak but the good news is that everything goes nice and slow and it's very un-likely that I'm going to ruin something at that speed. I sometimes wish I had 1/3 or 1/2 hp but when I think logically, I'm probably way better off with the 1/6. It takes a little longer but ..... If I was using it every week I'd want more power.

Since this picture was taken I've also added belt guards to keep fingers from being pinched. I can post pics of that and motor mounts later if you like.

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Do you all get a lot of "rim chatter" when using these?

Mike

Thanks for the responses....I'll have a closer look to see what'll work for me since I am worried about movement when its running....much appreciated,

Laurie

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Time you enjoy wasting is not wasted time.

Here's mine. This picture was taken just last week while I was sanding the back profile on a hurdy gurdy. It was the first use of the machine, having finally put it together in December. I ended up going with regular sheaves and a jack shaft rather than a gear reducer mostly because there is a large bearing dealer nearby so ordering the parts was easy. Going from 3.15" to 11.75" diameter sheaves twice gave the necessary speed reduction from 1500 rpm to just over 100.

Under the sanding dish there is 12" diameter steel plate that was welded to the shaft and trued on a lathe. So far it seems sturdy enough that I won't need any bearings (like a lazy Susan) under the dish. I designed the cabinet so that the sides rise above the dish. This will allow me to add stops if I decide that they will be necessary / useful.

None.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

So here is the link to the machine I built.

http://www.luthiersforum.com/forum/viewtopic.php?f=10102&t=3154&hilit=+rim+sander

What is most interesting are the belt tensioning system (Scott you might look at this for your machine) as the belts stretch and having an easily tensioned system is sweet. Mine works great. With mine I crank the motor out further and and everything tensions up. My motor is from a washing machine, 1/2 hp. It works quite well and will stall but not without some force placed on it. There was discussion about that fact that dust would be an issue with this motor. I have a made and sanded A LOT of dishes with this machine before I bought my cnc machine and I have never had a problem. I actually was just re-orging the shop, and had to move the rim sander and it was quite dusty, but the motor, protected by the motor cover, was not dusty at all. I now have a large 1/2" steel plate and have individual roller bearing in four places around the outside of the plate. Still I am planning on a gear reduction device like Brad's and a 1/2" plate mounted to that so I will not need any perimetre bearings.

Anyway, there is lots of food for thought here now Laurie.

Shane

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Canada

Hey, just wanted to say that I'm pretty darned impressed with some of the rotary tables out there - I feel like kind of a hack now but, I will say that not counting the cost of the dishes themselves, I couldn't have spent more than $50 or $60 on mine.

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http://www.birkonium.com CNC Products for Luthiers
http://banduramaker.blogspot.com

Hey Chuck, got a little question again.

Why do you use some sort of plywood disk between your dish and the lazy suzan bearing? I was planning to put my dish directly on the bearing but maybe I'm missing something.

Thanks!

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Probably everyone is moving away from this with those machines, but just in case there is someone who wants to do it more by hand, I place a dish over the ribs at whatever height, and then I use a divider to spile the shape of the dish to the ribs. This gives me an accurate cut line I can go to directly with whatever tool I want to use. Then the hand sanding part takes virtually no time. I just mention it because I once traded tips with a guy, and for that mater made him dishes, but he just didn't get the idea of spiling the dish until it was explained several times.

Is "spile" a Canadian word for what we could call "scribe" in the UK ?

I have to confess that I have never heard "spile" used in any context outside of brewing, where it definitely doesn't have any connection whatsoever with marking guitar sides ...

Alain, I use the 3/4" plywood spacer since I have two radiused dishes glued together (back to back), the spacer allows the dish to ride on the lazy susan since it would not touch the lazy susan otherwise...at least the lazy susan I have. I suppose the spacer could be mounted below the lazy susan to elevate it, if you like.

Chuck

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Thanks again Chuck!

It makes total sense.

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

Nice concept Shane. Does it have an agitate cycle? I recognized the motor... guy in town sells them... not a bad way to go at all!