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Trevor, I'm not convinced who's method is the more efficient. By the time you start planing, I'd be done with it if I had a motorised dish sander. Currently, it takes me about 5 to 10 minutes when sanding by hands (mostly because of my hefty neck blocks). Probably 2 to 3 minutes would be sufficient if it were motorised. (I do profile the sides prior to bending, which helps a lot).

Oh, and I lied a bit about never needing a beer. Once my mother in law spent the week at our place...

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

Ill get a better shot of it when I get home. It's just a low speed motor with a 90 deg on it. I should mount it to the wall.

I think you would have really good control with it mounted to the wall.

Can you take a shot of the model number?

Thanks. Michael

will do! I tried texting you the other day to talk about this. not sure if I texted the right number or not tho.

I have been thinking that one of the large floor buffer units that janitors use would have a great low speed motor that could be adapted to our use. I have seen these used for a reasonable price so I think I might take a closer look next time one becomes available for a low price.

Fred

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Fred Tellier
http://www.fetellierguitars.com
Facebook page http://www.facebook.com/pages/FE-Tellier-Guitars/163451547003866

Here's mine, takes about 10 sec to turn the dish over to sand the other side...I do pre-profile the sides

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That's a good idea! (that should have been mine!)

The couplers on those screw right into the plywood backers as well. Super quick changes, and plenty of tork..

How to mount it to the wall, or the bench top for those who prefer?

http://tw.page.bid.yahoo.com/tw/auction ... 2320854915

Get one of these and tip it over... It's a 24 inch disc sander

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

What a beast! I want one!

Here's another one...

http://tw.page.bid.yahoo.com/tw/auction ... 9774234556

Only costs around 800 dollars... really wanting one now. Use it as is for disc sander stuff, tip it over and attach a dish, and it becomes a motorized dish.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Here's mine, I use it to sand rims, of course, but also to finish sand the radius dishes I make and sell. The main component, the big steel disc, cost me several hundred dollars to have machined but this sander is much nicer and more robust than the lazy susan bearing version I first made.













The reduction gear is nice and smooth as well and was only about $130 or so.

Hope this lends inspiration!

Shane

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Canada

Shane, does the drive shaft from the gear reduction simply key into the bushing collar on the backside of the dish, and other than sliding on the shaft, is there any positive locking of the steel dish to the shaft and other than the centering pin, what keeps the dishes from shifting on the plate? How long a collar did you make in order to assure stability? Also, is there any other support on the table surface or is it all the dish and the mount? Who made your reduction gear, and at what ratio?

The reduction gear is 15:1 which when coupled 1:1 with a 1750 rpm electric motor (mine is 1/2 hp from a washing machine) gives you about 117 rpm, just about perfect! I bought my reduction gear, probably when it was on sale, at Princess Auto, which is a Canadian discount chain, like Harbor Freight. Here is a link to the product:

http://www.princessauto.com/pal/product/3840043/Standard/15%3A1-Speed-Reducer

The metal disc is keyed to the main output shaft of the reduction gear. There are no other supports so the top on the cabinet is for rigidity of the cabinet and I use it when adding a belt sander to clean up the edges of the radius dishes.

When I make radius dishes on the cnc and sand them I add a piece of non slip fabric on top of the metal plate, like this:



But for my own radius dishes I have added 3/8" wood dowel pins that fit in holes in the metal plate. Here are the holes in the plate and the pins in a dish:





And I made up a metal plate (which I gave to the machinist to use when he made my plate) to locate the pin holes in the dish, it looks like this:



The metal disc fits nicely over the shaft and I don't even need to lock it into the keyed spline as it is heavy enough and accurate enough that there is no movement. The disc was probably about $600 to have made and machined (it is a big piece of precision steel with a machined face and an accurately located and machined centre pin) but I just didn't like the slop in lazy susan bearings and individual roller bearings (I tried both). I could make my cabinet a little more rigid by adding more structure to the front but it doesn't seem to be an issue as everything is isolated to the relationship between the wall where the reduction gear is mounted and the top, both of which are 1.5" of mdf.

Hope this helps!

Shane

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Canada

If you'd like to get some ideas for gearing down a standard 1725 rpm motor using belts and pulleys, this site can be helpful:

http://www.mirror-o-matic.com/

It's a fairly simple device made out of plywood for grinding and polishing telescope mirrors and has more features than is needed for spinning a radius dish. I made one some time ago and adapted it more recently for rotating radius dishes. Another idler is needed to get the speed down to around 60 rpm.

Steve

Gear reduction can be accomplished by just stepping down the pulley's. Here is a thread of the first sander I made showing a nice simple and very effective speed reduction using a swing box that allowed the belts to come tight just by adjusting the motor tension.

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

Hope this is useful as well.

Shane

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Canada

Drool- nice rig Shane. Don't know for sure, but I'd check to see that the non slip stuff doesn't have silicone (used as a release aid when it's molded)

Jason, it likely is silicone, but it is only used on the bottom of the unfinished MDF which is later sanded and sealed with two coats of varnish. It never comes in contact with guitar wood.

Filippo, there is pau ferro or zircote or any other fine woods in this like some I know who makes awesome jigs!

Shane

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Canada

We use a potters wheel.

Probably not the cheapest but thought I mention something else. We have a ceramic dish on the top of our wheel that we have coated with Velcro we then contact cemented felt to the back of our radius dishes. Very easy and quick to change disk. ( our wheel is variable speed and we've never had the Velcro turn loose. )

Blessings,

Kevin