Official Luthiers Forum!

A few months ago there was a discussion on motorized sanding dish. There were a few posts on people using their drill press. Unfortunately all the pictures were lost thanks to PhotoBucket. From the discussion alone I couldn’t figure out how it could work.

Anyone have experience with this setup? I don’t understand how you can spin the dish from above and then, somehow, get the guitar rims onto the spinning dish.

Thanks.


Sent from my iPhone using Tapatalk

The one working unit I have seem had an "arm" that clamped to the drill press table. A lazy susan plate screwed to the arm and the bottom of the dish. A drum sander spindle pressed against the rim of the radius dish to spin it.

_________________
Brad Hall
Mystic Dawg Guitars

I did the same but quit. I didn’t like putting that much lateral pressure on my drill press main shaft. It’s not designed for that imo.

The way it is done is to have something (like a 2" sanding drum) chucked up in the drill press that acts as a drive wheel, and that rides along the outer rim of the sanding dish, which is mounted on a lazy susan so it spins freely.

I agree that drill presses are not designed for that, but beyond that, I look at it this way: if you are going to drive the outer edge of the sanding dish, there are more convenient things to use than a drill press.

I went ahead and built a dedicated dish sander. It really isn't that hard. Certainly no harder than McGyvering up your drill press to drive the outer edge of a 2 foot wide dish.

People are always looking for ways to re-purpose the drill press. I've done it too. I built a guitar buffer with my Powermatic. Had a base with a bearing, arbor in chuck and bearing. A little confining. Posted pics here. But in the end, I decided my Powermatic was just too expensive to ruin (people here convinced me). Those bearings are designed for normal loads, not lateral.

OK, thanks. I don't think I like that idea. Not opposed to building something, but I'm always looking to save space.

On building a dedicated version, I am wondering if one of those little 24V Servo motors would have enough umph at 100rpm. Like this (or endless Ebay variants):

https://www.amazon.com/uxcell-1000RPM-E ... 2B24v&th=1

It is 4Kg/cm or .3ft/lbs of torque, but I have no idea what that translates into real word experience.

U don’t build a dedicated station. Use ur bench. Figure out a motor attachment. Etc. put away when ur done.

100 RPM? Figuring a 1” rubber drive wheel, and a 12” radius disk, u get 8 rpm. Just what is the target RPM u disk spinners aim for?

"OK, thanks. I don't think I like that idea. Not opposed to building something, but I'm always looking to save space."

I have made two motorized dishes. The first used a bowling ball balancer - I made a "plug" where the ball would go and centered the dish on top of it. Originally it was kind of a "wild ride" but after recentering the dish it is much better behaved. It has a 1/2 hp motor, and is fairly compact and easily movable.
The second one used a food processor as the motor unit and has three speed settings. the nice thing about it is the dish removes easily and can be stored on edge and the processor fits in a cabinet. It has a reasonably strong motor but does slow down some under load.
I think they both spin at about 200 to 300 rpm (no load).

Here's another point of view. I've done many guitars and ukes on a drill press radius dish. For as little use as it will probably get, and provided you have a good size drill press, I doubt that you will damage the bearings. I have not been able to damage mine with the dish or even 1/2" router bits that I occasionally use in it. I admit it would be great to have a dedicated tool for the job, but unless you are producing a large amount of stuff, you are likely to spend very little time on the sander. It takes about 5 minutes to set up the sander on the drill press, and if you make your own dishes, it will cost you almost nothing to make it and take very little time to get up and running. The lazy Susan is totally unnecessary. I put a sheet of Formica on mine and a simple 1/4" brass center pin to spin the dish on. The table is held onto the drill press table with 2 carriage bolts and wing nuts in the table slots.I wax the Formica from time to time. The dishes have a 1/4" hole in them to receive the center pin. I expected holes in the MDF dishes to wear quickly and planned to put a bushing in them, but there has never been any wear issue. To use the unit, you mount the appropriate dish on the table, turn on the drill press and swing the table so that the rubber drive drum turns the dish. You can use your hand on the side of the dish to determine how much pressure to put on the drum and then lock the table down.To use the other option of a dedicated tool you will need to design the unit, buy a sheet of decent plywood, find a suitable motor, figure out the gearing or jackshaft or whatever, buy switching and wiring, and have the extra space to put it when not in use. If you are really into production, the dedicated unit would definitely be the way to go, but it does not do the job any better or worse than the drill press driven one. If you have a floor drill press, probably the biggest drawback is that the work piece will be at a little bit of an awkward height. I'm 5'11" tall, and the height still works for me. Once the sides and mold are on the dish, you don't really have to hold them up. Still, I agree it would be nice if the unit was lower. Enjoy your project, whatever you choose.--Bob

_________________
“ The meaning of life is to find your gift and the purpose of life is to give it away” Pablo Picasso

Here's my dedicated motorized sanding dish, fueled by caffeine, IPA, or chocolate depending:

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

Jay, do you have Popeye arms yet?

I'm 5'6" tall, and the chuck of my drill press is about the height of my sternum. Manhandling a mold and rim set at that height is the part of a drill press powered dish sander that would be really inconvenient for me. But, to each his/her own.

Like Mike said, your dish sander need not take up any additional floor space if space is an issue. You can put the innards under a bench surface and make the drive mechanism and center rotation pin removeable.

I built a free standing one because I had the space. It gives me a storage space underneath for dishes, and dust collection is easier to deal with than it would be otherwise.

I’ll build one because I am falling behind on getting guitars built and need to improve my efficiency.

But my problem isn’t floor space, my space is so small I’m out of storage space. I have bending jigs, vacuum press, neck jigs, binding jigs, kerfing jigs, etc. All that squeezed next to a table saw, band saw, planer, drum sander, spindle sander, drill press, jointer, AAAAGH!!! I have wood in the rafters acclimatizing, rolls of carbon fiber in tubes, and wood veneer still looking for a good home.


Sent from my iPhone using Tapatalk

"I have wood in the rafters acclimatizing, rolls of carbon fiber in tubes, and wood veneer still looking for a good home. "
Next thing, you'll be on one of those "hoarding" reality shows. What' cha at with the rolls of carbon fiber anyhow?
Ken

Same here, down to "not too long" after using a block plane and a spokeshave to profile the rims these days.

_________________
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 build guitars with carbon fiber, like the one in my avatar.


Sent from my iPhone using Tapatalk

I remember seeing pics. here on OLF a couple of years ago of a CF electric. Probably that one? Nice work.
Ken

Acoustics, but that is probably what your are remembering. Here is the link to the first one I made that didn't implode!

viewtopic.php?f=10101&t=45742&hilit=+carbon

When I sanded my first radius I made a paper template of the profile of the sides, top and back, and made a thin ply template from that. I now cut the sides, before bending, to the shape of the template which means sanding the radius only now takes a short while and can be done manually. I then glue on the linings, slightly proud of the sides and sand again for a few minutes on the radius jig and job done.

I built a wall mount unit with a gear motor that has a very small footprint and works really well. 40-60 RPM's (mine is 46 RPM's with a 3 phase converter), but you could just use 220 as well. It's just MDF, some simple wheels from Ebay, gear motor, 3/4" shaft and a couple sprockets that make the dishes interchangeable. Then again my drill press doesn't have a throat deep enough to be repurposed for something like this. I've been really happy with my results thus far outside of breaking a couple screw heads off and being unable to have anything other than a dedicated dish/sprocket set for 28' and 15' sanding operations.

This is easily the favorite tool/jig that I've ever built. Would have been easier had I had access to more 220V outlets (done now but still need upgraded power service). 3 phase is really nice though for fine adjustments.






Sent from my iPhone using Tapatalk