Spindle Adapter to use Shopsmith Accessories on Powermatic Lathe

[Dave Bunge]

Does anyone know of a source for a spindle adapter to convert from 1 1/4" 8 tpi threads on my Powermatic lathe to 5/8" male Shopsmith shaft? I have a 12" disk sander and a couple of faceplates from an old Shopsmith that I would like to use on my Powermatic lathe.

I sent a request for quote to Best Wood Tools, who I expect would make me a very high quality adapter for an upper end price. I'm wondering if there are other options.

Thanks,

Dave

[Brice Rogers]

I wanted an adapter to convert from 1-1/4x8 down to 3/4-16 (Craftsmen). I bought an adapter (around $8) from Grizzly to go from 1-1/4-8 (female) down to 1-8 (male). I put it on my metal lathe and removed the 1x8 threads and then rethreaded it for 3/4x16.

In your case, the job would be easier - - IIRC, the shopsmith shaft is smooth/no threads. So, you'd just turn the 1"x8 end down to 5/8 (male). If you don't have a metal lathe or a friend with one, it is possible to turn it down on your wood lathe. If you try that route, it would be easiest to do it with a carbide tool but it could also be done with HSS. You would want to have the absolute minimum overhang and take light cuts with a longer tool (scraping cut).

One caveat is that every adapter that you put in line may add a bit of run-out/wobble. But on a faceplate it isn't going to be a real big issue. On the sander it is a PITA to have wobble, but if you face the sander with something like MDF, you can turn it true.

[Dave Bunge]

Brice, great idea. You remember correctly, the shopsmith does not have threads, only a flat for set screws to register against.

Tell me more if you don't mind about turning steel on my wood lathe. I've done some brass and softer metals, but am a bit leery about taking on steel. Seems like a catch could be a spectacular event. I guess the proper approach would be a narrow tool, start from the end and work inward taking very small cuts? Use a flat carbide cutter, not a round one? Keep leverage on my side with minimal overhang and long tool handle as you say.

[Brice Rogers]

On a metal lathe, most good chucks only have a thou or two of runout (or less). On a wood lathe, the chuck may have more. So, you would want/need to put shims into the chuck to get the spindle adapter to run true.

An aside - - I recently turned down the base of a 14 inch tool rest (to lower it by 3/4") on my Grizzly G0766 wood lathe using a 2" wide tool rest, and a carbide cutter mounted into the end of a 2' long 1/2 x 1/2" bar. I saw a fair amount of runout so I shimmed the chuck with a piece of polyethylene (milk bottle) and miraculously, got it right on the first try. I took my time and it came out okay. So it is possible. But it is not the right tool for the job. I put a round collar over the carbide cutter to control the depth of cut. I pressed the collar against my tool rest to make things as solid as possible. I tucked the square tool holder bar under my arm for stability. If you limit the depth of cut to perhaps 0.010 to 0.030, that helps keeping catches from getting excited. At low speeds, you might just stall the lathe. Or at higher speeds perhaps chip the cutter. I limited the depth of cut (smaller is better and easier) and turned from one side to the other, advancing slowly. So my "chip" was very small. Occasionally I got things perfectly controlled and would momentarily have a metal curl coming off. Having a narrower tool helps concentrate the cutting forces and reducing chatter. So if you got a HSS (high speed steel) cutter and shaped it to be narrower, it would make your job easier. Sharpening a HSS is not hard, but it requires a moderate amount of homework (you'll want a rounded nose, positive rake, and relief on the front and cutting side).

When I was turning steel on my wood lathe, I didn't have any spectacular catches. I turned at slow speeds, controlled the depth of cut and controlled the lateral rate of feed. I cut on the centerline with minimal overhang (like 1/4 inch).

I would probably use a flat cutter rather than a round one. A round one would also work, but with a square cutter, the "contact area" could be less. I actually used a 1/4 x 1/4 "cemented carbide" cutter that I got from Harbor Fright. :)

It is likely that you'll get some chatter because you are hand holding the tool. So, use a digital caliper and when you get within (this is a guess on my part) perhaps 0.010 inches, switch to a metal file. Use long even strokes. Check with the caliper to see if one side is smaller than the other. You might end up with a fair amount of runout. But with the $8 adapter, you don't have a whole lot to lose.

Before starting this, check around to see if you have any friends with a metal lathe. It would be easier and the results would be better using a metal lathe. But.....it is possible with a wood lathe.

[Tony Rozendaal]

Have you considered using the morse taper in your headstock? Use a #2 morse taper collet with a drawbar, and a simple to machine 1/2 to 5/8 inch adapter. I think this would be an easier and possibly more accurate solution.

[William Bachtel]

Got mine at Craft Supply, high quality and priced right. I wanted to extend my spindle on my Powermatic 3520 1 1/4 to 1/1l4 so bigger bowls wood clear better, worked out perfectly.

[Clint Bach]

You may already have an adapter. The Shopsmith tailstock chuck adapter is number two morse taper to five eights. Mine is a well machined piece of heat treated steel. Came with the Shopsmith...

c

[David Delo]

I think this is what Clint was referring to. The only thing I'm not sure of is the length of your hubs on your sanding disks and faceplates. The older ones had a shorter hub on them and not sure your set screw would reach the flat spot on the 5/8" shaft. Here's the link to the part. http://www.shopsmith.com/ownersite/itemfind.htm?item=505603

(http://www.shopsmith.com/ownersite/itemfind.htm?item=505603)

[Clint Bach]

Yep. That's the part. It fits all the Shopsmith accessories like chucks face plates sanding disks saw arbors accessory arbors for buffing wheels etc. If it fits on the Shopsmith arbor it fits that adapter. The Shopsmith tail stock is no 2 MT.

However, a saw blade on that thing in a lathe would not be found on my lathe! Just too scary. This adapter is not made to use a draw bar.

c

[Brice Rogers]

Clint said "This adapter is not made to use a draw bar." This is a good point that I'd like to expand on to show that it can be a bit dangerous.

When a person uses a morse taper adapter, it will probably stay in place if there is a small constant force pushing the morse taper into the spindle bore. But if you ever have forces in the other direction (i.e., towards the tailstock), it is very likely that it will come loose.

So, maybe a person could get away with it using a sanding disk (stick your tool rest close to it just in case), and turning with tailstock force should work fine - - I advise against turning something without a tailstock applying pressure. You would want to use a drawbar.

But, if you find a Morse taper to Shopsmith adapter, you should be able to figure out a way to make and use a simple drawbar. If the adapter isn't hardened (easy to figure out) you could drill and tap it. If it is hardened, and you have access to a welder, you could weld a nut or a coupler to the small end of it.

[Dave Bunge]

Thanks everyone for the input. The morse taper option sounds like the way to go. I agree on the need for a drawbar. Drilling and tapping for 1/4" x 20 tpi allthread is something that I'm comfortable doing.

[Tony Rozendaal]

Interestingly, Beall seems to have what you are looking for.

http://www.bealltool.com/products/turning/tapers.php

[Brice Rogers]

Tony, nice find for the original poster.

[Dave Bunge]

Wow, the longer I wait, the better the options that come forward. Thanks Tony.

[Dave Bunge]

Just closing the loop on this thread. Turns out that the morse taper adaptor for the Beall buffing system (http://www.bealltool.com/products/turning/tapers.php) works well to attach Shopsmith accessories. Pictures show it with the 12" sanding disk. The disk runs very true with no visible run out.

The morse taper adaptor is aluminum. I don't think I will use with a faceplate due to the forces that would be involved if I had a catch. But it looks like just the ticket for attaching the sanding disk.

Thanks again to everyone who gave input.