Drive Sleeve: Gilmer -> Poly-V Pulley Swap?

[mjv]

Hello, all. Long time lurker, first time poster here.

I have owned my father's 1961 Goldie since 1995. With the exception of modern saw guards, I have tried to keep the machine as original as possible. But I have grown weary of replacing Gilmer belts.

For the first 52 years of its life it had one Gilmer belt. But in the last 12 years it has gone through four aftermarket belts. Admittedly, the last belt failure was my fault since I did not detect that the idler shaft eccentric bearing had slipped, which resulted in a loose belt and a headstock filled with belt remains. Nevertheless, I am done with Gilmer belts.

With the Gilmer drive system, even with old bearings in the quill and drive sleeve, the runout at the base of the arbor shaft was 0.0008" and at the tip was 0.0011". When I installed a new-style poly-v drive sleeve (aluminum pulley) with only 0.0005" runout, and a single-bearing quill with a nearly-perfect shaft (max 0.0005" runout along its entire length), runout at the base of the arbor shaft was 0.001" but jumped to 0.003" at the tip.

Testing has revealed that the increased base-to-tip wobble at the arbor shaft is due entirely to slop in the nylon "drive and ring" fitting. Switching to a new drive & ring does not correct the problem. Please note that there is no detectable wear in the splines on the quill shaft. Please also note that I do not want to switch to a 2-bearing quill because the 2nd bearing is clearly cover for the real problem, which is the drive & ring adapter, and at least to this engineer's eye weakens the quill shaft.

Clearly Shopsmith switched to the drive & ring coupler from the beautifully machined interior steel splines of the old Gilmer drive sleeve due to cost. That is understandable but also regrettable since the precisely-machined steel-on-steel spline interface clearly yields better runout performance than can be obtained by shoving a piece of nylon between the drive shaft and the quill shaft.

So I was wondering if it is possible to simply replace the pulley on the Gilmer drive sleeve with one of the steel poly-v pulleys (with the set screw) from an older style poly-v drive sleeve, thereby eliminating the drive & ring adapter and preserving the excellent Gilmer steel-on-steel drive system. Note that the Gilmer drive sleeve assembly on my machine is the latter style with the clutch and set screw on the side, roughly in the same position as the set screw on the old-style poly-v pulleys.

This seems very likely since Shopsmith probably used the same drive sleeve shaft (except for the quill shaft interface) when they initially switched to the poly-v belt. I understand that the switch would not be possible, or would be very difficult, with the new-style poly-v drive sleeve with the aluminum friction-fit pulley.

Thanks for your help.

Mike

[chapmanruss]

mjv,

Welcome to the Shopsmith Forum.

I believe what you are suggesting may be possible. I haven't had a Poly V Drive Sleeve Assembly completely apart, but both of the 2 common Gilmer Drive Sleeve Assemblies and the Poly V Drive Sleeve Assembly use the same size bearings. If the "gear pulley" of both are the same inner diameter they should be able to be swapped. Both Drive Sleeve types fit into all Headstock Castings. I would suggest using an early non-clutched Gilmer Drive Sleeve Assembly for this. If trying to use a clutched Gilmer Drive Sleeve Assembly use caution when disassembling it as it has a spring under compression in it. A disassembled clutched Gilmer Drive Sleeve Assembly is shown below. I don't have a picture of a disassembled non-clutched Gilmer Drive Sleeve Assembly but if I recall correctly, it doesn't have the ring attached to the sleeve. The only foreseeable problem would be differences in the sleeve itself which I believe is different between at least the non-clutched and clutched versions of the Gilmer Drive Sleeve Assembly. I'm not sure how they compare to the sleeve of the Poly V Drive Sleeve Assembly.

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Gilmer Clutch Type Drive Sleeve Parts.jpg (89.21 KiB) Viewed 4543 times

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The third Gilmer Drive Sleeve Assembly, version "C" as designated by its serial number, would not gain you anything since it changed to a nylon drive spline similar to the Poly V Drive idea. These are not often found anyway. I am guessing that your 1961 Mark 5 Goldie was made prior to the "C" units in March and April of 1961.

Someone else may have tried it and hopefully will post that here.