Shopsmith Forums

I've noticed wobble in my chuck, and the trouble has been narrowed down to the jaws, which appear to have gotten galled on their face so they don't hold bits true.

Thanks to YouTube, I've found several tutorials on how to do rebuilds, where the jaws and split nut can be replaced. But... which kit to buy?

ShopSmith doesn't market a rebuild kit, but surely they source the chuck from a specialist. My current one (~10 years old) looks pretty identical to the original from 30 years ago on my Model 510. For this era, what's the OEM (Jacobs?) and model number for this SS drill chuck? Or at least the compatible rebuild kit?


For the curious, it started by noticing wobble in my pen mandrel. I also pretend to be a machinist, so I had a test indicator handy to check. I presumed the mandrel was bent, but that turned out not to be the main culprit.

As I worked my way end-to-end, I found that the spindle shaft is running true (yay!), and the chuck is about 0.0003" (three tenths). But at the output of the jaws, runout is about 0.004", which gets amplified further out so it seems to be gripping at a slight angle. Loosening the chuck just enough to spin the bit independently showed no runout, pointing to the jaws as the source of the problem - it turned out they showed galling, probably from not being tightened well and maybe not inserting bits to near full depth. (I did clean and spray-lube the chuck in case crud was to blame. It moves very smoothly now, but that didn't change the results.)

I only have experience with older chucks those are a variation on a Jacobs #33 (due to being modified to mount on the Shopsmith spindle). Jacobs used to and may still sell rebuild kits for the #33. I don't know about later ones

This current 1/2" Drill Chuck is like the Jacobs 3326 Chuck but with a longer body. I do not know the actual manufacturer that makes this Chuck for Shopsmith so I cannot tell you if there is a repair kit available for it like the one Jacobs makes for the 33 series chucks.

You're right, that's the only Jacobs chuck that fits the specs, though it's clearly different. Practically, I could buy that chuck new for less than the rebuild kit (and half the price of SS's version), so I seem to be wasting my time.

But, looking at its specs, the runout I'm seeing appears to be within the spec for a new 3326 chuck, so I'm probably barking up a tree trying to improve it. In the world of machining, Jacobs-style chucks are regarded as low-precision; I just thought the bar was a bit higher.

I'm going to give a go with the ER32 collet adapter from Penn State. This is a more accurate tool holding system used in machining, with the advantage that one can obsess over tweaking the runout when needed.