Wobble on headstock with scroll chuck

[chief489]

Have changed the quill bearings and it's not them. Getting a 0.012"-0.014" runout on the spindle. Will look at the drive assembly next.

[chapmanruss]

Check the Drive and Ring attached to the Drive Sleeve Assembly first. It is the nylon part shown on the Drive Sleeve Assembly in the picture below. The arrow points to the location of the ring in the drive. It is a round ring that keeps the drive on the Drive Sleeve Assembly. If the splines in the drive are worn it can contribute to runout. There are no splines in the metal sleeve of the Drive Sleeve Assembly itself.

_

Poly V Drive.jpg (68.41 KiB) Viewed 20812 times

[chief489]

Check the Drive and Ring attached to the Drive Sleeve Assembly first. It is the nylon part shown on the Drive Sleeve Assembly in the picture below. The arrow points to the location of the ring in the drive. It is a round ring that keeps the drive on the Drive Sleeve Assembly. If the splines in the drive are worn it can contribute to runout. There are no splines in the metal sleeve of the Drive Sleeve Assembly itself.

_
Poly V Drive.jpg

Stripped everything down today and there is a good bit of movement between the drive and ring and the spindle. Have ordered a new drive and ring to see if that might improve things. Waiting to hear back from UK parts supplier on how much runout there is on a used quill assembly he has. Thanks for all the help so far!

[DLB]

For clarity, do you have a Poly-V Drive, as opposed to a Gilmer? And a single bearing quill as opposed to a two bearing quill? I think it's important to be clear about the versions because the failure mechanisms vary quite a bit. For example, a two bearing quill is much less dependent upon Drive and Ring condition than a single bearing for minimizing runout. And it has been reported that a bent spindle, sometimes caused by a 'catch' during turning, is more common in two bearing quills than single bearing quills.

I expect a two bearing quill to exhibit <0.002" of runout, though I haven't seen this specified anywhere. I don't have good numbers for Gilmer drives (which are metal to metal and don't have the replaceable Drive and Ring) or Poly-V with single bearing quills.

- David

[chief489]

Poly-V and two bearing quill.

[DLB]

Testing an uninstalled (no influence from the Drive and Ring) two bearing quill I get a radial runout of slightly over 0.001" but well under 0.0015". I'm measuring as close to the end of the spindle as possible to eliminate influence of the tapered flat, using a magnetic base on the quill barrel and 0.0005" resolution dial indicator. The quill is what I think is the latest version with a one piece spindle and the larger bearings. Sample size of one, but this is about what I expect, both installed and uninstalled. I think two piece spindle two bearing quills are about the same, but I don't have one handy to measure.

- David

[chief489]

The more investigation I do, the more I think it's the spindle. Bugger!

[chief489]

Has anyone bought anything from MKC tools? Have emailed them but no response. https://www.mkctools.com/mark%20v%20parts.htm

[chapmanruss]

Skip at MKC Tools has been around for a long time. He has done a lot of restorations besides machining hard to find Shopsmith parts mostly for use with the Model 10's. As I understand it he has begun to sell off remaining stock heading towards retiring from his MKC Tools business. It has been several years since I have talked to him. You might try calling him to see if you can get a response.

[chief489]

Skip at MKC Tools has been around for a long time. He has done a lot of restorations besides machining hard to find Shopsmith parts mostly for use with the Model 10's. As I understand it he has begun to sell off remaining stock heading towards retiring from his MKC Tools business. It has been several years since I have talked to him. You might try calling him to see if you can get a response.

Thanks. Any idea what time zone he's in? Wouldn't want to call in the middle of his night!