Main spindle alignment

[ameel]

I use my Mark V for wood turning exclusively, and recently I had a large piece on which caught hard on my bowl gauge. I then took the piece off and noticed that the main spindle is now spinning out of alignment, so that the whole exposed shaft traces out a cone as it spins rather than spinning in place.

I looked at a few threads here, with this one sounding closest to my issues,
http://shopsmith.com/ss_forum/general-w ... 9-s10.html

But after successfully replacing both bearings in the quill with brand new bearings, the problem hasn't improved at all. Any ideas?

[jsburger]

I would suspect a bent quill shaft.

[reible]

I would suspect a bent quill shaft.

That would also be my guess. I remember that this happen to at least one of our regulars here but don't recall who. Perhaps they will post?

The end result is that the quill needs replacing, sorry.

Ed

[ameel]

Thanks for the responses John and Ed, I was afraid of that, as it's a tough pill to swallow considering the age and condition of my machine. I appreciate you both helping me find closure all the same!

[chapmanruss]

I have replaced bent spindles on two of the Model 10's I have restored so it does happen. Shopsmith does not sell the Spindle without the complete Quill assembly which costs $179.11. Since you have already replaced the bearings, you may be able to find a spindle and change it yourself but finding just the spindle is rare. If you cannot find just the spindle shaft you may find a complete Double Bearing Quill for sale. They are available quite often.

Make sure you get the correct one. There are Double Bearing Quills, Single Bearing Quills and Single Bearing Quills for the older Gilmer Drive besides a special Quill made at the time the Mark 5 changed from the Gilmer Drive to the Poly V Drive. These Mark 5's have a C after the serial number and there were very few. This happened while the Mark 5 was painted in the "Goldie" colors. That's just the Mark V Quills. The only Quills that are interchangeable are the Poly V Drive Single and Double Bearing Quills but only as a complete unit. Sorry this is more history than you may need but is is important to get the correct Quill Assembly.

[everettdavis]

Some mitigation strategies on turning large bowls can help reduce the stresses on the spindle.

Most bent spindles I have heard about on any lathe seemed to have happened on a chisel hard catch on the outer radius when roughing the bowl to size.

1. Once you’ve established a turning center for the stock, rough cutting the stock round, on a bandsaw with single or dual bevels helps balance the load.
2. Using a live center on the tailstock with a #2 Morse taper extension can help during initial hollowing-out
3. I like to use a Forstner bit to progressively bore the live center down in steps as I go in with hollowing, ending up about 1/4 proud of the finish bowl depth before moving to the end without live center

Obviously, the wood itself and the chisels you use have a bearing. I love the Easy Wood chisels type personally.

I realize that doesn’t fix a bent spindle, but it may help prevent another one.

A machine shop with a hydraulic press and precision V block may be able to straighten your spindle. Cost might be a factor if you don’t have a friend in that business.

Everett

[everettdavis]

One last thing, bent spindles can happen during the pressing on or removal of bearings.

See my Shopsmith Bearing Guide on My Google Drive for more information and mitigation strategy to help prevent that from occurring.

Everett