headstock not holding properly on waytubes when turning

[peterag]

Hello Shopsmith Forum, and hello Shopsmith - wow, it's nice to see you back!

These are the two manifestations of my issue (or so I think):
1) When I brace and tighten stock between the head and tailstock, the headstock tends to move back (I have of course "adequately" [see below] clamped the headstock on the waytubes). I deal with this by bracing the opposite end of the headstock with a piece of wood against, say, the bandsaw. It works, but obviously it's a hack.

2) More importantly: I have the whole chassis adequately weighted down, so it does not move, but when I turn, the headstock wobbles more than I believe to be reasonable. I think the clamps (the "lock shoes") are at issue.

When I take the work off, and try to slide the headstock, it's not easy - I think that the vibration 'works' the locks into the waytubes - certainly further tightening the locks is not a great idea.

Suggestions? Are there others who have had to deal with this issue? I have cleaned both tubes and locks; to no avail. I have a much older headstock (1952 ish) that I could raid for its locks, and will, if there are no other ideas, but my conscience twinges at the thought of the robbery.

Thanks!

Peter

[chapmanruss]

Peter,

I would suggest checking the condition of the Lock Wedges. This will require removing the Headstock from the Way Tubes to really get a good look at the wedges. That and opening up the Headstock including removing the Motor Mount/Lower Cover to get a good visual of the Wedges. The Wedge surfaces that press against the Way Tubes should be smooth and flat on the two surfaces that contact the Way Tubes. These Wedges are a softer alloy and can become misshaped with over tightening of the lock. They can also accumulate dust and debris so cleaning them can help. While the Headstock is off, inspect the Way Tubes for any imperfections in the surface. This would also be a good time to clean and wax the Way Tubes.

[peterag]

Update: I took the headstock off the waytubes, and there is evidence that one shoe might be making more contact than the other, or before the other, with the waytube, and therefore (conjecture) possibly preventing its companion from holding adequately when one tightens. I've tried to rotate the shoes, so that when one the shoes are fully extended against the headstock (i.e. away from the waytubes, if the headstock were still sitting on the tubes), they would both lock against the headstock. I will keep trying, but so far, this evening, the distal shoe stops moving before the other does. This might be the way that physics always makes it to be, but has anyone found this to be an issue, or think that this is a red herring, etc? How do people "adjust their shoes?" Thanks.

[DLB]

When your locks are unlocked, the whole assembly should move freely over a short distance in and out of the headstock (a rattle check). Does it? (By whole assembly, I mean lock handle, lock rod, and wedges.) As you rotate the lock handle toward locked, neither wedge should rotate more than a few degrees as they engage the way tube. When locked, the outer part both wedges should be slightly but equally recessed in the headstock. My headstock is a "C" and I'd estimate this recess around 1/16".

If everything is working right, I think which one seats first is a red herring. But I'd kind of expect the opposite of what you report, so maybe not. Because the whole assembly moves freely in and out until locked, I feel like the user will tend to push in a bit when rotative the lock handle, thus causing the lock nearest the handle to move to its stop.(?)

My initial guess at this is that one of the locks is binding, either on the threads or in the headstock bore, and thus not fully/forcefully engaging with its way tube.

If none of this is helpful, you might include pictures showing the position of both wedges relative to the rod and headstock in both locked and unlocked positions. Photos might trigger a better response.

- David

[peterag]

Just to acknowledge your comment, David, as I'll be on the road for the next while. But when I get back I'll do some measuring of engaged wedge/lock/shoe depth.

[chapmanruss]

In the first picture below the Lock Wedges are almost against the Headstock Casting. Having the Wedges pressing but not overly tight, against the Headstock Casting on both sides does two things. First it makes it easier to remount the Headstock on the Way Tubes having the Wedges stay in place in the proper position. Second this is an easy way to adjust the Wedges on the threaded Lock Rod. Getting them adjusted correctly may require turning either or both Wedges individually so they rest against the Headstock Casting on both sides while leaving a couple threads showing between the Lock Lever and outside edge of the Wedge as shown in the second picture. Do that adjustment first leaving a couple threads showing between the Lock Lever and the front Wedge. Follow by adjusting the rear Wedge against the Headstock Casting. With this done turning the Lock Lever will draw both Wedges to the center of the Headstock and against the Way Tubes when the Headstock is mounted on the Way Tubes.

If either Wedge needs to be replaced keep in mind that one is right-hand threaded and the other is left-hand threaded.

_

Headstock B inside Goldie.jpg (168.79 KiB) Viewed 88609 times

.

_

Headstock B front Goldie lock arrow.jpg (81.86 KiB) Viewed 88609 times

[JPG]

Determine if one of the wedges has stripped threads.

[AllenH]

JPG, glad to see you back on the forum. I have learned a lot from you and Russ.

[chapmanruss]

A good point by JPG. The Wedges are made of a soft alloy and therefore the threads are more easily stripped.

Just an FYI, the rear Wedge can be replaced without having to remove the whole lock assembly. To replace the front Wedge the Lock Lever has to be removed from the (threaded) Lock Rod by first driving out the pin that holds it in place.

JPG,

I am also glad to see you back.

[peterag]

Quick update - success? Namely, it looks like DLB's "initial guess at this is that one of the locks is binding [ ... ] on the thread" is/might be correct:

I was having some difficulty adjusting the shoe on the lock lever side [with the headstock removed from the waytubes], so put a squirt of penetrating oil in the thread on that side, and all moved more easily. I reinstalled the headstock, and, if only by way of experiment, tried turning a 8 inch diameter bowl ["tried" is the word - the wood turned out to be cracked]. Contrary to recent experience, when I advanced the quill to push the stock against the center in the tailstock, the headstock did not slide backwards - which was promising. [see the initial post]. I did at first use the speed reducer, but when the piece was rounded, I installed it directly on the quill. Much more acceptable! But I will keep experimenting - and update one way or another... Meanwhile, I obviously should have checked, when I first experienced the issue, that the shoes were equally far 'in' when they were in the locked position - even though I'm not sure I would have seen anything, of course.

No matter what, thanks to all.