Sliding the headstock easier

[adrianpglover]

How do I go about getting my headstock to slide easier along the way tubes? I've tried both waxing and rotating the tubes, but I don't see much of any improvement with it. I'll get it to the point where it will slide pretty easily through some of the distance, but then it will hit a section with increased resistance. As far as I can tell there are no nicks or warping in the shape of my way tubes. Just watching some of Michael Young's videos and it takes me quite a bit more to get my setup changed over from one mode to another due to needing to brace myself against the tool to move the headstock.

[DLB]

This is like Jeopardy, all answers are in the form of questions... I'm just shot-gunning some starting points. The main possibilities here are that the way tubes are not parallel and/or one wedge lock is binding. The idea of rotating a way tube is that there is no perfect tube and you are trying to make the in-tolerance curves parallel. I've never tried to measure this parameter, but one could measure the inside or outside tube spacing to see how parallel they are. I don't know the tolerance, but if your machine is dragging perhaps that would imply one.

Your machine is very new from my perspective, and we are informed that sometime recently the company changed the Bench and Way Tubes material and construction to thin walled stainless steel. I have zero experience with the new tubes, so first question is do you know if your way tubes are thin walled stainless? If you don't know, my first suggestion: move the headstock to one end of the machine and partially raise the other; loosen the two setscrews on the top of the DT Base Arm and remove the Arm. 1) measure the wall thickness, which likely matches a standard sheet metal thickness. 2) Look for the seam on the inside of the tubes, in most cases they would be "clocked" the same as each other and likely in the 6 or 12 o'clock position. (Note - there could be anti-crush inserts in the tube making this more difficult, but as far as I know at present these are only found in the thin walled bench tubes.)

Does the carriage move easily throughout its range? (Test both with the headstock locked and unlocked.)

Does the headstock move more easily if the carriage is unlocked? Does the headstock move more easily if you further loosen its lock (try loosening it to its maximum)?

You might try removing the headstock and waxing the way tube bores. If that helps at all, I would repeat for the carriage.

- David

[adrianpglover]

Thank you for the detailed response. I had not realized that there was a change in the tubes at all, so I'll go check that.

I have rotated the tubes, trying to find the sweet spot. I thought the theory in this was more that the tubes may be straight, but somewhat out of round and you were trying to get the headstock to slide on more rounded part of it.

For the most part, the carriage does slide smoothly, though sometimes with the table on it I have some difficulty. I haven't paid attention to if this is more so from me pushing off center or if it's just getting stuck more easily with the table locked on it.

I've tried unlocking the headstock to maximum, and then sliding the lock forward and back to make sure the wedges are freed up, and this doesn't really change the behavior.

I think I'll check the tube thickness and then reclock them at either 6 or 12 to start over on that part of it.

[edma194]

I thought the theory in this was more that the tubes may be straight, but somewhat out of round and you were trying to get the headstock to slide on more rounded part of it.

I think it's more likely the tubes are not straight and the distance between them at any one point varies. By rotating you are trying to align two curved tubes so the distance between them is more consistent across the length. IOW () is a problem, you want )).

[JPG]

OR (( and not )(.

[DLB]

I've tried unlocking the headstock to maximum, and then sliding the lock forward and back to make sure the wedges are freed up, and this doesn't really change the behavior.

There is variation in wedge lock preset. When I unlock my headstock to maximum, the lock assembly won't move in and out because both wedges are fully retracted (outboard, away from the way tubes) into the housing. The 'other' way to reach 'maximum' is for the front side lock (wedge) to meet the lock handle and act like a jam nut. In that case, the wedges are less retracted allowing the assembly to rattle in and out. Mine will make just over 3-1/2 turns from locked to fully unlocked. That's way more than necessary for normal use, so I'm not suggesting that this is your problem, only that it is a variable to consider.

- David

[SAFECRACKER5947]

To DLB. David : I just purchased my 2nd Mark VII at an auction. After comparing how the wedge lock functions I have concluded that it is stuck. Only on the "front" operators side. I've turned the lock handle to the half-way position where it should wiggle in and out and it doesn't wiggle. I can see the backside wedge move. Oil and substantial "tapping" (both sides) hasn't freed it up. Suggestions?

Ernie

[DLB]

To DLB. David : I just purchased my 2nd Mark VII at an auction. After comparing how the wedge lock functions I have concluded that it is stuck. Only on the "front" operators side. I've turned the lock handle to the half-way position where it should wiggle in and out and it doesn't wiggle. I can see the backside wedge move. Oil and substantial "tapping" (both sides) hasn't freed it up. Suggestions?

Ernie

Welcome to the forum! For clarification, sometimes the term 'Mark VII' gets confused with 'Mark 7.' Mark VII refers to a 1960's production design while Mark 7 is the current production variant of the Mark 5/V series. I've never owned a Mark VII and don't know if these have the same/similar wedge lock design. The modern Mark 7 headstock has essentially the same wedge lock setup as the Mark 5/V, any technical description I provide is for the Mark 5/V/7 series and may not be consistent with Mark VII. Please clarify if your machine is a 1960's Mark VII as opposed to a third millennium Mark 7 (PowerPro).

Next, it would be good to know whether the wedge is stuck in the locked, unlocked, or somewhere in between position. And whether the headstock will slide on the way tubes when you unlock it. On a Mark 5/V/7 headstock the wedges will protrude noticeably (~1/8" - 3/16") when fully unlocked. When fully locked, the wedges will be slightly inboard from the outer part of their headstock bore, I'd say something around 1/16" or less. Again, if yours is a Mark VII this description could be off.

Here is a thread on another stuck lock: (viewtopic.php?t=23940).

- David

[JPG]

The Mark VII wedge locks operate similarly to the current Mark V 5xx/7 vintage. Only difference from a Mark 5/ V 500 is the wing nut is replaced by the lever.

[edflorence]

How do I go about getting my headstock to slide easier along the way tubes? I've tried both waxing and rotating the tubes, but I don't see much of any improvement with it. I'll get it to the point where it will slide pretty easily through some of the distance, but then it will hit a section with increased resistance.

Adrian;

I have a similar, though not identical, state of affairs on my old 500. If I unlock the headstock but don't unlock the carriage, it is difficult to impossible to get the headstock to move. Once I unlock the carriage, the headstock moves freely along the full length of the tubes. I don't need to move the carriage at all, just unlock it. Unlike your situation, however, I do not find any particular location along the tubes of increased resistance. Have you tried unlocking the carriage and headstock at the same time to see if the headstock still won't move freely? Might be worth a shot.