3520 tailstock quill locking

[john lucas]

I have always had this problem on my 3520A. Just saw it twice on 3520C's at the symposium. If you crank the tailstock quill all the way back it locks up the handwheel and takes a lot of force to release it. You learn not to fo that but still every once in a while it happens. I decided to solve the problem. The problem happens because the 2 mating surfaces are very precise so it's kind of like snapping your chuck against the spindle face. Takes a fair amount of effort to break it free. I turned a washer made from UHMW and it stops the problem. I think any fiber or plastic would work.

 

[Earl McLain]

Nicely solved. But now that you created a solution, you'll probably never back the tail stock off like that again!!
earl

 

[Bill Boehme]

Great solution, but I suspect that the reason for sticking so tightly is that the two mating surfaces don't quite perfectly match. That would lead to some deformation where the two surfaces meet.

How did you manage to get the piece of UHMW to stick to the block of wood?

 

[GRJensen]

I have always had this problem on my 3520A. Just saw it twice on 3520C's at the symposium. If you crank the tailstock quill all the way back it locks up the handwheel and takes a lot of force to release it. You learn not to fo that but still every once in a while it happens. I decided to solve the problem. The problem happens because the 2 mating surfaces are very precise so it's kind of like snapping your chuck against the spindle face. Takes a fair amount of effort to break it free. I turned a washer made from UHMW and it stops the problem. I think any fiber or plastic would work.

View attachment 46049


View attachment 46050

Thanks, John ... I've been futzing around trying to figure out a fix for this problem!

 

[Mike Hunter]

This is a great idea. A simple fix which will be my project on Monday.

 

[Daniel Henry]

I have always had this problem on my 3520A. Just saw it twice on 3520C's at the symposium. If you crank the tailstock quill all the way back it locks up the handwheel and takes a lot of force to release it. You learn not to fo that but still every once in a while it happens. I decided to solve the problem. The problem happens because the 2 mating surfaces are very precise so it's kind of like snapping your chuck against the spindle face. Takes a fair amount of effort to break it free. I turned a washer made from UHMW and it stops the problem. I think any fiber or plastic would work.

View attachment 46049

I have always had this problem on my 3520A. Just saw it twice on 3520C's at the symposium. If you crank the tailstock quill all the way back it locks up the handwheel and takes a lot of force to release it. You learn not to fo that but still every once in a while it happens. I decided to solve the problem. The problem happens because the 2 mating surfaces are very precise so it's kind of like snapping your chuck against the spindle face. Takes a fair amount of effort to break it free. I turned a washer made from UHMW and it stops the problem. I think any fiber or plastic would work.

View attachment 46049


View attachment 46050

I own a PM 3520-C. I learned the "hard way" that when you spin the hand wheel on the tail stock and the quill re-tracks rapidly and comes to a sudden it will jam. In my case, I learned how to take the tail stock assembly completed apart. Now, I no longer spin the hand wheel.rapidly.

 

[Ric Williams]

I ran into that ejecting a drill chuck with a slightly short taper on my 3520C. Glad to know there's an easy solution.

 

[GRJensen]

Off hand, does anyone know the diameter of the 3520C's lead screw?

 

[Tom Gall]

Don't know for sure (don't have a PM) but I think an O-ring might solve the problem with a lot less effort.

 

[john lucas]

Ever since I've owned my Powermatic 3520A if you crank the tailstock all the way back it locks up and really hard to turn the handwheel. Consequently I try to not do that. Hasn't been a major problem but at the symposium I noticed 2 instructors had their 3520C tailstock quill lock up. Fortunately I was there and quickly told them what to do to stop it from happening. So I thought it was time to solve the problem once and for all. Turns out the problem is really good machining. The back of the quill hits the flat area on the threaded rod and locks up much like when you twist your chuck onto the headstock spindle. It can be hard to get the chuck off without using the chuck key as a lever. The solution is quite simple. Add a fiber or plastic washer between the quill and the back of the treaded rod. While testing my theory on my friend 3520C I noticed that on his lathe with an aftermarket live center the quill is almost all the way back and locks up really easy because that Acme thread really pushes the quill. On that lathe the with that aftermarket live center a really thin washer would be needed. You could cut one from the plastic on a milk jug and it would probably work fine. I may send this tip to Powermatic as well. Its very easy to remove the handwheel and pull the whole quill assembly out do to this fix.

 

[GRJensen]

Don't know for sure (don't have a PM) but I think an O-ring might solve the problem with a lot less effort.

Depends on which 3520 you have and the live center you are using. John Lucas tested this on a PM3520C, and determined that a thin washer might be needed.

 

[Tom Gall]

Depends on which 3520 you have and the live center you are using. John Lucas tested this on a PM3520C, and determined that a thin washer might be needed.

Gerald, I still don't understand. John said he had to turn a plastic washer. An O-ring would just slip over the needed section. There may be a reason why that wouldn't work but I don't see it at this point.

 

[GRJensen]

An O-ring may or may not work. The O-ring may be too thick, which could effect operation of the self-eject.

I just completed John's fix ... I cut a piece from a plastic milk carton, attached it to a wooden drive block with double-face tape, and used a thin parting tool to cut a 1-1/4" washer with a 5/8" hole. Installed the washer over the lead screw and re-installed the quill assembly in the tail stock ... works like a charm!

 

[GRJensen]

Someone in another thread suggested using an O-ring, but that may or may not work. The O-ring may be too thick, which could effect operation of the self-eject.

I just completed John's fix ... I cut a piece from a plastic milk carton, attached it to a wooden drive block with double-face tape, and used a thin parting tool to cut a 1-1/4" washer with a 5/8" hole. Installed the washer over the lead screw and re-installed the quill assembly in the tail stock ... works like a charm!

 

[Lou Jacobs]

Thanks so much for this easy fix John! Just did it with a piece of a Clorox bottle and worked as you suggest. Yes, absolutely suggest it to Powermatic! It’s been a frustrating problem on an otherwise solid as a rock machine.