# Tailstock Locking Problem



## JWG (Jul 6, 2013)

I have a Craftsman 101.28940 12 X 36 lathe. I was trying to drill a hole with a drill chuck installed in the tailstock ram. While drilling the ram rotated in the bore of the tailstock. The ram became very difficult to move in and out. To rotate it back I removed the ram from the tailstock and now I can’t figure out how to reassemble the ram lock. There is a keyway down the side of the ram but I can’t see anything that slides in the keyway to hold the ram in position. The ram lock mechanism is simply two beveled sleeves with a bolt and the locking handle. Is there supposed to be a piece between the two sleeves that slides in the keyway on the ram and keeps the ram from rotating?


----------



## TOOLMASTER (Jul 6, 2013)

Sounds like you sheared  the pin or it backed out


----------



## rammed (Jul 6, 2013)

there should be a screw in the side of the tailstock. The screw has a small extension on the end .  Think of a screw you filed flats on 180 out. The little extention fits in the key way of the ram. Sounds like yours is worn or broken off. You adjust the screw til it sticks out far enough to engage the key way.
Hope this helps.


----------



## JWG (Jul 6, 2013)

rammed said:


> there should be a screw in the side of the tailstock. The screw has a small extension on the end .  Think of a screw you filed flats on 180 out. The little extention fits in the key way of the ram. Sounds like yours is worn or broken off. You adjust the screw til it sticks out far enough to engage the key way.
> Hope this helps.



) Thanks. That clears it up. I saw the screw but it wasn't protruding in the ram socket at all. I'll check it out and see if it's broken or just not adjusted correctly. I haven't adjusted it since I bought the lathe.

- - - Updated - - -



TOOLMASTER said:


> Sounds like you sheared  the pin or it backed out



Thanks, I understand how it works now.


----------



## wa5cab (Jul 6, 2013)

JWG,

As rammed wrote, the tailstock ram anti-rotate key is made from a headless slotted set screw.  But it comes up through the bottom of the ram bore, not the side.  However, it is not something that you routinely adjust, as there is no real adjustment.  The screw must be up just far enough before you slide the ram into the hole.  After that, there is no adjustment as you cannot turn the screw with ram in place without damaging the slot in the ram.  And if you pull the ram and advance the screw half a turn, it will most likely be too tall for the ram slot to run over.  

I imagine that the key screws were probably at least in the old days made on a horizontal mill with three cutters in the arbor and a purpose made fixture that held several screws at a time.  It wouldn't be as easy to do on a vertical mill and would take much more time to make the same quantity.  Even an NC machine would take three times as long as it would have to make three passes and a rotate.

You could make a new one but if you simply cut the end of the screw flat and then cut two flats on the sides of the screw, and install and try to use it, it may or may not work.  Plus if you hold the screw in a hole tapped in a block held by a vise on the milling table and rotate the screw 180 in the tapped hole to get at the other side, one flat will be longer than the other by half the thread pitch.  

When the screw is run up through the bottom of the ram bore, when the flats are parallel with the bore axis the tip must be at the proper height.  There is no adjustment.  It's either at the right height or you can't get it at the right height without cutting the tip off a little and screwing it in another half turn.

Easiest thing to do is buy a new one from Clausing.

Robert D.


----------



## rammed (Jul 7, 2013)

I couldn't remember were the screw was on my old atlas. I'm restoring a dunlap AA and the screw is on the back side of the tial stock.


----------



## wa5cab (Jul 8, 2013)

rammed,

No problem.  I sometimes forget that even the Atlas machines of different sizes have the same functions done in a different way.

JWG,

It occurred to me later that even if you buy a new screw from Clausing, you may have to fit it to your tailstock in order to get it exactly the ideal height.  Given the price point that these machines were built to, they probably didn't go to the added expense (time) to guarantee the angular location of the flats relative to the thread start as well as the location of the thread start in the tailstock.  So one made at random could be as much as .02 too low (another half turn would make it just too high).

Robert D.


----------

