1942 CK12 mystery

[69sg]

This new to my shop CK12 has got me stumped. While going through a cleaning and service… I found this mystery part … while inspecting and adjusting the end play of the cross slide thrust bearings. I cannot find a pic in the parts manual ( that I have) nor can I find any mention of it , or function, in the operating manual. I even checked other Monarch machine manuals of the era. The thrust bearings are housed in a threaded piece about 2 inches long. There is a locking screw on the square block ( that the manual calls the bearing block or housing). There are two castellated pieces that will engage each other after a grub screw is loosened on one … and slid together. The lead screw is then engaged and will turn the threaded bearing housing. ( as long as the locking screw is loo).There is not a big range of motion . What function is this. I have searched every pic and forum thread on the internet and can’t anything. Any help would be appreciated! Thanks

 

[texasgeartrain]

On most lathes i know, feed screw for cross slide is one piece if NO taper attachment. Thrust being controlled by dial side.

On lathes WITH taper attachment, feed screw is essentially two piece. Dial side being short with female splines for a slip joint. This short section thrust also controled by dial assembly. The longer acme thread portion has the male mating portion to slip inside the dial side shaft. Bearing and thrust for the longer acme thread section controlled at taper attachment side.

I can't see dial end, nor other pieces in pics, but i can guess.
1. The lathe had a taper attachment originally. Its lost, stolen, sold whatever. And someone had to make something to hold long part of two piece cross feed screw.

Or 2, someone was attempting to make a backlash eliminator for feed screw. Where adjusting it may push or pull threads of screw toward or away from cross feed nut. Thus removing any slop between feed screw and nut.

My two guesses anywho.

 

[69sg]

Thanks, sorry for not giving enough info.
The lathe is a complete Monarch CK 12 with taper attachment. The pics are of the draw bar, crossbred nut and screw , and this “coarse threaded adjustable thrust bearing block??”. One pic is with the cogs engaged ( which would turn the inner threaded piece) the other is with the cogs disengaged.
The other end of the cross feed screw appears normal to me with the telescoping shaft that slides into the dial.
If it’s diy… they did a crazy good and over engineered job of it… whatever it was.

 

[69sg]

This new to my shop CK12 has got me stumped. While going through a cleaning and service… I found this mystery part … while inspecting and adjusting the end play of the cross slide thrust bearings. I cannot find a pic in the parts manual ( that I have) nor can I find any mention of it , or function, in the operating manual. I even checked other Monarch machine manuals of the era. The thrust bearings are housed in a threaded piece about 2 inches long. There is a locking screw on the square block ( that the manual calls the bearing block or housing). There are two castellated pieces that will engage each other after a grub screw is loosened on one … and slid together. The lead screw is then engaged and will turn the threaded bearing housing. ( as long as the locking screw is loo).There is not a big range of motion . What function is this. I have searched every pic and forum thread on the internet and can’t anything. Any help would be appreciated! Thanks

Edit…
Here are pics of the device apart. You can see the inner coarse threaded portion. This inner threaded portion houses the thrust bearings.
If this is stock Monarch… what is its purpose?

 

[johnoder]

The ordinary TA lash up as on my '46 CW16

 

[gustafson]

Weeeead
All I know is my 12ck doesn't have that
I notice it is the opposite pitch of the leadscrew.
Perhaps some gadget for repeat turning tapers but I cannot imagine how it works

 

[texasgeartrain]

Without laying my grubby fingers on it, I'm more inclined to say backlash eliminator, based on more pics, and re-looking the original pics.

My theory, the short acme thread in bearing housing. Its opposite lead screw. So when its engaged, it can push lead screw toward taper attachment, applying pressure to the washer and nut at end of lead screw.

In doing so, you push lead screw to one side of threads in cross feed nut, removing slop.

If that's correct, I'd adjust to .001" or .002" free play on dial at the least used threads of lead screw. Because if you adjust where lead screw has wear, lead screw will get bindy where the threads are in better shape.

 

[69sg]

Weeeead
All I know is my 12ck doesn't have that
I notice it is the opposite pitch of the leadscrew.
Perhaps some gadget for repeat turning tapers but I cannot imagine how it works

Thanks for the help! I was hoping someone would tell me that isn’t standard. Not finding it in any IPC or pics on the web was wearing me out. Much appreciated!

 

[69sg]

Without laying my grubby fingers on it, I'm more inclined to say backlash eliminator, based on more pics, and re-looking the original pics.

My theory, the short acme thread in bearing housing. Its opposite lead screw. So when its engaged, it can push lead screw toward taper attachment, applying pressure to the washer and nut at end of lead screw.

In doing so, you push lead screw to one side of threads in cross feed nut, removing slop.

If that's correct, I'd adjust to .001" or .002" free play on dial at the least used threads of lead screw. Because if you adjust where lead screw has wear, lead screw will get bindy where the threads are in better shape.

Could be just as you say. When I get it back together I will just have to see how useful it is. It is made extremely well. The fit of the acme is impressive. Thanks for your help!