Clausing-col. 13x36 Threading Problem

I recently acquired a CC 13x36 lathe. It was filthy but now it is clean, painted, and running. I'm learning it, slowly. Today a friend brought me a job that requires turning down a 1.125 shaft to 1.00 about two inches on one end and threading that end to 16tpi. Same for a second shaft except left-hand threads. I know how to thread and have do so many times on my recently sold SB11".

As this is my first threading job on the CC I'm practicing on some scrap. It seems that no matter where I place the various levers I get very fine threads like 32tpi.

What am I doing wrong?

This is a wild-blue-yonder question because I've never fooled with a Colchester and with Downloads still down can't look at any catalogs. But does the machine have separate drives for turning and threading?

wa5cab said:

This is a wild-blue-yonder question because I've never fooled with a Colchester and with Downloads still down can't look at any catalogs. But does the machine have separate drives for turning and threading?

Click to expand...

The selector at the bottom of the head let's you select feed rate or this per inch. The lever just above & to right engages lead screw got threading. Lever on saddle engages/disengages threading. Levers on top of head and one on face of head set spindle/chuck speeds.

My first thought on reading your problem is that you may not be using the half nut lever when threading. I am making an assumption here and am just trying to help. On my clausing I only have 1 lead screw as I believe you do, Once the QC levers are set to the correct threads per inch, the half nut lever is used to power the carriage at the correct speed to cut threads which requires that the metal cutting gears in the carriage are in neutral. I use the back gears and the same number on the threading dial when cutting threads. If this is not the problem then I have missed the boat.

Have a good day

Ray

We need pics of the front of the head of the lathe as well as the apron, and then tell us exactly what you are doing, before we can be of much help.

Brian

I have a 13x40 CC mine has a shear pin on the lead screw sounds like you have the older round head not sure but I suspect it has one as well. There is a collar wear the lead screw attaches to the gear box shear pin is under the collar check for breakage. Mine also has a a shaft that transmits power to the apron for feeds when cutting and the lead screw which transmits power for threading. When in the threading mode only the lead screw should turn. Mine has a chart that gives a series of numbers and lettters like LB6S set the levers to the code and the pitch rate is set, Be certain that the levers are completely engaged sometimes they dont slide in without some manipulation. If none of the above then I suspect that you have a lever that has come loose and it is not switching the gearbox or your are getting some slippage in the geartrain at some point. Can you change the speed of the leadscrew by changing the setting for threadpitch, just by looking at the screw and not with the halfnut engaged, As mentioned alreaady a pic of the front of the lathe would be helpful

Thank you all. Today we are leaving early for a trip to Santa Barbara so I won't have time to try all your suggestions. Will be back next Monday.---Matt

Here is a photo of the feed and threads/inch selector on my 13x36 colchester round head.
The lever at the the top in the photo just above the selections table engages the threading lead screw.
The knob and lever at the bottom of the photo slides left and right and goes in the series of holes on a diagonal on the head stodk to select the threads per inch (or feed per revolution if the threading screw is not engaged). The two levers to the left are used to select match the row in the table of selections shown corresponding to the column selected at the bottom.
The levers on top in conjunction with the fairly vertical lever (highest on front face) select rpm of the lathe. You can match the left/right position of the levers to the selection chart on the top front of the headstock.
The little lever to the left selects forward or reverse.
The lever with the red knop is pulled up to start and down to stop rpm with full down acting as a brake. The small black knob on this same lever is your high/low speed range selector.
I have had a few times where the threading screw did not rotate. This could be either the shear pin or a gear comes loose under the cover to the left of the head stock. In my case the gear came loose and merely needed to be pushed back in and the knob tightened that holds it in place.
Hope this helps.

Ok pull the end cover off and have a look at your gear train the driver stays constant then 120 tooth then 42 B tooth and not the 35 B tooth gear this going off mine hope this helps
Cheers Kiwi