1956 Colchester 13x36 Engine Lathe - Follower bolt size ??

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dansawyer

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The lathe is a 1956 Colchester 13x36 Engine Lathe, there does not appear to be a model number. Does anyone have the bolt spec for attaching the follower? I have tried fitting both SAE and Metric taps and non seem to be a good fit.
Thanks in advance, Dan
 
British Standard Whitworth? They are inch sized but with a slightly finer pitch than on our coarse threads, tapped holes in cast iron on machine tools are generally coarse threaded, not SAE, and Colchester would likely not be metric back then. What diameter is it?
 
For instance, BSW 1/2" is 12 TPI instead of our 13 TPI, and the included angle of the thread is 55 deg. I have a large assortment of British taps and also some dies.
 
Thank you. Using a drill shank I measured the inside diameter of the threads to be 3/8 inch with a drill shank.
 
I'm guessing that it is either 7/16" - 14 tpi, US standard coarse, or 7/14" - 14 Whitworth, buy a US bolt and try it first, you may be able to run a US tap into the hole to clean it out and use the USA bolt to attach the follow rest. I do have the Whitworth taps if you want to keep it as it is and make bolts for it. I also have round adjustable split dies in 7/16-14 Whitworth.
 
I am surprised that there have not been any other responses to the question, especially from our neighbors to the north.
 
dansawyer said:
The lathe is a 1956 Colchester 13x36 Engine Lathe, there does not appear to be a model number. Does anyone have the bolt spec for attaching the follower? I have tried fitting both SAE and Metric taps and non seem to be a good fit.
Thanks in advance, Dan
Click to expand...
Clausing is still around, and is pretty responsive regarding support. I was looking at a Clausing Colchester a couple weeks ago (wound up buying a different lathe but whatever). I called Clausing, described the lathe, and the guy emailed me a manual. The pictures in the manual didn't match the lathe, so I emailed him back with photos of the actual lathe. He identified the model of the lathe and emailed me another manual. All of this in one afternoon, no charge.

He's unlikely to know the bolt specs, but once you identify the model of the lathe (and possibly get a manual) you have a head start.
 
Thank you all. I will try a 7/16 course. for fit. One of the holes looks clean and good, the other looks miss treaded. :(
I also e-mailed Clausing as well. Thanks for the tip.
 
If the hole is 7/16 BSW, a UNC 7/16 bolt will fit but the fit will be somewhat loose and the holding power about 70%. If a 7/16 UNC doesn't fit, the hole will be 7/16-18 BSF. My CVA is entirely BSF or BA for smaller screws.

If you have a British machine, you can get a set of BSW or BSF taps and dies pretty cheap. The taps are not great but good enough to clean up cruddy holes and mucked up bolts. The hex heads of Whitworth bolts are also sometimes a tad larger than a US wrench set will fit so I also have a fairly cheap wrench set.

Dave
 
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