What is it

[catmechanic]

I also wonder if @jriser would know.

He recently posted a thread with his collection of watch-makers lathes, here:
https://www.hobby-machinist.com/threads/my-collection-of-ww-lathes.87254/post-781806

-brino

@hman and @catmechanic ,

That's an interesting idea!

I went searching for such a beast.....

First I found a "homemade" version here:
http://www.cartertools.com/brooketh.html

And then a description of "Chase Screw Cutting" on lathes.co.uk here:
http://www.lathes.co.uk/chasescrewcutting/

that page says:


They give a few examples of lathes using this system:
http://www.lathes.co.uk/waltham/index.html
http://www.lathes.co.uk/karger/page2.html (with a sliding spindle!)
http://www.lathes.co.uk/ames/page3.html

-brino

I believe you've nailed it!! These appear to be for a larger machine as the pitch diameter is 1.375. Would be nice if could find somebody who could use them. That is a very interesting concept, gives food for thought for sure. Thanks for the effort on your part brino.

 

[silence dogood]

In the Unimat owners manual, it shows a picture of a thread chasing attachment. Unimat call these things pattern bushing and it is mounted between the chuck and spindle. Then the chaser attachment is a bar with a sliding guide and sliding cutting set up clamped to the lathe. The pattern bushings are external threads. What you have there won't work for the Unimat. What throws me off are the internal thread bushings that you have. Sorry, no pictures, but it's similar to what Brino has described.

 

[catmechanic]

In the Unimat owners manual, it shows a picture of a thread chasing attachment. Unimat call these things pattern bushing and it is mounted between the chuck and spindle. Then the chaser attachment is a bar with a sliding guide and sliding cutting set up clamped to the lathe. The pattern bushings are external threads. What you have there won't work for the Unimat. What throws me off are the internal thread bushings that you have. Sorry, no pictures, but it's similar to what Brino has described.

In your first post you suggested a thread chasing attachment, but me being old mechanic turned hobby machinist, thread chasing brought to mind a die nut. Anyway it makes sense how that could be a really accurate way to cut threads. An interesting note though, three of the (chasers?) are an acme thread. Why would it make a difference if the chaser was acme or standard, as long as the pitch was correct?

 

[silence dogood]

In your first post you suggested a thread chasing attachment, but me being old mechanic turned hobby machinist, thread chasing brought to mind a die nut. Anyway it makes sense how that could be a really accurate way to cut threads. An interesting note though, three of the (chasers?) are an acme thread. Why would it make a difference if the chaser was acme or standard, as long as the pitch was correct?

Good point. You got a keener eye than I do.

 

[hman]

@silence dogood - Now that you mention it, I think the accessory I saw was on a Unimat lathe!

@catmechanic - Durn! I missed that. My best guess (and ONLY a guess) is that the threads are Acme simply to remind the user to use the correct form tool to make the threads on his workpiece(?) Definitely going down a rabbit hole here ... but fun to speculate!