Re: Metric Thread Dial

Bill in OKC too

Disclaimer: I have never cut an English thread on a metric machine or vice versa, but with the metric change gears it seems to me that it SHOULD work. When I say things like that SWMBO says I'm "shoulding all over myself." ;) Anyone who knows better, feel free to school me. In the mean time, I would suggest trying it, and seeing. I hope to be finding out for myself, one of these days soon. I have an HF mini-lathe for which I still need to print a 100-tooth gear to go with the 127-tooth gear I already have. The lead screw on mine is 16tpi. I've also got a single-tumbler SB Heavy 10L that I hope to be able to add metric transposition gears to once I finish the restoration project. I seem to recall reading that it's not quite so straight forward on the single tumbler gearbox machines, but if I can print a gear for it, it won't be too expensive to try. 

Bill in OKC

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On Sunday, January 3, 2021, 09:56:36 AM CST, john kling via <jkling222@...> wrote:

Hm I don't feel particularly sharp today and have  not in the past thought about why the thread dial works - But would the imperial still coordinate the position of the carriage and the lead screw in metric operations on the imperial lathe. -if this is completely silly, ignore.

On Sunday, January 3, 2021, 10:08:19 AM EST, Steven H via <stevesmachining@...> wrote:

I have never heard of a metric thread dial. When cutting metric threads with an imperial lead screw lathe, one normally engages the half nuts and leave the half nuts engaged until you are done cutting the thread. Do not disengage the half nuts. Reverse the lathe to return the carriage to the starting point after backing out the cross slide. 

Steve Haskell
Troy, MI

On Jan 3, 2021, at 9:57 AM, Davis Johnson <davis@...> wrote:

The metric thread dial is intended for use with a metric lead screw, not transposing gears.

Conventional wisdom is that the normal threading dial is not useful with the transposing gears, no doubt why you are interested in the metric thread dial.

I have read a contrary opinion, that it will work if you reposition the carriage the same place for every pass (perhaps a carriage stop to the right of the carriage? might have to go on the rear v-way.) AND start on the same dial mark each time. It sounds reasonable to me.

I have been wanting to try this for some time, but haven't done it yet. Next best thing for me would be for you to try it.

On 1/3/21 8:58 AM, Al Costich wrote:
For some silly reason, I am in the hunt for a metric thread dial for a 9A.
Some time ago I acquired a 127/100 transposing gear set and some additional
Thinking forward, i would like to single point some metric bolts.
I'm not confident enough to make a thread dial myself.
So, should anyone have one that is superfluous to their needs,
contact me.



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