Easy simple threading

Great idea, especially if it means we can use a broken or dull tap that has been ground back to life.
 
Wasn't there a thread where the guy did this with a broken die also ?
 
So that's basically using a tap (or die) as a form tool, instead of a thread chaser as in Sparey's lathe boo)? Interesting idea, and much cheaper than buying chasers.
 
I believe I might have done something similar in the distant past. Works well as long as your lathe has the correct pitch available. You can also use a piece of a broken die.

Note that you don't need to have the tap of the correct dia, as long as the pitch and thread form is correct.
 
I was skeptical at first as you still need to use the lead screw and half nuts and I didn't see much advantage over single point threading. However, it would definitely be useful to cut tapered threads if your lathe doesn't have a taper attachment. I would think that you would want to use a pipe thread tap for the cutter rather than angling the tap to the taper angle as by angling the tap, you are also rotating the thread form which would cut a leakage path.

You will have to be very quick at backing out at the end of the cut as you cannot disengage the half nuts. He is also cutting with the heel of the tap and I'm not sure what effect that will have on the thread form.

I will be interested in seeing a report from someone from HM who has actually tried this.
 
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