Threading question for my pm1127.

Yes you can cut any thread you want, but on an Inch machine, you can not use a thread dial for Metric threads. This is not just on this specific machine, it is on ANY machine out there, no matter if it costs $1000, or $30,000. It is just the way the math works out. Other than once I actually did see a lathe that had a thread dial with a gearbox on it, and you could work it out and use it for metric and inch threads, but it was so complicated, its just easier to leave the half nuts engaged when doing metric. Once you do it a few times, it is not hard at all.
 
The thread dial indicator for the Emco Super 11 has three drive gears, one for Imperial and two for Metric. It allows you to cut metric threads on an Imperial lathe while using the half-nuts normally.

S11-threadingdial.jpg
 
That is a Metric Thread Dial, on a Metric Leadscrew, which will work for Metric threads, but you can't do Inch threads with that one and vice versa. Inch leadscrew, no thread dial for Metric threads. All Metric thread dials I have ever come across have 3 gears on them, just like that one.

The only way I have ever know it to be possible is with the Metradial, which probably costs as much as one of these lathes: Of course, there could be something out there that I do not know, but Ive never come across anything that will work other than this.
 
To further what Matt said, if you don't have a threading dial, you can still cut any thread you want, metric or SAE, (assuming your lathe will thread) by leaving the half nuts engaged. You will just have to reverse and back out each pass. It is just a bit slower of a process than if you have a threading dial.
 
Actually, the 16t gear is used on my Imperial leadscrew and cuts Imperial threads just fine. To cut metric threads on my lathe you use one of the other gears on the indicator and different marks on the discs on top to time the engagement.
 
3dshooter80 said:
To further what Matt said, if you don't have a threading dial, you can still cut any thread you want, metric or SAE, (assuming your lathe will thread) by leaving the half nuts engaged. You will just have to reverse and back out each pass. It is just a bit slower of a process than if you have a threading dial.
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I understand this. Martin Cleve refers to this as the Complete Reversal Method in his book, Screw cutting in the Lathe. However, it is possible to back off the half nuts to cut metric threads as Darkzero points out. There is a video on this as well but I don't recall the author.
 
mikey said:
it is possible to back off the half nuts to cut metric threads as Darkzero points out. There is a video on this as well but I don't recall the author.
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Video link is in my post as well. Video by Tom Lipton. IIRC Abom mentioned the method in a video recently. Could be others too.
 
mikey said:
I understand this. Martin Cleve refers to this as the Complete Reversal Method in his book, Screw cutting in the Lathe. However, it is possible to back off the half nuts to cut metric threads as Darkzero points out. There is a video on this as well but I don't recall the author.
Click to expand...
Inch lead screw, metric thread to a shoulder. Release the half nuts at the end of the cut, back out the tool, and IMMEDIATELY turn off the spindle before the position gets lost. Now, put the lathe in reverse, start the spindle, and re-engage the lead screw on the same thread dial mark it was on for the cut. Return to starting position. You have only temporarily disengaged the threads and then re-engaged them, nothing is lost, unless you let the dial turn around too long and lose the original engagement position. It works fine, I have used it several times...
 
Thanks, Bob. I have a thread dial indicator that works for metric threads so no real issues. Well, it works for the pitches I've had to cut, which have only been a few of them.
 
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