Double Lead 12-28 Thread Question

Upon a closer look, they do look right handed, but a closer up picture would settle it, also screwing it into its "nut" would prove it.
 
I have a 12/32 R.H. tap and die if I recall correctly. Might help you perhaps?
 
Likely LH thread.

That way the post moves opposite the top.

When one unscrews the knob on the shaft, the shaft tries to screw into the plane.

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What you want is commercially available. I went through this a couple of years ago for fountain pens. The really good ones use a triple start screw on cap so the user isn't inconvenienced. You look at the thread end and see if it has 2 openings 180 degrees apart, or 3 openings 120 degrees apart. You Google multi start taps (or dies) and the companies that make them will appear. This time around I found a chart that show the degree settings for making your own. Be aware that if you have a real multi start thread, the tap and die will cost well over $100 each.

Looking at the picture, it looks like you have a left hand thread and a right hand thread, 2 different sizes. It looks like a regular set of threads. The threads don't look right for multi start. You can get 12-28 multi start tap and die.
 
tq60 said:
Likely LH thread.

That way the post moves opposite the top.

When one unscrews the knob on the shaft, the shaft tries to screw into the plane.

Sent from my SM-G781V using Tapatalk
Click to expand...
Both are right handed. The small one travels faster than the larger one. The result is the bracket moves in or out.
 
Chewy said:
What you want is commercially available. I went through this a couple of years ago for fountain pens. The really good ones use a triple start screw on cap so the user isn't inconvenienced. You look at the thread end and see if it has 2 openings 180 degrees apart, or 3 openings 120 degrees apart. You Google multi start taps (or dies) and the companies that make them will appear. This time around I found a chart that show the degree settings for making your own. Be aware that if you have a real multi start thread, the tap and die will cost well over $100 each.

Looking at the picture, it looks like you have a left hand thread and a right hand thread, 2 different sizes. It looks like a regular set of threads. The threads don't look right for multi start. You can get 12-28 multi start tap and die.
Click to expand...
Thanks, I know they look left and right but they are both right handed. small is 3/16-28 double start. the larger is 1/4-28 standard. Yeah I know they are expensive (based on the taps I found) . I have looked but haven't had luck finding a 12-28 double lead/start set. At least so far.. If you run into a source link let me know I would appreciate it. Not sure I want to spend to $100+ . but it would be nice to know I have the option.
 
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