QCTP holder

A common complaint with the Chinese made holders is that although the holders themselves are good, the set screws are not. I'm sure that the majority of the holders that I have (all except the original set that came with the Yuasa tool post) were made somewhere in the Orient, as they mostly came from Wholesale Tools. But I've never had the problem with them. Maybe they were all made in Taiwan.
 
I found the t nut I need on ebay and it is drilled for 14-1.5 threads. I want to try and make my own post so I picked up some 5/8" cold rolled steel bar at Home Depot that I will turn down to 14mm for the t nut end. Measuring both the existing post and the 5/8" bar, the 5/8" bar is about 0.33mm smaller. Assuming it is straight, is that too much difference to cut 16-2 threads using a die?
 
I bought a 14mm MF tap at my local store, Sorry 16-2 won't work.

Robert, I found it easy to buy Grd 8 set screws to swap in my holders very cheaply.... It was worth it just for the peace of mind.
 
I think I answered my own question. I found it at www.engineersedge.com. For 16-2 threads the maximum stock size is 15.962mm and the minimum is 15.682mm. My bar stock is just above the minimum. I may try to find something bigger and turn it down closer to the 15.962mm.
 
Why would you be looking at M16-2 when the T-nut you bought is M14-1.5?
 
The post that came with the BXA is threaded M16-2 and I want to keep that size from the top nut through the body and the turn it down to M14 to go into the t nut. If you don't turn it to down to M14 there is no meat left for threads on the narrow side of the vertical part of the t nut.
 
Then what you will need to do is to first turn one end of the M16-2.0 stud down to 14.0 MM for a distance equal to the thickness (height) of the T-Nut. Then cut a thread relief groove about 1 MM wide down to the minor diameter of M14-1.5. Thread the stub with a die nut up flush against the M16 diameter. Repeat with the die nut turned around to cut the thread up against the shoulder. Confirm that the M14 will screw into the top of the T-nut until the M16 shoulder contacts the top of the nut.
 
Thanks wa5cab. One question. Is the thread relief groove supposed to separate the 16mm and 14mm sections?
 
Thanks wa5cab. One question. Is the thread relief groove supposed to separate the 16mm and 14mm sections?
Click to expand...

You will be threading up to a shoulder so you will need a relief to dis-engage your tool ( assuming single point threading ) and it will ensure that you have a square shoulder to tighten to on your t nut no matter how you thread the stock .
 
Yes. Technically, it is part of the M4 sub-section. You could also try it the other way around. Turn down the M14 part, thread it, run the die on reversed to cut a little closer to the shoulder, and screw the stud into the T-nut finger tight and measure the remaining gap. The only purpose, as you already indicated that you were going to use a die nut instead of trying to single-point it, is to ensure that the shoulder hits the nut rather than standing proud when the incomplete male thread bottoms in the female thread. Depending upon what the two materials involved are, the interference fit could lead to galling and difficulty in removing the stud at a later date.

The reason that you want the shoulder to bottom on the face of the nut is that it will be a little stiffer assembly that way.
 
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