Tap making

[microcarve]

As many of us know, screws from different makers will vary slightly...
as there are no 'standards' for multi-start screws. A nut from one may
or may not work with a screw from a different maker.

And often, someone may not even know who makes the screw, or
where to locate the 'right nut'.

So we have to make taps sometimes.

I have to make them from time to time, so I finally tried to come up with
a predictable and consistent technique. It works Great....but it needs a mill,
and a lathe is also very helpful.

Basically....

I used a ball mill.

Lock the acme scrap in the vise.

Cut a single fairly groove offset toward the cutting edge by about .015

Dull the non-cutting edge with a file...(I used a diamond file...carefully)





I tried this about 3 times to be sure it does it consistently. Mine is a 3/8"
acme 2 start, but the technique should work on any size with few tries
at it.

The single groove working so well really surprised me. I expected to groove
the other side, but it didn't need it.


Pictures coming up....


John

[microcarve]

I made a little strip of aluminum so the acme would sit up
near the top of the vise so I could watch progress....






I locked the acme between a softer piece of aluminum so as to not
damage the threads. I could've used a second aluminum bar, but I
know how tight I can lock it in the vise without problems....






So it all fits well and looks secure enough.....

Next, the taper needs to be done before the groove milling. I used
2.5" as the taper length. I just used some rough files in the lathe to
do the taper. That was quick & easy. Then polishing it up a bit....








More pictures coming up.....

[microcarve]

It worked out that a 1/4" ball mill was just the right thing for
the 3/8" acme....






Cut a little bit at a time. Not too deep per pass....








The tapered end will spring a bit, so several passes are needed until
the groove looks good on the tap end.

[atwooddon]

Great info, Thanks John I think I need to head to the shop and try this.

Don

[microcarve]

Presto!...A nice deep grooved tap that works excellent for making
plastic nuts....














Naturally, your mileage will vary. But I was able to make 3 out of 3
tries at it all work....once I figured out a procedural way of doing it.

The old way was a huge PITA using cut-off wheels and grinder bits.
Only problem with this is the mill is pretty much needed. But it's quick,
easy and predictable.


John

[microcarve]

Great info, Thanks John I think I need to head to the shop and try this.

Don

I thought I'd need grooves on both sides, but it
works amazingly well and smooth with just the one....

An old drill chuck is the thing to hold it. Cutting the ends square like
on a real tap will weaken the soft steel...besides just being more trouble
than it's worth...

From past experience with un-hardened homemade taps....they're
good for hundreds of delrin nuts.


John

[jckstrthmghty]

Thanks for taking the time to share. A mill and lathe are on my wish list.

[prcdslnc13]

I just got a Mill. and have lots of delrin and some scrap 1/2-10 5 start, and a 1/4" ball mill on the way. Guess what Ill be doing this weekend. Ill post up some results