tapping butt caps

D

Dana Hackney

Joined
Nov 1, 2005
Messages
174
Hi folks,

I need some help with how to go about tapping a hole (1/4 x 20) in a butt cap (NS)
where I do not want to tap completely through it. I want to sink and thread a hole
about 3/4 the way through so I can attach the butt cap to a threaded tang.

Should I be using a bottom tap? If so, where's the best source for buying one?

Thanks and best regards,
Dana Hackney
Monument, CO
 
Yep, that's exactly what a bottoming tap is for.

Enco (www.use-enco.com) or MSC (www.mscdirect.com) are good sources.

Enco typically ships out of Nevada and has items to my door in two days at ground rates. (I'm in UT)

Dave

Edited to add: If you have enough threads engaged with your plug or taper tap (whichever you are using) you can grind down the end-most threads on your tang to fit the mostly-tapped hole. I.e., profile it like the tap. The first couple of threads take most of the load, anyway, so you won't lose much, if any, strength. I don't know how deep your tapped hole is, so this may or may not work for you. I would only do it if I were using supplemental means to attach the cap. I.e., JB Weld, pinning to the tang, etc. Best just to get the right tap.
 
For the help. I might try experimenting with grinding down the tang but I'll also probably order the right tap, as well.

Thanks again,
Dana
 
what is the difference between H1 H2 and H3 for the ground thread limit?
I'm looking at the ENCO catalog and am not sure which H's I should get.

Thanks again,
Dana
 
Dana,

The Hx numbers are x * 0.0005 (1/2 thou) oversized. I believe "normal" for 1/4-20 is H3. H2 or H3 should be fine.

Dave

PS - One other workaround. If you have a spare taper tap, you can just grind the end off...
 
Dana, what I like to do, is drill a shallow hole in the center of the pommel material with a center cutting endmill. This will give you a flat bottom hole, whereas a drill bit will give you a "V" bottomed hole.

Then get yourself a stand-off. These are threaded sleeves. Specialty hardware stores carry them, but I just order them from K&G.

Hard solder that into the hold, then you'll have a BUNCH of threads to use, rather than trying to get some into a blind hole.

The blind hole does work well, but the big advantage to the stand-off, is that you can use a really thin/sleek pommel.
 
Good trick, Nick! :thumbup:

I had to figure it out the hard way, but what I wound up with is a way to make it work very well instead. I took a bottoming tap and flattened it even more. Did the same with the corresponding drill bit. Then the key is to reshape and thin out the web on the tap and the drill. Its kind of tricky to get the dimensions right, but worth it in the end.

Drill and tap with a normal drill and bottoming tap, then use the special drill and tap to finish your threads right to the bottom.

Then the only thing left to do is to flatten the end of the threads on your tang and make sure it all fits up properly.

Oh and one other thing: This technique seems to work better with the fine threads, i.e. use 1/4-28 instead of 1/4-20.
 
Thanks Nick, Dave and Jeff!!! I will also be adding these suggestions to
my file.

I never fail to get the very best expert advise here. You folks on the forum have saved
me from a lot of frustration and extra work.

Many thanks!
Dana
 
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