tapping for hidden bolts

[Burchtree]

I checked around but didn't find an answer. How do you tap a recessed hole, or is that even possible? I want to tap a piece of damascus for the ned of a bowie without drilling all the way through it (hope that makes sense). Are special taps/dies made for this? Thanks --

 

[howiesatwork]

A bottom tap will get the furthest down without modifying a tap.
I grind a tap to make it so the cutting edge is the bottom of the tap, and grind it at an angle to get some more chip clearance. It is tricky to do, and I'd have to take pictures to show it.
Someone who can explain it better will be along shortly, I'm sure...

btw: what's "the ned of a bowie "?

 

[Burchtree]

you don't know what the "ned" of a bowie is? sheesh.

Thanks for the help -- I'll see what I can do. BTW -- does anyone have any good tap charts? I have a 1/4 hole to tap so what size drill bit would I use?

 

[MJ Hofbauer]

Here's a link for a drill-tap chart. http://newmantools.com/tapdrill.htm

-MJ

 

[fitzo]

Michael, there are "regular", "plug", and "bottoming" taps. I use all three successively when tapping a hole for the "ned" like you plan on and for pommel screws. They are commercially available through places like MSC and McMatser-Carr. Never have ground one, though recycling a broken tap and regrinding it ain't a bad idea at all......

According to the tap chart, one uses a #7 (0.2010") for 1/4-20 and #3 (.2130") for 1/4-28. My personal opinion is that given the fact you may epoxy it all together, I like a little less bite (thread overlap) and would use a #3 or even a 7/32 for a 1/4" threaded hole.

Hope that helps a bit.

 

[jhiggins]

Howie said it first. Mike Fitzo expounded on it. Now I'll drive it home!

Buy a bottoming tap. When you use it, you will know your money was well-spent. You will know by feel when you have reached the bottom of the hole. One thing to consider when looking at the design of a bottoming tap is that the last thread and a half that are formed aren't entirely symmetrical with the preceding taps. Either give yourself a little deeper hole, or use a little shorter screw.

Oh, and always remember this little tip when buying taps: Four flutes in ferrous, and two flutes in everything else except Ti.

 

[NickWheeler]

Actually, those answers suck!!!

Just kidding

I agree with the guys completely.

BUT! Let me throw a wrinkle in there.

I used to do pommels with blind holes and used bottoming taps.

The problem that can POSSIBLEY arise, is you often have to use a fairly thick, almost (sometimes VERY) clunky looking pommel. I'm not saying that's a given... as you really only need a couple/few turns on the threads.

You can use REALLY thin OR thick material (if you wish) by welding or soldering a stand-off to the pommel material.

I buy them from K&G, but you can get them from places like McMaster Carr.

Since a picture is worth a thousand words---

And here's an example of how you can do a thin, domed pommel with this approach. The 416 for these pommels started off as 1/8" but was then domed, so it's quite thin. However, because of the stand-offs, there is about 1/2" of threaded sleeve wrapped around the tang, up inside the handle.

Hope this helps Michael
-Nick-

 

[mete]

Some of us get our bottoming taps when we break a regular one !

 

[Burchtree]

Very intersting. I like that idea quite a bit Nick -- do you recommend drilling into the piece and using a bottom tap in conjunction with a welded on spacer for that little bit of extra security?

Here's a piece of the "ned-cap" with the rest of the hardware. I haven't attached the hardware yet or obviously silver soldered the steel bolt onto the tang yet, but I think that method will work well for this blade.

Thanks all --

 

[NickWheeler]

Michael-

I don't drill into the pommel material at all, unless it's going to be a through tang with a pommel nut.

Ideally, you solder the stand-offs on with high temp solder (or braze). Welding is really strong, but can warp the thin pommel material (and cause a big mess if you're not a pretty good welder, which I am NOT).

I have made knives like this and beaten them to death, with no problems associated with the stand-off/pommel combination.

If a guy wanted to be more anal about it than I already am, I would recommend drilling into the pommel material with a center cutting endmill and then grabbing a few threads into the pommel material. I haven't found a need for this though.

BTW- Where's your damn picture!?!?!

-Nick-

 

[NickWheeler]

Oh, now you've got your damn picture up!

That handle's gonna' be awful short though

Just kidding, I did read your post

That's going to be a really kick ASS piece of bladeware Michael!!!

-Nick-

 

[fitzo]

But Nick, the question wasn't "Alternate Attachment Methods for the Ned?"

You buy those, eh?

 

[NickWheeler]

But Nick, the question wasn't "Alternate Attachment Methods for the Ned?"

You buy those, eh?

HeeHeeHee!

Actually, I buy my knives pre-made in China and then just stamp my name on them!

To be perfectly honest, I really have no idea how they put the damn things together!!!

-Nick-

 

[fitzo]

Well, Nick, at least you change the blade and handle and hardware, so I guess that's ok.....