Drilling and tapping titanium

J

J-san

Joined
May 26, 2006
Messages
26
Hi,

I have an AG Russell Frame-lock spear point knife and love it. I'm using it as my EDC knife and would like to relocate the pocket clip. Problem is, the handle is titanium and I'm not sure how well I can drill and tap it, especially with such small screws. I want to reloacte the pocket clip so that I can carry the knife with the pivot facing down into my pocket. That way, when I pull out the knife, the quillion catches on the hem and flicks the blade open and locked in one smooth motion.

Thanks,

- jason
 
Jason. Hello. I don't believe we have met.

Welcome to the forums. I'm a few posts too late on that welcome I guess.

Anyway, I assume you will be doing this by hand so here is what I'd do in your shoes.

You will need some torx head 2-56 screws. I doubt the A.G. Russell knife has that size screw especially if it is Japanese. You can buy all you need at a knife supply company like texas knifemaker supply or Jantz supply among many others.

Things you will need besides screws are the taper taps for 2-56 screws and the wrench to use them. You will need a #50 drill bit and a #44 drill bit.

What I recommend is that you use a drill press. Mark the holes using the pocket clip. You will want to drill both holes using the #50 drill bit. I usually do one and thread it and then mount the screw to hold the clip in place until I'm ready to drill the next hole. If the titanium is really thick which I'm thinking it is since you said it was a frame lock, I'd recommend following the first #50 holes with the #44 drill bit. Whatever you do don't exit the other side though. You just want to drill down about 5/8 to 3/4 of the way and stop so that all that is left is the last .040 or so of titanium drilled out to the #50 size. This way all you have to thread is a thin piece which is still plenty strong for a pocket clip or anything else. Trust me on this. If you try to thread that .125 or .150 thick titanium by hand without doing it this way you will just break off the threader inside the handle and its a real bear to fix sometimes.

Even doing it this way be very careful to not bind the threader by pulling it laterally. I mean sideways when I say that. Stay away from jerky movements and sideways forces. If you notice some particles of metal on the teeth of the tapper knock those off so they don't get caught in it and bind the threader causing it to break.

As an added thing to look for you may have to drill out the holes in the pocket clip to a bigger size using that same #44 drill bit. I'd do that last though if the clip is stainless. Its probably hardened to about 45 on the Rockwell scale and it may dull the bit pretty good so I'd do that last for that reason.

Also, you will most likely have to shorten the 2-56 screws some. Buy 1/4" length button head screws and drill a couple of holes using that #50 drill in a thin piece of brass or aluminum and stick them through there after threading them. This will give you a chance to get the hang of threading by hand. Use that scrap to hold the screws for you to shorten them using a thin kerf cut off disc for a mandrel and dremmel you can buy at Lowes, Sears or Wal-Mart. You can also just sand them down on a bench sander or grinder wheel using the scrap you threaded holes in to hold them for you.

Hope that helps. I think I covered everything.

EDIT: I'd recommend you get more than just one threader. They break easy and you may need two. If one breaks you can sometimes back them out with a good vice grip taking it slow and easy. If not you can use pool acid to eat the screw out. It won't hurt the titanium but you will have to remove the scales and have the ti out by itself. It takes about a day to eat out a #2 size screw.

STR
 
Titanium work hardens like stainless.
Slow speed , very sharp drill and keep the feed on.

Tapping . No problem but you need a new ,sharp tap. Not junk. Get a top quality HSS tap.
 
Well, the worst case has happened. Just as I was finishing tapping my first hole, my hand slipped and snapped the tap off flush with the handle :grumpy: This is my second broken tap and I'm starting to really doubt my abilities. Luckily, the first one snapped off with plenty of tap to grip and twist out with pliers. So, I guess I'll have to resort to sulfuric acid or drill thru from the other side and try to back out the tap. Why is it a bad thing to drill completely thru the handle? I was thinking that if I wasn't able to tap the handle effectively, I'd use some thin hex nuts and thread a 4-40 screw thru the handle. Having been a radio controlled car mechanic and racer for years, I have a ready supply of small screws and nuts. Also, I was thinking my Plan B would be to drill a hole wide enough to accomodate a small nut on the blade side of the handle so that it would be flush (or close to flush). Then I'd drill the screw hole slightly oversized so I can thread the screw thru without needing to tap anything and tighten it down with the nut. Sounds like it would work in theory anyways.
 
Don't use sulfuric acid. Use Muriatic acid (pool acid).

If you used a carbon tapper these are made to chip apart so you can tap them out of the hole with a thin punch. But even that can be tricky. You won't be able to do that with a HSS one.

It is not a bad thing to completely drill through the handle. You want to drill completely through the handle with the #50 drill. You just don't want to drill clean through when you follow it to enlarge the hole with the #44. Only go down about 3/4 of the way with the larger #44. You want to thread that last part at the exit that is #51 size. In other words you are drilling to exit with the small number 50 drill which is the size you need to make your threads. Then you are enlarging most of your hole to the larger number 44 size diameter so you don't have to thread the whole thickness of the slab of your handle. Hope that makes sense.

STR
 
Yup, that makes sense. With confidence shattered, I've decided to not go with the tapping method and just countersink a small nut and use that to tighten down the screw. That turned out better than I expected. I simply drilled out the hole all the way thru the handle and then drilled a countersunk area the size of the nut on the other side facing the blade. I then thread the screw thru and tightened everything down. Nice and snug!

Thanks for your help! I'll see if I can't chip out the broken tap. If that doesn't work, it's off to the pool supply store to find the acid.
 
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