Rethreading a foil tip - I'm doing something wrong!

[GrimRiposter]

Greetings, everyone! I've got a problem rethreading the tip on a foil. I've done some research on this forum and other places, and managed to do it once, but I'm thinking that was beginners luck now. Here's what I'm doing...

1) I have a section of foil tip that I'm practicing on. I cleaned it up, cut off the current threading and removed the wire
2) I shaped the tip to have a bevel on it to help get the threading die started
3) I soldered a straight pin into the groove and made sure the solder didn't have too many ridges/bumps
4) I then apply some cutting oil, enough to slick the thing up pretty well.

When I then start to work on the threading die, I get a very polished surface the right shape, but no threads. I tried the die one side, then the other. It's not marked "this side forward" as my 6 mm is and the result is the same either way. I'm working on a segment of an Absolute Standard blade, so nothing fancy, or at least not FIE.

I'm sure I'm doing something simple and wrong here. If anyone can point out the dumb thing I'm doing wrong, I would greatly appreciate it!

Thanks,

The Grim Riposter

[pjsise1]

This is difficult to diagnose without being there. Try varying the amount of pressure you apply while turning the die. It can sometimes take quite a bit of pressure. You may be spinning the die in place without it really spiraling onto the end of the blade. You may also have ground down the blade too narrow when trying to shape it.

That being said, I have had success with many fie foil and epee blades, but I have never been able to successfully rethread an absolute standard foil or epee. The steel simply does not cooperate for me. Also, while I was at the USFA Armorers College, we tried rethreading a batch of blades, again, success for many of them, but none of the AF blades were able to be rethreaded.

[thekoby]

I had the same issue while rethreading a broken epee blade so I could use it as a practice weapon. Although no threads were present on the blade itself, I was still able to screw on the practice tip without any issues. I've been using the blade for almost 5 months now without anything falling off or coming loose.

However, I agree with the above statement that it may be slightly too narrow to rethread. Are you wishing to use this as a tournament weapon or practice with an electric tip?

[GrimRiposter]

Mostly they'll be electric club blades. I'll do someone's tip if they really want to salvage a favorite blade, but that's about it.

You can add STM to the "blades that may not work" list. I tried one this afternoon and had the same luck or lack thereof.

I'm using differing pressure, from gentle to cramping my hand. I varied the width of the tip from probably too much to barely any.

Dumb question, but can I assume there's a "front" and "back" to the die, or will it work either way?

This is rather difficult to describe online, I know. I think I'll throw some of this into my tool bag and bring it to Nationals on Thursday. Maybe someone there will have a few minutes to demonstrate.

[fencerbill]

Start off with the attitude that you have nothing to lose, right? So if you crum it up, all you have lost is the time invested.

One possibility is that the steel is too hard, which may be why it broke where it did. You may also not have the best die for the job. Only experienced machinists really know all the differences between dies and which would have been the best one for this job.

Here is what I would do. Clamp the blade in a heavy vise (acts as a heat sink) with about half an inch sticking out. Heat the end of the blade with a propane torch, such as you might use for soldering copper plumbing. Stop as soon as the tip of the blade glows a little. Don't get it red hot. Let it cool by itself. Don't quench it with water or oil.

If you are lucky, you will soften the blade just enough to get the die to start cutting threads. Only the part of the blade that was sticking out of the vise will be affected, the vise acting as a heat sink will prevent the rest of the blade from being affected.

I assume you did have a very shallow taper to the end of the blade before you started using the die. Too steep a taper can also inhibit the die from starting to cut the threads.

When I recut tip threads I often have to touch up the groove at the end so the wire will come out of the center of the tip diameter. If the groove is too shallow, threading the barrel on can cut the wire or nick it so it grounds out.

Good luck, remember you have nothing to lose.

Yes, there is a front and back to the die. But it can be hard to see.

[GrimRiposter]

That was my thought, too. Worst case scenario is the blade stays in my scrap pile.

I did put a taper on the blade various ways trying to find something that would work. I may have done a bit too much on one attempt. Heating the steel sounds interesting, but I don't have a torch and not sure how much use I would really get out of one. Still, possibly a good justification to finally get one.

One question. It sounds like there is a front and back to the die. How does one tell? There's writing on one side, but nothing helpful like "This side front". That would be asking too much, I guess. I'll be at Nationals on Thursday. Maybe I'll run it over to the armoring table to see if anyone there would take pity on me and show me how to use the thing.

Thanks for all of the help so far, everyone!

[Mergs]

Well, my experience with threading a blade at Armorer's College was equally frustrating (especially for the Mechanical Engineer and grandson of a Tool and Die maker in me!!!) until I found out that the blade I was trying to thread was a maraging blade! I still say Dan slipped it to me knowing full well that they are very difficult to thread.

Anyway, everyone here has already touched on the main points. The main thing is that the end of the blade should be tapered (grinding wheel helps) about 1/4" to 3/8" from the tip. Try threading without the cutting oil to begin with. As for determining the front and back (I'm really not sure what you mean by this, but I'm going to assume that the back is down when your threading and front is the face pointing up), examine the cutting threads - one side should start with incomplete threads i.e not cut to the full depth, and the other should have full depth threads. The 'back' side is the one without the full depth threads.

I found that you have to have a lot of downward pressure and go slowly when you are trying to start the thread. It can be frustrating. I'd anneal the metal as fencerbill described as a last resort.

Good luck.