Shocking!

[matt9476]

Can anyone tell me what might be some reasons for why I'm getting an electric shock in my weapon hand while I fence? Recently, my middle and ring fingers have been getting shocked while I fence. Nobody else in my club has this problem.

[Mergs]

Are you fencing foil? Is it after you've been sweating? Is your grip insulated?

My bet is the answers are: Yes, Yes and No.

Electric foils always have current running through them when hooked up (a normally closed circuit). When you sweat through your glove and have an un-insulated grip, the current goes through your fingers to ground, instead of through the body cord.

Suggestion is to change out your glove or use an insulated grip.

[matt9476]

My grips are insulated, but I haven't checked to see if the insulation has worn away anywhere. I sweat when I fence, but not to the point that the glove is saturated or anything. My coach checked that last night. Yes, this is foil. I don't have this problem with my sabres.

[jkdjeff]

Is the current involved enough to be potentially hazardous, or just uncomfortable?

[matt9476]

It's not hazardous by any means, but it's pretty annoying, and it's a distraction while I'm fencing.

[telkanuru]

Does it occur with only one specific foil, or with any given one?

[chinbeard]

Originally Posted by matt9476

My grips are insulated, but I haven't checked to see if the insulation has worn away anywhere. I sweat when I fence, but not to the point that the glove is saturated or anything. My coach checked that last night. Yes, this is foil. I don't have this problem with my sabres.

Maybe it's a sign that you should switch to epee.

[TBean]

Originally Posted by chinbeard

Maybe it's a sign that you should switch to epee.

Originally Posted by matt9476

I don't have this problem with my sabres.

Right idea but wrong weapon.

But seriously Matt, have you tried removing variables from this - as somone asked is it all your wespons or just one, is it with the same body cord, is it always on the same strip or all the strips. Have you tried fencing with someone else's weapons. I'll ask our armorer tonight if she has any ideas.

[thekoby]

anybody mind if I use this issue as a possible troubleshooting topic for an armory class?? I has a few foil students that are wanting to learn how to build an electric foil (instead of paying me to do it for them), and I want to teach them more than just glueing a wire into a small groove.

[SJCFU#2]

Originally Posted by thekoby

anybody mind if I use this issue as a possible troubleshooting topic for an armory class?? I has a few foil students that are wanting to learn how to build an electric foil (instead of paying me to do it for them), and I want to teach them more than just glueing a wire into a small groove.

I would suggest first teaching them how an electric foil is supposed to work (i.e. a normally closed circuit, which is only supposed to open when the tip is pressed against something), then discussing troubleshooting and repairs for common problems such as intermittent off-targets and touches not registering at all. Only when they have a grasp of the basics should they move on to troubleshoot infrequent (and often intermittent) problems.

You might also want to cover assembling a foil from a wired blade before getting into how to rewire a blade. That alone may be enough satisfy their curiosity and get them out of your hair enough to allow you to concentrate on more important things (like actually fencing - something armorers rarely seem to have the time to do).

[matt9476]

Originally Posted by telkanuru

Does it occur with only one specific foil, or with any given one?

This has happened with at least two foils, maybe all three.

Originally Posted by TBean

But seriously Matt, have you tried removing variables from this - as somone asked is it all your wespons or just one, is it with the same body cord, is it always on the same strip or all the strips. Have you tried fencing with someone else's weapons. I'll ask our armorer tonight if she has any ideas.

I've had this same problem with multiple weapons on multiple strips. I'm not sure if I've used more than one body cord since this became an issue. I will try my backup cord tonight. I haven't tried anyone else's blades, since nobody uses the same grip I do, but I'll try that tonight, too.

[Robert Smith]

Shallow well for the hex nut on your grip, maybe? I've known people with small grips where the hex nut has protruded a little from the well, and from where you say you get zapped the uninsulated nut might be the source. Maybe it's worn the glove thin; maybe the glove's permeated with conductive products of perspiration? If that's the case, you could try taping over it to see if the shock goes away.

[brtech]

The thing that is bothering me the most about this is that you can feel a shock at all. That shouldn't happen. Normally, you shouldn't be able to feel the current involved in a fencing machine. Shock detection IS influenced by water (sweat or saliva). You can put your finger across a 9 volt battery and not feel anything. Touch it with your tongue and you will. That is because the water lowers the resistance, and absent any limiting mechanism, the lower the resistance at a given voltage, the higher the current, and thats what you feel.

A fencing machine should have current limiting, and you shouldn't be able to feel anything, even if you are wet.

What kind of machine is it and how old?

Just to confirm that it is resistance-sensitive, try changing your glove when you feel it to a very dry glove and see if it still happens. I assume that sweat is involved, but even if the glove was dripping wet, you should not be able to feel the current. It's typically something like 12 volts and less than hundred milliamps.

Machine failures can cause a problem, and some older machines are much more likely to have that kind of problem.

[Robert Smith]

Originally Posted by brtech

The thing that is bothering me the most about this is that you can feel a shock at all. That shouldn't happen.

We used to fence on an old Russian machine that would give distinct jolts on a valid foil touch if one had a wet glove. The jolts were enough to spasm muscles in the wrist.

Now we use Favero Full-ARM 01's; they're not as juicy, but if I'm really sweaty and take a hit to the mask, it will register on target and I can taste it through my dental work.

We also had one of our fencers test a foil out on his tongue, just out of 'satiable curtiosity. He got a 9V battery-style zap that still tingled several hours later. No permanent effects though, far as we can tell.

[Beloit Fencer of Old]

We used to use a home made machine in college when our regular one went in for service. That one used to shock us at the neck (where the lame touched)...God I hated that thing.

Anyway, I always bring three or four gloves to each competition, and change between rounds to a dry one. It's refreshing, too...kind of like a fresh change of underwear on a humid August afternoon.

[matt9476]

All of the machines are no more than five years old, so it shouldn't be that. Plus, nobody else in the club has this problem. If it was a weapon problem, it's pretty much a moot point now, since I broke all three of my foils on Friday. Naturally, when I was trying all the different variables on Thursday and Friday, I didn't get shocked once. This appears to be a some-of-the-time thing. Very frustrating.

[matt9476]

The problem came back even when I used someone else's weapon and switched to a bone-dry glove. In talking to my coach, he suggested it might be that I'm building up static electricity and getting the jolt when I touch my finger to either the plunger or screw on the body cord. Does that sound like a possibility to anyone else?
At this point, we're thinking the problem is the body cord, since we've ruled out weapon, strip and glove.

[DHCJr]

matt9476 you may have something there.

I was told about a tournament at the Air Force Academy where they had to put down static plates that the referees had to touch before they turned on the machines.

If they didn't they lost a machine as it would be fried.

Depending on where you are located, you might need to touch some grounded metal before you hook up.

[fencerbill]

Originally Posted by matt9476

The problem came back even when I used someone else's weapon and switched to a bone-dry glove. In talking to my coach, he suggested it might be that I'm building up static electricity and getting the jolt when I touch my finger to either the plunger or screw on the body cord. Does that sound like a possibility to anyone else?
At this point, we're thinking the problem is the body cord, since we've ruled out weapon, strip and glove.

By plunger or screw I infer that you mean the retainer on the 2-pin plug.

On every body cord that I have ever seen, the whole retainer assembly should be isolated from any conductor or lead. Look for a stray wire strand when you take the plug apart. They can be very small.

[Chuck F.]

Matt,

I can't believe you're still having this problem! I remember when you mentioned it over a year ago. If brtech can't figure it out, then I sure as heck don't stand a chance. Let me send out a couple emails and see if anyone else has any ideas.....