Fencing/Electrical Equipment Repair
NOTE TO READERS: This book assumes the reader has general knowledge of the sport of Fencing and the associated equipment.
Electrical fencing equipment has entirely replaced the old jury system in all levels of competitive fencing. All of the equipment - the box, reels, wires, strip, and weapons - is for the sole purpose of determining the arrival and validity of touches.
At Foil, hitting the opponent's lamé with your weapon's tip causes the colored light on your side to go on, indicating a valid hit. Hitting anywhere else will cause your side's white light to come on, indicating an off-target hit. However, hitting your opponent's weapon or the conductive strip (if used) will not cause either light to come on.
Additionally, scoring machines have two small, usually orange, grounding lights that come on when either fencer touches their weapon to their lamé. On modern machines, this extends the lamé circuit to the weapon, causing a hit on the weapon to register as a valid hit. It also usually prevents the affected fencer from scoring.
At Épée, only the colored lights are used, the white lights are not used at all. Hitting anything except your opponent's weapon or the conductive strip with your weapon's tip will cause your side's colored light to come on. The grounding lights are still used, they indicate a hit on the strip or your opponent's guard. However, hits made on your opponent's tip in a way that depresses both tips (an extremely rare occurrence) should result in double touches if the internal springs are the same.
At Sabre, like Épée, only the colored lights are used. The white off-target lights are used only to indicate a problem with the circuitry. Touching any part of your weapon (not just the tip) to your opponent's lamé or conductive mask will cause your colored light to go on. For obvious reasons, hits made with the guard of your weapon (rather than the blade) are not allowed.
Touching your weapon to your lamé at Sabre has the same effect as at Foil - hits made on your weapon will register as valid touches and you will not be able to score. This is a much more common occurrence at Sabre for two reasons:
- The valid target area includes the arms, bringing it very close to the weapon.
- The entire weapon (not just the tip) is "hot", i.e. able to score. If one fencer's weapon is touching their lamé, any blade contact will cause a hit to be registered.
How it works[edit | edit source]
General Circuitry[edit | edit source]
Foil[edit | edit source]
The foil Bodycord has only two prongs, current flows in one and out the other to make a circuit. The tip closes or turns on the circuit in the default or undepressed position, when depressed, the tip breaks the circuit. If the circuit is broken the scoring "box" checks to see if another circuit is closed. The second circuit is made up of the lamé or metallic jacket worn by the fencer. The lamé is grounded into the box and current flows out of the tip of the foil in the depressed position. If the tip is depressed while in contact with the lamé a hit is counted. If the tip is depressed on anything else then a white "bad hit" light goes off and the bout is paused briefly.
Épée[edit | edit source]
In épée, the body cord has three prongs on either end. The two prongs closest two each other are the A and B lines, the far prong is the C line. The A and B lines are used to determine when a touch has been made. When the tip is depressed, the A and B lines are connected completing the circuit and causing the light on the box to go off. The C line is used to ground the bell, preventing hits scored on it from landing. The barrel at the end of the épée contains a tip and two springs. The small spring is the contact spring, preventing the circuit from closing until the tip has travelled a certain distance. The larger spring is the pressure spring, to make sure the circuit isn't closed until the force of a 750 g weigh is applied to it.
Sabre[edit | edit source]
Sabre is the simplest of weapons and has only one (bayonet) or two (standard) prongs in the Bodycord. Fencers wear lamés that are grounded into the scoring box. The whole sabre blade is electrified and acts like a giant switch. The box does not do anything unless current is flowing through the grounding wire, then a hit is counted.
What goes wrong and how to fix it[edit | edit source]
General Considerations[edit | edit source]
Foil[edit | edit source]
The point won't support the test weight
This is the easiest problem to fix, and can be set right between bouts. All you need is a jeweller's screwdriver.
Take the tape off the tip just far enough to expose the set-screws. If your foil has a Leon Paul tip, unscrew the set-screws just enough to allow removal of the tip. Make sure the tip doesn't fly away when you undo the second screw! (It helps to hold the tip in the depressed position while undoing the screws.) If your foil has an Allstar tip, you must completely remove the set-screws in order to remove the tip. Be careful not to lose them, and hold the tip while removing the screws. If you are not sure what kind of tip your foil has, ask another fencer. Take out the tip and fish out the spring with the point of the screwdriver, if necessary. Stretch the spring out a bit (you want it to be about a millimeter or two longer than it was when you took it out). Then, put it back into the barrel, put the tip back in, and secure it in place with the set-screws.
If you have an Allstar tip, there's a trick to putting the screws into the tip. The tip has a brass collar with threaded holes for the set-screws. These holes must be lined up with the holes in the barrel. To do this, depress the tip, and if the holes aren't lined up, put the blade of the screwdriver into the screw-hole in the barrel and turn the collar until the two holes are lined up. Then, while still holding the tip down, put the screw in position and tighten. If the threads don't take hold, turn the screw backwards until the threads are lined up. Once the first screw is in, the other one will be no problem.
Be sure to replace the tape on the barrel before using the weapon in combat. Otherwise, you may ground out your opponent's electric jacket - the scoring circuit would pass from your tip to the electric jacket and back through your uninsulated barrel - and the apparatus would fail to record your valid on-target hits.
If you have the opportunity, you should test your weapon before taking it onto the piste with you. You may not have stretched the spring enough!
The off-target light registers when you haven't hit anything
This problem is caused by the closed circuit breaking when it shouldn't. Fortunately, it is often very easy to correct. Sometimes, it isn't even the fault of your equipment.
The first thing to find out, if possible, is what you are doing when the problem occurs. If it happens when you advance or retreat at a given spot on the piste, the problem is very likely in the reel. There could be a "dead spot" on the contacts - two dead spots at the same time, actually, since the reels have two sets of contacts - the reel would have to be replaced.
If the weapon fires when struck sharply (like when you do a beat or parry), your problem could be one of three things. First, the barrel could be loose on the blade. See if the barrel can be "wiggled" from side to side. If it can, grip the barrel in a pair of pliers and tighten it (clockwise, looking down at the tip) carefully but firmly. This can be done while on the piste, without even unhooking the foil from the body cord. If this is not your problem, you will have to use another weapon for the bout.
The second possible cause is if the set-screws have worked loose, causing the circuit to break between the tip and the barrel. You will have to take the tape off the tip to find out, so you can't check it out on the piste. The cure, of course, is to tighten the set-screws.
The third possible problem is a break in the wire which parts (cutting the circuit) when the blade is vibrated. You can check for this by bending the blade up, down, and sideways. If bending the blade causes the light to fire, you probably have to rewire the blade.
It may be that the light goes on if you jostle your sword hand. This happens mostly with Leon Paul guard sockets. First, try tightening the screw on the very end of the body cord plug. If it is tight, try scraping the centre of the brass contact disc inside the guard socket, and shaking in some graphite lubricant to enhance electrical conductivity. Failing this, change your weapon (because it is easier than changing your body cord!). If that fails, change your body cord, and inspect it later for bad or broken connections under the plastic boots that cover the plugs at either end.
Your weapon will not register a hit at all
This means a short-circuit that closes the circuit behind the point, so that breaking the circuit at the point has no effect. First, unplug your weapon. If the scoring box does not show a white light, the problem is not your weapon. Start unplugging equipment, starting with your body cord and working back, until the light comes on. The last unit unplugged is the one at fault.
If your weapon is at fault, you are going to have to look for the problem after the bout. Hook into a personal test unit, and then loosen the pommel (or hex nut, for an orthopedic handle) while keeping the point depressed. If the tester's light comes on, the wire was probably pinched between the handle and the guard. Take off the handle and check for a spot not covered by the plastic "spaghetti" tubing. If this looks like the problem, carefully slide the tubing over the problem area. Then, tape the wire to the inside of the bell so it goes away from the grooved side of the blade at a right angle. Finally, slide the handle back on, making sure that the notch in the handle goes over the wire. (There had better be a notch in the handle!) Tighten the pommel or hex nut, making sure the handle doesn't twist and attack the wire again. Then check the weapon to see that it works properly.
If this isn't the problem, you probably have a bare spot in the wire somewhere along the blade or in the tip. Just to be sure, though, try this test before giving up and rewiring. Take the tip out of the barrel. Then, hook up a test unit. If the light goes on, the blade probably has to be rewired.
If the light doesn't go on, inspect the spring - it is probably bent out of shape, and is shorting against the barrel. In any case, the blade shouldn't need rewiring.
The weapon registers all the time
First, unhook your weapon and short out the body cord plug - hold both contacts against your guard. (On a Leon Paul body cord, the contacts are the screw at the end of the plug, and the spring-loaded disc behind the metal bar.) If the scoring light ceases to register, the weapon is at fault. If not, pull your body cord out from the reel plug just far enough to short it with a screwdriver. The plugs to short out are the centre one and the one farthest from centre. If the box stops blinking and making a racket, the problem is your body cord, which you must change. Otherwise, it is the President's problem to solve.
If the problem is your weapon, you may have lost the tip. Don't rip the weapon apart before you check!
If the tip is still present, the problem is almost always a broken wire. If you are lucky, the break will be at the connection with the guard socket. Just lift the pad and see if the wire is still hooked on. If it is loose, it should be an easy matter to cut back the "spaghetti" tubing, scrape off the insulation, and reconnect it. You should need less than a centimeter of bare wire to make the connection.