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Post by LC Foil on Dec 17, 2003 20:53:57 GMT -6
I was just curious what anyone knows about these. I've heard they will have a 2mm travel like an epee tip. I guess that will mean shim tests in foil soon.
(Although I've heard they used to do shim tests in foil years ago).
Anyone know where we can see or buy one?
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Post by MTD on Mar 20, 2004 22:54:25 GMT -6
The term "Mangiarotti point" as it is being used seems to refer to two different things: 1) a point with certain new behaviors which the USFA now thinks may be desirable, and 2) some specific points manufactured by Mangiarotti as a sort of proof of concept. NOTE: In this message, whenever I write " new rules", I mean the experimental new FIE rules, which may or may not yet actually have been written out as formal rules, which will apply to FIE junior competitions in October. They won't apply to adult FIE competitions, they have nothing to do with USFA rules, and they may even be abandoned as an unsuccessful experiment. But, on the other hand, they may end up being translated into English and adopted as new USFA rules. Anyway, that's what I mean by new rules. The real questions we need to be asking is: For anybody to whom the new rules apply, what characteristics do new foil ponts need to have to be legal, and from whom will anyone buy them? There is a claim that the FIE Web site ( www.fie.ch) has a description of the Mangiarotti point. I have not been able to find it. Maybe this was a misunderstanding between me and the person of whom I asked the question. What I wanted was actual technical rules which could be used to determine if a point were legal under the new rules. For examples: the threading with which it connects to the blade (presumably still 3.5x0.6M etc.), permissible barrel diameters, permissible barrel lengths, permissible pointe d'arrêt diameters, as well as required mechanical and electrical behaviors involving triggering. What is at the FIE Web site is the decisions of the FIE Congress (which are broad policy statements rather than technical construction rules). As best I have been able to gather, the required new characteristics of foil points under the new rules are: - must lift a 750 g weight instead of 500 g
- must have a travel before triggering (lighting stroke) of at least 2 mm instead of the current 0 mm or épée's 1 mm
- the required travel must (ether because of a specific rule or because nobody would be caught dead trying to do otherwise) be in the inward direction only and will not be able to be provided by soldering a 2 mm spring in front of an existing pointe d'arrêt which could compress inward 2 mm but would leave the point susceptable to diagonal hits which would not have to involve an inward travel of 2 mm to occur before triggering would occur
I have not been able to determine any statutory requirements about internal construction to accomplish this. However, it seems that Mangiarotti used, and everybody else is likely also to use, a system where two springs in series (not necessarily touching or in immediate proximity to each other) are pressing the front surface of the pointe d'arrêt outward. One is stiffer than the other. When you depress the tip, only the soft spring compresses for a while, until finally the soft spring is so compressed that its coils start hitting each other and it just transmits the force to the second spring. When the second spring moves, whatever was allowing the current to flow finally separates and the tip triggers. (I don't know exactly how Mangiarotti did it, but for sake of illustration consider taking an ordinary foil tip apart -- not the whole point, but just the frontmost part, the tip -- and and arranging for the front to be pressed forward relative to the back by spring with 2 mm of give before it starts forcing the traditional backmost pieces of the tip to have to move. But, make sure to picture this in a way where the traditional sides of the tip still exist and are still connected to the traditional front of the tip, so the barrel still requires tip travel to be inward, and the new spring probably extends forward within the shell of the tip.) If you're still having troubles picturing how people could build devices where a switch opens (unlike épée's switch closing) only after some travel has happened, think of this mechanical analogy. Go get two chrome napkin dispensers from your local diner -- you know, the ones which are chrome boxes with one face having a rectangular cutout which leaves only a narrow border at the edges. There's a spring-loaded pusher plate which, without any napkins, is flush against the inside of the large rectangular hole on one face. Disassemble the dispensers and, by substititing parts or performing atrocities on one of the springs, arrange to reassemble them where one has a much stiffer spring than the other. Now, go get a can of vegetables (in a can a little narrower than the opening for napkins). Solder one end of the can to the pusher plate in one napkin dispenser and the other end to the pusher plate in the other napkin dispenser. Now, be sure that when you reassembled the napkin dispenser with the stiff spring, you coated the sides and back with insulation so that neither the pusher plate nor the spring is in electrical contact with the case except when the pusher plate is pressed against the rectangular opening. Now, connect one wire (call it the "C" line) to the case of the dispenser with the stiff spring and (through s tiny hole in the case) connect another wire (call it the "B" line) to that stiff spring. To finish the construction, take some sheet metal and attach to the sides of the stiff napkin dispenser and projecting forward just far enough to overlap the other napkin dispenser, a rectangular cross section, internally lined with insulation, protective enclosure and guide track within which the napkin dispenser can slide directly toward and away from the stiff dispenser. Now you have a foil point. Hold the case with the stiff spring, orient the apparatus so the other case is performing an initial offensive action involving your arm extending and the other napkin dispenser case continuously threatening valid target. When the apparatus hits your opponent, the first thing that happens is that both the B and C lines, still connected to each other, are now also connected to your opponent's lamé. The next thing that happens is, as your arm continues to be extending, the front napkin dispenser starts compressing, with its weak spring. Only after a while does that napkin dispenesr "bottom out" and start causing the stiff dispenser to start compressing. The moment that compression occurs, the case and the pusher plate come out of electrical contact, so the scoring apparatus sees the B and C lines no longer connected to each other and, since it sees your B line connected to your opponent's lamé, it knows the hit was on valid target, and signals such with the colored lamp on your side. However, you must realize that if your opponent bashes his napkin dispenser apparatus against the side of your napkin dispenser apparatus and displaces your front napkin dispenser from threatening valid target even momentarily (note that mere incidental napkin dispenser apparatus is not sufficient), your napkin dispenser apparatus will still function as described, but you will have lost right of way against any immediately begun parry by your opponent and will need to bash your apparatus against his before resuming your quest to compress your apparatus against his lamé. The reason the USFA is trying to change anything at all has to do with two discoveries involving the old-style napkin dispenser apparatuses. They were originally designed with the intention of being used in a thrusting fashion against your opponent. First, after their original invention, it was discovered that if you whacked your opponent with the dispenser like a flail, it would cause the registration of a valid hit. Second, it was discovered that the sort of forces involved with being hit with a napkin dispenser used as a flail are hideously large and can exceed the structural integrity of human skulls. And, before you protest that human skulls are protected by masks, they are only protected against thrusts by masks (and the thrusts aren't anywhere near as forceful as the flailing), but do not protect the back of the skull from flailing attacks. So, the USFA is trying to make the use of a napkin dispenser apparatus no longer register a valid hit when used as a flail because the front napkin dispenser does not get pressed straight inward the necessary distance to cause any hit at all to be registered. Hence, people will stop using napkin dispenser apparatuses as flails. Now, back to actual points. There probably will be no rule which requires you to change barrels. But, Dan Dechaine believes that the new parts won't be able to be made short enough to fit into any existing foil barrel, so expect to have to buy an entire new point. This means rewiring every foil in existence (ignoring the affect of attrition in old foils and the purchase of new foils or new pieces for repairs). It seems that there is no commercial manufacturer of "Mangiarotti" points yet. But, before USFA-only fencers will ever have to deal with the situation, ground will already have been broken by FIE fencers.
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Post by Dan Gorman on Mar 21, 2004 6:09:20 GMT -6
So i'm lost now. Why can't you just use a current style tip that's essentially 2 mm longer?
As for the implementing, I'm sure it'll be like with the sabres where they were phased in other several seasons.
Dan
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Post by MTD on Mar 21, 2004 22:41:01 GMT -6
Answer:
If this were épée and the lighting stroke were mandated to be 2 mm longer, the current design could just have 2 mm grafted into it. The already existing system for having a nonzero lighting stroke could be adjusted to provide more. (In fact, you can do exactly that with your épée right now. Clip 2 mm off your contact spring. Grind the slots longer and grind some off the front end of the barrel so you can travel that additional 2 mm.)
But, this is foil. Foil already works with a lighting stroke which is zero. There is no mechanical provision for the tip to have any travel at all before the circuit breaks and the touch is signaled. The second spring has to be introduced to allow something to soak up travel distance before the contact breaks.
An alternative to the two-spring system would be to give up entirely on the way the contact is made and broken in current foil points. Right now, the switch is the tiny widening at the back end of the tip being rammed by the spring against the bottom of the annulus which is fixed to the barrel -- and the moment the tip moves backward against the spring at all, the tip+spring comes out of electrical contact with the annulus+barrel.
If you changed that so there were a wiper on the inside of the barrel pressing against the side of the tip, you could control how far the tip needed to travel before the wiper found the tip to narrow out of its reach, or to transition from a conductor to an insulator. But, nobody wants to use wipers for anything in fencing except reels. And, certainly nobody wants to ise really tiny wipers on the insides of barrels. To assure a good electrical contact, there would have to be decent pressure against the side of the tip by the wiper -- creating drag. With the current system, the pressure to provide good electrical contact is in line, and indeed is the very pressure which is also used to lift the 500 g test weight.
Okay, I came up with another way to do it with existing technology. It involves using a complete épée point perversely. Mount the assembled épée point and end of blade facing the wrong way on a foil blade -- take a bracket which is attached to the front of the foil blade, reaches around the épée pointe d'arrêt and grasps the épée barrel. Then, install a spring between the end of the foil blade and the épée pointe d'arrêt which keeps the épée tip depressed. And, finally, attach another bracket to the épée pointe d'arrêt which goes outward, forward paralleling the epee barrel, then converges to form the actual point of contact with the opponent. You have now taken a normally-open (épée) point and perverted it to function as an normally-closed (foil) point, and the épée point already has provision for an adjustable amount of travel between its full compression and the compression at the trigger/no-trigger point. But, what you'd have is a three-spring point -- more complicated than the Mangiarotti point!
(Actually, exactly what I described still wouldn't work electrically. There is never any conductivity between an épée pointe d'arrêt and barrel. You would have to take one of the épée wires and connect it to the foil barrel, and take the other one and arrange for it to connect to the very front of the assembly where it contacts the opponent's lamé.)
Personally, I'd prefer a longer foil barrel with new two-spring guts.
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Post by MTD on Mar 21, 2004 23:07:14 GMT -6
Okay, here's yet another way to think about it.
Picture your existing foil tip. Now picture the horrible moment your German tip has the front 90% come unscrewed from the back 10% and fall out, or the moment your French tip comes unpeened and the front 90% fall out of the back 10%. Note that when this happens, you have no idea it has happened because the box doesn't signal anything. This is because the switch part is still completely intact, and it's only the front 90% which provides both mechanical and electircal connectivity between the opponent's lamé and the actual switch which fell out. You lose multiple points in the bout before you become absolutely convinced your weapon is dead in your hands. You offer it to the referee, he takes one look, and starts chuckling, annulling only the one previous point.
Some time later, somebody trips over the missing 90% and asks in a loud voice if anybody lost his tip (not technically true, as only 90% of the tip was lost). You claim it. If you are a cheapskate like me, you reconnect the two separated portions, and take steps to discourage future disconnections.
Well, to implement the new rule, you could do something a little unorthodox. Before reconnecting the front 90%, through the annulus, to the back part, perform microsurgery on it. Remove the skinny post which passed through the annulus and connected to the widening which stayed lodged between your spring and annulus. Graft into its spot an épée contact spring. And, attach that to the back portion. I suggest spot welding using a stereo microscope. This newly altered tip will have some compression in the "post" before the back part will start moving against the spring. This particular design requires the épée spring to be narrow enough and compress symmetrically enough that it never brushes against the inside of the annulus. Now, here's the problem that requires the barrel to be made longer. Right now, the post just isn't long enough to have an extra 2 mm through which to shrink. So, you end up with your ersatz "post" being 2 mm longer than the original post. This pushes the front 85% of the tip 2 mm farther forward than it used to be. But, the length of the current barrels are right to provide a guide for current tips in their current locations. If the tip is moved forward 2 mm, there is so little of the barrel guiding it to travel straight, it becomes highly susceptible to jamming instead of sliding when the hit is oblique (picture trying to push in a dresser drawer with oblique pressure when the drawer has been pulled out too far -- it jams in the casing). So, you end up making the barrel 2 mm longer after all.
Okay, there is a way around this. Take the annulus and cut most of it away, leaving 20% of its original circumference at each of the spots where the two screws are. Give up on German points, as this can only be done with French. Then, in the 30% gaps you created, extend the plastic body (with or without Sport-7's metal cladding) of the current tip backwards through the gaps, and, if you wish, for good measure once you have passed the rump annulus, you spread entirely around the circumference again to cause the tip to have a much longer effective length against jamming due to oblique pressure.
I do not look forward to being an armorer working with these two tiny fragments of rump annulus!
(Dan, stop gloating that you don't recall ever having these sorts of problems with your saber points. DId someone say "capteur"?)
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Post by Dan Gorman on Mar 22, 2004 4:39:31 GMT -6
Why not just add a 2 mm sleeve the tip travels through before it breaks contact thus opening the circuit? If you machine it right there's no need for additional moving parts and the only change is the tip and barrel are about 2 mm longer. Over 2-3 years, everyone changes to the new equipment as their weapons/wires break.
Dan
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Post by schlager7 on Jun 28, 2004 21:18:31 GMT -6
I have heard that the Mangiarotti tips will not be ready in time for the 2004-2005 season. Anyone have anything firm on this?
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Post by MTD on Jun 29, 2004 12:50:10 GMT -6
I have heard that the Mangiarotti tips will not be ready in time for the 2004-2005 season. Anyone have anything firm on this? A trustable U. S. armorer has cited Dan DeChaine of the SEMI committee as having stated this -- specifically that neither the 2 mm lighting stroke nor the 750 g spring requirement of the Mangiarotti points will be enforced because things just aren't far enough through the pipeline. This has no relationship to the other changes (like scoring apparatus timing changes). Having said that, all I've done is be more specific about hearsay, not provide anything firm. Also, just as a reminder, this concerns FIE junior competitions, so either way it has no immediate effect on any USFA competitions. For the USFA, it only affects what smart money is betting, and for when they are making the bets.
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Post by MTD on Jun 29, 2004 13:06:06 GMT -6
Why not just add a 2 mm sleeve the tip travels through before it breaks contact thus opening the circuit? If you machine it right there's no need for additional moving parts and the only change is the tip and barrel are about 2 mm longer. Over 2-3 years, everyone changes to the new equipment as their weapons/wires break. I've been trying for a while to picture how to add on to an existing foil point, as Dan desires, to meet the new specifications. No matter how you look at it, the hard part is that existing points are built so that the moment the tip moves, the circuit is interrupted. Providing for any existing part to travel 2 mm more would only mean that the tip could continue inward 2 mm farther after (not before) interrupting the circuit. However, it's not impossible to preserve the exsting point. I'm just not sure I could recommend it. Picture soldering a soft spring to the front of the tip, one which compresses through at least 2 mm before the force invoved reaches 500 g. This would allow the altered point to function -- in response to direct thrusts only -- just as the new specifications require. But, it would not respond to diagonal or sideways forces as required. This can be accommodated, though. Leave the new soft spring exactly where I described. Now, add a new shell around the old point, constructed so that it slides forward and backward along the barrel, but extends forward around and past the point. Because of the geometry of this sliding roughly-cylindrical shell, no matter what the direction of the thrust, the shell itself will respond only with rearward motion. The new spring provides resistance weaker than 500 g in that direction to that motion for at least 2 mm of travel before it bottoms out enough to start moving the original tip. I fear, though, that in practice any such sliding outside shell will have so many practical problems that a fencer and armorer would decide to treat one exactly as they would, for example, an épée which has a barrel go sour -- and react by replacing point hardware and rewiring.
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Post by schlager7 on Jul 5, 2004 17:51:49 GMT -6
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Post by Fencingfodder on Jul 7, 2004 14:22:55 GMT -6
We'z been scammed!!!
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