A lot of clubs probably have bungee systems to get rid of expensive and high maintenance reel systems. I have been playing with designs using bungees and decided to try my hand at a gravity system. Using a double compound system, I found a relatively easy way to get 60 feet of travel out of a fifteen foot side wall. One of the nice things about the system is that there is no increase in tension as you move down the strip. See the attached drawing
Last edited by Joe biebel; 01-03-2008 at 04:23 PM.
I'm a foil fencer, and I can change, if I have to, I guess.
That looks cool, Joe. However, I have almost had my eye taken out by newbies who release their hookup at the middle of the strip, and the overhead reel system whips back at a frightening speed. Will we now have to watch out for the kid who decided to sit under the weight? Or should the weight mechanism be built into a tall box? It looks like there would be VERY LITTLE MAINTENANCE required for your design.
Last edited by Beloit Fencer of Old; 01-22-2007 at 01:30 PM.
Reason: misspelling
A lot of clubs probably have bungee systems to get rid of expensive and high maintenance reel systems. I have been playing with designs using bungees and decided to try my hand at a gravity system. Using a double compound system, I found a relatively easy way to get 60 feet of travel out of a fifteen foot side wall. One of the nice things about the system is that there is no increase in tension as you move down the strip. See the attached drawing.
Hmmm...
If I understand your drawing correctly, you will get 30 feet, not 60, out of that setup. OTOH, I am not at all confident that I am understanding it correctly - could you please post a 2nd drawing with both fencers and the box drawn in? That would improve understandability.
Would the setups interfere if one has several pistes close by? How about the portability?
How about a standalone block-and-tackle system? It would remove the need to do stuff to the walls, and be as portable as a reel system. OTOH, it would be bigger than a reel system, due to the need for relatively large wheel diameters.
Reminds me of the PBT wall mounted reels... with the addition of the run along the cieling (though it doesnt seem to me that it would have to be directly over the strip), and without the box... but an interesting concept...
I'm up for any solution that satisfies the following: nothing right above my head to catch my blade, minimizes things to trip over, minimizes maintenence, can be quickly repaired / bypassed so as to not slow tournaments down, and isn't a danger if it should become detached from the fencer (some of the reel ends really pack a punch when they come flying off a fencer who is 2/3 of the way down the strip).
I had first thought about this type of system over twenty years ago. The problems I see are twofold: How to control the velocity of the "dropped" connector (i.e. that weight crashing down unrestrained while pulling in the fencer socket at high speed), and the limitation of using this only when you have a good wall immediately behind the strip. In our current club, one side of the strips ends right before a wall ( with decent setback). The other side is over 15 feet from a wall, over an area used for other things. I'm not sure I'd want to continue the wiring and weight setup that far past the end of the strip.
Overall though, the concept has value, especially by eliminating the constant adjustments as the bungee system ages.
Oh, and Peter, the thirty foot movement of the weight cable, allowed by the 15 foot vertical movement around it's pulley, gives 60 feet of movement for the fencing cable when run through a pulley of it's own.
Hmmm...
If I understand your drawing correctly, you will get 30 feet, not 60, out of that setup. OTOH, I am not at all confident that I am understanding it correctly - could you please post a 2nd drawing with both fencers and the box drawn in? That would improve understandability.
Actually, Joe's right. You get the 30 feet of travel from the pulley system and then you get an additional 30 feet from the cord, provided the pully on the wall opposite the weight/pulley is mounted 30 feet away and you have at least a 65 to 70 foot cable.
Joe, have you tested it out yet?
Remember those who put their lives in danger for your sake.
I don't have an engineering degree, but it seems to me that the pulley system would be 15 feet high, which would mean that the reel probably wouldn't fit into most clubs, and would be hard to fix.
If you add a compression spring and washers between the fencing cable pulley and the weight system top pulley of sufficient travel and resistence, you can probably solve the problem of the "dropped" fencer-side connector, especially if you also place some closed cell cushioning beneath the weights. The compression of the spring under force should decelerate the weight slowly near the end of it's travel.
I tested this system today in a room with a 10' ceiling. The room is 38' long and so the "small strips" we have there, still work with some cable left over when you get to the far wall. It worked extremely well.
I had not thought of such a system for a portable system, it would not, on the surface, seem appropriate. With the cables, connectors and pulleys at a 15 foot height, maintenance would require a ladder, that is a given. What is especially nice, is that with a weight instead of a bungee, you don't get twisting on any of the cables. This system makes it nearly impossible for cables to get jammed or fall off of the pulleys.
I have been using 2.5" dia. pulleys and 4 conductor flat telephone wire. I tried telephone wire a few years ago in a pinch, and found many advantages to it. Obviously with resistance hovering at about 5 ohms in an 80 foot length, it's not FIE. This is simply not a problem because there is no resistance variation from contacts, etc. The telephone cable is extremely light, durable, and does not "want" to twist. I think it is ideal for overhead systems.
I must admit, I have not given a thought to the safety aspect. Fortunately, no one has ever let a cable go in the middle of the strip here. I suspect that the acceleration of the plug would be more from the bungee than from the weight. Just a feeling.
I just got up. went to the fencing room, grabbed two cables (one from a bungee system, the other from the gravity system) walked to the middle of the room and let them go. Whoa! they arrived at approximately the same time and with quite a smack. So you posters that mentioned the safety aspects did have a point. I don't have an obvious fix for that. On the other hand, the weight itself, when placed very near a wall is almost impossible to land on somebody. I'd do more testing, but I can't get any volunteers. The old building I'm in has tubes by the fire doors that shield people from the counterweights contained within. As I am trying to keep it simple, I shall continue to test the system with the minimal number of complexities. It may be that the system will work fine and safely by merely making sure of proper placement of the various elements.
cable
I'm a foil fencer, and I can change, if I have to, I guess.
If you add a compression spring and washers between the fencing cable pulley and the weight system top pulley of sufficient travel and resistence, you can probably solve the problem of the "dropped" fencer-side connector, especially if you also place some closed cell cushioning beneath the weights. The compression of the spring under force should decelerate the weight slowly near the end of it's travel.
I just can't get my noodle around this concept. Read it several times, but still don't get it. Can you explain again with smaller words or sketch it or something, please?
I'm a foil fencer, and I can change, if I have to, I guess.
Joe - can you tell me if I got the coordinates right? After a bit of finger-twisting, this is how I read it:
Z: Up on the screen equals Up in reality X: Sideways on the screen equals Transversal direction of the piste in reality Y: Normal to screen surface equals Lengthwise direction of the piste in reality
Did I get that right? European and American conventions for coordinates in technical drawings are different, which can muck up things.
I don't have an engineering degree, but it seems to me that the pulley system would be 15 feet high, which would mean that the reel probably wouldn't fit into most clubs, and would be hard to fix.
If a double pulley was used on both the top of the wall and the weight, you could get away with less than 15 feet of wall. The weight would have to be heavier, though.
Regarding the rapid drop upon disconnect, you would probably want to put the weight in some sort of track to keep it from swinging about anyway. At the bottom of the track you could put a large spring and shock absorber (like an automotive strut) to absorb the impact. (Also, you could charge a buck each time someone disconnects without properly releasing the tension. )
Last edited by parrythis; 01-22-2007 at 04:55 PM.
One test is worth a thousand opinions. I ain't as good as I once was, but I'm as good once as I ever was. - Toby Keith Living life without taking the occasional risk is like lemon-pepper chicken without the lemon-peper. It's just chicken.
I have seen descriptions of essentially the same type of system, I believe from Uhlmann or Allstar. They do put it in a box but also use multi-spool pulleys on the top and bottom. Divide the length of the cable by the number of pulley ends to get the travel of the weight.
If you go with a weight in the pipe concept, you might have a way to slow down an accidently dropped end. The thought process is something a bit like this:
Using a circular weight inside a pipe, say PVC, where the ID of the pipe is about 15% bigger than the weight, when the weight drops down, it tries to compress the air in the pipe, but doesn't because it escapes through the space between the pipe and weight. This will tend to slow the decent of the weight. The down side is that it will create some slack in the wire/pulley system when going backwards, and create tension in the wire when going forward, unless you put a check valve in the base of the pipe that will allow air to go into the bottom of the pipe but not out.
Just a thought.
Remember those who put their lives in danger for your sake.
Joe - can you tell me if I got the coordinates right? After a bit of finger-twisting, this is how I read it:
Z: Up on the screen equals Up in reality X: Sideways on the screen equals Transversal direction of the piste in reality Y: Normal to screen surface equals Lengthwise direction of the piste in reality
Did I get that right? European and American conventions for coordinates in technical drawings are different, which can muck up things.
How much does your counterweight weigh?
Have a nice time!
Peter Gustafsson
I believe you do have it right. As you look at the picture/sketch, the weight and the socket are near the floor. I have two reels set up, one with 7.5 lbs. and one with 5 lbs. both work well.
I'm a foil fencer, and I can change, if I have to, I guess.
I just can't get my noodle around this concept. Read it several times, but still don't get it. Can you explain again with smaller words or sketch it or something, please?
If a double pulley was used on both the top of the wall and the weight, you could get away with less than 15 feet of wall. The weight would have to be heavier, though.
Regarding the rapid drop upon disconnect, you would probably want to put the weight in some sort of track to keep it from swinging about anyway. At the bottom of the track you could put a large spring and shock absorber (like an automotive strut) to absorb the impact. (Also, you could charge a buck each time someone disconnects without properly releasing the tension. )
The weight stays in a very compact area regardless of cable movement. I have it mounted 4 inches from the wall and while playing with it, could not make it leave it's linear path by more than an inch or so. I did however like the shock absorbing idea, so I tried an experiment of changing the cord that is attached to the weight to a bungee. Huge difference. It makes the cable travel with less "wow and flutter" and tends to smooth out the action. When I let go of the cable, it still sends the end flying at a high rate of speed, but seriously reduces the shock to the electric wire.
It is required, that fencers stand in the two meter area end of the strip to attach or disconnect from the system. We charge $5.00 for the priveledge of disconnecting elsewhere.
I'm a foil fencer, and I can change, if I have to, I guess.
If you go with a weight in the pipe concept, you might have a way to slow down an accidently dropped end. The thought process is something a bit like this:
Using a circular weight inside a pipe, say PVC, where the ID of the pipe is about 15% bigger than the weight, when the weight drops down, it tries to compress the air in the pipe, but doesn't because it escapes through the space between the pipe and weight. This will tend to slow the decent of the weight. The down side is that it will create some slack in the wire/pulley system when going backwards, and create tension in the wire when going forward, unless you put a check valve in the base of the pipe that will allow air to go into the bottom of the pipe but not out.
Just a thought.
Now this is brilliant, if not a little complicated to get right. It does make me think though, how about a pnuematic system?
I'm a foil fencer, and I can change, if I have to, I guess.
Ah, of course. This would obviously work. I used a left over piece of bungee to replace the weight cable. I had to play with the length a little but it really helps for our purpose a lot.
I'm a foil fencer, and I can change, if I have to, I guess.
Originally Posted by Joe biebel 
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