Clear Plastic Barrel

[reawl]

I'd need to look at my repair manual to see if this is even possible, but I was wondering if people had any thoughts on a clear acylic/plastic barrel for foil. I was poking around the product reviews on this site and LP had a cut-away view of one of their points that I thought was a clear barrel and it got me thinking.

Advantages:
It would insulate, so you wouldn't have to put tape on it that got stuck in the weight and/or prevented your tip from going off (yes I realize a good tape job will take care of this problem too, tell it to the millions of fencers I've refed for who couldn't take that extra minute)

It would allow you to see the action in your tip. When it feels crunchy you can see why. Jammed spring? Now you can see it.

Disadvantages:
Could get scratched up and would be hard to see though if poor material was choosen.

Reminds fencers of clear lexan masks and sends them into convulsions (maybe this should also go under advantages ).

[KD5MDK]

I think the durability would be somewhat questionable. Also, don't you need a conductive barrel so that the circuit can stay Normally Closed?

[Purple Fencer]

I think the durability would be somewhat questionable. Also, don't you need a conductive barrel so that the circuit can stay Normally Closed?

Keeee-rect. Also, find me any plastic that will take a beating when it's that thin....the STEEL ones get dented.

[SJCFU#2]

As KD5MDK (and the Purple one) mentioned the barrel is part of the normally-closed foil circuit, and most plastics don't conduct very well.

I also doubt you would be able to see much once dirt starts to get inside the tip.

[reawl]

Maybe a metal shunt along the wall then to allow the conductivity?

Maybe I have too much faith in plastic. Why worry about dents when they pop out like something from rubbermaid? Or what about a polycarb tip that can also deflect bullets? I'd be surprised if there wasn't a plastic out there for this kind of thing.

[Larrison]

Keeee-rect. Also, find me any plastic that will take a beating when it's that thin....the STEEL ones get dented.

Hmm? Woven carbon fiber? Thinking off the top of my head, carbon-fiber composites are quite a bit stronger than steel, and carbon fiber is definitely conductive. But... depending upon the matrix the carbon fiber is laid up with (usually an epoxy base of some type), that may not be as conductive, and may be more brittle (prone to fracture) than steel, although with a much higher static strenght.

Again, off the top of my head -- it would be lighter, and perhaps stronger, but would probably be more expensive (harder to make).

[KD5MDK]

As far as I know, most commercial plastics can be very strong, but are usually quite brittle, and so I would consider them unsuitable for repeated bashing such as a weapon tip gets.

[remise]

On a similar note regarding dented barrels, most fencers, when having a problem with their foils, will 'slap' the tip against the ground in an attempt to dislodge any dirt that may be affecting conductivity. Imagine what would happen if someone slapped a plastic barrel onto the ground. You'd have parts flying all over the place.

[parrythis]

Hmm? Woven carbon fiber? Thinking off the top of my head, carbon-fiber composites are quite a bit stronger than steel, ...

My understanding of carbon fiber is that it's strength lies in "tension". That is, put an end-to-end pulling stress on it and it will surpass steel in strength. I don't think it is stronger in "compression".

[Larrison]

My understanding of carbon fiber is that it's strength lies in "tension". That is, put an end-to-end pulling stress on it and it will surpass steel in strength. I don't think it is stronger in "compression".

Depends upon how it is designed, I believe. I've worked with carbon fiber structures that were amazingly strong while lightweight and which took their loads primarilly in compression.

[PeterGustafsson]

Hi!

I'd need to look at my repair manual to see if this is even possible, but I was wondering if people had any thoughts on a clear acylic/plastic barrel for foil.

Advantages:
It would insulate, so you wouldn't have to put tape on it that got stuck in the weight and/or prevented your tip from going off (yes I realize a good tape job will take care of this problem too, tell it to the millions of fencers I've refed for who couldn't take that extra minute)

It would allow you to see the action in your tip. When it feels crunchy you can see why. Jammed spring? Now you can see it.

Disadvantages:
Could get scratched up and would be hard to see though if poor material was choosen.

Reminds fencers of clear lexan masks and sends them into convulsions (maybe this should also go under advantages ).

I had a look at matweb.com to check up material stats that I did not have in my head. For steels, the ultimate strength in tension generally starts at 200 MPa for the low-grade steels. There is no plastic listed in matweb that is both transparent and has that ultimate tensile strength. If one sets the strength limit to 100 MPa, one comes up with 4 plastics that have useful transparency: one class of amorphous nylon and 3 polycarbonates. The nylon is just too soft, so that leaves us with the polycarbonates. All polycarbonates are electrical insulators, so there goes the conductor criterion.

It is in general quite difficult to combine electrical conductancy and optical transparency. Matweb does not list any polymers with both those properties, as far as I could find. There are some electrically conductive ceramics, but they either are opaque (some carbides), have too low mechanical properties (graphite, silicon), or are not listed as transparent (TiB2). There are conductive and transparent coatings, but they would in all likelyhood not survive the beating a fencing barrel gets treated to.

Aluminum oxynitride is transparent, and mechanically strong enough to be used as armor windows. However, it is not electrically conductive.

IF one would design a plastic barrel - and forget about the visibility criterion - another thing would come to the front. Plastics have in general much lower densities than metals, so the new barrel would weigh maybe a 5th of the old one. The consequence would be that flicking would become considerably harder to do (not just to get them to stick). If one wants a metal to reach this goal, one needs reasonably low density and sufficient strength, since all metals have sufficient conductivity for this application. Aluminum passes the 1st criterion, but not the 2nd. Scandium passes both, but costs far too much. Matweb comes to the rescue again: Minimum E-module of 100 GPa and maximum density of 5 g/cc gives a list of 243 materials. Most of those are titanium alloys, which barely pass both criteria. Beryllium passes both by a big margin, but it is highly toxic. There are two good candidates left: Al/Al2O3 and Al/SiC metal/ceramic matrix composites. Both are reasonably light (Al/Al2O3 has a density of 3.5, compared to pure Al of 2.7) and have E-modulus comparable to, or considerably higher than, steel. Neither contain costly or especially toxic materials.


Have a nice time!

Peter Gustafsson

[reawl]

Thanks Peter! I had not considered the benefit/consequence of the weight differential between plastic and metal in regards to the flick. I wonder if anyone else (ie. the FIE) would be interested in such a proposal in lieu of longer debounce times?

But then would it really be that noticably different. I'm thinking about my practice blade which has a plastic dummy tip on it and it's not too hard to throw a flick when I want to.

[WhipLash]

peter, i remember reading in Discover abt a new metal. I think it is amorphous metal and has very good "rebounding" properties and very strong and light, though it is not transparent. have you heard of it?

[EpeeBunney]

Beryllium point foils? Fencing in hazmat suits! So thats where they got the idear for the transparent visor masks from!