Sword construction

Am watching a thread on RPGnet about larp safety:

forum.rpg.net/showthread.php?p=1 … st12803093

Thought this was interesting:

[quote=“Llewellian”]Its without doubt that there are better materials out there, way better. But in the calculation for Safety, Durability and Weapon building costs, you find one Maximum in the threesome of Plastazote, GFK and Latex that is finished with Boatgelcoat.

And the only two real new “Safety/Durability Inventions” that came up in the last 15 years were:

1: Dont glue foam layers parallel to the deforming stress (aka “Sandwich” of 3 foam layers), but take two THICK foam layers, and glue them rectangular to the blade and cut out your weapon from there.

2: Tip safety (Thats one of my inventions that is now pretty much used everywhere in the EU, even the Larp weapon producers in India and China copy that): Glue on top of the tip a tube of Plastazote the same diameter than the rod and wrap that in one layer of Kevlar. The socalled “Kevlar Tip”. Way better than flexible PVC tubes, leather and whatnot. Is lighter, smaller, absolutely unbreakable and Kevlar cannot be pierced by GFK - At least not with the power of a human. Makes smaller and safer tips.[/quote]

I think this guy is involved with Forgotten Dreams, one of the biggest latex weapon makers.

So, to break this down and compare with typical practice here in NZ:

First off, for materials he’s saying use Plastazote (a brand of closed-cell foam), fibreglass rod (“GFK”), latex, and a top coat of “Boatgelcoat”. That’s all pretty standard for making latex weapons here in NZ, except that we haven’t really found a local product that makes a good top coat to go over latex. I’m curious to know what Boatgelcoat is, and whether it’s any less toxic than the roofing sealent used as a topcoat in the UK. Also, it’s interesting he also complains somewhere that carbon fibre rods are more dangerous when they break, as they create a more splintered result than fibreglass.

Then the construction:

  1. We use the sandwich of three thin layers approach. The innovation of using two thick pieces instead and gluing them so that the seam runs down the blood gutter sounds interesting (at least, I think that’s what he’s suggesting). It means that you won’t be hitting people with glue seams, which is a good thing because those tend to be harder than the foam. And presumably pure foam will cope with the beating the weapon edge takes better than the seams of glued layers of foam. However, this would require us to acquire thick pieces of foam. Some people are using camping mat (even though it’s probably not dense enough to be ideal for weapons), which doesn’t come in this form.

  2. This is a totally different approach to tip safety, and it sounds nice. Basically you extend the length of the fibreglass core with a piece of foam the shape of the core, then you glue a sheet of kevlar around the foam “rod extension” and the fibreglass rod. I dunno what kind of availability we have for kevlar here, but possibly another material could be substituted. I can see how this would result in a core with a softer extension that won’t break, but wouldn’t be able to push through the main foam of the sword or to skewer a person if it was somehow exposed.

I agree its a good approach, and I’d use it if I could find the materials (OTOH, I haven’t moved up to swords yet - I’ve only done daggers, maces and axes).

At Chimera I noticed a couple of people had shields which appeared to be made out of a single slab of thick foam. What material is this, and where can I get some? And would it be thick enough for this sort of approach to swords?

The tip idea sounds good.

Kevlar is not difficult to get hold of in NZ. I’ve used it for fire toys before.

[quote=“IdiotSavant”]At Chimera I noticed a couple of people had shields which appeared to be made out of a single slab of thick foam.
What material is this, and where can I get some? And would it be thick enough for this sort of approach to swords?[/quote]

It’s possible you’re talking about my new shield:

But it isn’t a single layer of foam, it is three layers glyed like ply, which I think you’re trying to avoid.

I like the new construction suggestion. It’s a bit more like tongue-in-groove construction, which as the person suggests, means there is no glue on the edges.

But I think it’d work really well if you could get your foam pre extruded. You may find that it’s a bit more work to try and create the foam by hand.

Yeah, that was one (Andrew’s kite shield was the other). It looked like one slab; guess I was wrong.

Different topic, but how did you get it to bend and stay bent? Fabric between the layers?

I use a slightly different construction method which involves a sail batten and only two layers of foam. The batten is rectangular in shape, so is a good match for a sword shape. The two layers of foam are glued directly onto each other, with the batten sandwiched between.

The glue seam is the same as the sharpened edge of the sword, however I haven’t had any problems with the edges being too stiff.

We also laminate the end of the batten to prevent punchthrough. Have never had a punchthrough incident (and most of our swords are over 10 years old), although we have seen tips start to split at the end of batten (from flexing).

I experimented once with using camping mat instead of EVA, never again, it’s just too soft and easily ripped.

Dunno what Derek did, but I’ve made two curved shields solely from foam. I used two layers of foam about 8mm thick, no fabric in the middle. If you glue the two layers of foam together (i.e. laminate them together) while they are both curved, the foam retains the curve.

Personally I think two layers of foam is enough - I reckon three layers looks a bit on the thick side.

I think it’s not just about punchthrough though. It’s also about creating a more flexible extension of the core at the tip. This flexible tip absorbs part of the blow by giving slightly, making it feel less hard hen you get swiped with the tip.

My experience with the tips with fabric laminated over them for safety (which is the approach I’ve always used too) is that they tend to feel a bit on the hard side, and be ungiving, having less flex may make them more likely to tear away from the blade.

By comparison the latex weapons I’m stocking now, which use something more similar to this kevlar-rod-extension approach, have surprising flexible tips, and I think they’re onto something with it.

So I think it’s something worth trying out.

[quote=“IdiotSavant”]Yeah, that was one (Andrew’s kite shield was the other). It looked like one slab; guess I was wrong.

Different topic, but how did you get it to bend and stay bent? Fabric between the layers?[/quote]

No, I just glue it together bent:

  1. Apply glue to both surfaces.
  2. Bend the inner layer around something curved, like a 200L plastic drum, or a couple of BBQ gas bottles
  3. Stick the other layer on
  4. repeat for the other layer…

I also have a fibreglass rod through mine for the handle, it stops about 200mm from each edge, so there is a lot of squish.