What Type Of Plastic Are Coils/skid Plates Made From?

[jasong]

Anyone know what types of plastics all the manufacturers use? I am looking at printing some skid plates and coil bodies if I'm able to get some time to experiment with making my own coils next season if this Algoforce rolls around and we have use for non-chipped coils again. 

I can 3d print strong plastics like polycarbonate and nylon, leaning towards one of those. But I'm just curious, is there an industry standard for the types of plastics used for the injection molded coils? I feel like maybe nylon, but I'm unsure. I like the idea of transluscent polycarbonate coils so I might try that first (inspiration from Strick's x ray posts). 

Seems like the cheaper spools like PLA, PETG, even ABS all might be kinda too weak. I know layer adhesion makes 3d printing non ideal for wear parts, but the ability to quickly print and prototype different geometries seems compelling for experimenting. 

Anyone know what like NF uses for example with the modern coils like Evos? Anyone printed a coil yet and determined how robust (or weak) it is compared to injection molded of same plastic?

[Lead Detector]

I don't have an answer for you, but I have considered making skid plates out of kydex. It's seems similar to what the skid plates are made of, and is easy to form and holds its shape well. 

[jasong]

I think kydex is similar to PVC sorta? I think that would be toxic to print (or cut with a laser) so you'd be limited to sorta hand forming with it maybe, like with holsters.

I could see it being good for skid plates though, or vacuum forming a coil body maybe if you could get thin enough sheets of it to not be too weighty. I definitely need something I can design in CAD to exact dimensions and then print though. 

[GoodAmount]

I just did a burn/sniff test with an old Sadie skid plate and it smells like styrene. I’ve been 3D printing replacements in ABS though and it works really well.

[jasong]

2 minutes ago, GoodAmount said:

I just did a burn/sniff test with an old Sadie skid plate and it smells like styrene. I’ve been 3D printing replacements in ABS though and it works really well.

Does it seem like the coil body itself is some burlier plastic? I have one I can try to burn and sniff but I'm a bit hesitant haha. But I think you are right on the styrene for the skid plate.

Did you have any issues with layer adhesion using the ABS over time?

[phrunt]

X-coils do standard and (heavy duty) polycarbonate skid plates, the standard ones wear our quicker but are quieter on the ground, the polycarbonate ones are extremely tough and last a very long time, heavy-duty full-time prospectors that are coil scrubbers have reported them lasting multiple seasons in Australia on their sharp rocky red soil.

They've also experimented with another black plastic type, it's a bit rubbery, kind of weird but is even tougher again and is quieter on the ground.  I like this one the best but I'm unsure what it's made of, very rubbery sort of plastic, if it is plastic at all.

The standard white ones you will be familiar with Jason as you coils would have them, this is a white standard one after a full season is OZ.

This is a polycarbonate one, same guy, another full season in OZ.

Scratches everywhere, but no real problematic wear.

This is the 3 types they do; my favourite is the black rubbery one so far but they haven't been tested near enough and are not released yet, followed by the Polycarbonate, not sure what the White plastic ones are made out of, their advantage being quieter on rocks than the polycarbonate ones for coil scrubbers.

The polycarbonate ones are semi transparent.

This is the black rubbery ones; I could find out what they're made of.

[jasong]

Thanks Simon, yeah I haven't even worn through a single X Coil skid yet. I was going to ask you what they were but I wasn't sure if it was some trade secret or something.

So with the softer material - I can kinda do that too with a plastic called TPU. It's the same stuff as they make like wheels for carts for. Or actually, if anyone has a cell phone protector where the case is hard plastic but the outer edge is soft material, that's often TPU.

I thought about trying to make a coil cover with regular plastic for rigidity and then TPU on the edges/bottom (like a cell phone case) but my initial attempts at multi-plastic printing with TPU were...uh...messy to say the least haha.

But seeing as metal detectors are modernizing, seems like there is some potential for the coils too. But it looks like X Coils is already kinda doing it. That's cool!

[GoodAmount]

5 minutes ago, jasong said:

Does it seem like the coil body itself is some burlier plastic? I have one I can try to burn and sniff but I'm a bit hesitant haha. But I think you are right on the styrene for the skid plate.

Did you have any issues with layer adhesion using the ABS over time?

I’m not game to burn/sniff the coil housing either. 🙂

I haven’t had any troubles with layer adhesion in use. Skidding it around on rocky ground smooths the layers out pretty quickly and so far I haven’t had any layer splitting. But I’ve been adding a bit of meat around the wear surfaces on the rim to increase longevity, so that will also strengthen the part. The only trouble with ABS is that with large surface area parts it wants to warp and peel off the build platform, so you’ll need a heated chamber. Mine chamber heats to 75 deg.

PETG should work well though, and doesn’t warp as much.

[GoodAmount]

This is the profile section I'm currently using, working on the premise that I can 3D print plastic volume where I need it and taper it down where not required. This means I can reduce overall weight while increasing wearability. 3D prints are inherently lighter anyway as the density of plastic is reduced given there's micro air gaps between the extrusion lines, whereas a typical  vac-formed part comes from a 'solid' sheet of material.

I've been finding if the fillet on the leading edge is too small it catches on rocks, so I've left it fairly generous. For printability, I've had to leave an intersection between the base and the leading edge for better printability, but it doesn't seem to catch on rocks much and it smooths off relatively quickly. I'm testing a few different profiles to see if I can get lighter weight and better performance for both for wear longevity and slipperiness through the terrain. I'd be interested in your thoughts - I'll add an stl to the downloads section for anyone to try.

[jasong]

@GoodAmount Does it help the cover stay on if you angle the vertical edges in towards the coil some small amount like 0.5 or 1mm to keep the edges on the coil in tension? 

A solid TPU skid plate might be interesting too - it's flexible so you could angle the lip in quite a lot or put a locking ridge on the top, and pop it over a coil with no tape at all - just like a cell phone case. And it would be way quieter to detect with. TPU is tough enough that it would be interesting to get rid of the skid plate altogether and see if just a layer of it on the sides and bottom of a coil would be sufficient. I think I could actually print a layer onto existing coil bottoms with some kind of glue or bonding agent, too bad the sides aren't really doable. 

Watching some vids on it last night, I think oven/water annealing might get a 3d printed coil to closer to the same toughness as a vacuum formed or injection molded. Between that and a good material selection, I'm thinking now it's probably possible to make an equal if not better coil housing/skid (in some cases) on a 3d printer than the commercially available ones if done with annealing and using tough plastics.