What Plastic For Fin/Leash Plugs??

Hey guys,

I have just machined up some alluminium mould tools for fcs type plugs and also leash plugs, I have access to most plastics so am wondering what the best plastic for these applications? Im going to be installing them with poly and epoxy…

can anyone tell me what the current plugs are made out of…

Dont worry, Im not a company trying to develop these, just for me and a few mates who are hooked on building boards because of sways…

I have access to a cnc mill and metals here at work so its a learning curve to see what will and wont work in reguard to shapes…

Any sugestions for plastic please???



I believe this article has all your looking for.


glass filled polycarbonate (Bahne finbox)

glass filled nylon

Of course you don’t want to machine a glass filled plastic. Delrin or high density nylon would work well. But if you got a mold, use a glass filled nylon, it should do the trick quite well.

And you could get by with PVC esp for a leash plug but unless you are scraping the bottom of the barrel for costs why use such a weak plastic…although I know some people who say you can take PVC pipe ends and drill a small hole in two sides of it and put a brass rod through the holes and call it a leash plug.

…PP and/or PC…

Thanks alot, I am going to be using a plastic injection moulding machine so will definatly give polycard and polyprop a go, will post pics of the moulds and finished plugs once i have made a few…

Thanks alot

Are you sure about polypropylene, Reverb?

Polypropylene (and polyethylene) are well known for being some of the worst plastics when it comes to having any other plastic stick to them. That’s why PP or PE pots are used for pouring polyester resin: resin won’t stick to them. You use them for molds, too, for the same reason.

Making leash-plugs from those plastics would be a nightmare trying to glue them inside a blank… Same for glass-on fins. Would work for fin-box fins, though, I guess.



may be I misunderstood the question

"… for fcs type plugs and also leash plugs,…

can anyone tell me what the current plugs are made out of…"

so some fake FCS plugs are made of PP and PE

and yes, they re crap

the new FCS are made with PC

Thanks, Ploycarb it is…

So would i be right to assume that if i moulded some glass on fins out of poly carb then the glass should be able to adhere to them is i rough them up good and propper??

Thanks, Ploycarb it is...

So would i be right to assume that if i moulded some glass on fins out of poly carb then the glass should be able to adhere to them is i rough them up good and propper??

The newest FCS plugs are not polycarb. Too brittle. The original plugs were PVC, then polycarb, then a glass filled nylon.

If you mold fins out of polycarb in standard thicknesses they will be WAY too flexy. You will need to make the fins substantially thicker, or, add glass. Tom @Daum makes the plastic fins for a number of people, and they are nylon with a LOT of glass added to get them up to the same, or higher, stiffness as fiberglass fins in reasonably standard thicknesses.

I would not glass on plastic fins.


what are the Nylon filled with glass fcs plugs?


You can add glass to plastics before you mold them…called plastics loaded with glass fiber.

The Bahne singlefin finboxes are polycarbonate with glass if I was informed correctly. The Tom@Daum fins are nylon with glass.

Nylon, in addition to making wonderful leisure suits, can make hard high performance plastics with materials properties similar to polycarbonate - except much less translucent and much less brittle. Delrin is comparable in materials properties on a gross first approximation type scale. PVC and PP are typically much weaker.

The glass loading ramps up the stiffness and strength, and makes them very difficult to machine (molding only, really). If you check out some plastic fins, you will find some that are floppy, and others as stiff as fiberglass fins - those fins are glass loaded. The range of plastics used in fins are not stiff enough for most people without glass loading.

…sorry Blakestah my bad

I should put which not what…

my question is based that I only see the PVC s or PCs but I think not the pellets filled ones

the newest ones, from the very long thread a few weeks ago…they changed the plastic in the plugs, again, and also introduced their new box.