Hi I have a ice hockey boot that I'm converting to quad skate. The boots sole has a large holes in ball of foot an in heel. I want to fill the hole in to make sole stronger when the plate/ wheels gets bolted to boot. 

The hole depth is 8mm in depth to make up . What is best way of filling hole in....layering up carbon fiber or is there a light weight foam core that can be used?  If there is a foam core is it suitably strong if i needed to put bolt through compression wise?
I was then thinking a layer of carbon fiber across whole sole to tie it all together.

Thanks for any help and advice.

OK, interesting project.

For filling in the two holes, a lightweight core would be an option but it will complicate matters when you come to bold down through it; not impossible but a little more complicated. Also, given the relatively small size of the holes, even filled with solid material I don't think you'd be adding much weight so just casting some resin mix in would probably be the logical way to go but what you could do would be to add some glass bubbles to reduce the density of the resin; you could probably halve its density. You could also add some milled carbon to add tensile strength to it too and reduce the risk of cracking it under compression or twist. So, you could make an epoxy casting slurry using a blend of EL2 epoxy laminating resin - slow hardener, glass bubbles and milled carbon fibre. To ensure the holes are 'flush' with the surrounding sole you should slightly over fill them and then sand them flush with the surrounding plastic, keying the surrounding plastic at the same time.

For the new carbon fibre 'sole' I'd suggest using some more of the EL2 laminating epoxy with some 200g plain weave carbon fibre. 200g carbon is only 0.25mm thick per layer and so it would make sense to use a couple of layers so that you're adding 0.5mm of carbon, this would be a bit more substantial.

Getting a bond onto the plastic could be interesting. If the existing sole structure is made from ABS (which a lot of them are) then you can get a decent bond from epoxy resin by 'flame treating' the ABS. To do this, start by keying the ABS to scratch it up, this creates a more complex surface with more surface area. You can then you a blow-torch (or even a cigarette lighter) to 'flame' the ABS so that is slightly discolours. By oxidising it you make the surface much more bond-able.

It would probably be a good idea to test this *first* before you do anything else to make sure you can get a decent bond onto the plastic. If you can't, perhaps because the plastic is some other type of plastic that is very difficult to bond to, then the whole project might be much more of a challenge.

I hope this helps and look forward to hearing how you get on.

Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales