:: View topic - Mdf cost

I'm just about to start on my mould and I'm wondering how much the mdf costs for a mould like the one in the how to section on this site. How thick of mdf should i get? 1 or 2inch thick ?

We use 3/4" mdf and it is around $30 for a 4x8' sheet. You will probably need 1.5 sheets for 1 mold (2 ski mold).

Kelvin

I just found out about your site, and I have to say it's awesome. I passed the link along to the folks at Make and they posted it on their blog of diy coolness.

I was looking at the white plastic cutting board in my kitchen thinking it might be made of noncrappy plastic. By looking around the internets it turns out that cutting boards with the "NSF approved" (not the National Science Foundation nsf.gov, look at nsf.org) are made out of HDPE. Now I think that HDPE isn't as strong as ABS or UHMWPE but it might be a worthwhile option. Since you can get cutting boards almost anywhere.

Edit-

I forgot to mention that you'd probly want to profile the tipspacers with the core since cutting boards are ~1/4" thick.

Thanks! the make site is pretty cool.

I believe HDPE and UHMW is very close and are in the same polyethylene family. I don't see why HDPE wouldn't work.

from what I know, HDPE does not bond with epoxy at all. That may cause some problems.

why not just make a small test piece? you can try flametreating the plastic beforehand.

http://cgi.ebay.com/15oz-Triaxial-Woven-Fiberglass-Cloth-Tape-6-7-8-wide_W0QQitemZ7552650747QQcategoryZ1268QQrdZ1QQcmdZViewItem

It's going cheap, and theres lots of it. It's triaxial, but 15oz, so I wanted to know if I'd be able to use it on skis.

It's a little light, but I don't see why it wouldn't work. You could double up the layers and probably be good.

Kelvin

What is ideal for the 'weight' of the fiberglass? I have a friend who is working with me, and his father is involved with some fiberglass companies, so he can get us pretty much anything at a good prices.

Triaxial braid, and what else should he be looking for?

to be honest, i really don't know what the ideal weight for fiberglass would be. we've been using 22 oz. triaxial fiberglass and it seems to work really well.

after looking at some of the karhu/line and elan videos it seems as if they're using the same thing. it's hard to tell but it looks really close.

what does the weight of the fiberglass effect? would a 'heavier' one be stiffer? I'm sure I can find out tons about it talking with people, just wanna get a sense of it if you know.

The kind folks at vectorply helped me chose my product by looking at what ski/board mfgrs are using. Looks like pretty much everyone is using 22oz with a little 19oz mixed in here and there. I will be using 2 layers of 22oz on my skis. 2 layers of 19oz on my kids & 1 of each for my wife's. I think that there is a small increase of stiffness relative to increases in weight of the glass. Regarding the Triaxial proporties of. Make sure that your are getting strands oriented at 45*/0*/-45. One third of the fibers are orriented allong the length of the ski. There is triaxial fiberglass fabric with strands orriented to 45*/90*/45 which will not work properly. Also, fabric called "braided" is not prefferred. The up & down of bending over & under other bundles of fiber causes pinch points which weaken the glass. The fabric you procure should be "stitched" In this fabric the glass is laid down in three layers, one in each direction, then thread is stitched down the fabric binding the fiber bundles into place & creating the fabric.

I see no reason that the fabric that was availabe on that ebay auction couldnt be used. You would need to double it up though.