I am using a 10mm on my LLMini and a 8mm on my Promo(class5). As for pulleys usually smaller is cheaper but larger is easier to use. I use a large rachet block as this is easier on your rope and hands

Try eBay for pulleys

cheapest route - I think I'm going to try to adapt some roller blade wheels. Found 3 pairs enough for 12 double ball bearing pulleys! I'm considering ways to re-profile them and probably make them thinner (for 1/2" rope). Then it's just a matter of bending a "U" strap out of aluminum and reusing the bolts and nuts they came with.

To reprofile the roller blade wheels, freeze them [I'm told it makes machining easier]
Clamp the roller wheel between a couple of large washers with a nut and bolt so it cant spin on the bolt.
Use the bolt to secure the roller wheel in the chuck of your lathe- [or drill press]
Reprofile with either proper lathe tooling- or a big rat tail file.

my theory only........let me know if it works

stephen

Junk that is the kind of lateral thinking I like,off to ebay i go !!

Junk I would only use it as finishing cloth if the resin will soak into it.

Re: spun polyester - bummer. I have to admit when I first picked it up, I thought "polyester cloth with polyester resin...what a good match". Thanks landyacht and docheckle for your help.

Ok, after some experimentation here's the result of my (racing) pulley setup. Sn, I did freeze the wheels and used a bolt and washers so they didn't spin in a hand drill then used the power planer at 90 degrees to the wheel to get the deepest groove - thanks. Planing them does generate quite a bit of heat but I just went ahead and did it in one pass without re-freezing. The drawback of the rollerblade wheels as sheaves is that the rubber compound (and my lack of a deep groove) does not lend itself well to letting the rope find the lowest position of the sheave. So the work-around was to use use a bent wire guide. That works well - with a slack rope and "up side down" position the rope gets positioned just right every time. The wire guides are slightly different dimensions depending on what angle the rope exits and if I need more rope angle, they can be flipped over. There is a hard black plastic spacer that keeps the sides separated and a piece of garden hose over that which keeps the blue fastening rope always centered - to also aid in preventing a slack system from getting cock-eyed. The blue rope passes through 2 holes in the white garden hose.

The setup below is from paul's helpful "racing sheeting" diagram. I was intending to incorporate some other sheaves in the smaller blocks, but the ended up being more problematic. I found the blue rope didn't mind navigating the as-is diameter of the plain roller blade bearing and it gave a real smooth action. Plastic side washers were cut from (hdpe) food container tops. Black plastic spacer again at the ends and I reused the nylon "bearing spacer" that came with the wheels over the center bolt. To ensure the sides didn't bind the ball bearing, the bearing spacer was cut with about 1/16" of the wider portion attached, It was then trimmed to the same diameter as the rest by just nipping it with a knife against a fixed surface - of course if you have a lathe that would be more direct.

Much appreciated, thanks paul.