I'm guessing from your description that you have a pipe-based boat, and do not have a wooden crossplank? I ask because with a wooden crossplank, there are better options than pipe to attach the runners to it.
If you must rely on these 1" pipes, then perhaps the bottom of them could be slotted to accept the runner blades? You should be able to do this with a hacksaw. Then a bolt through the pipe and blade should hold it... but personally, this seems like it would be weak. How are the blades attached to the pipe now?
As for the blades themselves, you could have a metal shop cut them from 1/4" mild plate steel for you, then you could sharpen them. I don't think that would be too expensive. Our local metal supply (Dutchess Sheet Metal, Poughkeepsie, NY) sold a friend of mine three pieces of 1/4" stock, about the size he needed, for under $20. He then cut the blades out with a hacksaw, to the shape of DN runners.
I would not suggest a plumbing flange for attaching, as these are brittle, and will brake under the strain. Don't ask how I know!
But if you do have a wooden crossplank, then you can go the simple way I show for homebuilt runners in my Icester plans. As I suggested to Dave Farmer a few posts ago, "Although most resources will suggest "chocks", a boat will usually be able to keep it's runners on the ice, in most conditions, without them. The chocks are the metal mounts which runners are bolted into, so that the runner can "rock" a bit. But crossplanks have a bit of "twist", and ice is usually pretty flat, so runners bolted right to the springboard work pretty well.
"That being said, runners made from 1/4 inch thick angle iron work very well, and are cheap and easy to make. For a boat of your size, a runner length of 18" to 24" would do it... Sign post stock, galvanized, can be gotten in 2 1/2" x 3 1/2" size. The 3 1/2" dimension should be used as the vertical.
"Give the forward edge a curve, so it "rides" over bumps. Sharpen the bottom with a file or grinder, finishing up with a file. An angle of between 45 and 55 degrees is good... 45 is better as an "all around" angle... as in both soft and hard ice."
The sign post stock I mention is also convenient as it has a double row of holes along one side... perfect for mounting directly to a crossplank with 1/4" bolts. There is really enough twist to most planks to keep the runners on the ice, without resorting to expensive and more complicated "chocks". You can find signpost like this easily... go to your local highway garage, and ask. Most garages have a scrap pile of posts, which were replaced when hit by cars. There is usually enough straight stock to make your runners, on one post only. I've gotten two posts in just this manner... totally free.
You can cut the runners out with a hacksaw, and grind them down with one of those $20 4 1/2" angle grinders. A good file will a good sharp edge.
|