Tony, I used to have a lot of problem with that until I finally reasoned that the wire which rests on the template is cooler than the wire that is inside cutting the foam. I made some dummy separator templates out of 1/8" balsa that are slightly smaller than the actual templates and hence will not contact the cutting wires. These then are placed between the foam blank and the actual templates. That way the short bit of cutting wire on the edges of the foam blank passes through air and will be warmer at the edges of the foam blank. I don't know if I needed them with all kinds of templates, but with thick templates or aluminum templates, I found this to be effective. It certainly is easy enough to implement. Try it on a sample and let me know if that helps. I worry about hand guided cutting giving the proper kerf across the entire airfoil. However, that is another can of worms. ----- Original Message ----- From: "Tony J. O'Hara" <[EMAIL PROTECTED]> To: "Soaring List server" <[EMAIL PROTECTED]> Sent: Tuesday, November 20, 2001 5:18 PM Subject: [RCSE] Foam cutting : Further info/help!
I want to thank all who responded to my first request. I have simple changed the CompuFoil horizontal ramp to curve as an extension of the leading edge curve. However----- I am on a quest to totally eliminate the ridges caused by some remaining "twanging": of the wire! I should have mention before that I am using hand feeding/guiding etc of the bow! It's very hard to eliminate the wire "twanging" as it scrapes over the templates! I haven't achieved it yet! Has anyone? Here is what I have found so far! It's very hard to get wooden templates smooth enough Adding epoxy helps-but not enough Adding graphite helps-but not enough Using other materials such as aluminum or PC board doesn't seem to help enough A test running the wire over a metal tube is best! But I can't figure how to use this practically! Holding the ends of the wire with fingers (ouch!) near the templates helps! But haven't tried it with a cut! Making the pressure of the wire on the template quite low-helps appreciably! So the most significant practical improvement seems to be keeping the weight on the templates low! How can I do this? I am going to try a suspension system and maybe also a gravity auto feed. I have seen some designs on the web but most look much more complex that I think it needs! As I am trying to cut wings for a Xmas gift, I can't afford too much more time. So any further help or ideas would be much appreciated! I am particularly interested in hearing if any one has experimented with wire tension, wire diameter or even a "wheel" system of guiding the wire/bow over the templates! Tony Colorado RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
