Hi gtslabs,
You can get amazing accuracy out of a well tuned bandsaw. But, your bandsaw must have the ability to be tuned. Rolling guides are a must and a good bi-metal blade will be a big help. I prefer a 10 pitch or coarser blade for aluminum and use A-9 or another parifin based cutting fluid. (You can get by with some of the home brewed things you see posted on the web but you will find a big difference in the stuff thats formulated for cutting aluminum.)
So, basic points:
1. Set the guide rollers so they pinch the blade just hard enough to guide the blade but not past the point that you can still turn the *clean* bearing by hand.
2. Use an agressive pitch blade. Make sure you have it properly tensioned. I like to twang the back side of the blade and get it to play E-flat above middle C. Seriously, as you strum the blade (don't get cut doing this) listen to the sound. When it starts to make a musical sound it is just getting tight enough. Tighten a little more but not to the point that it quits making a nice tone. Thats too tight.
3. Run your saw at least 150 feet per minute. I like to get mine going 280.
For what its worth, a word about bi-metal blades. They are pricey little devils and if not treated properly can sometimes break in short order. So, set the blade on the saw and tighten it just to the point below making the musical note. Close the blade guards (!) and start the machine. (The blade will normally stay on and if it doesn't its because it wasn't quite tight enough.) Let it run for 2 or 3 minutes and then tighten it further while its running. Let it run for another few minutes. Then turn off the machine and tension as listed above. Some manufacturers pre-stressed their blades, but not all. If it isn't done the blades will crack near the teeth and the crack will quickly develope into a failure. All this according to the blade guy that comes around our shop. I think he's right as I haven't had a new blade failure since he showed me how.
I have cut square plate into rounds with my lathe and I don't care for it. You didn't mention if you were going to have a hole in it or if you were going to rough it in with a jig saw and turn it round in 2 steps with the outside jaws.
Anyway, I hope this helps. -Doug
Sorry it got so long winded...  |