Good subject, and something I've struggled with for years. Recently I made a fixture to mount the tube to my rotary table. A bi-metal hole saw mounted in the mill-drill does the cutting.
I bought a cad program to help design my frame. (I've always been a "Hume Cad" kind of guy myself, but am being won over by this technology now.
) If anyone is interested the program I'm using is Alibre Design and is pretty easy to learn. Once the tube is designed the program lets me find the angles and offsets that I need to cut the tubes.
I found the real benefit to this in the downtubes on the frame I'm building now. The joint at the neck is off center on each side and they meet the lower tubes at an angle. With this set up and an electronic protractor mounted perpendicular to the tube centerline for rotational angle reference I was able to cut them to fit properly in just a few minutes on the first try, with no scrapped parts or hand fitment required.
It worked out really well for me and save a lot of time. I am able to get precision offsets and angles with the calibrations on the mill table and the rotary table. The electronic protractor on the tube requires a little finesse to get the tube clamped in the fixture in the proper position but isn't too bad.
I haven't been able to find anything on the market that is affordable to the home builder to do this kind of tube notching, so maybe this will help someone.
BAILEIGH, if your company comes out with a similar set up after seeing this, I expect a royalty, or at least a complimentary sample
, and a donation to SSS for the site.
