Originally Posted by crussell85
... but cboy doesn't the tube ever want to pull up in the center and not shape to the board or does it just roll right around. How heavy of tube do you think you could roll that way?
I didn't have any trouble with the center lifting up but that might be due to the size and shape of the particular curves I was bending (long, relatively gentle curves). The roadster rear quarter curves were the only bends I made using this technique so I can't guarantee it would work as well with other shapes. And I'm quite certain this technique would not work for really tight of sharp bends. The tubing would kink up as you suggest. That is the reason I had to come up with the bending die for my HF bender - also shown above - to make tighter and sharper bends.
Also, if you read the journal section I linked to, you'll find that there IS one other limitation for the come-a-long bender. No matter how hard you pull the tubing tight to the curve pattern, it will retain a bit of it's memory and want to straighten out a bit. So the last bit of bend, to fit the pattern perfectly, has to be coaxed into the tubing some other way. I used my Harbor Freight pipe bender in very small increments to do this. Another option would be to cut a second pattern out of particle board which would have a smaller radius and then over bend the tubing (put a little too much curve in). Then lay the tubing back on the correctly sized pattern and clamp or hammer it down around the curve to fit perfectly.
One final note regarding this bender. My body fabrication's are far short of rocket science. The bends made with this concoction (or any of my other bending techniques for that matter) are not things of great precision. If you need something bent within tight tolerances, you may need a more professional level tool.