Typically you'll have problems with the tube collapsing/wrinkling from when you get the end of arm travel and have to yank the pin and move it to the next hole to reset the arm. The tube relaxes in the die causing a small air gap and that's where you'll get wrinkling/collapsing/etc. We had the same problem with my buddies JD2 Model 3. Alot of the newer benders have a pin that drops when you get the end of arm travel or "anti spring back" systems to maintain pressure on the tube while you re-pin.
If you're planning on using the bender alot, like mondale said, hydraulic is the way to go. Sadly a system like he's talking about (bending past 90 degrees in a single pass) is extremely expensive if you're not making money off of it. I use a JD2 Model 32 with a Harbor freight air to hydraulic ram and SWAG offroad bracket (which with you machining ability, I'm sure you could just fab something up)
http://www.swagoffroad.com/Tubing-Be...ount_p_53.html
I'm not gonna lie and pretend its the quickest or most powerful option, but it certainly does the job, bends about 65 degrees before you have to move the pin. I have the bender mounted on an engine stand since it doesn't have to be bolted down and just roll it wherever I need it and can stand right over the degree wheel operating the ram with one hand and hold a cold beer in the other. If you find a 20% off coupon the ram only costs like $65 too.
Enough of my little ramble though, I just love fabrication tools. I really like how your front end turned out. I've been considering something very similar since my core support it so rusted and nasty, but have to wait until my tax return to buy my tig. I cant wait to see the finished product when its all painted and everything! Keep up the great work!
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