Thursday, October 29, 2009

Rackufacture: Hand Bender Do's and Don'ts

Education ain't cheap. Just ask any college student. I paid my dues tonight.

I've been making good progress on a rack for my Karate Monkey and was excited to get home tonight and make a little more. I knew exactly what my plan was: Take the u-bend from last night, clamp it to the bench, engage the bender and then "roll" it 13 degrees to get the bend in the right plane. The setup went just fine.



But when I went to bend it, halfway through the bend, I felt the pressure on the handle give, which is a sick feeling and means your bend has crimped. F@#K. That was a whole 4' length of tube that just went into the toilet.

Since it was already trashed, I decided to bend the other leg and that one crimped too! DOUBLE F@#K!!! And more importantly WTF! These benders do a great job and I couldn't figure out what the hell had just happened. Here's the difference between a normal and crimped bend.



I ended up making a buncha bends and burning a buncha tubing to get this figured out, but it was worth it. The deal is that, in order for these benders to do a good job, the "shoe" has to keep the tubing in tension as it pulls the tubing around the die. I thought I was doing that in the arrangement above, but the body mechanics required to do that bend make it extremely difficult to maintain tension. And if you don't maintain tension, the tube separates from the sidewall of the die and bad things happen.

I just noticed that your eyes glazed over. Sorry. And that was a sucky explanation, I know.

Condensed down, don't bend anything the way I tried to unless you want to throw it in the garbage. Clamp your bender in a vice and do it that way instead. Money.

And speaking of money, here's how I spent mine tonight.



But wait. Yeah, I hear ya. There's some interesting shapes in that pile. Hmmm.

3 comments:

FBC Spokane said...

That pile of pipe reminds me of the mess in my basement that is my plumbing. Though, your pile seems to make sense where as my plumbing does not.

Jim G said...

Great post, thanks!

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