Bender Woes

[chevysmithz71]

I think My die may be the wrong size!

I am very confused about an article from pirate 4x4 that many people are going off of. This article is what my measurements are going off of to start my cage. In the article it explains by using a 90 with the tube inside, the dimple marks should be the die size. My die is 1 3/4 with 5.5 bend that is stamped on the die. When I put my bent tube in a 90 It comes out to 6.5 at the dimples. What is going on?? Is it just me or the die?

Please help!!


http://www.pirate4x4.com/tech/bendin_tube/index.html

Thanks Ryan

 

[tRustyK5]

That's called "springback". The die is 5.5 CLR but the material will always bend slightly larger than that...and now you know exactly how much springback you're getting.

There is nothing wrong with your die set, or your bender.

Rene

 

[chevysmithz71]

Springback is a whole inch on either side? I read it was in the lines if 1/4 to an 1/8 inch??? So what is the deal with the pirate thread? The article states it is a 5.5 and thats what was measured on the tube with the 90.

 

[tRustyK5]

Springback really depends on the quality and wall thickness of the material being bent. Better quality and thicker wall will spring back more than thinner or lesser grades. Even on a press brake to get a 90 degree bend you need a die capable of going beyond 90 degrees. Even though you're not bending spring steel, all steels have some springlike qualities.

The point of the pbb thread was to give you a way to find your actual CLR for the size, grade and wall thicknees of what you're bending with the dies you have.

My JD2 with 5.5" CLR die set netted me a 6.25" CLR using 1.75" x 0.120" wall 1018 HREW.

Rene

 

[BadDog]

The point in that article was to forget CLR. Instead, just bend a 90* piece, find out where on your die the bend starts and stops (dimples on the 90*), and measure to see how much distance it takes to "complete a bend". With that and some chalk drawings you can do pretty much any single plane bend. If you're using Robs method, forget the CLR stamped on your die, it is no use to you at this stage other than identifying the die.

 

[BadDog]

BTW, the "CLR" is the radius of the bend in the center of the tube. So if you take your CLR of 5.5, add 1/2 the tube at 0.875, you get 6.375. Add only a little for spring back and you get your 6.5 *outside* radius. Nothing wrong with your bend or die...

 

[chevysmithz71]

Awesome. Thanks guys. It' hard to start out with the bender and figure it out. Looks like I have a lot of hard work coming soon.
Wouldn't have it any other way.

 

[smalltruckbigcid]

Thanks thats the best complete definination of spring back I've seen.
George

BTW, the "CLR" is the radius of the bend in the center of the tube. So if you take your CLR of 5.5, add 1/2 the tube at 0.875, you get 6.375. Add only a little for spring back and you get your 6.5 *outside* radius. Nothing wrong with your bend or die...

 

[fairlane_68]

I'm not intending to plug a TV show, but the best display of cage building I've ever seen is from the TV show "Musclecar" on Spike. I've learned more about fabrication watching Lou than I have by reading any article. The guy knows his stuff. You can buy individual episodes on iTunes, and you'll wanna get the "Mustang Outlaw Road Racer" episodes. He builds the entire structural part of the car from scratch, as well as the front and rear suspensions, and explains every step, and how he gets his measurements. I just wish the shows were longer.

 

[mtnman]

My JD2 with 5.5" CLR die set netted me a 6.25" CLR using 1.75" x 0.120" wall 1018 HREW.

Rene

Hey I'm about to buy a JD2 and am wondering if I should buy a 5.5 or 6.5 die set. What are your thoughts? Why did you choose 5.5"? Price or other?

 

[blazinzuk]

The tightest CLR you can get the better. I have used a 1.5 die with 4.5 clr and a 1.5 with a 5.5 I wish I had the 4.5 all the time. It is pretty rare in cage building where you want a bend to be bigger than it is

 

[BadDog]

True, but min CLR is determined by material, diameter, and wall thickness. Assuming apples to apples (i.e. not 4140 vs 1018, different diameters, etc.), the main consideration is wall thickness. If we are talking "mild steel" of, say, 1.75" diameter, then going with a larger CLR will allow you to bend thinner wall tubing. A smaller CLR will require thicker walls to bend without crimping. And even at that, you'll get more flattening with the smaller radius.

All that said, most of us use a 5.5 CLR die to bend 1.75 x 0.120 mild steel HREW or DOM tubing. It just "looks" better (to most of us) and works fine for typical tube used. Going smaller would give excessive flat spotting and might even cause a kink/collapse. That's why you generally see 5.5 as the smallest size offered.

 

[mtnman]

Thanks guys! I have ordered the JD2 model 3 with 5.5" dies and am now waiting like a kid @ Christmas for the UPS man!!!

 

[muddermilitia]

Thanks guys! I have ordered the JD2 model 3 with 5.5" dies and am now waiting like a kid @ Christmas for the UPS man!!!

Let me know what you think of it once you try it out. I'm planning on getting the same bender when its time to start rear tubework and exo

 

[mtnman]

I have it in the dining room in my house!! But, winter isn't gone yet and I have no shop - so - no bending yet!