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Author Topic: tubing benders for chassis and cage build  (Read 12754 times)
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isiahstites
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« Reply #30 on: December 14, 2008, 05:17:51 PM »

Kent, you haven't steered me wrong yet tongue..I readjusted to 35 degrees...

http://www.frsengineering.com/pp27.jpg



Good one, funny man..........  afro
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1212FBGS
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« Reply #31 on: December 14, 2008, 09:53:20 PM »

scott... i bet it took him all day to come up with that one grin
chops... 1.25 with .120 wall... the problem was with the chineese dies that didnt fit the tubing... i held the tube up to the die and the ID was too small (cheep cast piece of crap) crushing the inside..... the dies will need to be ground to fit the tubing better.... the second problem is with the cheep 1 piece  follower that is stationary... it streaches across the tube and galls the outside.... i guess the more ya use it the better it will probably work as the dies and followers wear out... i guess i/m just a picky SOB
kent
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Rex Schimmer
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« Reply #32 on: December 14, 2008, 11:43:12 PM »

Kent,
Grease is the tube benders friend. Use some heavy grease on the follower and it will work much better.

Rex
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Rchop
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« Reply #33 on: December 14, 2008, 11:48:28 PM »

Kent, I ordered my 1.25 die just before Thanksgiving. They said it would be shipped out the next week. When it didn't arrive that soon I called and was told they were having problems because they weren't happy with that die and were remaking it. Maybe Randy should call and get a replacement. The contact points on the follower on mine are aluminum. Along with the grease, they didn't mar the tube

Maybe your tube is too soft wink wink
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isiahstites
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« Reply #34 on: December 14, 2008, 11:54:10 PM »

Maybe your tube is too soft wink wink

That's probably not the first or last time he has heard that............ shocked
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bak189
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« Reply #35 on: December 15, 2008, 12:08:09 AM »

Pull it back to 31 degrees....your not building a
"chopper".......................................................................

(Sorry Willie)..................................................................
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JimL
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« Reply #36 on: December 15, 2008, 12:21:01 AM »

Here's a Huh  The early JD2 (used to build the old 797 mod roadster) had a block and screw arrangement to tension the shoe.  My new JD2 has the shoe floating.  Anybody know what's going on?  I kind of liked the old setup, because the tube stayed put when you were moving to the next ratchet or pin position.

Any ideas why they changed?

thx, JimL
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Rchop
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« Reply #37 on: December 15, 2008, 08:58:50 AM »

Pull it back to 31 degrees....your not building a
"chopper".......................................................................

(Sorry Willie)..................................................................

35 degrees was my intended rake when I built the jig. When I tightened everything down, the angle of the shoe pulled it another 2.5 degrees out. I loosened the neck jig and welded it in place. It now stays at 35 degrees which gives me the trail I feel comfortable with. I may not be building a "chopper" , but I'm not building a road racer either.
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bak189
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« Reply #38 on: December 15, 2008, 11:16:34 AM »

Back to tube benders......the best bender we have is one we build ourselves it lays flat on a steel table...is hydraulic....uses steel dies....and a sliding follower on bearings...........for some of the roadrace frames .049- 4130 is used.....real tricky to bend.
I think steel dies is a must over alum. when using the bender for production runs................
Also weld a loop on the top side of the die to keep the tube tied into the die....use grease when bending.
It should be noted that most of the tubing we bend is of a max.  dia. of 1.25 with .065 wall........
no roll-gage dia. and wall, only M/C and sidecar frames.
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Rex Schimmer
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« Reply #39 on: December 16, 2008, 12:52:06 AM »

When you start to bend thin wall, high strength tube in small radi the whole machine gets a lot more complex. Generally you will have some sort of mandrel that is inserted into the tube to prevent the collapse of the tube wall. Sometimes it is just one piece that is cut off an an angle and then generously radiused and polished, this is positioned so that it is just in line with the begining of the bend radius of the bend die and it wipes the inside of the tube to keep the outside wall from collapsing in. If the bend radius is real small say 2 x the tube diameter you may use a "ball mandrel" which looks like a number of polished balls that are connected together and feed into the tube, they are located such that as the tube is bent the balls go partially around the bend die so they wipe both the inside and outside wall to keep the wrinkles out. And if you are going to go with really thin wall, .020 say, and high strength material, 625 inconel say, you are then going to have a pusher which grips the tube behind the bend clamp and pushes the tube into the bend as the wiper shoe bends the tube around the die. This actually move metal into the outside of the bent tube and prevents it from tearing. Of course all of this causes big friction so it takes big power to make it happen. All of the good machines are hydraulic powered.

Tube bending is as much art as science. What save us is that we are bending heavy wall tubing that does not have an extremely hight yeild strength and we bend at pretty large radii so we don't see any of these problems but when you get into the stuff that Bak189 is working on it gets a little more interesting.

Rex

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1212FBGS
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« Reply #40 on: December 16, 2008, 01:17:08 AM »

i fill all my thinwall stuff like fairing brackets and ex tubing with sand
kent
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alnapier
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« Reply #41 on: December 17, 2008, 04:03:41 PM »

Count me amongst the JD2/WD-40 guys.  No problems with 'moly down to .058 or MS down to .083 on mine as long as the tubing is cleaned first and then sprayed.  Have put 1"  1 1/2  1 5/8 & 1 3/4 through it up to about 100 degree bends without drama.

The only issue I've found is that when bending a funny car style cage (main cage hoop) that if I make the first bend, then feed the tubing in some more and make the second bend from the same direction the two bends don't exactly match and I have to mess with it afterwards.  If I pull the tubing out, reverse it, and bend it from the other direction they come out virtually the same but that's a PITA for me.

No idea why this happens........

Al (I think I'm gonna like it here) in CT
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jdincau
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« Reply #42 on: December 17, 2008, 04:34:17 PM »

My Son bought a JD squared bender. We used it to bend all the chassis parts for my brothers streamliner and new rear cage uprights for my roadster. It was all 1 5/8 dia. x  .120 wall DOM and the bends all came our just fine. No necking or kinking, we followed the instructions and cleaned the tubing and lubricated it prior to bending. He has also built some 1 1/2 dia. .090 wall bumper, shock mount, bed reinforcement and fender mounts for his truck with no problems.
Jim
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