Bending Roll Cage - Help Needed

[03marshj]

Hi All, This is my first post so please forgive any bloopers!

I am a panel beater however building my own track car and looking to bend up a cage / space frame myself.

I originally started off with a bender which pressed straight against the pipe vertically with a former (the cheap and nasty ones) which keeps creasing the pipe.

Since then and after looking around i thought i would try to knock up a bender which pulled the tube around the former. I just tried it for the first time and it creases the tube at where the metal first hits the former. Any Ideas, modifications or advice to start again :/ would be appreciated:

http://i1298.photobucket.com/albums/ag46/JackWealdCoachworks/IMAG03161_zps6b341c78.jpg

 

[chevy2]

Heres a pic of my machine below,
If you look at the two big threaded adjusters the left one is important,
It ensures that you support the guide at the same point as where the tube is touching the former while pulling the bend, it needs to bite earlier on thin wall tube and later on heavier wall,
What you need to do to yours is adapt it so that there is threaded adjustment so that there is pressure on the outer guide at nearly the same point as where the tube is at on the former,
Hope this makes sense?
Oh and welcome!

 

[agrimog]

firstly, you talk about bending a cage for a track car, is this for fun days, or serious competition, next, are you aware of the difference between tube and pipe, then how competent a welder are you, and are you willing to risk your life on your skill level. once you have answered these. what you have there isnt the right tool for cage building, you'll need a budget aproaching £500-£1000 for a bender and dies for the job, then the ability to carry out the stress loading calcs if its for serious use (competitions), why not take the easy option and look at one of the established cage builders and either buy a ready to fit cage or if your desperate to weld it yourself, one of the kits that are on the market. Im not trying to put you off, but a cage in a car is a safety device and should be treated like such

 

[03marshj]

Thanks Chevy2, I will try adding an adjustor like so as soon as i can. Also it seems to crease at the point of where the tube first touches the former, almost as if it where 'bunching' up at that point would it be worth starting the bend further round the radius of the former instead of the sharp edge at the start?

Also I have done my research in to tubing etc. going for t45, I will be building the main section of it to an existing plan from a roll cage company. And planning on letting a colleague of mine who is a full time welder do the final honours. I am just planning on taking part in the odd track days. Thanks

 

[Fastfingaz]

Is the bender suppose to bend that radius in one push?? I've never seen or used a machine that looks like that one,, the ones I've used always bend horozonaly and the radius pushes into the pipe or tubing??

 

[Paul99]

I have no experience with bending steel tube / pipe but have plenty with copper using manual benders that operate similar to your version. It maybe that the former is positioned where it is just for the photo but kinking like that often happens if you're trying to start the bend too close to the end of the former - I'd be looking to have the former pushed right through so the end was near enough touching your restraint pipe - you can always release the pressure and slide the former out several times if you need a longer bend. I think this is the same / similar suggestion as that offered by Chevy2. It's also got to be worth trying to start the bend further around the die to see what happens.

 

[Shox Dr]

There are many types of bender some good some not so.

For tube not to kink when formed you need to pull the tube through the dies swaging the tube as it goes: the tube is clamped to the die and is pulled through the backing former. Your's doing to opposite.


(It's early hope that made sense)

 

[chevy2]

Is the bender suppose to bend that radius in one push?? I've never seen or used a machine that looks like that one,, the ones I've used always bend horozonaly and the radius pushes into the pipe or tubing??

Thats the bow n arrow type pipe bender you describe,
They're only any good for soft wall water, gas pipe and chs steel,

To bend thin wall tube and stuff like T45, cds, chromemoly etc you need a machine thats a rotary type machine like i pictured that has a former with a guide that supports the tube while bending.

 

[Jim Davey]

If you haven't got access to a mandrel bender (lets face it at 10K+ most of us don't) there are ways of bending relatively thin wall, large diameter tubes.

One is to cap the tube, fill it with sand, compacting it as you go, then cap the other end, this will support the tube as it bends, effectively the sand is incompressible and the tube cant wrinkle as it would have to displace the sand to do so.

The other option is to freeze water in the tube and bend it, this also achieves the same thing. However its easier by far, to take some measurements and get yourself down to your nearest motorsport fabricator, and get them to bend you up what you need.

 

[Big Mick]

That design is fundamentally flawed as others have suggested. The half pipe support bit should be stationary and start much further back along the work piece. All the rotary draw type benders rotate the die and have a loop that holds the work piece snugly against it.
Your work piece is kinking because when the half pipe starts to rotate around the former, there is a large gap between it and the fixed support.
Watch this, it shows all the things I mentioned.
http://www.youtube.com/watch?v=LHnBnuS1hdo
So sorry, but this machine will never work for your application.

Cheers, Mick.

 

[chevy2]

That design is fundamentally flawed as others have suggested. The half pipe support bit should be stationary and start much further back along the work piece. All the rotary draw type benders rotate the die and have a loop that holds the work piece snugly against it.
Your work piece is kinking because when the half pipe starts to rotate around the former, there is a large gap between it and the fixed support.
Watch this, it shows all the things I mentioned.
http://www.youtube.com/watch?v=LHnBnuS1hdo
So sorry, but this machine will never work for your application.

Cheers, Mick.

My rotary machine pictured above does not rotate the die,
The rotating arm rolls a wheel around the outside of the guide as it bends,
does the same job but in reverse to some other types.

 

[Brad93]

What is the make of your machine Chevy? im looking for a good pipe bender that can bend some roll cage tube.

 

[chevy2]

What is the make of your machine Chevy? im looking for a good pipe bender that can bend some roll cage tube.

Mines a Hilmor rotary hydraulic no3,
also sold under the trade name of anglia power bend, some red and some yellow in colour,
unfortunately no longer trading, plenty of used ones out there but dont often come up for sale and try finding one with as many formers as a good selection can be more than treble the cost of the bender,

Although new machines look into jd squared, pro tools and stakeseys versions which will all do a similar job.

 

[Fastfingaz]

Thats a nice modern machine, does a great job!that looked like a 1-1/2 inch pipe,,,,,, the other one not so modern, but I think it would still be effective if you get the procedure right, those machines were designed to do the job ,, just got to know how to use them,,

 

[langy]

Mines a Hilmor rotary hydraulic no3,
also sold under the trade name of anglia power bend, some red and some yellow in colour,
unfortunately no longer trading, plenty of used ones out there but dont often come up for sale and try finding one with as many formers as a good selection can be more than treble the cost of the bender,

Although new machines look into jd squared, pro tools and stakeseys versions which will all do a similar job.

Very nice tube bender, it did this very nicely

 

[Big Mick]

My rotary machine pictured above does not rotate the die,
The rotating arm rolls a wheel around the outside of the guide as it bends,
does the same job but in reverse to some other types.

Chevy2, I was commenting on the original posters machine, not yours.
His won't work because the support directly under the start of the bend moves around the former leaving the tube unsupported and able to kink.

Cheers, Big Mick.