I am going to try to make a new roll bar for my seven,

I have borrowed one of those hydraulic pipe benders you can buy from Machine Mart,

What size bar and thickness should I buy? Any tips on using the tool?

Cheers,

B

Good luck - i recon you'll need it with that tool on any sort of tube that'll be sufficient for a proper roll bar.

Will be interested to see how you get on anyway

Those benders are useless for bending thin tube, but also you dont want to be using heavy tube on a light car.
I recommend getting the bends made

The MSA Blue Book specifies for roll bars

Cold Drawn Seamless Carbon Steel minimum yield strength 350N/mm2, mimimum dimensions 45mm x2.5mm or 50mm x 2.0mm

Should do you if it satisfies the MSA

Hi.

Firstly I should point out that I've never used a Machine Mart bender but I think the formers are made to bend nominal bore pipe.

To explain:-

NB pipe, for a given size, has a fixed o/d; but is available with different wall thicknesses. This is termed the schedule. (e.g. 80, 40, 10 etc)

A suitable roll bar size would be 1 7/8" o/d, 2.5mm wall. Do you have a former this size?

This is 1 1/2" nominal bore, schedule 10 and is written as 1 1/2" NB SCH10


My own roll bar is this size stainless steel tube and I bent it using a pneumatic 6 tonne bender.

Hope this helps
Paul G


Edit to add,

You asked for "how to use" tips.

The outer pins will mark the tube. Place some scrap ally plate between the pins and your tube.

[Edited on 29/5/10 by 907]

It can be done (assuming you have one of the 12tonne benders) but to do a good job you need the right formers for the tube (as above not pipe formers) and to add heat to anneal the tube at the bend point.

See this thread from NS Dev from when he did his grasser's cage
http://www.locostbuilders.co.uk/viewthread.php?tid=80519

tube bending using a Machine Mart bender