OK - thought I had this sussed but a bit of searching on here and I am confused

I have some 1.75" CDS tube 3mm thick wall, that I want to bend up for my roll bar. I thought i would be OK hiring a bender from speedyhire or somewhere for a week and it would bend this easily BUT...

After reading previous posts what 'pressure' do i need ? will a 10 ton hydraulic type do the job? and will it bend the pipe properly or will it kink?

it it helps the maximum bend will be about 75 degrees

Also - the adds all say 'a selection of formers' do they usually have 1.75" or have I shot myself in the foot there?

I know i can pack the pipe with sand and heat it to get a good bend but would need proper gas kit for that and would rather not bother...

was thinking of this one:

linky

Yes I know i can ring them - but I can't do that right now.......

Cheers

[Edited on 29/5/07 by DaveFJ]

Hello,
That pipe bender will just kink the cds tube you have, the formers won't fit the tube properly unless your lucky, a pipe is measured internally and a tube externally. But even if the former is a good fit the tube needs to be supported all the way round unless the wall thickness is very heavy

I bought one of these which does perfect bends but I only have 1 inch, 30mm and 1.5 inch formers, otherwise I would have offered to bend it for you if you aren't too far away

http://www.pro-tools.com/105.htm

Cheers
David


[Edited on 29/5/07 by Minicooper]

you need a mandrel pipe bender

Dave

would you like to borrow my proper tube bender to do the job properly.

Tim

Now there's a thought.....

Have you got enough to try a sample first?
If it were me I think I'd take it along to a friendly local engineering workshop - somewhere on the more agricultural side perhaps (somwhere that might have some time for you and not tell you it can't be done without a mandrel bender etc etc) and see if they can bend a sample ok.
If they cock it up they'll probably not charge you, saves hiring a bender and finding out the hard way!

I have a 6.6m length of the stuff so I do have a small amount spare - not sure how much yet though because I want to put in rear braces and a crossmember......

you mean like


tiger1

full service design, lenght calculated, cutter wrappers

see http://www.locostbuilders.co.uk/photos.php?action=showphoto&photo=tiger3.JPG

and
http://www.locostbuilders.co.uk/photos.php?action=showphoto&photo=tiger2.JPG

Actually more like this....

Description
excuse the crappy drawing.

The main hoop is as you designed Tim when you came round that time. The rear braces will have to be made, I think, after the main hoop is in place so that i can g accurate measurements. the Horizontal tube is for the seatbelt mounts.

And before eveyone piles in - yes i know that the design isn't 'optimal' for strength etc - but i like it

quote:

---

Originally posted by DaveFJ

The main hoop is as you designed Tim when you came round that time. The rear braces will have to be made, I think, after the main hoop is in place so that i can g accurate measurements. the Horizontal tube is for the seatbelt mounts.

---

Sounds good

quote:

---

Originally posted by Minicooper
Hello,
That pipe bender will just kink the cds tube you have, the formers won't fit the tube properly unless your lucky, a pipe is measured internally and a tube externally. But even if the former is a good fit the tube needs to be supported all the way round unless the wall thickness is very heavy

I bought one of these which does perfect bends but I only have 1 inch, 30mm and 1.5 inch formers, otherwise I would have offered to bend it for you if you aren't too far away

http://www.pro-tools.com/105.htm

Cheers
David


[Edited on 29/5/07 by Minicooper]

---

tube bender

main hoop 2

main hoop

PS I did no calculations and no CAD drawings, made it all to fit, and its within a couple of mm of being right in all the right places.

Trickiest bit, no matter what you use to bend it, is the get the hoop in an exactly flat plane.

On a 7 its not too bad as the upright lengths are pretty short, but on a full size cage they can end up quite a bit out at the bottom.

You need to allow a good amount of extra length on each leg, then cut it back to suit, bit by bit. You waste less doing it this way than you do calculating it accurately and getting one of the 4 bits too short.

[Edited on 30/5/07 by NS Dev]