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Tube Bender Die Sizes
liam.mccaffrey - 26/12/07 at 10:41 PM

We have a mandrel bender at work. Thing is the dies are for nominal bore piping. I have mesured what outside diameter tubes will fit into each die. The measurements I took are in the following table.

Mandrel Sizes
Mandrel Sizes

What i wanted to know was how close the die and tube OD should be for a good bend.

I am assuming I could get DOM/CDS tube sized on an appropriate OD if it is close enough to the die, but how close does it have to be??

This is for my roll cage btw

joolsmi16 - 26/12/07 at 11:24 PM

Hi liam, cant help with your die Q, but does your workplace do small steel tubing fabrication work, laser cutting , etc.

If so Iam in Haverfordwest so can ring for a quote on the fab required.

Cheer

Jools

liam.mccaffrey - 26/12/07 at 11:41 PM

no sorry not in milford any more.
u2u sent

Chippy - 26/12/07 at 11:54 PM

Liam, if the die is too loose you will get flattening of the tube on the bend, (SVA fail). Might be worth wasting a bit of 2" o/d on the 49.05 die though, as that's only .95 mil out, and you wouldn't get flattening, I would be inclined to give it a go. HTH Ray

indykid - 27/12/07 at 12:07 AM

quote:
Originally posted by Chippy
Liam, if the die is too loose you will get flattening of the tube on the bend, (SVA fail).


sva doesn't have any requirement for roll structure, so unless you intend to race, it won't fail scrutiny.

i'd rather have it well made for my own peace of mind though
tom

liam.mccaffrey - 27/12/07 at 02:16 AM

quote:
Originally posted by Chippy
Liam, if the die is too loose you will get flattening of the tube on the bend, (SVA fail). Might be worth wasting a bit of 2" o/d on the 49.05 die though, as that's only .95 mil out, and you wouldn't get flattening, I would be inclined to give it a go. HTH Ray


unfortunately 49.05 is the Internal diameter of the die so 2" OD tube probably won't fit

also the car won't be subject to SVA as i live in oklahoma and i do plan to race over here though

[Edited on 27/12/07 by liam.mccaffrey]

Alan B - 27/12/07 at 11:49 AM

Liam, I think I'd go for the 1.5 die with the 1.762 dim.....and use 1.75 tube...only 12 thou' clearance...should be Ok I would have thought.

Alan

Chippy - 27/12/07 at 10:59 PM

Hi, think that you better check your copy of the SVA reg's mate, as there is a requirement regards deformation of tube in bends. Cheers Ray

indykid - 29/12/07 at 04:49 PM

but for sva, no roll structure is required.

i've seen roll bars made from square tube welded in the corners and i assume they weren't all pre sva. they definitely wouldn't pass scrutineering for competition though.

is a roll structure therefore like a reverse light? if it's fitted, it has to be right, but equally, the car can pass without? i'd imagine the deformation of tube referred more to the main spaceframe, but for completeness, i'd be interested in an actual reference

tom