Tight bend / kink in tubing
Discussion
Once I've learned to weld to a good enough quality I'm going to consider making up a subtle cage at some point to strengthen my bodyshell up. My mig welder which can only handle up to 2mm, so for the tubing, my thoughts are: CDS, maximum of 50mm OD, 2mm wall.
Thsi is the sort of thing I'm considering to bend the tubing: http://uk.ebid.net/for-sale/hydraulic-ton-pipe-ben...
after watching this, from 1min36sec on: http://www.youtube.com/watch?v=CcRI8pbyvFg&fea...
So my question is, how would I get a sharp bend in tubing, of just, say 7-10˚ - as in, for example a sharp but shallow kink rather than a radiused or curved bend, if that makes sense, without deforming the cross section?
Thsi is the sort of thing I'm considering to bend the tubing: http://uk.ebid.net/for-sale/hydraulic-ton-pipe-ben...
after watching this, from 1min36sec on: http://www.youtube.com/watch?v=CcRI8pbyvFg&fea...
So my question is, how would I get a sharp bend in tubing, of just, say 7-10˚ - as in, for example a sharp but shallow kink rather than a radiused or curved bend, if that makes sense, without deforming the cross section?
Since you'll probably only have to bend the main hoop, get some to do it for you. CDS is a right PITA to bend, and you really do want mandrel bends with no kinks in them. The tube can oval slightly, IIRC the narrow side has to be 90%+ of the tube OD or it isn't acceptable for motor sport. And there's little point making a cage out of CDS if it's not up to spec, even if you never intend racing.
205alive said:
Thsi is the sort of thing I'm considering to bend the tubing: http://uk.ebid.net/for-sale/hydraulic-ton-pipe-ben...
after watching this, from 1min36sec on: http://www.youtube.com/watch?v=CcRI8pbyvFg&fea...
That is a PIPE bender, not a tube bender. Looks like the guy in the video doesn't understand the difference either. They are commonly known as "tube kinkers" by people that try to use them for cages/chassis etc. but you can them to do an ok job under some circumstances e.g. using too small a die, or by adding a rigid strap around the top of the die to turn it into a crude kind of mandrel.after watching this, from 1min36sec on: http://www.youtube.com/watch?v=CcRI8pbyvFg&fea...
g7jtk said:
If you pack the tube with kiln dried sand the heat the area to cherry red then bend on a jig you should be able to ben almost any shape you want.
Have you actually tried this? It's much easier to say than to do, since you have to pack the sand in under a lot of pressure. This means you have to weld plates over both ends of the tube, and having one end threaded for a large bolt so you can compress the sand.2mm is fine for 50mm, it's thicker for smaller diameter.
However, as said, what you're trying to do is the wrong way to go about it, those benders are for pipe, not tube, and they will crush and distort the tubing, especially 50x2mm. Even on my rotary bender I use relieved dies for something that large and that wall thickness.
However, as said, what you're trying to do is the wrong way to go about it, those benders are for pipe, not tube, and they will crush and distort the tubing, especially 50x2mm. Even on my rotary bender I use relieved dies for something that large and that wall thickness.
Edited by PhillipM on Friday 22 June 02:01
Thanks for the suggestions and comments, should've been a bit clearer - the project isn't for a track car or anything, just an attempt to strengthen the shell a little; so as such I reckon CDS is fine for my needs.
After watching additional vids of people using that sort of pipe bender I'm happy with the results they've got and at £100 ish it's cheap enough to try, once my welding's good enough.
After watching additional vids of people using that sort of pipe bender I'm happy with the results they've got and at £100 ish it's cheap enough to try, once my welding's good enough.
If all you want to do is add some tubing to the shell in a non-roll cage way, don't bother using CDS as it's expensive and over the top for what you want. Hell, kit car chassis are made from ERW.
Although I still don't get the point of doing it in anything other than the way you would for a competition car.......
Although I still don't get the point of doing it in anything other than the way you would for a competition car.......
Snake the Sniper said:
If all you want to do is add some tubing to the shell in a non-roll cage way, don't bother using CDS as it's expensive and over the top for what you want. Hell, kit car chassis are made from ERW.
Although I still don't get the point of doing it in anything other than the way you would for a competition car.......
What I want to achieve (ideally) is an unobtrusive cage or cage-like internal structure - but what I visualise and what I could come up with might be two different things...not really looking for a full structure with lots of diagonals - if it's possible to strengthen what's already there, in a practical and subtle way without having to take into account the sort of requirements full competition spec installations need, then I would be happy with that.Although I still don't get the point of doing it in anything other than the way you would for a competition car.......
Thanks for the suggestion of ERW, will look in to that, see what the strength/weight/cost is in comparison. Cheaper is better as long as it's not a good deal heavier.
205alive said:
What I want to achieve (ideally) is an unobtrusive cage or cage-like internal structure - but what I visualise and what I could come up with might be two different things...not really looking for a full structure with lots of diagonals - if it's possible to strengthen what's already there, in a practical and subtle way without having to take into account the sort of requirements full competition spec installations need, then I would be happy with that.
Thanks for the suggestion of ERW, will look in to that, see what the strength/weight/cost is in comparison. Cheaper is better as long as it's not a good deal heavier.
Steel is steel for weight considerations. Whilst I'm not suggesting a full multi-point weld in climbing frame, a simple rear cage (with possible the front half too) with properly bent tube sounds like it will give you what you want. As for the look you're after, any sort of cage will be obvious: they're 2" tube and you can't really hide it in a car the size of a 205!Thanks for the suggestion of ERW, will look in to that, see what the strength/weight/cost is in comparison. Cheaper is better as long as it's not a good deal heavier.
Having said that, why do you feel the shell needs to be stiffer? Having had a 205 Mi16 before with all the strut braces, I found it too be too stiff and hard riding for the road. Sometimes stiffer is not always better!
Snake the Sniper said:
...Having said that, why do you feel the shell needs to be stiffer? ...
The main concern is improvement of shell strength and protection rather than going for stiffness but if that's a side effect, I'll live with it. No strut braces installed but will look at that further down the line.205alive said:
Snake the Sniper said:
...Having said that, why do you feel the shell needs to be stiffer? ...
The main concern is improvement of shell strength and protection rather than going for stiffness but if that's a side effect, I'll live with it. No strut braces installed but will look at that further down the line.Gassing Station | Home Mechanics | Top of Page | What's New | My Stuff