Hi...I'm thinking I need to build an alignment frame for my resto (https://www.mig-welding.co.uk/forum/threads/ae86-booter-project.101029/), but am not sure what material to use.... would I be best using small I-beam or 80x40mmx3mm box on it's end? It'll be just a basic rectangle with one or two cross members .... it's in the earliest stages of design Thanks Myles
Weight for weight the box will be stronger but even a 100 x 50 UB is twice the weight of the box you have. If you can bolt it to something solid, like a concrete floor when you are trying to straighten something I'm sure the box can be made to work. It’s down to the unsupported length and force you are applying (or trying to resist) so if you reduce the unsupported length by bolting to something solid or by bracing you increase the capacity of the member. Sorry if I can’t be more helpful, the devil’s in the detail, but 80 x 40 x 3 is far heavier than anything in cars with space frames, which will be doing a lot more work. I'd give it a go, it will be far easier to fabricate than using beam.
https://www.jalopyjournal.com/forum/threads/build-a-chassis-jig-any-ideas.39147/ It sounds a bit light from what i've seen in the past, all depends what you want to do with it ?
Similar build to this style was how we did ours. But then again you could just use 2 I beams to pick up the floor pans.
Really depends what the purpose of the jig is and how many mounting points you intend to have. I used 100 X 50 X 3mm for the body jig part of my GT6 rotisserie, but I still cross brace the body tub since there are only 4 mounting points....
No, that is helpful... I've used I-beam for my bench, and one of the lengths was bent slightly, laterally....and box would be easier to work with. Also my local suppliers cuts were far from straight....
Well, I've a chassis rail that's 5mm too high, but it appears it was welded on by a previous restorer, so it'll be a case of removing and reinstalling as opposed to applying force. So I guess the main reason is to keep the shell straight during rust repairs and stitch/seam welding.... If I could attach it to the rotisserie that'd be a bonus...
The GT6 has a separate chassis so the jig picks up on 4 of the original 8 mounting points. For a true monocoque the subframe or suspension mounting points would be good.... But you need to ensure they're structurally sound. Also make sure you have enough room to perform repairs and that the jig isn't going to get in the way. Here there's enough room to replace the floorpan from underneath...
I made a 100 x 50 box section frame to put a fiat 500 on a rotisserie, it was bomb proof, however it was a very short car. I’ll see if I can find photos but it was a long time ago.
Here’s a 5mtr long car on the rotisserie I can’t find a picture of the old jig but google ‘Celeste’ there’s nothing better
I used C section for mine. Really bad as it had no torsional stiffness so I had to keep checking it with spirit levels. Was OK if supported on the floor, but no good on a roticerie. If you need torsion stiffness then box would be best. For floor mounted C section was handy for bolting supports to the flanges.
I had one of those, tried to sell it and no takers so it went in the iron The problem I found making spits with box section is it almost needs a jig just to make them, without a bit of thought they can end up like a banana when welded up. Bob
that breaks my heart to read that we had one where I worked years ago and it was brilliant but sooooooo big it was actually a pain to move plus all the extra parts for it taking up room
