Julian B
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 posted on 24/3/07 at 07:52 PM |
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Bending chassis question
Hi
I was wondering how those of you who have built your own chassis, managed to combat chassis bending when welding the peices together?
Cheers
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Simon
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| posted on 24/3/07 at 07:59 PM |
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When you start, make sure all the bottom pieces of chassis are champed to the board.
Pieces of wood screwed to board either side of rails, and pieces on top too.
Tack on verticals, then the next layer followed by triangulation pieces. When all tacked (whilst still clamped), you can start fully welding.
The clamping to base board and triangulation should prevent any warping.
Make you you do mirror welding - ie one weld on left, same weld on right and so on.
ATB
Simon
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ecosse
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| posted on 24/3/07 at 08:21 PM |
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quote:
Originally posted by Simon
When you start, make sure all the bottom pieces of chassis are champed to the board.
Pieces of wood screwed to board either side of rails, and pieces on top too.
Tack on verticals, then the next layer followed by triangulation pieces. When all tacked (whilst still clamped), you can start fully welding.
The clamping to base board and triangulation should prevent any warping.
Make you you do mirror welding - ie one weld on left, same weld on right and so on.
ATB
Simon
Yeh, completely as above was how I did it (stock up on G-clamps  ) , and my chassis is within 3mm everywhere I can measure (which i think is not bad
going  )
Cheers
Alex
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Chr!S
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| posted on 24/3/07 at 09:03 PM |
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Thought id add that if you get the tubes aligned perfectly (ie no gaps at the joints) then with the correct clamps you can do it very accurately.
I tried the board method and the front moved. Junked it and did everything free-standing with clamps: max error of 1 and a bit mm  Although the
board method put the front (LC/LD? cant remember) went nearly 4mm to the left :s Managed to 'pull' some of it back in the end.
Basically make sure its held solid before welding and I mean SOLID. It *will* deform but it will be much less than millimetres if you clamp it right
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caber
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| posted on 24/3/07 at 11:38 PM |
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Assume there will be some deformation and weld your suspension pick up points so they provide square wheel locations. i.e. measure and mount to
absolute dimensions with a jig don't rely on mounting dimensioned off the chassis itself. My chassis is about 4mm out but suspension pick ups
are about as right as I can make them, say ±1mm.
Caber
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robertst
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| posted on 25/3/07 at 04:02 AM |
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i haven't clamped the chassis, or used a jig, just a huge workbench...
i even skipped the tack welding and welded everything fully as i went, welding is now complete, and the chassis is as straight as an arrow
Tom
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JB
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| posted on 25/3/07 at 07:51 AM |
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It will move, if you are lucky it will move equally and end up something like afterwards.
The best thing you can do is mount and weld the critical points (suspension etc) last so they can be made to take into account and chassis twist /
bending.
I layed all my tubes on a rough garage floor and levelled them with shims etc then tacked them. The suspension went on last.
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