romer
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| posted on 11/12/09 at 04:45 PM |
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MS Box Section Strength
Hi guys, a quick pick of your brains please.
I want to weld two pieces of MS hollow box section into a tin top to fasten a bucket seat to.
The box section will be welded to some load bearing spreader plates, which in turn will be welded to the inner sill and the centre transmission
tunnel. The box sections will be approx 8” to 10” apart.
Each of the box sections will have two vertical holes drilled, one each side to bolt the seat mounting bracket to. Will drill one side of the hole
larger to drop an anti-crush tube into and tack weld it to the box section.
This is for rally car usage.
I have heard different sizes of box being advised, ranging from 25x25x? to 40x40x3.
I was thinking of using 50x25x? (2, 2.5 & 3mm wall thickness available), with the 50mm section across the top to give the seat mounting bracket a
greater area to sit on and also a wider span for drilling the bolt hole.
The thing is I can’t find any info (probably wouldn’t understand it if I did find it anyway) on the Net that I could use to calculate what loading for
eg a 50x25x2 by approx 22” span box section would take.
I’m about 14 to 15 stone and am thinking I would use M10 bolts through the box section, but would use M8 if you think they would be fine. I actually
think the 4 seat side mounting bolts are probably about M8 anyway.
Any suggestion would be most appreciated.
Cheers
Romer
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mr henderson
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| posted on 11/12/09 at 05:38 PM |
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I had a mk 2 rally escort this had been done on, and it worked fine. I reckon 25x25x2 with sleeved holes and plates at each end will be plenty
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will121
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| posted on 11/12/09 at 06:13 PM |
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if as a rally car is there any MSA or other govening body guidance on mounting seats ive got something somewhere, which has roll cage, seat belts etc
mounting i will try dig it out and have a look
found something look under safety section K of MSA regs link page 166 para 2.2
MSA regs book
[Edited on 11/12/09 by will121]
[Edited on 11/12/09 by will121]
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Peteff
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| posted on 11/12/09 at 07:51 PM |
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I'd brace it to the floor as well with a couple of upstands made of the same stuff with a nut welded in the end and a spreader plate to go
through the floor ( well I would if I weighed 15 stone  ) M8 8.8 bolts should be fine.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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romer
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| posted on 13/12/09 at 07:37 PM |
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Thanks for the info guys, looks like 3mm it is then!
Romer
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