Hi
For various reasons i'm going to have to put an M8 bolt through a 25mm square section tube, and then they'll be quite a load on it.
My plan is to drill a 12mm hole right through the 25mm square tube.
Weld a 12mm od / 8mm ID x 25mm length of round tube into the hole - welding right round the circumfrence each side, & grind flush.
My theory being that this will leave a nice strong length of tube and a hole to bolt through that won't crush.
Am I deluded and this is a really bad idea..
Is there a better method?
Your thoughts appreciated, working on the theory that the bolt's goto go where the bolts goto go..
I used an old 1/4 drive socket to fill the void, assuming you can get to one end of the "open" tube and slide it in
quote:
Originally posted by JimSpencer
Hi
For various reasons i'm going to have to put an M8 bolt through a 25mm square section tube, and then they'll be quite a load on it.
My plan is to drill a 12mm hole right through the 25mm square tube.
Weld a 12mm od / 8mm ID x 25mm length of round tube into the hole - welding right round the circumfrence each side, & grind flush.
My theory being that this will leave a nice strong length of tube and a hole to bolt through that won't crush.
Am I deluded and this is a really bad idea..
Is there a better method?
Your thoughts appreciated, working on the theory that the bolt's goto go where the bolts goto go..
Sounds ok to me, I did similar all around my build.
Rich
Not sure about the 'grind flush' as unless you are happy that you got a decent penetration you could be removing most of the weld. Can you not leave the tube projecting a couple of mm ?
I did the same - but i welded in a threaded tube. Around the edge of the hole i used the centre punch to bend the metal into the tube a little and widen the gap between the threaded insert and the tube. This allowed the weld to penetrate more and provide me with some more confidence - its whats holding my gearbox in place!
Yep that's how you should do it.. Like other said though careful grinding it flat.
Had a similar issue on the MK roll bar, ended up using a 4xm8 cap heads on each side of the hoop with with a 8.5mm hole in the box section in one
side, and a clearance hold for the head on the other, so the cap-head camped only the edge of one tube. Not ideal, but I can't weld, would be
best to do as you say..
Dan
If you can't weld in a tube (and i'd really really try to) make sure you have a large very thick washer to spread the load over the tube
with the hole - especially making sure it goes over the edges of the tube.
But again - try to weld something in, its the best approach.
Hi All
Thanks for that, tube cutter and welding kit it is!