Bolt Selection thickness

[grain_r]

Hey guys thank you very much for the help. I have ordered some smaller drill bits and a centre drill to see if that gets me more accuracy I think I must have been off a little on square and but then tapped the hole square which has then given me a problem I will try the top rails for the other side next at least they are accessible for the nuts if needed.

Neale I think maybe the double skin is a rather good idea. I can get to the ends and weld them but I was wondering does it flex a lot when drilling the centre ? or did you go from the outer edge and bold along to keep the strength at all.

thanks

Rob

[Neale]

I actually welded the extra strip in place. I drilled the box section at intervals between the places where I was going to drill for rail hold-down bolts, used a wooden wedge arrangement to slide down the box section to hold the strip against the inside of the box, and then welded to the strip through the holes. Bit of grinding to clean up the outer surface of the weld and job done. Other people have used Gorilla Glue to fix the strip in place - it only needs to hold while you are drilling and tapping and then until you bolt in the final item. Your idea of welding at the ends and then working along, bolting as you go, would work as long as the strip does not sag too far when you take the bolts out to fix the final item in place. In the case of my long rail supports, these are 1800mm and would have needed fixing at more than just the ends.

[Jonathan]

A split point drill bit should help you - e.g. http://www.arceurotrade.co.uk/Catalo...-Bits---Cobalt

[grain_r]

Hey neale

Thank you very much for the reply. I have ordered some 40x5mm to put in and will weld the ends up and I might Bolt the middle and the a small tack weld on the bolts to stop me forgetting to leave them alone in the future. Good Idea with the wood I will do that thanks very much.

Thanks Jonathan I have had a look on the site which seems a really good site and I will look at getting one of those drill bits I have the centre drill on order and I'm going to give that a go too.

thanks

Rob