First time build - Steel Frame CNC Router

**examorph** · 02-03-2016

Been a nightmare finding a local supplier that does box section without a 7.5mtr minimum order charge, but got one eventually who can do me some off cuts at a 3mm wall for a good deal.

Will the 3mm wall thickness box section be OK for the bed support beams and horizontal supports shown below in green? Will it also be OK to weld?
Attachment 17786

**Clive S** · 03-03-2016

Originally Posted by examorph

Been a nightmare finding a local supplier that does box section without a 7.5mtr minimum order charge, but got one eventually who can do me some off cuts at a 3mm wall for a good deal.

Will the 3mm wall thickness box section be OK for the bed support beams and horizontal supports shown below in green? Will it also be OK to weld?
Attachment 17786

The main problem apart from resonance with 3mm box is that it is not quite thick enough to tap 4mm or 5mm would be a better option. If it is just for the green bits then it is probably OK

**Boyan Silyavski** · 03-03-2016

3mm is ok, if size is 80x80 or 100x100. I wouldn't use it for smaller than that.

No problem with tapping and screwing 3mm, just have to be careful and drill holes using a guide so they are true 90degree square to profile.

**Clive S** · 03-03-2016

No problem with tapping and screwing 3mm, just have to be careful and drill holes using a guide so they are true 90degree square to profile

6mm bolt in 3mm I beg to differ its right on the edge and suppose he wants to tap 8mm

**Davek0974** · 03-03-2016

Yep, I would not tap past 3 or 4mm into a 3mm beam, just not enough thread engagement.

**examorph** · 04-03-2016

Thanks guys, to confirm, it's just the green bits in the last post its being used for (2x bed supports and some braces).
Only place it needs to be tapped is on the bed supports, so that I can bolt down the ply wood bed onto there. Any options for this with the 3mm box section? Maybe drill through and use a nut/bolt setup?

**Clive S** · 04-03-2016

Originally Posted by examorph

Thanks guys, to confirm, it's just the green bits in the last post its being used for (2x bed supports and some braces).
Only place it needs to be tapped is on the bed supports, so that I can bolt down the ply wood bed onto there. Any options for this with the 3mm box section? Maybe drill through and use a nut/bolt setup?

You don't say what size bolts you want to use. If you drill through the box without a spacer in the box you have the chance of squashing the box of course you could use self tappers.