First time build - Steel Frame CNC Router

**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.

**Davek0974** · 04-03-2016

If the bolts are near the ends of the tubes, get in there first and weld in a reinforcement plate - a lump of 6mm etc welded in from the end would work.

If not then there are very few options really, you could drill a larger hole opposite the bolts so you can pass a socket and nut through to the front but that will only give you strength of the front 3mm section on the bolt, i doubt the hole will make any difference to the beam strength.