welding steel base or just getting aluminium extrusion

**reefy86** · 10-12-2017

Originally Posted by JoeHarris

What's with the parquet bed?!

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using keyshot as a quick render and was looking in the wood library and thought this looked quirky lol

**cropwell** · 10-12-2017

Originally Posted by routercnc

If the holes really are 4.5 mm diameter in the rail they are expecting you to use M4 cap head bolts to allow some adjustment. You need a 3.3 mm drill for the pilot drill, followed by an M4 x 0.7 pitch tap (coarse thread).

But I would expect a 25 mm rail to use M6 cap heads? If so these would need a 5mm pilot hole then an M6 x 1 pitch tap (coarse thread).

Why a coarse thread ?

**reefy86** · 10-12-2017

Originally Posted by cropwell

I didn't think they would be that small, an M4 screw is pretty weedy, there must be lots of them

. As a good rule of thumb tap drill size is screw diameter - thread pitch, so for M4 normally 0.5mm pitch would mean a 3.5 mm drill.

Helpful cheers for that

**JoeHarris** · 10-12-2017

Originally Posted by reefy86

using keyshot as a quick render and was looking in the wood library and thought this looked quirky lol

Yes it looks cool! Not such a good idea in reality?! Wish I could afford keyshot, looks amazing. Btw you probably won't need two mounts for the spindle and it will make it harder to align.

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**reefy86** · 10-12-2017

Originally Posted by JoeHarris

Yes it looks cool! Not such a good idea in reality?! Wish I could afford keyshot, looks amazing. Btw you probably won't need two mounts for the spindle and it will make it harder to align.

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you can get better results using vray in 3ds max but i can't be bothered to spend hours making materials and setting render up lol. thanks for the heads up on the mount i will remove one of them

**routercnc** · 10-12-2017

OK, then either:
pilot 3.3 mm for an M4 x 0.7 (coarse thread)
pilot 3.5 mm for an M4 x 0.5 (fine thread)

In general I would use coarse thread, especially into aluminium. Get a countersink to clean up the hole and get snug fit of the rail onto the plate - snail countersinks are great.

Also, thread lock (the type you can undo) the screw into the hole as the spindle vibration can undo them.

**reefy86** · 10-12-2017

thanks mate ill take a look at those

**reefy86** · 10-12-2017

Originally Posted by routercnc

OK, then either:
pilot 3.3 mm for an M4 x 0.7 (coarse thread)
pilot 3.5 mm for an M4 x 0.5 (fine thread)

In general I would use coarse thread, especially into aluminium. Get a countersink to clean up the hole and get snug fit of the rail onto the plate - snail countersinks are great.

Also, thread lock (the type you can undo) the screw into the hole as the spindle vibration can undo them.

is this what you was talking about for thread lock or is it the stuff in a bottle?
http://www.longlok.com/s.nl/it.A/id.42699/.f

**spluppit** · 10-12-2017

Before he goes and drills the wrong size tapping hole. Metric coarse is M4 x.7 which is the standard metric range. So you need a 3.3 tapping drill.

Sorry, posts crossed having a crappy slow internet today and refresh problems.

**EddyCurrent** · 10-12-2017

Inside the box section I used a length of 6mm flat strap to increase the thread length for the rails; http://www.mycncuk.com/threads/6565-...4981#post54981
If you are using the epoxy levelling method, don't forget to allow some thread length for that.