First time build - Steel Frame CNC Router

**JAZZCNC** · 18-02-2016

Originally Posted by examorph

Thanks Dean and wow 90kg...I massively underestimated how powerful these things are.
Any chance you have any reference costs for 100x50x4 and 50x50x4 mild steel box section? Will be buying in standard lengths and cutting it myself.

Yes don't underestimate these little things when attached to ballscrews. The mechanical advantage the screws give is massive, it will snap your arm like carrot and carry on like it never happened.!!

It's been while since bought any steel but last time I paid about £35 for 7.5mtr lengths 50x50x4. If you work on just less than double that for 100x50 you'll be close.

**longy** · 18-02-2016

Dean, steel is right down in price now with all the dumping from China. Brundle's are about the cheapest I've found http://www.fhbrundle.co.uk/products/..._6m_Grade_S235 £23.54 + del + vat

UK delivery on orders less than £150 is just a tenner.

Mike :)

**JAZZCNC** · 18-02-2016

Originally Posted by longy

Dean, steel is right down in price now with all the dumping from China. Brundle's are about the cheapest I've found http://www.fhbrundle.co.uk/products/..._6m_Grade_S235 £23.54 + del + vat

UK delivery on orders less than £150 is just a tenner.

Mike :)

Ye just looked and I paid £31.50 inc vat and that's delivered but it is only in next village so not million miles away.

**examorph** · 19-02-2016

Originally Posted by JAZZCNC

it will snap your arm like carrot and carry on like it never happened.!!

Ahh, i'm gonna have to get used to keeping a finger on the emergency stop

Cheers for the help guys, will search around locally for suppliers but don't think many will beat the supplier Mike recommended.

**examorph** · 21-02-2016

Noticed that I might have some difficulty cutting the motor mount slot accurately on the gantry side, so made it a separate adjustable support plate allowing for the Y axis ball screw to sit more central, more adjustment and lets me get started on welding the gantry before getting access to a mill

Attachment 17667 Attachment 17669 Attachment 17670 Attachment 17671 Attachment 17672 Attachment 17673

I am going to start welding soon and have next to no experience with this so hope you guys can keep me right:

Attachment 17674 Attachment 17675

1. Whats the best way of handeling this, tack up the full frame whilst checking squareness and then weld up fully when happy or do it all in sections?
2. I read on here that short runs are the way to go. Would a 50mm single run along one side of the 50x50 box section be ok or do I do this in two separate runs (25mm)?
3. Are there any parts of the frame I could stitch weld? Maybe the x axis rail support and all of the gantry/side plates? If so, whats the typical size of weld and gap between stitches?
4. Any tips on this/recommended welder settings?

**Davek0974** · 21-02-2016

Mig? Arc? Tig? What sort of welding?

Yes, always tack up first, when choosing where to weld, always think of contraction - the two sides of whatever you weld WILL be drawn together as the weld cools, no two ways about it, it will happen.

On a box frame I would tack up and check all square, then weld the inside 90 deg angle on opposing corners first. Next I would do the outside edges followed by the two faces. Welding the inner/outer sides first should help resist the tendency of the frame to buckle if the faces are welded first.

Test your settings well on scraps first.

**Davek0974** · 21-02-2016

Stitch welding is fine, in the right place - if you were welding a plate to the side of a box structure or maybe a corner fillet plate inside the legs, I would stitch, maybe 1" runs. For something like box section legs then seam welding is in.

Think of the stresses the part will encounter, it will help decide how to weld it.

**examorph** · 22-02-2016

Thanks Davek, I will be using a Mig welder for this. Should have the steel in this week and welding started this weekend.
Will tack up the entire frame and gantry assembly first and check if its all square, once OK I will fully weld/stitch where needed whilst baring in mind contraction.

Is epoxy leveling recommended for a build this size?

**Davek0974** · 22-02-2016

The chances of it being square when done are slim, treat it as sections and concentrate on getting each section as perfect as possible, whatever method you use there should be a method of tweaking the fit later - my plasma table is 1500 square, it is made up of two side frames bolted together with cross-tubes - i could shim the joints as needed which wasn't in the end but handy still.

The plasma was built in 2mm box section but carefully braced where needed to gain rigidity. I used about 21v / 140A and 0.8mm wire with a tri-mix gas (hobbyweld5) you need to get hot and fast, don't run the power low because it might warp.

Cant help with epoxy, never used it I'm afraid.

**examorph** · 27-02-2016

Hi guys, came home to find that the linear components had arrived today!! Woohoo

Attachment 17739 Attachment 17740 Attachment 17741 Attachment 17742 Attachment 17743

Seems to be great quality and Fred was a great help, excellent service and I understand now what you all mean by him being a great guy. Will keep these to a side until I get the epoxy and aluminium sorted. Blackburns offered 5754 as the nearest grade to MIC6 and quoted me £85 for 500 x 500 x 20 plate, is 5754 a suitable grade?

Also, steel arrived earlier this week so will be welding this weekend and hopefully have a frame/gantry setup soon.