3mm Box Section

[GeorgiePorgie]

Mild steel.

I am constructing a CNC machine and I've opted to use 3mm Mild Steel box sections as the frame or bed,this has to be rigid in construction and precise to eliminate various problems ie Flexing,damping ect,ect.

I'm told that when welding the box sections together its best to have a fraction of a gap to eliminate twisting(for want of a better word)of the metal when it becomes hot under the weld.

Would I be better with the Gas weld or No gas weld? and what size wire would you recommend 0.6 or 0.8mm?

Thanks for any input.

 

[gav0994]

I would use gas and go for the 0.8 wire as it will give a much better quality weld.

 

[GeorgiePorgie]

Thanks,gav0994

I made the right choice in wire then.

How long does a bottle of 110kg gas last about? as I'm only just starting to try my hand at mig welding.

Cheers

oops! correction,make that 390g.

 

[Sid]

390g is about 200L. You will probably weld at 8 to 10 L per minute, although I'm sure my hobby type regulator feeds gas slower than this (compared to a full size regulator). But you will get about 25 minutes of trigger time with the slower rate, 20 minutes at the higher rate. CO2 is better value than the argon mixes in the hobby bottle sizes because the gas is liquid in the bottle. If you go to an argon mix you will probably want to go for the rented/big type of gas bottles.

 

[chunkolini]

Get a regulator and rent a full sized bottle, it sounds as though are likely to be doing a fair bit of welding, this would pay for itself in no time at all.
Something like argoshieldlite, try to avoid using BOC, there is lkely t be a decent gas supplier near you.
Somebody here will sort you out with where to go.
There are lots of gas suppliers, word of mouth is a good way to find the best ones.

Chunko'.

 

[GeorgiePorgie]

Hi Chunko'

Not really sure its a lot of welding as such? the box section will be mainly be 3x25x25mm square and a couple of 3x50x25mm struts.

So therefore its quite short burst of the welder,I suppose I should calculate how many end pieces I'm going to weld and work it out whether it worth buying larger bottles?

 

[FranV8]

One small point about disposables - every time you finish a bottle you can guarantee you'll be in the middle of a weld, and you'll be finishing them relatively frequently.

Go for a pub gas bottle if you can find a source? (CO2)

 

[GeorgiePorgie]

Not really looked into this bottled gas senario,but where do I get this bottle tanked if I need it? Propane seller? I have a seller on the dock area that fills my Propane bottle for my plumbing torch.

 

[chunkolini]

Mig welding with Propane?
Can I come and watch.
Do a google search for welding gas suppliers in your area, or ask any local metal botherers.
Mine charge a yearly rental and a contents charge when I change bottles and do free delivery. Their phone girl is also really flirty.
Liverpool? should be a few in dump that size.

Chunko'.

 

[GeorgiePorgie]

Liverpool? should be a few in dump that size

Hmmm! nothing wrong with the City,Chunko'....what good has ever come out of Herefordshire?

 

[Engineer]

If its only a small amount of welding and there is a need for accuracy, get everything properly prepared and clamped down to something solid to help prevent distortion, then take it along to someone who can TIG weld it for you.

This should cost less than getting hold of a large gas bottle, and is likely to be far more accurate.

 

[GeorgiePorgie]

Hi,Engineer
Problem is I spent £150 on the Gas/NoGas welder,but on saying that if I aquire a decent level of welding then a few small jobs might pay for its keep.

Cheers.

This is basically what the frame will look like but mine will be a bit more complicated because I intend to incorporate the computer in the units bottom cage with aluminium isolating the bottom cage to protect it from cuttings from wood shavings/dust with a possible view to Aluminium milling?

The box will be square but with a moving gantry? rather than a static gantry as in the link.
http://www.cooperman.talktalk.net/files/2.htm

 

[GeorgiePorgie]

question again if I may

Box section,since the size is 25mm wide is there a need for me to zigzag the weld? as opposed to just a straight weld.

Cheers.