you know the feeling, youv'e read the book, youv'e started your build and all the lower frame bars are lying in place and all you need to do is tack weld them and you can then say that you have definately started your build.
But the book (and everyone) says to use mig.
So you buy a mig (that you have no experience of using) set it up and it don't work! (second hand maybe not so great an idea after all)
And so to my point, I'm a good gas welder has anyone built their frame using gas?
Please advise me, I need help.
But then don't all of us?
Regards
Ewan

I have heard horror stories about using gas based welders on tubular steel. Basically the gas can go into the tubing unburnt, build up, and then explode.
Not sure if it's true but it does sound reasonable.

Whenever a problem with mig welding crops up on this forum, I advise people to do what I did, get an experienced welder to adjust your machine and teach you how to use it. If you don't already know somebody suitable, then perhaps there is a mobile welder in your area who could call. My teach-in cost me £20, but if it had cost £100 it would still have been worth it.

Mig is the correct welding system for our type of chassis construction, even if gas didn't have safety issues mig would still be quicker and better

John

Go on an evening class!

I'm not gonna repeat again why IMO they're so great but I assure you it's worth £100 for 30 hours worth of instruction!

HTH,

James

The actual welding with gas isnt a problem as such, it is the amount of distortion that comes with it. Gas welding takes a long time to get any heat into the metal before welding can commence, which means more of the tube is affected in the first place. With MIG it is instant, keeping distortion to a minimum.

Use MIG! Gas welding will cause your frame to distort badly... MIG uses an inert gas which amongst other things helps to stop the metal getting too hot.

Sounds like you just need to practice on some sraps to become more proficient.

What problems are you having with your welder?

PS. Keep your welder in the house in wet weather - rusty wire is bad news!

Thanks for the advice chaps.

Should have explained fault with mig.

Wire rusted into feeder all the way from motor to handle, pinch rollers seized, reel seized to spindle & motor running constant due to handle switch fault.

Should have checked when i bought it , not three months later eh?

So repairs so far, removed remains of old rusty wire, cleaned wire guide from motor to handle and renewed reel.

Freed off pinch rollers and cleaned away rust, re aligned wire into groove and re set guide tube angle to pinch rollers.

Striped handle to resolve constant contact to find switch just as rusty as wire and broken in two!!!

At this point i gave up.

Anyone selling a mig that works?

Have considered further repair of mig but where do you draw the line.

Regards

Ewan

have been taught how to weld by a fabricator in gas and arc, isn't mig a cooler combination of both

Regards

Ewan

For what its worth, a lot of professional aircraft welders still use gas for welding 4130 chromoly tubular frames. The following site has some more info

http://www.tinmantech.com/html/faqs.html

You can't Mig Chromo... that's why.
You can Tig or Gas. Gas allows you to pool better and if you are good, you get a better weld.

Many pro car race organizations only allow TIG welding.

I want a TIG.... already have gas, arc and mig. I work with magnesium alot, and have thought about a mag frame. You can TIG mag.

4130 can be MIG welded, there are special wires for the purpose. Granted though, CroMo is usualy TIG welded these days.
There isn't any point trying to gas weld it as that would put too much heat into it. Brazing/silver soldering 4130 is the time honoured method.
4130 was invented to be brazed for aircraft frames during WWII.

When I said gas I ment brazed, guess I should have clarified.

I didn't know you could mig 4130... you learn something new everyday.

Get in touch ,I will probly be able to help out with a nice mig that works ..,you know where to find me !