Thread: Me and MIG

Hi Mick,
Heres some stuff I wrote a good while back.
its hangs around as a sticky now.

- sorry could not hyperlink it go to stickies metalwork Lessons in MIG Welding

I hope there something useful for you there.

cheers Grahame

Originally Posted by johncar

Far too expensive for a regular home user including me but I figured it would just be a loaner and I would sell it once the main project was over. Only trouble is I like it too much and will be hard to part with :/

Yeah I have a few things like that. You need to change your perspective: since you did such a good job on the boat, you DESERVE to keep the welder.

Originally Posted by Grahame Collins

Hi Mick,
Heres some stuff I wrote a good while back.
its hangs around as a sticky now.

Thanks Grahame, I vaguely remember that when you put it all together. I didn't read it at the time as I wasn't relevant to me, but having just read through it all, I have to say that you did a really good job there. I've got a few things to try out when I get out to the shed now. Thanks again.
- Mick

OK, I’ve been doing a bit more reading – firstly of Grahame’s MIG lesson series, and then a bit broader. Lots of stuff out there to read. I put the following together as a summary of what I’ve gathered on the major variables – if you’ve got any corrections don’t hesitate to speak up.

Shield gas: the higher the percentage of CO₂, the hotter the arc will be for a given voltage. The downside is you also get more splatter and angrier arc. A small percentage of O₂ in the gas improves bead fluidity and edge wetting. You need an argon proportion greater than 80% if you want to use spray transfer (only useful in limited situations), and your gas needs to be 100% argon if you’re welding aluminium.

gases.JPG

Voltage: Set the voltage first. Voltage should be set in accordance with the thickness of metal your welding. Voltage is the primary control of the heat of the weld and hence the penetration. Miller - MIG Welding Calculator (or the equivalent smart phone app) has a pretty good starting guide. One of the better all round lookup charts I’ve come across to date is at the bottom of this page: MIG Wire Charts Page 2 - Airgas.com. It’s all imperial but we can’t have it all can we?

Wirespeed/Amperage: Wirespeed controls the amperage, so when you adjust this setting you’re changing both parameters. Set wirespeed after you’ve set the voltage. The actual setting depends on the voltage and wire diameter. The wirespeed should be optimised by doing a test weld and listening for a bacon frying even crackling sound. Too higher wirespeed results in stuttering, stubbing and excess splatter. Too low and the arc will be intermittent with blobs melting off the wire inconsistently. Making Your MIG Sizzle - YouTube has a good little sound guide.

Stickout: make sure the wire stickout from the contact tip is maintained consistenty during the weld as the stickout will affect the actual weld voltage/amperage. Generally it should be 0.8 – 1.2 cm. Long stickout will make arc starting harder and cause more stuttering in the weld Mig Welding Lesson - Watch Your Stickout and Ground - YouTube demonstrates this (fast forward to 2:04).

Push vs Pull: Doesn't really matter as long as you can see the puddle and your torch angle isn't too exaggerated (say 15 degree max). Pushing is recommended for aluminium, so the shielding is better concentrated on the leading edge of the weld.

I'm going to try and get out to the shed later on an run a few tests.

Good stuff there Mick, good to see you just not charging into it and getting some good info first. I guess I prefer to push the gun for most MIG work when using gas although no doubt times when pulling may be needed. I use the pull method though if using flux core wire.

Might be a typo with your stick out, assuming 0.8 - 1.2 cm

Hope you are having fun, enjoyable welding when it's all running nicely.

Ahh yes... definitely cm not mm! well spotted. Too late to edit now though.
I'd like to accept your complement about not charging into it, but as it turned out, I started building something after about 5 minutes of practice. But if your complement applies to retrospective research, then I'll take it !
Unfortunately, I didn't get out to do any welding over the weekend. So filled in the odd bits of time I had on that summary. Got lots of small projects lined up, so just gotta get around to doing them
Cheers
- Mick

Originally Posted by WelderMick

Ahh yes... definitely cm not mm! well spotted. Too late to edit now though.

Fixed

All good, don't blame you for wanting to get stuck into it with the new machine and it's probably as good a way as any to give it a go first and see what happens. I am sure you will really enjoy it, there are certainly some nice features using the MIG but having the repertoire of gear is great and nice to have choices.