I just wanted to share with the forum an epiphany I experienced last weekend.
I had been using a mig welder for decades, just like many here. I had NEVER ever had any training of any kind, read a bit, but mainly just practise.
Results? Well, the best thing I can say is that they are strong, if not a bit daggy in appearance. I trust them.
I had a good look over the chassis a few months ago (with a 'critical' eye) and thought that some of the welds COULD look better. Ive seen some of the struff on soem machines on here and other sites and the welds looked very attractive (no doubt they are structurally sound for the most part as well).
My car is due to front up to the Head Scrutineer some time later this year and be assessed for the issue of a CAMS logbook. They can only assess the welds by their appearance as they obviously werent around when the welding took place.
Therefore I wanted the welds to look better. With this in mind I contacted one of my old work colleagues (back when I was a TAFE teacher...prolly tradeschool to you guys) who is a welding teacher and asked him for a final touch up on those welds I wasnt happy with.
This occured last weekend. And I should have seen this coming....
Mate, Im not always gonna be available to do this for you...... Yeah, So what? I says....
Im NOT going to reweld your chassis. Im going to teach YOU how to do it.,.... Oh shxt! Ok...
So what I would like to do is share with those lesser gifted welders on the forum (like me!!) my lessons from the day and some results.
Before I begin, NOT all my welds needed redoing. The majority were quite ok. Just sayin......
Ok, first thing he did was make me just grab the machine and weld some scrap.... he watched then looked over everything.
From there he made me strip my helmet and clean it. Bloody hell! What a difference that made. I do do it, but hadnt for a while...slack... lesson one, do it regularly.
Second thing was I used his helmet and its so different. Its a very good unit, so you do get what you pay for. But the main thing was
magnifying lenses. Nothing to do with poor eyesight just getting it all into clearer perspective. Very very nice to use. He had a set for me but my helmet didnt have the clips to mount them (they go inside). Out came the race tape. Fantastic and only a few bucks at your welding supply joint.
He then made me strip my handpiece, remove the lead from the machine and cleaned out the liner (compressed air). Mine was liberally coated inside with copper dust from the wire coating. New tip, shield and shield mount (mine was a bit loose and the shield was sliding back). Refitted to machine.
Reduce the copper dust by adjusting the feed roller correctly. The tension setting should be tight, but not so tight that you cant stop the wire roll from turning with one finger. Any tighter and the roller crushes the copper coating on the wire and eventually causes problems with copper contamination inside the liner.
Ramification number two. I had had a problem whereby occasionally the tip would 'stick'...arc would burn up to the tip and the wire would lightly 'stick' to the nozzle. Just a twist with the handpiece and away you go again EXCEPT my rollers would continue to feed wire and it would be a tangled mess on the feed into the liner. This no longer happens as the feed roller now slips on the wire rather than force feeding it.
Tip dip.... Use it. It makes a hell of a difference to the crap that sticks to your shield. Apparenty for a while there was a rumour that this stuff produced a carincogenic gas when burnt. Not so, just an old wives tale.
Gas pressure, yeah..uhm.. no idea what it should be ..just enough..?? Cleaned my gauge glass (oops bad huh?) and set it to about 12 to 15 psi. So why isnt the 25 like I had it set at better? The gas comes out too fast and acts like a venturi as it leaves the tip and draws air into the weld pool causing oxidisation while welding.... ahhh... that made sense..... Also...SHUT THE BLOODY WORKSHOP DOOR! Tried it open (sort of a windy day) yeah it made a difference allright, stop the major drafts folks....keeps the gas shielding the weld pool like it is supposed to....
My technique with the handpiece was ok (apparently) and the difference was amazing upon my second attempt.
We discussed the benefits/disadvantages of drawing the hand piece or pushing the hand piece. He was happy for either to happen, whatever I was comfortable with, BUT you tended to get deeper penetration with a drawing hold. I am a natural 'drawer' that is the hand piece is pointing back towards the weld as I move my hand. In his opinion there was no 'correct' style, whatever worked best for the application and the individual. The text book says that pushing or square to the weld plane is the 'correct' style. Whatever.
We then experimented on various sized pieces of steel to find the correct 'tune' for the wire speeds and voltages. No big revelations here except that local current draw on the grid around you can make a difference. At around 12:30 (saturday) the machine required retuning. His opinion was that people are arriving home from work and the grid load just increased... food for thought....
Final thing. Dont try and weld right around the tube in one go if it isnt comfotable to do so. Do it in segments and concentrate on a smooth deep bead....
OK Grind like hell and then do some welding..... results....
What I was producing (this is an ok one)
