pfenlon Posted September 16, 2018 Report Share Posted September 16, 2018 (edited) I made some seat runner mods for my MX5 seats that are going into the Spitfire. I took them to a pro welding firm to have them welded up, after all the seats must be ultra secure. the bloke who welded them made it look so easy and the welding looked like it had been done by a machine. I mentioned to him that I had a welder but never got the results he did. He said its all about the correct wire feed speed, put the handset on the metal pull the trigger and then aper the wire feed until it starts to "crackle" it works too. Edited September 16, 2018 by pfenlon Quote Link to post Share on other sites
Dic Doretti Posted September 16, 2018 Report Share Posted September 16, 2018 Aim for a sound like sizzling bacon for a good weld. Cheers Richard Quote Link to post Share on other sites
RogerH Posted September 16, 2018 Report Share Posted September 16, 2018 Aim for a sound like sizzling bacon for a good weld. Cheers Richard Aim for a sound like sizzling bacon for a good sandwich - yum yum Roger Quote Link to post Share on other sites
john.r.davies Posted September 17, 2018 Report Share Posted September 17, 2018 Pete, You are indeed right that there has to be a balance between the 'heat' of the weld and the feed rate, and these are influenced by the thickness of the metal, whether it's level or vertical, and the technique of the 'dither' as you move the wand across the weld. The best advice I was given was to think of MiG welding as "Taking a drop of molten metal for a walk". The weld pool follows the torch, and the faster it moves the higher the feed rate, as metal is left behind, anthe slower, the quicker it will burn through. And like the New York cabbie, asked how to get to the Philharmonic Hall, said "Lady, ya gotta practice, practice, practice!" Looking at your photo, are you really happy with that? As a series of tackwelds it's fine, and after a lot of filling it it will look fine. But as a 'weld' ..... JOhn Quote Link to post Share on other sites
littlejim Posted September 17, 2018 Report Share Posted September 17, 2018 Wire feed rate is just one of the variables a beginner has to contend with. Web searches provided starting voltage settings for the metal thicknesses I was welding, (chassis first) and suggested wire thickness. Think I looked at every MIG article on the web (eg. Lincolnmigwelding guide.pdf) which got me started on wire size, and current settings. Then there is the gas rate setting, eventually I settled on 12 L/min which I bump up a bit on thicker stuff. In my case I used a reel of wire during the learning phase. One of the local comedians says he invented non-stick Velcro. For most of the first reel of wire I thought I had invented non-stick welding. I previously posted that when you swap wire sizes it pays to be careful to hang on to the last bit going on to the reel. On my first go I didn’t, and learnt it takes quite some time to wind about a mile of wire back on to the reel. Quote Link to post Share on other sites
RogerH Posted September 17, 2018 Report Share Posted September 17, 2018 Hi LJ, I'm sure there are Non-Stick welders on all continents. Back in the 70's my chum Sid welded a pair of front forks onto a motorbike frame. When the young lad (the owner) held them in the vice with the frame hanging out they parted company. Imagine if the weld was just little stronger In mig welding all sorts of things over the last 20+ years it is only now that I am getting good welds. I could generate the biggest heaps of chicken sh*t with ease. Now they are just welds that look good and work. Roger Quote Link to post Share on other sites
pfenlon Posted September 17, 2018 Author Report Share Posted September 17, 2018 Pete, You are indeed right that there has to be a balance between the 'heat' of the weld and the feed rate, and these are influenced by the thickness of the metal, whether it's level or vertical, and the technique of the 'dither' as you move the wand across the weld. The best advice I was given was to think of MiG welding as "Taking a drop of molten metal for a walk". The weld pool follows the torch, and the faster it moves the higher the feed rate, as metal is left behind, anthe slower, the quicker it will burn through. And like the New York cabbie, asked how to get to the Philharmonic Hall, said "Lady, ya gotta practice, practice, practice!" Looking at your photo, are you really happy with that? As a series of tackwelds it's fine, and after a lot of filling it it will look fine. But as a 'weld' ..... JOhn No John its not a weld as you point out but it isn't going to fall off. Long runs of weld do distort very easily which is why I have gone spotty. you are spot on though.... Quote Link to post Share on other sites
littlejim Posted September 17, 2018 Report Share Posted September 17, 2018 Pete makes a good point. To avoid distortion it pays to do small bits at the ends and in the middle of the section you are doing, and do the fill in with a fair bit of separation. Even doing this I had to anchor the ends of the chassis to the garage floor, as I was starting to get the dreaded 'chassis creep', as the welding started to pull the chassis away from its original angle. Quote Link to post Share on other sites
John Morrison Posted September 17, 2018 Report Share Posted September 17, 2018 Great Idea to resist distortion is have an airline in the lefthand, every two or three spots, blast with cold air. John. Quote Link to post Share on other sites
john.r.davies Posted September 17, 2018 Report Share Posted September 17, 2018 Thanks for that tip, the other John! But you have a little weld there, Pete. Distortion won't occur (imho). Long seam welding usually can be done in short, 1-2" lengths, moving to the other end while the first cools. Often, there's no need to complete the weld, as intermittent 'stitch' welds convey sufficient strength. Another technique to try is a butt weld, so that both sides are on the same level, or else to use a "joddler" tool that puts a step in the edge, so that it's an look like a butt weld while still overlapping. Good luck! JOhn Quote Link to post Share on other sites
barkerwilliams Posted September 17, 2018 Report Share Posted September 17, 2018 I always felt there are two sorts of welding based on a simple question: what will happen if the weld fails? If failure is dangerous then I get a professional to do it, If its an inconsequential, preferably hidden, weld then I weld it. And boy, can I get through lots of sanding discs. Alan Quote Link to post Share on other sites
foster461 Posted September 18, 2018 Report Share Posted September 18, 2018 Looks like an acceptable repair to me Pete. I would do the same multiple tack welds when butt welding in a sheet metal patch. On that corner there is a lower chance of distortion but still easy to blow a big hole in it by trying to do too much too fast. Quote Link to post Share on other sites
Ian Vincent Posted September 18, 2018 Report Share Posted September 18, 2018 The MIG welding forum recommends hit and miss welding for thin sheet. I used it extensively on my TR3a. Here is a link to the relevant page on the forum. https://www.mig-welding.co.uk/thin-metal.htm Rgds Ian Quote Link to post Share on other sites
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