|
|
Im doing my first project with MIG, and I cannot seem to make the welds come out evenly. All my welds are uneven in height -- high at the starting end and low at the finish. (And sometimes a bump in the middle, but I think thats when I let the wire get ahead of the puddle and lose the arc.) Also, there is always a dimple at the end of the weld. Ive done half a dozen projects with oxyacetylene and two with TIG, and can get a decent weld with either process, but I dont have much control with MIG, at least with thin metal.Im using a Hobart 190 with 0.030 ER70S-6 wire and C25 gas. Im welding 16 gauge 1 1/2 square tubular steel, with a 1/32 gap between the edges. My settings are V = 1 (lowest range, around 16 volts), and wire feed set to 35 (roughly 165 ipm). Im using a push motion and a zig-zag pattern. I tried the next highest voltage range, but kept burning through the metal.The arc usually sputters for a couple of seconds at the start, and then settles down to a smooth crackle. Because I have a closed shape which is too big to clip the ground clamp to directly, I attach a C-clamp to the piece, and attach the ground clamp to the threaded part of the C-clamp.I know I need more practice, but it feels like I keep making the same mistakes again and again. Any suggestions will be appreciated! Thanks. Attached Images
Reply:Mig is notorious for cold starts in general. My guess is part of your issue is that once the material starts to heat up, the weld is starting to fall thru the thin material. I'd want to fine tune the settings a bit to cut down the heat and filler allowing you to move a bit slower, allowing the base material to get up to temp, but not putting in so much heat into it that it wants to fall thru.If this was me, I'd probably opt for .024 wire vs the .030 for 1/16" / 16 ga. This will give you a bit more room to adjust your wire speed and fine tune your settings. I'd also probably play a bit with scrap and see if I couldn't open the gap slightly say to 1/16" or put a slight bevel on the pieces. This would allow you to get better penetration using a slightly lower heat setting. With thin material you will have a very narrow "window" to work with as far as the setting range and joint prep.The other possibility I see is that you might be changing your stickout as you go along. With mig, the closer the gun, the "hotter" the weld. If you are starting out with more stickout and then moving in (possibly rolling the gun as you weld and changing your angle), that might also explain what I'm seeing. This technique will also allow you to fine tune your heat a bit. If you back off the gun slightly as you go, you'll lower the amount of heat in the weld. It's an advanced technique and requires that you have a very good understanding of the puddle and how to read it, as well as being able to make rapid adjustments in a very short period of time to be successful on such a short weld.FYI, clamping to the screw is a good way to F up the screw on the clamp if you don't get a good ground and you get any arcing. It might pay to invest in a dedicated clamp type ground, or grind away the paint from the clamp body. You can also clamp or tack a "tab" to the work that you can ground to and grind off the tack and remove the tab when done. Personally I usually use a tab or a vise grip welders clamp and clamp to the vise grip if all I need is one or two grounds on an awkward piece. A poor ground might also be a cause of a cold start. You don't get full energy transfer until the ground clamp arcs and makes a solid contact, essentially welding itself to the screw.Last edited by DSW; 07-03-2012 at 03:18 PM..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Best wire for non MIG welders like me is JW Harris "Twenty Gauge" .030. Best thing since sliced bread. Used it on some very thin exhaust pipes with great success. I don't believe you can purchase it anymore.This stuff will literally not burn thru even the thinnest metal"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Yeah, tried to find it..............doesn't exist anymore. Uses a 75/25 mix. If you can find some buy it, good stuff"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Originally Posted by farmersammYeah, tried to find it..............doesn't exist anymore. Uses a 75/25 mix. If you can find some buy it, good stuff
Reply:My LWS has it still on there shelf I think in maybe 2# spoolsMiller Pro 300 SS w/ cat Miller Bobcat 250Miller Diversion 165 Miller 211Miller Xtreme 375Miller 12vsMiller Dynasty 200 DX Miller Passport Plus w/ Spool GunMiller 30a spoolmaticLincoln AC225 Buzz Box VictorMathey Dearman - H&M
Reply:Originally Posted by farmersammBest wire for non MIG welders like me is JW Harris "Twenty Gauge" .030. Best thing since sliced bread. Used it on some very thin exhaust pipes with great success. I don't believe you can purchase it anymore.This stuff will literally not burn thru even the thinnest metal
Reply:Once you get the hang of your machine and the settings for a wire size you can run it hot and do a push on that thin stuff. A push will direct the arc and the heat at the joint but let the puddle freeze a bit faster behind your direction of progress. Helps stop the bottom from falling out 2/3rds of the way across a section."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:are you dragging that mig should be pushed not pulledLincoln Power Arc 4000 Thermal Arc Fabricator 252 iThermal arc 186Thermal Arc 26 tigTweeko 200 amp spool gunHobart AirForce 400WP-17V-12R
Reply:Originally Posted by assassin_worksare you dragging that mig should be pushed not pulled
Reply:dsw snap i must of missed that part it looks alot like a pull from the image but if it is a push i would slow the wire speed down a bit more till he gets use to the machine a bit moreps practice practice practice you will get better then you will want to run hotter dont be scared to turn up the heat it just means that you will have to work it faster to avoid burn threw good luckLast edited by assassin_works; 07-04-2012 at 12:24 AM.Lincoln Power Arc 4000 Thermal Arc Fabricator 252 iThermal arc 186Thermal Arc 26 tigTweeko 200 amp spool gunHobart AirForce 400WP-17V-12R
Reply:Thanks, DSW, for all that helpful advice. I have plenty of scrap, so I'll try your suggestions one by one and see what works. I'll post again when I have better results.Last edited by desertWelder; 07-04-2012 at 10:59 AM.
Reply:Thanks for the suggestions, assassin_works. The confusion about push or drag may be partly my fault, since I took one photo from one side, and one from the other.
Reply:Thanks for the tip, Sandy. Seems like the general feeling is that I should work hotter. I'll give that a try.
Reply:Are you snipping the wire with side cutters each time you start? Also if you snip at a diagonal the wire has a fine point to fire up on. Also pull the wire with the snips to take out wire slack in the gun. Those welds are really not a disaster. Often it takes half an inch for things to stabilize when starting a weld. They just don't look perfect I know but they are free of porosity and no craters at the end.
Reply:I had a job doing a bunch of cabinet caster frames, with the exact same material. The corners were 90s, and mitered. I went for as close a fit up as possible, and had the gun pointing straight down. One the top side of the frames, the welds had to be ground down, since the cabinets sat on top of them. Penetration was good, and the parts were joined together just fine.-AaronJet 17.5" Drill Press1942 South Bend 16x84 Lathe1980s Miller 320A / BP --- 2013 Power Mig 2562012 Jet 7x12 Horizontal BandsawVictor O/A Setup
Reply:Originally Posted by lotechmanAre you snipping the wire with side cutters each time you start? Also if you snip at a diagonal the wire has a fine point to fire up on. Also pull the wire with the snips to take out wire slack in the gun. Those welds are really not a disaster. Often it takes half an inch for things to stabilize when starting a weld. They just don't look perfect I know but they are free of porosity and no craters at the end.
Reply:Originally Posted by rabidchimpI had a job doing a bunch of cabinet caster frames, with the exact same material. The corners were 90s, and mitered. I went for as close a fit up as possible, and had the gun pointing straight down. One the top side of the frames, the welds had to be ground down, since the cabinets sat on top of them. Penetration was good, and the parts were joined together just fine.-Aaron
Reply:As DSW has pointed out, the first thing I'd do is switch over to an .023/.024 wire.If you have the out put set hot enough, travel on this thickness should be straight along the joint without any zig-zag (side to side) oscillation.ESAB Migmaster 250 Hobart Ironman 230Multimatic 215TWECO Fabricator 181i & 211iHH125EZ - nice little fluxcore only unitMaxstar 150 STH - very nice
Reply:Try tap 3, wire speed 50. That is what is recommended per the 190 manual.
Reply:Originally Posted by weldermikeHere ya go bud! Like I said, PM me if your interested , no charge bro, forgot I even had it Sam, just glad to help someone
Reply:Originally Posted by DanAs DSW has pointed out, the first thing I'd do is switch over to an .023/.024 wire.If you have the out put set hot enough, travel on this thickness should be straight along the joint without any zig-zag (side to side) oscillation.
Reply:Originally Posted by ProChargerTry tap 3, wire speed 50. That is what is recommended per the 190 manual. |
|
发表于 2021-8-31 23:09:18