Welding advice please

[Jerry]

I have a Hobart 189 MIG welder and on the lowest setting the patching of auto panels is making holes as much as patching holes. I find that a quick zap is the only way I can tack the panels together.
Is there a trick that I am missing?

Jerry

 

[big6]

Jerry

All I could fine on the net was a listing for a Hobart 187. That particular standard welder comes with flux core wire but has a regulator and hose setup for shielded gas welding…

Are you using the flux core wire or shielded gas when you are welding? If you are using flux core wire is probably your problem. It is extremely difficult to weld thin gauge steel with a MIG and flux core wire. Buy a bottle of 75% Argon 25% CO2 shielding gas and solid .030 gauge wire. Only use 100% Argon gas for aluminum welding. You will also need the matching torch tip. For the Hobart 187 you will need to change the wire drive wheels as well. Looks like you just need to flip the drive wheels around.

If using shielded gas have you tried increasing the wire speed or the torch distance from the work? The rule is the closer the torch to the work the hotter the weld. Too far from the work the shielding gas does not protect the molten metal.

Are you butt welding or lap welding? If lap welding you may try punching 3/16 inch holes about 1 inch apart in the upper plate and using the hole to spot weld the clamped panels together. Usually works better than continuous welding if you are first learning to weld. Continuous welding will distort thinner gauge sheet metals. If you need a continuous weld then weld very small spots at a time moving around the weld seam allowing metal cooling time for each of the small weld spots. Concentrated heat on the metal causes the metal to shrink. The result of continuous welding on thinner gauge metals is a smaller wavy piece of metal. Also the wire welder seam is harder than the sheet metal. That makes it difficult to use a hammer and dolly to work the MIG welded metal. This is the advantage of using a TIG welder for sheet metal panel work as the weld seam hardness is the same as the sheet metal being welded.

About 40 years ago in welding class, the rule of thumb was you cannot use wire or rods thicker than the substrate gauge of metal you are welding. 22 gauge steel is .0299 inch thick and 20 gauge steel is .0359 inch thick. If I remember correctly flux core wire thinnest gauge steel you can successfully weld is either 14 or 16 gauge. (The smaller the metal gauge number the thicker the metal.)

 

[GregW]

You can also get MIG wire in a .023 thickness. Since it melts faster it could save the base metal from blowing out.

 

[TRMark]

A lot of good info at this site so look around a bit. On the page linked is a video on pulse welding, technique for thin metal.

 

[Jerry]

To answer all the questions:
187 Hobart, I forget the number at times.
It is NOT using flux wire, I have the gas mixture.
size of the wire is 0.30
I found a brief zap was putting a spot weld on that did not blow thorugh but I was worried about strenght. IE: at best you have spot welds every inch. I pressed hard on one spot and weld came loose. I will try the distance method next.

I was doing a lap weld this time. So I will try doing punch holes and see if that works.
Any other advice? I appreaciate all the thoughts so far.

Jerry

 

[TRMark]

I use the earlier version of that welder. If you are using .023 wire and C25 and study the technique at the site I linked, there is no reason, with a little practice, you should not be able to butt weld 20 gauge steel. Make sure the steel is clean. Also if the welder is new to you check the polarity. Solid wire uses a different polarity than flux. My welder came set up for fluxed.

 

[big6]

Jerry,

Another thought, If the polarity is set correctly also verify the shielding gas regulator is set correctly and that the shielding gas is exiting at the tourch. If you do not have the shielding gas setup correctly the steel will burn-thru immediately when you pull the torch trigger regardless of temperature setting, wire speed setting, wire gauge size, or metal thickness. Attempting to MIG weld without shielding gas, the metal will rapidly oxidize and act more like a cuttting torch instead of a welding torch. The weld, if you can get it to stick, will be very brittle. Before welding pull the trigger and run out four to six feet of wire and then cut the wire back to 1/2 inch from the tip. This will allow the shielding gas to get to the torch before starting to weld. Your last posting of the welded area not having strength brought this to mind. Also, I found using .023 wire is very difficult. You will spend more time cleaning tips with the wire welding itself to the tip with .023 verses .030. That is why I prefer .030 when using my Hobart 210 Ironworker MIG welder for body panel welding. I also use a spool gun for aluminum welding and when converting back to the torch for steel I sometimes forget to switch the shielding gas valve directing the shielding gas to either the spool gun or torch. When the torch trigger or spool gun trigger is first pulled reminds me if I forgot to change the shielding gas valve. The metal (aluminum or steel) without shielding gas will immediately burn thru at first arc...

 

[Jerry]

I did switch the polarity when I switched from flux wire. It sounds like I need more practice. I will try your suggestions.

Jerry

 

[Trevor Jessie]

I once went to help a friend figure out why he was having trouble welding in patch panels. Turns out he was blowing holes through the metal because it was paper thin. The back side had rusted greatly. So... be sure you are working with solid and shiny clean metal.

 

[Jerry]

New panel to old 1967 Ford Cortina. there are parts of the Cortina that have seen better days.

Jerry