Welding tight joints?

[Grinding- wheel]

I’ve got to make a couple welds where the angle is very small so it’s difficult to get down into the joint. I’m saving for a nicer MIG/FCAW machine. Well specially a Millermatic 211. Right now I just have a cheap FCAW only machine as well as an old 250 amp AC/DC machine.

So long story short I’ve got a welding project I’m trying to complete. One of the welds I have to do has a very tight angle. I wish my stick welding was up to par. Because this would be perfect for a stick machine. I recently started welding again after a very long time of not doing it. Anyway I set my machine up to the chart parameters. If I shove the contact tip down in the joint so I maintain the proper stick out I inevitably stick the contact tip to the metal. If I hold the gun back a little to keep from sticking the contact tip I’ve got to use a much longer stick out. Which obviously causes lower voltage and issues of its own.

In a situation like this if you had no option but mig or fcaw it is it acceptable to crank up the voltage to compensate for the stick out? The weld acts just like it needs more heat/voltage. Or will that cause a problem with the wire melting to soon due to the increased resistance? I’m running .030 wire the little machine I’ve got can run either .030 or .035. If having to use a longer stick out than normal would running a larger wire make any difference? Also would the wire feed speed need to be increased? I would not think it would but just asking.

I’m planning on setting up some practice pieces today to mess with the settings but I wanted to see if their where any issues with long stick out besides the obvious.

Thanks

 

[welder4956]

MIG machines are constant voltage machines, so increasing stick out does not change the arc voltage. What does occur is an increase in heat due to the I^2 x R heating affect. Resistance (R) is increased resulting in more preheating of the wire before it reaches the arc. Increasing wire feed speed results in and increase in current (I). So, you may actually need to reduce wire feed speed slightly to compensate for the higher stick out. If it were me and I did not want to deal with finding the right settings on the actual pieces to be welded, I would use some scrap and make a mockup of the joint to simulate the conditions and get the settings right before making the actual weld. Plus it gives you some practice runs.

 

[welder4956]

One other thought - flux core wire usually needs 3/4" to 1" of stickout to run properly. If you have been running it with shorter stickout, just increase it with the same settings and see if it runs better.

 

[Grinding- wheel]

MIG machines are constant voltage machines, so increasing stick out does not change the arc voltage. What does occur is an increase in heat due to the I^2 x R heating affect. Resistance (R) is increased resulting in more preheating of the wire before it reaches the arc. Increasing wire feed speed results in and increase in current (I). So, you may actually need to reduce wire feed speed slightly to compensate for the higher stick out. If it were me and I did not want to deal with finding the right settings on the actual pieces to be welded, I would use some scrap and make a mockup of the joint to simulate the conditions and get the settings right before making the actual weld. Plus it gives you some practice runs.

I did make a couple mockups of the joint. I figured their would be less voltage at the arc if the wire was longer due to resistance but I guess the machine can sense that and increase the voltage. Anyway I just decided to pay attention to the arc not the setting on the machine. Wound up making it happen. Weld was not perfect but I’m no pro and it’s a non critical weld. I was fixing some handles on a grill.

 

[welder4956]

Anyway I just decided to pay attention to the arc not the setting on the machine. Wound up making it happen. Weld was not perfect but I’m no pro and it’s a non critical weld. I was fixing some handles on a grill.

Glad you got r done. Reading the arc and puddle is the best way to do it.

 

[slowtwitch73]

Fwiw I have a Miller 211 and wouldn't buy it again. It's fine... but that's it.

 

[fast85pony]

FWIW I love my 211

 

[BukitCase]

Guys, Miller wasn't smart enough to give the newer inverter MM211 a different name, or at least add an "i" on the name, so you may both be right.

I had the transformer MM211 for a few years, found a half-price deal on a MM252 with un-used 30A spool gun, sold the MM211(t) to a friend; then about a year later I bought the newer MM211(i) - nearly everything I griped about on the 211T was improved on the 211i.

Still got the MM252, but it's not quite as portable as the MM211 :=) - So the 252 tends to stay in "small wheel territory" and the 211i does everything else unless the job requires stick or tig - My "offroad" cart for the (much) lighter 211i -

https://www.tractorbynet.com/forums/build-yourself/387658-container-weld-shop-build-20.html

Later... Steve