[sweetfarms]

I have been welding for 25 years (mig and AC stick). I have never welded with a DC welder. I am going to do some welding on a bridge on my farm and thought that renting a poratable DC welder would be my best option. So, any tips on welding with the DC unit- rods? polarity? settings? Thanks

[Otto Nobedder]

Welcome.

With your years of experience, I'd have to agree the DC welder rental is a good idea. However, a bridge can be a "critical application."

DC welding with the rod I'd recommend can be rather tricky when you're accustomed to AC, so some practice might be in order before you lay out that rental money, if possible.

If your MIG is heavy enough for the job, and you can weld vertical up, you might consider renting a generator that'll run the MIG.

Several of us can make recommendations for either option, but I'd like to know more about the bridge first.

Is this a repair? What is the bridge used for? (D-9 Cat? Hiking trail?)

Got a picture of what you want to weld?

I ask because I'd hate to give the wrong advice for your needs.

Steve

[Ultralow787]

Yes! Lets get into some more detail on this bridge. I am also planning to build a new bridge spanning about 40 feet over a river on my property.

[sweetfarms]

Thanks for the response. I am putting in upright supports to hold guard rails on the sides. 1/2" steel- horizontal and vertical welds. This is a small bridge that is used for small utility equipment.

[Otto Nobedder]

Since guardrail supports are not critical to the support structure of the bridge, you have a couple of options. I'd make my decision based on cost.

You could, as I suggested earlier, rent a generator that will run the MIG you're already familiar with. The downside may be to bring what you need for wind-block.

If you go the DC welder route, your best bet is probably 7014 rod. I'll ask others here to back this up, or refute it, as in 30 years I've never used it. I'm told it's the easiest DC rod to transition to from AC welding, has a 70 KPSI rating, and apparently works well in all positions.

Best of luck, and let us know how it turns out.

Steve

[sweetfarms]

Thanks for the help. I decided to go ahead and rent the portable DC rig. That is probally a bad decision - I will want to buy one!!!