Welding Tips and Tricks

I mentioned this is my Intro thread but thought it would be best to start a new one here. I have an 05 Nissan Altima that has the floorboards completely rusted through. It's a common problem because of an HVAC drain line that gets clogged up. Anyway, I'm going to cut out the rust and weld in new metal. I'll be working with a hobart FC that runs on 110v. I'm planning on drilling holes and tacking in the new sheet. I have access to a shear and a box brake that will do 16ga which I just found out today and am pretty excited about that because I'd otherwise have to cut with an angle grinder with a metal cutting disk. That's what I used to cut out the rust. After I get it in place, I'm going to use seam sealer and I was thinking about using Por 15. I only have experience welding with a HF Stick. I have an auto-darkening helmet that I bought when I got the welder. It only took me a couple of hours to start laying beads with it, so I'm thinking FC should be even easier. Is there anything else I'm missing? And yes, I know to disconnect the - terminal before I start welding in my car

Here are some pics I took. Rusty Floors

Thanks for any help you can provide.

Your post mentions you'll have access to a shear and brake capable of 16 gauge steel. I have to look these things up, and when I did I found that 16 gauge is 0.0598 inches thick. I also looked at the Miller welding calculator for flux core wire, here:
http://www.millerwelds.com/resources/ca ... ulator.php
On that calculator the thinnest material showing is 3/32" or about .0938".

The flux core process does not work well on thin materials, and 16 guage is about half as thick as the thinnest material mentioned on that calculator. I'm thinking this would not work out well- I don't mean to rain on the parade, and I'd be happy to be corrected. Anyone used FCAW successfully on 16 gauge?

1,5 mm is thick

Since you plan to do overlapping welds paint the surfaces that will be concealed with weld thru primer. Just the sealer wont protect enough. Only use that primer where no other paint will reach, they dont like each other.
(You might have products that match well, this is only my experiences)

Ok, so I gave up on Flux core and got a bottle of 75/25 and converted to MIG. Now the issue that I'm facing is doing plug welds. I can't get enough penetration and it just blobs up. I've tried adjusting both wire feed and voltage but it doesn't seem to help. I'm starting in the center and swirling around. My test is using scrap 16 ga angled steel with 3/16" punches. I have them separated about 1/4" from each other and after doing all of them and letting it cool down, I can break it with my hands. I am starting at one side, going all the way to the opposite side until they meet in the middle. I'm running Lincoln .024 wire and gas is set at about 22. It's one of those stupid bubble regulators so I'm just between 20-25. I've been watching every video I can find but there aren't many for this particular situation. I can lay down a nice looking bead all day with this setup but can't get the plug welds to stick.

My first question would have to be, if you switched from flux-core to Mig, did you change polarity on your machine? They use opposite polarities. I'm not saying that you don't know this, I'm just saying I don't know if you know.

Len

Yes, I did. I printed out the whole manual and read it cover to cover.

I haven't done a lot of plug welding but when I did it was where I cut out spot welds in sheetmetal and the holes were about 3/8 to 1/2" and I had to clamp the 2 peices tight together to do a nice job. When you say they're 1/4" apart, I hope you're talking about spacing between each one and not the gap between the two peices being welded, correct?

Len

What machine are you using?
Does it have a arc control setting?

Sounds like one or two things. 1: running way too cold. 2: settings on your machine.

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I was thinking "cold" too. Is the weld metal clean, no mill scale, paint or rust?

Or maybe... have you applied the techniques featured here:
http://welding-tv.com/2014/08/13/mig-we ... cs-part-3/
... starting with measuring 6 seconds worth of wire? The starting point wirefeed speed for your application would be
.0598 thickness in inches x 1000 to convert to thousandsth x 3.5 multiplier for 0.023 wire = 209 inches per minute

The miller calculator suggests 17-18 volts for 16 guage (although it does not talk about .023 wire for any thickness of metal). Is that about what you're using?

I wondered about the polarity swap from FCAW to GMAW too, but then I remembered you said you could lay down beads just fine and only the plug welds were causing you grief.

BTW Hope this doesn't sound preachy, just trying to help out.

Artie F. Emm wrote:BTW Hope this doesn't sound preachy, just trying to help out.

Not preachy at all. I welcome any and all comments. I worked on it a bit last night trying to fit my replacement pan into place. It involved a lot of persuasion with a BFH but it's close. I also got a sheet of 14 ga and tested laying beads and doing spot welds. It's getting better since I ramped up the wire feed speed and voltage. Cleaning the mill scale off seems to have made a difference too. I wish I could find the old POS faceshield that came with my cheapo HF buzz box so I could record my technique for critique. This Hobart 120 only has a few settings for voltage, which sucks. I need something in between 16ga and 18ga.

Braehill wrote:I haven't done a lot of plug welding but when I did it was where I cut out spot welds in sheetmetal and the holes were about 3/8 to 1/2" and I had to clamp the 2 peices tight together to do a nice job. When you say they're 1/4" apart, I hope you're talking about spacing between each one and not the gap between the two peices being welded, correct?

Len

Yes, I tack the L-bend with the holes punched at about 1/4" apart directly to the flat sheet underneath. Then I start spot welding from the top to the bottom to distribute the heat until I meet in the middle. The punches are 3/16" in diameter, which seems a little small to me. I'm getting a mechanical hole punch with bigger sizes to see if that makes a difference.

Why don't you get a set of the HF step drill bits? They're cheap and if they last through this job they would pay for them self.

If you're welding the heavier sheet to the top it will be a little harder to get even penetration between the 2 sheets, but not impossible.

Len


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I have just about every cheapish tool HF sells including the step drill bits. 10 of the 27 LED lights, 8 tape measures and more 9 LED flashlights than I can count. I think I have one in every drawer in my house I'm actually using the air punch/flanger from HF to make my holes. It's 100% faster than drilling them but I think something bigger than 3/16" might be easier to do. Only time will tell. I'll get my new punch tonight thanks to Amazon Prime 2 day shipping.

You can even try cutting slots with a grinding wheel about 2" long x the width of a regular grinding wheel, that way you're sure to get a good tie-in. As long as you can get the 2 pieces tight together you'll have a much easier time of it. You don't want to spend anymore time than you have to on the thinner metal and still melt the edges of the heavier and trying to weld through a 3/16 hole is only going to allow you to put the heat on the thinner sheet below, that's why I suggested a bigger hole or a slot.

Len

That's a good idea. I never thought about cutting a flange like that as that's the first I've ever heard of it and I've read A LOT on this topic in the past week. I'm gonna try with this without drilling any holes and see how it goes: Spot Welding Nozzle If that doesn't work out, I'll try your suggestion.

Is there a possible ground issue with the part the plug weld is not sticking? A good ground on both parts is important

Based on Jody's charts, you target would be, .059"~60A .... 60x3.5=210ipm
Based on my recent Handler 150 measurements and looking at the specs, you should be good starting on Tap #2 and setting wire speed around 2.6-3.0 This should yield about 210ipm@18v ... Pay attention to sitck-out.

GlenC wrote:Is there a possible ground issue with the part the plug weld is not sticking? A good ground on both parts is important.

I've brushed it down to get all the mill scale off and the clamp is holding the 2 pieces together. I think that is a good ground.

GlenC wrote:Based on Jody's charts, you target would be, .059"~60A .... 60x3.5=210ipm
Based on my recent Handler 150 measurements and looking at the specs, you should be good starting on Tap #2 and setting wire speed around 2.6-3.0 This should yield about 210ipm@18v ... Pay attention to sitck-out

That's exactly what I'm running with 5/8" stick-out.