Big welding job for a poor welder

dewbane

dewbane

Michael McIntyre
H-M Lifetime Diamond Member
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Mar 2, 2018
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When I did that steering shaft part for one buddy of mine, another buddy said, "since you're a machinist now," and hit me with a fabrication and welding project. Uh. Machinist. Mill. Lathe. Just installed DRO. Just learned how to cut gears. Not a fabricator.

It's an interesting project though, so I'm going to try it. He has a 30' goose neck car trailer, and he wants to make a moveable mount for a winch. It's basically a big H-shaped construct with a Reese receiver in the middle. The winch attaches to the Reese receiver. The idea is he can move this thing anywhere on the trailer to get a better angle, while he pulls pickup trucks out of bottoms for idiots who tried to drive to the deer and stuff like that. The H frame thingie, more like |-------------------------------------||-------------------------------------| mounts into four stake pockets on the trailer. He will use a couple of ratchet straps to hold it down tight. It seems like a viable design, though I am not an engineer!

So... I'm not a very good welder. All I have available are a 120V flux core welder, and an oxy-acetalyne rig. I have very little welding experience, and basically my greatest success was welding up the bottom of a mower deck.

I'm not sure if I can do adequate welds for something like this. I'm not sure what gauge steel to use. I'm not sure if I can actually weld steel of sufficient strength.

I'm thinking about making it so the sides connect to the center bar with mortise and tenon type joints, and using bolts to hold the parts together. I would still have welds on the feet that go into the stake pockets, and on the tenons. I have no idea about attaching the Reese receiver securely. This thing will be pulling up to 12,000 pounds, so it wants a very secure mounting.

Anyway, I'm kind of meandering at this point. There is no time limit on the job, and he knows I might not get it done until spring. I thought I'd pick the collective brains of all you kind folks and see if I can start getting my head around what this job will actually involve.
 
Most 120 volt flux welders can only get good penetration to about 3/16ths of an inch of thickness in mild steel. This is going to be the most limiting factor in your design. I am guilty of overbuilding, and frequently use far more metal than what is needed for a design. However, you are not just working against "static loads", but also "dynamic loads" which have high peaks. I would suggest you do some coupons (practice pieces) which you cut into, and verify the penetration you are getting with your welding machine (and technique), to ensure you are getting the depth and strength of weld which you will need. Keep in mind that pre-heating your metal with the Oxy torch will help your flux welder get more consistent and deeper penetration of your flux weld... so you can cheat a bit.
 
Remember if your welds look bad 'grinder n' paint makes me the welder i aint"
 
Consider overlapping steel and bolts. If your weld is suspect, use a tongue in groove style fixation, bolt the center and weld the edges. Kind of a belt and suspenders approach. The bolt should be strong enough, the weld should be strong enough, together they are over-kill and you should be good to go.
 
While the welder may be limited to 3/16" or there abouts, there is nothing that prevents you from welding heavy material. You will need to be sure to establish a nice V that can be filled. Then work to put in the first weld concentrating the heat in the weld area. Don't try to fill the V on the first pass. Instead just concentrate on the very bottom of the V and making sure you get the base metal to pool nicely to create a solid weld. Then remove the flux, brush or grind any imperfections out and make a second pass half on the weld you just made and half into the virgin base metal. Repeat the process always over lapping until the V is filled.

It isn't hard to do. Had to do it many times, on stick, and MIG both shielded and core. Have build a pump skid that weighed in at almost 2500 lbs with a Lincoln 185 welder (gas shielded). Used 6"x2" channel with 1/4" web and 4" schedule 120 pipe to connect the two channels to create the skid. Then build the supper structure to support the two pumps, surge tank, piping and explosion proof valves. The valves were required because this was going to a refinery. Code says that all valve in the area where this pump was to be used had to be a specific type. Way over kill as they were also flanged and the smallest size was 2" larger than any of the pumps inlets or outlets. Pumps were moving mostly water but there was crude in the pond too. Hence the need for the valves.

The method is sound. I watched a friend at work who was joining two channels that were about 1.5" thick, Web was 4 feet. They were welding them back to back to make an I Beams that would be used in the construction of a bridge. They would lay rod down 8.5 hours a day, and only raise a hood for break or lunch. Had three guys going around feeding wire in from large diameter spools. They would see the wire getting close then stand there with the end of a new spool, when the last of the old spool started down into the machine, they would shove the new wire in behind it until the machine caught it. It was seemless as the welder rarely saw the transition from old wire to new. But they filled this huge V in the same process that I described above.
 
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NC Rick said:
Particularly if he is using this setup commercially, I would have reservations based on potential liability.
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He isn't, and this is one of the few guys I could ever trust not to lawyer up if the rig breaks. You do raise a huge point though. I'm starting to realize I probably shouldn't do work for anybody, ever, because who can you really trust not to sue you in this day and age? Nobody. Liability insurance costs more than I could ever make in a month with my 70 hour day job soaking up most of my time, and I should probably just stop answering my phone entirely, and complete my transformation into a completely isolated hermit.
 
dewbane said:
He isn't, and this is one of the few guys I could ever trust not to lawyer up if the rig breaks. You do raise a huge point though. I'm starting to realize I probably shouldn't do work for anybody, ever, because who can you really trust not to sue you in this day and age? Nobody. Liability insurance costs more than I could ever make in a month with my 70 hour day job soaking up most of my time, and I should probably just stop answering my phone entirely, and complete my transformation into a completely isolated hermit.
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I'm not a big CYA guy and don't worry about my friends. I would be more concerned with one of his customers insurance company seeing what sticks to the wall. I also based my comments on your own judgment of your welding equipment and skills vs the whole high load and potentially dangerous situations one can get into when attempting to fix others screwups as it sounds like your friend does. My intentions are not to "tell you what to do" or pass any judgment, only to provide my perspective as food for thought.
 
This is a DOT concern. I am very careful about automotive weld jobs that I will do for other people. I don't want any part of the liability of a rigged-up system integrating a 10,000 lb hitch for someone else's behalf. If you don't know immediately what types of materials and techniques are adequate, then stop. Any blood on your hands will be hard to wash off as you live with your decision to not politely decline a job that was out of your wheelhouse.
 
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