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spot welder or not?
#11
(12-01-2019, 10:01 AM)Hemikiller Wrote: I'll agree with Geoff, it's just not a practical tool for what you're doing.

I have plenty of experience with industrial spot welders and I can see all sorts of failure points on this unit just like David pointed out. I did all of my panel replacement with a MIG doing plug welds. You do get pretty darn good at it after a while. Don't use a grinding wheel, use a flap disc. A quality disc will grind like a wheel, but leave a nice smooth finish.
 @ Hemikiller, did you mean Eric?  

 My comment would be fine for setting up and tack welding only, then mig or tig. Heat control is critical so panels don't warp or oil-can.
Geoff.

I learn something new every day!
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#12
Howdy from Idaho,
I have been a welder almost all my life. A great deal of it within the profession of tool and die making. The spot welder works well when it is performed at a certain skill level. Also a certain setting level with "very clean steel". Which is what you find on the assembly line at the Ford plants. Contamination within the spot weld will severally weaken its ability to hold. If you had a blow out and the car shook vilantly or a bent rim was run with vibration the welds could pop loose.

Dont get me wrong Im not saying you couldn't prep it correctly and weld it correctly with the spot welder. Im saying there are some factors that you cant control totally.
By drilling a hole this leaves the sheet metal very clean and ready for a weld. Improves the odds of no contamination. It also gives a stronger weld surface by increasing the surface area heat area.
We just finished a trunk, the drops, qrt panels, inner and outer fender wells, tail light panel on our Mach 1. We wire feed welded all of it. I feel confident it is a stronger way to do the job.


[Image: mustang-rear-qrt-replacment.jpg]

[Image: new-trunk.jpg]
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#13
Thanks for your input! So I get it, required are skill, correct settings en clean metal. About that last thingy, clean metal, is bare OK? sanded? 80 grit or finer? Does it need to be primed in acid?
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#14
You do not want paint on it. The two pieces being together is most important and that the tips align to each other. The welders in the stamping and assembly plants can put hundreds of lbs. of force to pull joints together. Look at how the rocker boxes are welded in our cars. You can see the distortion from clamping. They do use a weld thru sealer on most joints but you should not. Add sealer after you weld. 
I put rocker boxes, running boards and floors in VW bug with my Miller spot welder and also repaired my Mustang. 
You are very good a preparation of your parts which will help lots. When you get the longer arms on you will see that the clamping force goes way down so secondary clamps become important. 
Resistant spot welds hold most of the vehicles on the road together. But also remember back in the day when they built race cars they left the sealer off spot welded at the assembly line then they MIG welded at the race shop. Some flex is good, look at a large truck frame, tractor trailer. You will note that nothing is welded either bolted or riveted. If it were welded it would fail in a very short time.
That is one fault I had with John Deere. They insisted on MIG welding everything. I asked about hot rivets and they said Deere banned them years ago and would not use them. So you will see lots of stress cracks on Deere equipment show up over time. They have to use much heavier metal also to prevent failure.


When a man is in the woods and talks and no women are there is he still wrong??
Tongue
David
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#15
I don't have a lot of experience with welding, other than working on my Jeep and Mustang (more so the Mustang, since I pretty much had to put it all back together).

Plug welding using a wire-feed MIG set-up worked best for me.  We had an awesome Miller spot welder, and after about 2 hours of fighting with the damn thing, I produced exactly 1 viable spot weld when trying to zap down a patch panel on my Jeep's passenger side rear corner.

Once I put the spot welder away and busted out the Miller wire-feed MIG, stuff started happening.  I practiced on a few pieces of scrap, and was immediately much happier with the results.

My skills developed over time and I'm at the point where I will trust my welds, even though they're not as pretty as more experienced welders can produce (some of those guys are artists!).  I've burned some welds that are absolutely inspirational... and popped out so many more dog turds it's not even funny - which I blame on my not knowing how to properly set-up the welder for the weld.  Our local community college offer a welding class, which I plan on taking someday so more of my welds will be of the 'inspirational' sort.

But honestly, if given the choice, I would plug weld all day/every day over spot welding.

Eric

[Image: mach1sig2.gif]
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#16
(12-02-2019, 02:02 AM)Vinnie Wrote: Thanks for your input! So I get it, required are skill, correct settings en clean metal. About that last thingy, clean metal, is bare OK? sanded? 80 grit or finer? Does it need to be primed in acid?
Hi Vinnie,

No need to sand it or prime it. You could use a hand spray bottle with muratic acid in it to clean the metal. Or just use good ol soap and water removing any oil residue from over seas shipping. 
As you can see my wifes Mach was a terror to get done. You will be just fine, take your time and go slow. They built these machs in a day on the assembly line.........but we cant do that at home.
Send us some photos of your progress sir.
Thanks
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