welding pinholes in sheetmetal,TIG?

toplessHO · Saturday at 12:18 PM

Ive got some pinholes from rust in a trunk floor.
I dont want to go thru the replacement of trunk floor.
I have a small 140A multiprocess welder,that Ive bought a scratch start
TIG gun for,but wondering if thats the right way to go.
Should I scrap the scratch start and go with a finger control?

KwikFab · Saturday at 12:24 PM

toplessHO said:
Ive got some pinholes from rust in a trunk floor.
I dont want to go thru the replacement of trunk floor.
I have a small 140A multiprocess welder,that Ive bought a scratch start
TIG gun for,but wondering if thats the right way to go.
Should I scrap the scratch start and go with a finger control?

Clean it all up nice and clean on both sides.

Wear a respirator for anything that may burn off and be harmful (adhesives, etc).

Worst case you blow through it and you replace a larger panel anyway but it won't hurt to work on what's there already for practice.

If you're not used to TIG at all, practice on some scrap first on a table. The trick is establishing the arc and maintaining a proper distance, followed by flicking it to kill the arc and hovering back over to provide shielding gas.

Watch some videos, and learn some technique before doing the actual project.

LopezBart · Saturday at 12:43 PM

You should be able to weld this w/ a brass or copper block/ heavy sheet held underneath the floor against the hole using a MIG or TIG welder turned down quite low. Eastwood makes a little magnetic gadget to help hold it in place; a piece of brass sheet and some strong magnets should work as well.

dscheidt · Saturday at 12:46 PM

Have you cleaned it yet? You are likely to find you have more holes than you think.

toplessHO · Saturday at 1:06 PM

LopezBart said:
You should be able to weld this w/ a brass or copper block/ heavy sheet held underneath the floor against the hole using a MIG or TIG welder turned down quite low. Eastwood makes a little magnetic gadget to help hold it in place; a piece of brass sheet and some strong magnets should work as well.

Yes Ive used copper plate and various pieces of busbar to back up the voids.

toplessHO · Saturday at 1:07 PM

dscheidt said:
Have you cleaned it yet? You are likely to find you have more holes than you think.

yes even spot blasted it.

ctandc72 · Saturday at 1:07 PM

dscheidt said:
Have you cleaned it yet? You are likely to find you have more holes than you think.

What he said. Get the flap wheel out. Where there are pinholes there are at least weak spots or other rot. At least take a dead blow / sledge and see how sound the floor is.

toplessHO · Saturday at 1:23 PM

Cleaning is done... knotted wire wheel,then blasting
what Im most concerned about is the need to regulate heat,
but I dont want to use a foot pedal

K13 · Saturday at 1:35 PM

Just use the MIG. Scratch starting while trying to do pinholes would be a nightmare and you are 100% going to need amperage control with a TIG for doing that type of work. Quick burst at low amperage with a MIG will be easier than the TIG if you don't have a proper set up, might even be easier than if you did. I TIG pretty much all my automotive sheetmetal work but would seriously consider using my MIG for pinholes in a trunk.

The Cobbler · Saturday at 2:07 PM

mig with pulses . on/off .
might need to back it up with brass or copper depending on size of pin hole
you can also drill the pin holes out a bit larger & make round plugs to fit the hole ( weld a coat hanger to a pc of metal , put it in a drill and use an angle grinder to make it round & to size. tack in place, followed by pulses to weld it solid
Fitzees Fabrications on You Tube has done several episodes where he welds up pin holes using the above technique .

yhprum · Saturday at 6:45 PM

I know you didn’t ask and I might get roasted but have you thought about filling the hole with solder. Acid free and would have to be absolutely spotless. I have a large electric soldering iron that would put the heat right where it’s needed.

rlitman · Saturday at 6:55 PM

toplessHO said:
Cleaning is done... knotted wire wheel,then blasting
what Im most concerned about is the need to regulate heat,
but I dont want to use a foot pedal

Yeah, out of position foot pedal control is annoying. I have an SSC Controls Touch 4 fingertip paddle, and find it no less intuitive than my SSC pedal. Me, I'm like a fish out of water without power control. YMMV, but if you're looking to find a way to get pedal like control without the pedal, there's good stuff out there that's not crazy expensive.

Sumboodie · Saturday at 7:07 PM

I usually use fiberglass Bondo. The metal is lilely paper thin and trying to weld will be tough.
Will end up turning a 1/4" hole into something like a 3" welded area.

v8nutz · Saturday at 7:10 PM

If metal isn't perfectly spotless with a tight fit up TIG is really hard to work with. It keeps getting bubbles in it . MIG is way better for this.
I have a finger control for my TIG that I don't use, it's really hard for me to control it that way, pedal is much easier.

toplessHO · Saturday at 8:16 PM

yhprum said:
I know you didn’t ask and I might get roasted but have you thought about filling the hole with solder. Acid free and would have to be absolutely spotless. I have a large electric soldering iron that would put the heat right where it’s needed.

I may still do that in some areas,but will use body solder(lead).

Firebrick43 · Saturday at 8:27 PM

No way I would use my tig for rust hole repair, no matter how clean you think it is, it isn't clean enough. And i have have a thumb control if I need it. Scratch start makes it worse.

Copper block behind with Mig if you are stuck on welding.

If the holes are small a moisture cured urethane like Chassis saver, POR15, rust bullet, or sherwin williams corothane applied and then while wet put 1.5 oz chop strand mat then apply another layer of POR15.

Or coat with epoxy and a layer or two of 1.5 twill weave fiberglass. Don't use polyester resin as its hydroscopic.

toplessHO · Saturday at 8:59 PM

rlitman said:
Yeah, out of position foot pedal control is annoying. I have an SSC Controls Touch 4 fingertip paddle, and find it no less intuitive than my SSC pedal. Me, I'm like a fish out of water without power control. YMMV, but if you're looking to find a way to get pedal like control without the pedal, there's good stuff out there that's not crazy expensive.

been looking at a finger control,Im calling manufacturer Monday and see what they say.
Im pretty sure they offer a foot pedal so finger trigger should be same.

Heres an Eastwood video showing both MIG and TIG repair.

kmacht · Saturday at 9:14 PM

Filling that pinholes with a welder rarely works. The rusted area is usually super thin to start and even if you get a weld to fill the hole, when you go to grind or sand the weld down the surrounding metal starts to designate. If it’s a trunk floor and nobody will see it you will be miles ahead just laying some fiberglass down over the area if you don’t want to cut and patch with metal.

MOS3522 · Saturday at 9:28 PM

A lot of good advice in this thread.

In the hands of a good welder, may be possible.

But for us average mortals, bondo - or cut out and replace the whole damaged and weld in a new piece of sheet metal.

The Cobbler · Sunday at 12:50 AM

The Cobbler said:
Fitzees Fabrications on You Tube has done several episodes where he welds up pin holes using the above technique .

about 33 minutes in . not pin holes but larger holes

dffay · Sunday at 8:40 AM

Silicon Bronze rod if TIG or SiB spool if MIG will manage your lower heat due to thin sheet metal concern. Pure Argon and DCEP.

rlitman · Sunday at 10:38 AM

toplessHO said:
been looking at a finger control,Im calling manufacturer Monday and see what they say.
Im pretty sure they offer a foot pedal so finger trigger should be same...

Not all fingertip controls are created equal. I had a Miller side wheel that was an absolute piece of garbage. The only two on the market that I feel are worth a damn are the SSC Touch 4, and the TIG Button.

toplessHO · Sunday at 12:51 PM

The Cobbler said:
about 33 minutes in . not pin holes but larger holes

Good tips,thanks for that.
Note to self,lifes to short to restore rusty Datsun pickups

toplessHO · Sunday at 1:17 PM

I see some chatter on a wire made by Harris nicknamed 20 gauge.
Anyone tried it?
Comments I read were all positive

lilredex · Sunday at 1:56 PM

This one, think it was discontinued.......remember looking for that stuff about fifteen years ago.

toplessHO · Sunday at 2:14 PM

lilredex said:
This one, think it was discontinued.......remember looking for that stuff about fifteen years ago.

yep.
Harris has gone thru alot of restructuring.
No idea why it was discontinued
Im going on an easter egg hunt to see if I can find a dusty spool .

BigMike782 · Sunday at 8:08 PM

My .02?
.023 S6, surgically clean, a copper spoon will give the best results.
If you have never TIG’d before(amperage control be damned) you may want to lay your grapes on the workbench and give them a good hard smack with a hammer, it will be less painful.

LopezBart · Sunday at 8:39 PM

Using a MIG doesn't require a nutcracker.

Sumboodie · Monday at 4:08 AM

toplessHO said:
Good tips,thanks for that.
Note to self,lifes to short to restore rusty Datsun pickups

Is 18 Guage normal thickness for a floor?
I would have figured like 12 or maybe 14 at the thinnest.

toplessHO · Monday at 10:05 AM

Sumboodie said:
Is 18 Guage normal thickness for a floor?
I would have figured like 12 or maybe 14 at the thinnest.

on a quiet night you can hear a Datsun rusting...I know Ive had a few

welder4956 · Monday at 10:17 AM

TIG would not be my first choice for this work. "Pinholes" in metal due to rust are never just a small hole straight thru the metal. If it looks like a pinhole on the inside of the car, the area on the bottom side will be a larger rust pit and thinned. MIG with 0.023 wire, low amps and quick bursts will do a better job.

toplessHO · Monday at 12:58 PM

lots of good results posted on the JW Harris "twenty gauge" wire in .030.
Any idea where to find any of this?
Ive called Harris and no luck

The Cobbler · Monday at 1:14 PM

Sumboodie said:
Is 18 Guage normal thickness for a floor?
I would have figured like 12 or maybe 14 at the thinnest.

I bet a lot of newer cars are 20g. the strength comes from the bends , beads & deformations that are pressed in

scooby074 · Monday at 1:31 PM

Problem is pinhole rusted thru areas are usually surrounded by quarter-sized paper thin metal. When you weld it, it blows through the paper thin area!. Really need to cut and patch with full thickness metal larger than the thin area

larry4406 · Monday at 3:13 PM

@MP&C uses an ice pick to check for thin sections as I recall.

At least OP isn’t covering it with kitty hair and Bondo.

welder4956 · Monday at 3:39 PM

toplessHO said:
lots of good results posted on the JW Harris "twenty gauge" wire in .030.
Any idea where to find any of this?
Ive called Harris and no luck

Sounds like it may have been discontinued. You might try calling Harris back with the part numbers in the pic below.

LopezBart · Monday at 3:58 PM

Note that MIG .025 solid wire and 75/25 argon/CO2 is considered a good solution for thin sheet metal welds; I've had good luck w/ .030 as well.

toplessHO · Monday at 4:19 PM

welder4956 said:
Sounds like it may have been discontinued. You might try calling Harris back with the part numbers in the pic below.

Thanks for finding the factory specs
When I talked to Harris/Lincoln,I did provide part #s.
I asked"If this product was so revered and respected,why was it discontinued?
Was it because of the merger?" Rep said it basically was because Lincoln already had a product,
which he gave me part# E70C-6,which is a powdered metal filler,but geared towards industrial apps
with smallest being .045. So short answer is they discontinued without a replacement

545_days · Tuesday at 7:32 PM

dscheidt said:
Have you cleaned it yet? You are likely to find you have more holes than you think.

I cleaned a rusty part with Evaporust and it damn near evaporated.

toplessHO · Wednesday at 8:41 AM

If anyone has a full or partial spool of that JW Harris "Twenty Gauge"
wire,I would be happy to purchase.

welding pinholes in sheetmetal,TIG?

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