rossette (plug) welding with a MIG welder..HELP!

[marklaken]

okay what am i doing wrong....

i am trying to replace my inner rocker panel on the drivers side of my '67 westy...i drilled out the old one with 1/8" drill bit, and fitted the new one so that it closely follows the contours of the floor rib where it attaches. I clamp it together very tightly. I have weld-thru primer on both the bottom of the floor board and the top of the flange on the replacement rocker.

i set my welder (Hobart Handler 135) on voltage 1 and set the wire feed speed to 10.

when i make my plug welds in the 1/8" holes, i get really bad strength and very little indication that i have good penetration...the holes seems to fill up very quickly.

The Hobart has a weird feature that it only has 4 voltage settings and then adjust the voltage based on wire feed speed internally. It recommends using setting 1 for 18-22 gauge steel, and a feed speed of 10 which works well for butt welds on 22 gauge from my experience.

Should i increase the voltage and reduce the wire feed speed to get better penetration for plug welds?...Is there something else in my prep that i am doing wrong?
_________________
Wish List:
1967 Wesfalia SO-42 Parts Needed: Kitchenette, Cot Poles

'65 rear left beetle fender

15" Bus Wheels in fair condition

Mark Laken
Fort Collins, CO

[TimGud]

That would work. Do you have any scrap sheet metal around to practice with? If so try cutting peices out of the old metal drill your holes in one of them and do your experimenting on it rahter than the bus.

[marklaken]

on scrape metal pieces, i have had better succes with my plug welds in general...that's why i tried it for real (unsucessfully now on two attempts!)...the two surfaces are alot easier to get nice fits on little practice pieces...

in the real world, i don't think i can get the two pieces to fit as perfectly as i can on small scrap metal pieces...i've ground and smopothed and cut and bent and fitted about as best as i could get for that replacement inner rocker...i don't see any gaps and it is well clamped...

should the weld-thru primer be at the spot of the weld or should i remove it so i have bare steel for the weld to stick to? seems like poor adhesion (again bad penetration)...
_________________
Wish List:
1967 Wesfalia SO-42 Parts Needed: Kitchenette, Cot Poles

'65 rear left beetle fender

15" Bus Wheels in fair condition

Mark Laken
Fort Collins, CO

[TimGud]

I like to have bare metal for good adhesion and would add alittle more heat for better penetration.

[Mr. Bungle]

did the scraps you practiced on have weld thru primer on them?

i found out that weld thru primer is finnicky stuff. it pops and spits and its hard to get a weld to stick.

heres what i did.

practiced on scraps with holes drilled in them and coated with weld thu primer. i found that taking the 1/8 drill bit and running it in the hole just to get a bit of the primer off the od of the hole helps too. turn up the voltage (the primer seems to need more heat) and turn down the wire speed.

practice as much as possible on scraps before hitting the vehicle. it's a good way to get comfortable with the technique.

[diy570]

you could try your heat at around 2 and wire speed around 4 or 5. the weld thru coating will cause it to spatter quite a bit but you can remove it where you are gonna do your plug welds. do you have your gas turned up to 15-20?

[marklaken]

irievolks, that's exactly what i ended up doing and i got much better welds...and maybe i got my gas too high? (got it set at 25)...

i was afraid of blowing out the welds, but i didn't really have an issue by setting it up at 2 and had much better control of my weld pool with the lower wire speed...it did pop alot with the weld thru primer, but at 2 there didn't seem to be an adhesion issue with leaving it on the metal...

thanks, mark
_________________
Wish List:
1967 Wesfalia SO-42 Parts Needed: Kitchenette, Cot Poles

'65 rear left beetle fender

15" Bus Wheels in fair condition

Mark Laken
Fort Collins, CO

[Chad M]

I have the same welder and have been using the weld thru primer with similar results. I would have thought that 20-25 was too high. When I first got the welder I fooled around with the gas pressures and I could have sworn the argoshield was messing with the weld until I turned it down to around 12-15. I think the best advice here is to make sure that primer is cleared out around the hole to be filled. They should call it "weld near primer" cause that's when it works the best. Maybe when you're welding heavier metal and you can afford to be in the 3+ heat range it can be burnt off with very little bother to the weld.

[volksaddict]

That first weld spot has to be the back panel, not the part with the hole in it. The weld wants to attach to the hole part cuz it's nice bare metal, then it just fills the hole without getting into the other piece. I use a hole a bit bigger than 1/8"

[Big Jim]

1/8" is way too small for good spot welds. 1/4 is about the minimum. When you start, you want to have the wire in the middle of the hole so it arcs on the back piece and starts melting it first. Then you can carry the puddle around the edge of the hole and you will have a solid weld betwee the two pieces.

[CymonSez]

ditch the weld thru primer its crap.

[diy570]

[CymonSez]

not a matter of corrosion the state mandates it for repairs here to cover bare metal so we just make sure we paint the entire weld area. Its a bit of a pain sometimes but the primer doesnt weld correctly and that could be more of a problem later (like when your repair comes apart). If your only worried about the corrosion.. fog the part with a good sealer and paint.

[diy570]

[marklaken]

i don't even think weld-thru primer is all that tough to work with...just a little more prep time and clean up time...turn up the voltage and go...so it pops and stinks...wear eye protection and a welding mask and you should be okay....buy a die grinder with bits for $10 at harbor freight and clean up the mess...no biggy...the whole area will be masterseries'd, primed and repainted and then the floor will be installed over it anyways...

I will try 1/4" holes for the rest of my rossette welds...i didn't have bad luck with 1/8" holes, except that i got more grinding to do because the weld pool grows too fast even on the lowest wire speed with my mig setup...penetration and strength seem good to me, though...
_________________
Wish List:
1967 Wesfalia SO-42 Parts Needed: Kitchenette, Cot Poles

'65 rear left beetle fender

15" Bus Wheels in fair condition

Mark Laken
Fort Collins, CO

[Mr. Bungle]