Plug weds

[moggie1947]

Hi,
First post, but been lurking on here for some time.
I am returning to welding after a long absence now that I have a rusty Minor to play with in retirement.
Just bought (on trusted advice) a Portamig 185, and having blagged some new steel sheet off cuts from a friendly local fabricator. Been experimenting all day with this lot, and nearly there I think.
However, although fairly happy with edge welds, I am having trouble with plug welds which spring apart a soon as I release the grips. Problem seems to be lack of penetration, but when increasing time/voltage/wire speed etc I keep blowing through the two sheets.
Am I right in aiming the initial strike should be in the centre of the drilled hole, and moving in a circular
motion, or are my settings out?
This type of weld is important to this application, as I have to fix a large panel with access from outside only.
Thanks in advance.
John

 

[gordon stephenson]

What size hole are you drilling in the front plate, If practicing try starting with something like 8mm, then arc in the centre of the back plate and then circular motion as you describe above,

 

[Kent]

firstly are the prepped welds free from oils and the sheet free from coatings or treatments? Next up is your settings you need them quite high to do this well. its an easy weld to perform too cold as there isn't much time before you have filled a small hole with a big heat sink capability in the lower sheet

 

[moggie1947]

Ah, maybe my holes were too small at 4mm, but flanges that I am going to weld through are only 10mm, do you still recommend 8mm? or do you mean just for practicing?
The material is brand new stuff, clean but may have preservative coat which I will now grind off.
Don't go away you two--I have to get this car ready for next weekends Rally!!!

 

[BChild]

Now I had the same trouble when I started doing plug welds - 6mm hole in top 16 guage steel and same steel behind it - hit the centre and then round and round and I kept blowing the centre of the back sheet out before I'd finished the plug weld I think I just wasn't going quick enough for the power levels.

I changed the method hit the outside edge first and round and round finishing in the centre so I had more heat soak at the start - no more holes
and nice strong plug welds

This helped me till I got the hang of the speed thing and now I'm happy to do them either way

 

[BChild]

Oh and 6mm is what I use to plug weld an outer sill onto a middle sill - approx 10mm lip to play with - a mate does them with 4mm holes but I prefer 6mm as they end up flatter plugs

 

[BChild]

I'm also using a Portamig 185 but I'm cautious about sharing settings as from experience in other threads they aren't the same but for 16 guage on 16 guage with a 6mm hole for the plug I'm using 0.8mm wire and Coarse 1 Fine 2 or 3 depending on ambient (winter time definately 3 summer and I can drop to 2 or just work faster) and wire speed around 5.5

Like I said the machines do vary a little maybe not so much the power level but wire speed for sure where I use 5 another Portamig owner I know would be up in the 7 mark.

 

[doubleboost]

This may help

 

[Cobbler]

The first time I tried plug welds it was a complete failure, I used the hole punch on a joddler to make the holes, you would think that it would be the correct size as that is what it's made for, but it's far too small, the hole is filled up before its hot enough to penetrate I found. Drilled bigger hole & much better.

 

[moggie1947]

I'm also using a Portamig 185 but I'm cautious about sharing settings as from experience in other threads they aren't the same but for 16 guage on 16 guage with a 6mm hole for the plug I'm using 0.8mm wire and Coarse 1 Fine 2 or 3 depending on ambient (winter time definately 3 summer and I can drop to 2 or just work faster) and wire speed around 5.5

Like I said the machines do vary a little maybe not so much the power level but wire speed for sure where I use 5 another Portamig owner I know would be up in the 7 mark.

Thanks for advice to all--comforting to hear I am not alone in my experience.
I am using similar settings for my machine, but tried backing off the fine to 1 but made no difference. The only difference could be panel size, forgotten what 16 gauge is, as I am using 1mm?
I will try the suggestions when I have finished making yet more joining plates to fit badly fitting "repair panels", particularly the hole size, which seems to be favorite, and report back.

 

[moggie1947]

Just watched the video suggested, and it gives me another clue. I supported the sheets that I was practicing with on a piece of board,so this could have contributed to the lack of penetration.

 

[mike 109444]

The first time I tried plug welds it was a complete failure, I used the hole punch on a joddler to make the holes, you would think that it would be the correct size as that is what it's made for, but it's far too small, the hole is filled up before its hot enough to penetrate I found. Drilled bigger hole & much better.

I have found the same issue with the joggler/punch (would have been nice if it had been a 6mm punch. But if you punch two holes next to each other forming an elongated hole this works better. Easier than trying to drill sheet and avoiding the drill grabbing in the sheet.

 

[mike 109444]

Failing the above then punch with joggler/puncher and open hole out with a center drill in a slow cordless drill. Gives a nice counter sink hole