pinholes in plug welds

[stuartsports05051985]

hello, so as my car floor repairs continue today, i was trying some plug welds, they looked really good until o ground them down, some had little pinholes in them, whats the main reason for this?

 

[Omniata]

Contamination?
What wire were you using and which gas?

 

[nickk]

porosity,harmful contaminants,such as oil underseal,a draft wafting across during welding,interruption in gas flow-is your nozzle & tip area clean is your regulator providing continuous gas flow? its likely that whatever caused the porosity, rectified itself during the end of the weld & so didn't show until you ground thru that top layer of weld.

 

[stuartsports05051985]

Contamination?
What wire were you using and which gas?

0.6mm clarks finest, newish roll, clarks finest argon/co2 mix

 

[stuartsports05051985]

porosity,harmful contaminants,such as oil underseal,a draft wafting across during welding,interruption in gas flow-is your nozzle & tip area clean is your regulator providing continuous gas flow? its likely that whatever caused the porosity, rectified itself during the end of the weld & so didn't show until you ground thru that top layer of weld.

i was using weld thru primer on those panels, could well be regulator

 

[Omniata]

0.6mm clarks finest, newish roll, clarks finest argon/co2 mix

Little cans of gas?
If so really not a good idea IMHO.

 

[stuartsports05051985]

Little cans of gas?
If so really not a good idea IMHO.

how come? are they junk?

 

[nickk]

i was using weld thru primer on those panels, could well be regulator

place the nozzle close to your ear & hold the trigger on for 60 seconds & check you have continuous gas pressure/flow.

 

[mike 109444]

"i was using weld thru primer on those panels, could well be regulator"
Think you will find that's the cause. Remember the metal is going from stone cold to melting in a fraction of a second and any crap/contamination will try and boil off BUT you are filling it's escape rout! so it forms voids. You could try upping the power (for the spotting) then reset back for normal welding.

 

[Omniata]

how come? are they junk?

They contain barely anything unfortunately, you'd be better off asking your local if you could borrow a bottle of CO2...

 

[stuartsports05051985]

ok,

so should what gas should i be asking for, co2/argon mix again?

 

[Omniata]

Either mix or pure CO2, both will be fine, pure CO2 will be cheaper though if you get on well with the landlord at your local pub...

 

[mike 109444]

Note you will also req a suitable new regulator if going to full size bottle and connection/adapter for your pipe work

 

[stuartsports05051985]

ok cheers, was looking online to see whats local and i notice there is a hobbyweld distributor.

Would hobbyweld 5 original be suitable? yeah will need to but a regulator from somewhere....

 

[Omniata]

Go for it, 5 will be fine, get a flowmeter with the reg too

 

[Parm]

Either mix or pure CO2, both will be fine, pure CO2 will be cheaper though if you get on well with the landlord at your local pub...

I use my local pub supplier for CO2, they will do cash sales with joe public. 15 quid deposit for the bottle (refundable) and 15 quid for a refil

Google will be your friend to locate a cellar goods supplier in your area

 

[stuartsports05051985]

ok so got some hobbyweld5, new reg and done a quick test on some scrap, seems much better.

also i have been using one of the clarke air hole punches, but the hole measures around 5mm. i was sure i had read a 7mm hole was preferable for plug welding?

 

[mike 109444]

I find there hole punch (I have both the air and manual ones) have to small a diameter at 5mm. As you say a 7 to 8mm is better IF you have enough of an edge to put that size of hole in. What I sometimes do is punch two holes over lapping this gives an elongated but more of a hole to weld into. Or I may punch the holes then open them out (if I am happy with there positioning) using a stepped drill and this can leave a nice counter sink to the top plate.

 

[Mee]

I use my local pub supplier for CO2, they will do cash sales with joe public. 15 quid deposit for the bottle (refundable) and 15 quid for a refil

Google will be your friend to locate a cellar goods supplier in your area

That seems a bit steep, round here they charge around £10 for a refill at the local.

 

[Parm]

That seems a bit steep, round here they charge around £10 for a refill at the local.

Where is round here ?