20 replies to this topic

[miniboo]

how do you spot weld sills if you don't have a spot welder?

Is it just a case of drilling a hole in one of the panels and welding thrugh that n to the bit the the panel is attaching too?

hope that makes sense!!

[cowboy]

you can use a mig welder with a special attachment to do spot welding, but i would only spot weld the lip and weld the rest propperlly myself

and i dont recomend drilling a hole and filling it with weld, though in theory it would work if done propperlly

[miniboo]

so does everyone else on here who does there own welding have a spot weld attachment?

If not what do they do?

[Jordie]

heard the drilling thing before so must be a common way.

I dont weld so cant give any more advice then that. But when you work it out, i know where to fetch my mini

[miniboo]

lol

i cant weld.........yet

i might try and teach myself though

[miniboo]

I have been looking at spot welders on ebay and they just plug into the mains!

might get one as they look well easy to use!

http://cgi.ebay.co.u...1QQcmdZViewItem

[stormduck]

I dont have a spot welding attachment on my gasless mig. By lighting up in several places along the sill you can tack it to the body. This way you can make sure it's sitting properly before completing a seam weld all along it. Forget drilling holes, just make sure the mating surface is ground down to bare metal and tack the lip against the body. Once seam welded, grind along the weld to smooth it down. For something like the sill where it's under constant attack from water, grit etc. i'd use a strong seam sealer like the one frost do in a tube. This will cover any possible gaps in the weld. Once it's painted with chassis black you're likely to see the join but if it's done right it won't rust again.

[DaveCoxon]

'Plug Welding' is highly effective when done properly. Properly is the key word. You have to ensure the parts are earthed together well, the panel with the hole is clamped up to the panel with the hole (molegrips either side) and that you have a steady hand.
Basically, you hold your nozzle so the wire is going to come out, and hit the lower panel straight through the centre of the hole on the upper panel. Easiest way to do this is by first donning a pair of welding gauntlets, then holding the Mig torch near the nozzle with one hand, the other hand on the trigger.
This way, you can make sure the wire willgo where you want.
Once the weld has started, and is working, draw back, and with a single circular motion (again, using the hand near the nozzle to guide it), basically fill in the hole.

Done properly, it is easilly as strong as a spotweld - in fact, possibly stronger.
Spotwelds are easy to screw up by an amateur. Too little current and the weld will fall apart, too much and you 'sink' into the metal weakening it.
I do have a hand-held spotwelder that i use for 'external' seams - a-panels, sill seams, wing tops, etc. But the plug welding technique is always used when i replace sills (you won't find cover sills on any mini of mine :wink: ) for welding the 'lower/inner' part of the sill to the floorpan.

[Jammy]

How big should the hole be? 3-4mm??

[Guess-Works.com]

I have a hole punch which I use, and creates a 4 -5mm hole

Like this... Clicky

[charlie croker]

Is this a restoration or for an MOT?

MOT regulations now state that welds must be continuous, so in effect a seam weld for replacement sills.

[miniboo]

how do you seam weld along the lip where it is horizontal?

[miniboo]

this is the bit i mean

[DaveCoxon]

I hate it when folks weld along there (like when coversills are welded into place).

Do the job properly, and no MOT man will fail it. Basically, if it looks original (original sills) then it'll pass.

I've done three minis in the past four years welding the sills properly. Last one, I even cut out and replaced the inner sil (ok, techically the outer floor pressing) from the doorstep right down to the horizontal of the floor. With a new sill welded over the top, with what looked like factory spotwelds, and the MOT tester commented on how solid the mini was, and how he hadn't seen one in years with the original sills.

I simply kept my mouth shut.

Incidentally, each time it's been a different MOT tester - so no favouritism there!

[Al*]

I'm in complete agreement with dave coxon on this one and I work in a bodyshop.... don't do a continuos weld like that, do things the original way.... if you don't have a spot welder then plug weld it.... as dave said, thats what I've done to my minis.

Al