MOT Welding Standard

newshound laid this down on his screen :

I first tried stick welding long ago and can make a respectable job on that, but struggle much more with MIG. The secret with either, seems to be practice and confidence. An auto-darkening faceshield helps a lot too.

Think I've tried everything. Was told my welder - a best buy in a hobby mag - was rubbish. So changed the motor speed controller to a PWM type to keep the speed consistent at low feed speeds. Did make a very satisfactory job of welding thicker ally and stainless steel with it, though.

Could be because I do so much soldering. ;-)

Stainless with a MIG/MAG? While ally can be done by MIG I thought TIG was a prerequisite for stainless?

Got some stainless wire from Halfords. Welded a bush for an O2 wideband into a SS exhaust - off the car. Seemed to make a pretty decent job - it's still there years later. Of course it may not be as strong as TIG.

Thanks, I have a MIG welder but never used for anything other than steel. It's very old and I'm sure a more modern unit would assist in better quality welds. I'm trying hard to find an excuse to buy a TIG machine :-)

Yup. When I built the kitcar (30+ years ago) I quickly found the factory 'universal' side exit SS exhaust was way too loud for my tastes and so bought a stock 'Grundy' (?) SS system for a Mk2 Escort Saloon, shortened it by 10" to suit the kitcar wheelbase and re-welded it with std steel wire on a MIG welder and it's all still on there now. ;-)

I'm not sure how much stronger mine would have needed to have been if it's already lasted 30+ years. ;-)

Cheers, T i m

A good starting point would be a high speed motor, PWM-controlled, coupled up to a suitable gearing system. I've thought about doing this many times myself to add a MIG facility to my big old Oxford arc welder. Seems a waste of space and money to buy a dedicated MIG inverter when there's not that much involved in adding a MIG function to a MMA welder.

Nope. They made stainless rods for MMA welders; have done for decades.

No point unless you're doing exotic metals in pristine condition that need to look pretty.

I guess all welds can be ground and dressed. But TIG gives better control over puddle creation and use of filler rod.

My recent MIG work has been a bit hit and miss, although I can wire brush to a mirror like surface I still find the deposition is still rather variable. I could blame my welder of course!

I'm waiting to hear if it passed?

Mike

So am I. My Dad's car has just gone to the garage for 2 new wings and the sills welding.

I'm surprised it's worth the cost of doing that - unless a classic.