welding tips please

Post by **Cam** » Tue Nov 23, 2004 4:34 pm

You can weld Ally with AC MIG (not brilliant but it's possible) although TIG is far superior.

I did not know that the good quality machines used smoothed outputs! I would not like to see the size of the capacitors!!

Post by **Alec** » Tue Nov 23, 2004 5:11 pm

Hello Cam,
modern electronic power units these days are very sophisticated, and bearing in mind the portable sets are usually single phase I would imagine that it is thyristor switching rather than capacitors. I must admit to guessing a bit here but there has been a huge advance in variable A.C. and D.C solid state generation in the last few years.
Not as visibly impressive, however, as a mercury arc rectifier, which incidentally was often 6 phase to aid smoothing.

Alec
P.S. seem to have got a little off topic.

Post by **Cam** » Tue Nov 23, 2004 5:31 pm

modern electronic power units these days are very sophisticated,

Oh yes I am aware of that......... I was not aware that the technology had got as far as welders!!

Hell of a thyrisor though to switch such a huge current with a reasonable duty cycle. I know it's VERY possible though (technology wise) as my mate works in power line design as has done a lot with thyristor switching / phase compensation.

Post by **Alec** » Tue Nov 23, 2004 6:05 pm

Hello Cam,
just did a quick look on RS, http://img-europe.electrocomponents.com ... 652-01.jpg 90+ x 30+ x30 mm 130\160 amp thyristor.

Alec

Post by **Cam** » Tue Nov 23, 2004 8:15 pm

Not cheap though I bet!! My mate did some REALLY high current stuff, but it was a proper research project externally funded so cost was not a problem.

Post by **Alec** » Tue Nov 23, 2004 9:06 pm

Hello Cam,
I didn't price them, but considering the sets I'm refering to are about £500 (I think) you can buy an equivelant rated (a.c.) welder for probably a 10th ot maybe a bit more of the price. What is so good about them is they are so light so portable. Where I work you could be carrying them 40 or 50 metres from floor level that counts.

Alec

Post by **Cam** » Tue Nov 23, 2004 9:10 pm

Where I work you could be carrying them 40 or 50 metres from floor level that counts.

Yeah, that reminds me of my dad's old works stick welder - years ago! It was about 2 foot cubed!! (basically a massive transformer). It took about 4 big blokes to lift it!!! I don't think you would be carrying that up scaffold!!!

Post by **Alec** » Tue Nov 23, 2004 9:34 pm

Hello Cam,
good old Oxford or the like, oil cooled, as you say a huge transformer. I bet there are plenty still around, still working well, bit like a Minor really

Alec

Post by **Cam** » Tue Nov 23, 2004 9:37 pm

Not sure of the name, but yes it was oil cooled - jogged memory!

Probably are plenty around and why not? If it does the job!

Post by **lowedb** » Thu Nov 25, 2004 8:03 am

Hi again.

I'm fairly sure the rectifier is in the main output. It's a bit big to be just supplying the feed system. I'm fairly sure it was full wave, not just half wave.

I'll double check and take some photos if I get any time in the garage.

Post by **chickenjohn** » Tue Dec 07, 2004 9:15 am

Hi Grainger!,

are you the same one on the SOS forum with the same name and traveller??? Must be!!

I was in almost the same position as you- traveller needed welding, needed to learn to weld! In fact thats what i've been doing the last 3 months. Cutting, shaping metal, welding...

First of all- don't get a gasless welder- I've heard they are crap, the Clark turbo 250 te is a good one, 150 amps gives plenty of power in reserve.

I'd say you also need to get a few other things:-

1. pub gas bottle- can be refilled for ~£20 (needs a regulator-about £50 ish)
2. angle Grinder with cutting discs (I like 1mm cutting discs)), and grinding disks.
3. decent weldin g helmet, by that I mean an automatic one that darkens when you strike the arc- well worth the £100.
4. Decent leather gauntlets.
5. decent fire retardant cotton overalls
6. fire extinguisher
7. a spot weld cutting drill is ideal if you decide to remove the whole inner wing.
8. Lots of clean degreased steel of about 1mm thickness to practise on.

It took me about two years of occasional practise, and lots of asking tips and advice from professional welders in the local MM club, before I felt confident enough in my welding to work on my car.

Practise lap welds (a small overlap between the two pieces of steel to be welded) to start with as they are easier to master without blowing holes. Then try butt welding. (where the two edges of the pieces are "butted" together).

On the turbo 150 TE, I set the voltage to 2/ minimum for thin metal (inner wings etc) and two maximum for thicker stuff (chassis). wire speed to around 4. Don;t overtighten the wire feed rollers, set the co2 on your regulator so when you pull the trigger you can just hear it hiss. Use 0.6mm mig wire and 0.6mm contact tips. Have a supply of contact tips because they do knacker up and need replacing.

Steel needs to be absolutely clean and de greAsed and free of paint, underseal, rust, waxoyle ect before welding it. I use a rotary wire brush attachment on my grinder which takes everything off in seconds, leaving you with bare steel. If there is an overlap or you are welding the last piece closing a box section, then use weld through primer (available from frost.co.uk) this is zinc based and you need to let it dry before welding with it.

What else?? dont try to weld to pitted metal, even if all the rust is removed, as you will end up blowing holes.

Take your time, and don't skimp on materials, equipment or preparation time!

I'll post more when I think of it.

cheers

cJ (na)

Post by **Cam** » Tue Dec 07, 2004 10:17 am

Use 0.6mm mig wire and 0.6mm contact tips.

Really? I find that 0.6 is prone to jamming (and not in a Bob Marley sense!). I use 0.8 and find it much better. I also use a Teflon liner to help with the wire feeding too.

Like you I use 2/minimum but set the wire speed to around 2 or 2.5 (probably due to the thicker wire I use).

Automatic welding helmets are good and very useful (especially if you have your head in funny positions), but they are not an absolute nessecity. I have been using a conventional flip type for years with no real problems.

Post by **rayofleamington** » Tue Dec 07, 2004 10:43 am

Really? I find that 0.6 is prone to jamming (and not in a Bob Marley sense!). I use 0.8 and find it much better. I also use a Teflon liner to help with the wire feeding too.

I got fed up to the back teeth of jammed wire when using 0.6 (it welded to the inside of the tip, then the tip became damaged and it all gets worse, until you can't free the wire from the tip and you start again with a new tip) .

After switching to 0.8 it has been a complete dream in comparison, so I'll second Cam's comments. (I wouldn't even use 0.6 wire and tips anymore even if they were free)

The wire speed settings are completely different with thicker wire but it doesn't take long to guess the new settings.

Post by **bigginger** » Tue Dec 07, 2004 11:51 am

And I'll third them. I'm hardly the best welder in the world, but with 0.8 at least some of my welds are adequate!
a

Post by **guydenning** » Tue Dec 07, 2004 3:30 pm

corr - i feel like a naughty boy whose snuck into the broom cupboard to listen in at a masonic meeting. the start of the thread i thought - yeah - i wanna learn to weld. at the end of it i just realise the danger of 'a little bit of knowledge'. if in doubt had it over to an expert - i'll stick with that i think. or araldite. i used to be able to fix anything on a vespa with araldite...

no?

Post by **Relfy** » Tue Dec 07, 2004 3:50 pm

O Bosh. If I can have a go, then so can you..... mind you I havn't actually picked up a welder yet....... just watched the videos!!

Post by **bigginger** » Tue Dec 07, 2004 3:57 pm

Araldite? Nah mate, gaffer tape!
a

Post by **grainger** » Tue Dec 07, 2004 5:06 pm

hi to chickenjohn, nice to see you over here mate ... lots of good stuff there, cam and others have already said its best NOT to get a gasless mig ... there is the question of expense, but this week as the traveller is on the verge of being really finished, ive found two more major points that will have to be welded beside the rear wheel arch. that is the front bumper support where it goes through the arch, and the two b posts. now if i hand this over to a welder its going to cost a couple of hundred quid, so i might as well save up a little bit longer and invest in one like cams got ..

to see you nice
gr

Post by **bigginger** » Tue Dec 07, 2004 5:16 pm

Ha ha! Finally had a couple of hours of consistently good welding this afternoon. Here's hoping that whatever 'finally clicks' after hours and hours and hours and hours of practicing has 'finally clicked'!

a