Metal thickness

Discuss Bodywork problems here.
Forum rules
By using this site, you agree to our rules. Please see: Terms of Use
cadetchris
Minor Legend
Posts: 1182
Joined: Wed Aug 12, 2009 7:38 pm
MMOC Member: Yes

Metal thickness

Post by cadetchris »

I am just about to start a lot of welding on my minor but I am still to buy the metal I’ll be using.
What thickness of steel should I use?
mogbob
Minor Legend
Posts: 1280
Joined: Thu Apr 02, 2009 3:43 pm
Location: Esher
MMOC Member: No

Re: Metal thickness

Post by mogbob »

Sheet steel....First a warning , avoid galvanized steel - it gives off poisonous fumes....so even if it's offered free decline.
Try and pick up sheet steel off cuts from a Metal Fabricating Firm on the local Trading Estate. " I just need a few off cuts , as I'm teaching myself to weld and I've got to practice on something " sort of line. You never know you're luck ,even if you offer to pay.

Classic car metal is circa 1mm 19swg grade but most Steel Stockholders only carry 20 swg = 0.914 mm which is OK for most things. It's all " nominal " sizing , so if you're able to measure before you buy , opt for the closest to 1mm.
The thicker it gets , the more difficult it is to shape / bend and cut.

If a thicker piece is required for more " structural " stuff ( Always try to replace like with like ) e.g chassis legs /parts / floors then 16swg = 1.5/ 1.6 mm or 14 swg = 2mm , might be required.
Welding Supply stores often hold small sheets ( convenient and sometimes just a little more expensive - check .
(If they don't stock themselves , they will usually be able to point you in the right direction of a local supplier ).

Don't always assume that DIY is the easiest / cheapest / most convenient solution to your bodywork repair / replacement. Morris Minor specialist suppliers have developed a large number of convenient repair panels to sort out all the known problem areas.
Consider 1.your expertise ( that will improve with practice and time ) 2.time available 3.Is there a convenient repair panel available off the shelf that will cover the whole repair area. 4 Is it a complex shape to replicate from scratch.5 Cash available , if it's safety critical don't stint !

I won't promise that every panel doesn't need fettling in some way to achieve a perfect fit but that's life !

Just study the part of the car carefully , measure carefully from sound , clean metal and compare to the suppliers website photos of the panel / panels available. Work out the fabrication order.. you can't weld to thin air...don't cut out all the rusty metal in one go. You need measurements and datum points to get it all back in the right place and alignment ( especially steering / suspension / door and boot openings, etc ).

Have fun with it , the sense of achievement is tremendous , spend valuable prepping the metal and degreasing it. Meths in a spray bottle and a rag / paper towel works a treat ! Keep the Meths away from sources of ignition though.
Bob
cadetchris
Minor Legend
Posts: 1182
Joined: Wed Aug 12, 2009 7:38 pm
MMOC Member: Yes

Re: Metal thickness

Post by cadetchris »

Thanks for the advice.
I was planning to use replacement panels and just use sheet steel for the odd little bit here and there.

As for the actual welding, I am getting quite good with oxyacetylene and I had intended to use that for the welding. As brazing isn’t allowed on the car, would it be recommended to use steel rods as a filler or not?

That may be a stupid question but I can braze beautifully and I can weld steel together, but I haven’t used a steel rod asa filler. So I thought it best to ask and then spend a few weeks practicing and getting up to scratch before I start hacking bits off the car and not being able to replace them.
dp
Minor Legend
Posts: 1045
Joined: Sun Aug 14, 2005 6:26 pm
Location: Southend
MMOC Member: No

Re: Metal thickness

Post by dp »

mogbob wrote: Mon Sep 23, 2019 12:26 pm Sheet steel....First a warning , avoid galvanized steel - it gives off poisonous fumes....so even if it's offered free decline.
Does this go for zintec too? I've been using this but wire wheeling the edges to be welded down to bare steel first. The zinc comes off easily so I suspect a different process to galvanizing.
Image
paul 300358
Minor Fan
Posts: 467
Joined: Thu May 11, 2017 8:23 pm
Location: South Cheshire
MMOC Member: Yes

Re: Metal thickness

Post by paul 300358 »

Galvanizing is hot dipping to coat with zinc, when welding Zintec the zinc burns off as an off white (yellowish) fluff. I would wire brush whilst wearing a breathing mask prior to welding.
IslipMinor
Minor Legend
Posts: 2147
Joined: Mon May 10, 2004 9:10 pm
Location: Oxford, UK
MMOC Member: Yes

Re: Metal thickness

Post by IslipMinor »

Oxy/Acetylene creates a lot of heat and will very likely distort body panels. MIG is very much better for body and thin gauge metal welding.

During the 1990's I replaced the whole perimeter of the floor pan (sills, chassis rails, inner wings, rear boot floor, plus the central floor panels and the crossmember), using almost exclusively panels from Charles Ware and found that with a little fettling they fitted pretty well. Generally they were not as thick as the original, but 20+ years on the underframe is still very solid. They do NOT fit like a modern car and DO need the welding to fill in the gaps, so I would not want to gas weld - the heat is just too much, let alone the fire risk of any trim, glue etc. that inevitably will be left after even the most careful strip down.

As for sheet metal oddments, I would suggest getting some 1mm (20g), 1.5mm (16g) and 2mm (14g) pieces to use where required. I don't know what the current repair panels are like, but I didn't find much requirement for 'in-fills'.

Good luck with the welding work, and please keep the Messageboard updated with progress!
Richard


cadetchris
Minor Legend
Posts: 1182
Joined: Wed Aug 12, 2009 7:38 pm
MMOC Member: Yes

Re: Metal thickness

Post by cadetchris »

Humm, I had a feeling that too much heat would be a thing.
Tbh as it’s the floor and I’m not too bothered about it being slightly rippled.
I’m slightly loathed to get a mig welder as I was never really any good with it, though I’ve never tried TIG welding so that may be an option, though the oxyacetylene would have to go to fund it, either that or the treadle lathe.

So anyone who has a tig welder and would like a lovely working treadle lathe or an oxyacetylene kit with half a huge bottle of acetylene, then let me know.

If not, I’ll have to have a sit down and think.
IslipMinor
Minor Legend
Posts: 2147
Joined: Mon May 10, 2004 9:10 pm
Location: Oxford, UK
MMOC Member: Yes

Re: Metal thickness

Post by IslipMinor »

MIG not TIG. MIG is reasonably straightforward to get to an acceptable standard, and creates the least heat of all the welding processes. It is also less cost, but don’t tempted to go ‘gasless’ as fluxed wire can get very messy.
Also get proper 95% argon mix and NOT CO2.
Richard


oliver90owner
Minor Legend
Posts: 1653
Joined: Thu May 12, 2016 6:33 am
MMOC Member: No

Re: Metal thickness

Post by oliver90owner »

Well, I am going to disagree (a bit) with Richard.

Most certainly MIG is used extensively for thin bodywork repairs these days. However, gas welding is a viable option for panel work, but requires a good deal more skill to effect an equivalent repair. I’m not an expert welder and have generally had a proper welder to do important structural jobs. Bodywork is different to chassis work, but MIG is generally good enough for most welding on vehicles.

I was lucky to work at a place where these skills were available. Whatever system (MIG, gas or stick with appropriate ‘tin plate’ rods) is used, the job can be done effectively. MIG is just faster, easier and more convenient as most bodywork joints are not classed as a likely high failure risk.

My stock of tin plate rods has diminished to almost zero and I don’t even know if they are easily available these days. One needs a good stick welder to operate consistently at the low current settings used. Most cheap ones are fairly useless in this respect.

First question might be whether or not the body shell is completely free of anything that is combustible, in the area of welding.
paul 300358
Minor Fan
Posts: 467
Joined: Thu May 11, 2017 8:23 pm
Location: South Cheshire
MMOC Member: Yes

Re: Metal thickness

Post by paul 300358 »

cadetchris
Minor Legend
Posts: 1182
Joined: Wed Aug 12, 2009 7:38 pm
MMOC Member: Yes

Re: Metal thickness

Post by cadetchris »

Having had a bit of a think and done some research over the past few days, I’ve decided that a mog welder for the thin stuff I’ve got to weld would be an easier way than blowing holes in everything with gas.
As I sold my mig welder last year (typical) I am going in invest in a new one. Which brings me to a supplementary question, gas or gasless mig?

I could never get the gas one to work properly, so I’m learning towards gassless, but what are others opinions?
Myrtles Man
Minor Legend
Posts: 1081
Joined: Wed May 16, 2018 10:49 pm
MMOC Member: Yes

Re: Metal thickness

Post by Myrtles Man »

cadetchris wrote: Sat Sep 28, 2019 9:04 am ...I’ve decided that a mog welder for the thin stuff I’ve got to weld would be an easier way than blowing holes in everything...
Sounds to be tailor-made for working on our cars - where do you get 'em from? :D
IslipMinor
Minor Legend
Posts: 2147
Joined: Mon May 10, 2004 9:10 pm
Location: Oxford, UK
MMOC Member: Yes

Re: Metal thickness

Post by IslipMinor »

Oliver,

I have not come across 'tin plated' welding rods, what are they used for? The usual plating for steel welding rods or wire is copper.
Richard


cadetchris
Minor Legend
Posts: 1182
Joined: Wed Aug 12, 2009 7:38 pm
MMOC Member: Yes

Re: Metal thickness

Post by cadetchris »

A mog welder would certainly be a good and appropriate welder, but I fear that my dyslexic fingers have made a typo, so it was meant to be a mig welder.

As for tin plated electrodes,I’ve never heard of one of those either.
IslipMinor
Minor Legend
Posts: 2147
Joined: Mon May 10, 2004 9:10 pm
Location: Oxford, UK
MMOC Member: Yes

Re: Metal thickness

Post by IslipMinor »

I bought a SIP Autoplus 130A MIG welder 25+ years ago when we started the Minor's restoration in 1992, and it is still being used well today.

From that experience I would suggest:
  • 130A as a minimum - old adage of 1A per 0.001" material thickness. So fine up to 3mm, 0.125" or 10g material.
  • 0.8mm wire and tip (good down to 40A for 1mm material). For very thin material use 0.6mm wire and tip.
  • Use Argoshield 'Light' gas or equivalent, but NOT CO2.
  • Use a 'proper' size bottle and regulator - the throw away cans are desperately expensive! I used to use BOC, but they kept increasing the annual rental, so have changed to Hobbyweld 5, which is either identical or very close in spec.
  • Non-live torch - sounds insignificant, but just try using a 'live' torch, and you will see instantly why 'non-live' is SO much easier to work with.
  • An 'auto-darkening' face mask - leaves both hands free to control the welding torch! They are not expensive - around £30.
MIG welding is not tolerant of weld area contaminants - rust, oil etc. Good metal preparation is essential. If the welding process does not sound like sizzling sausages, there is something wrong!

I have no experience of 'gasless' MIG, but have heard that it does not work well on thinner gauge materials, i.e. typical Minor panels, and creates a fierce arc with a lot of smoke. The advice seems to be get the suppler to demonstrate on a piece of 1mm or less material.

To a large degree, like many things, you will get what you pay for. As a rule, a good brand will give good service, and also be more saleable afterwards.

If you are anywhere near the Oxford area, pop in and have a play with my MIG welder.
Last edited by IslipMinor on Sat Sep 28, 2019 5:28 pm, edited 1 time in total.
Richard


IslipMinor
Minor Legend
Posts: 2147
Joined: Mon May 10, 2004 9:10 pm
Location: Oxford, UK
MMOC Member: Yes

Re: Metal thickness

Post by IslipMinor »

As a more general comment on Minor panel replacement, I did not try to replicate the original spot welding with either spot welding again or plug welding. After tacking, checking, checking and checking, all the joints were 'double seam' welded throughout the bodyshell. After some dressing with the angle grinder, the results are very neat strong joints, and of course they are completely sealed from the elements.

The whole shell was thoroughly cleaned before painting and very well prepared by the paint shop, undersealed everywhere underneath, so today 21 years and 60,000+ miles after completion there is no rust anywhere. It often goes out in the rain, but practically never when the roads are salted and lives in a dry, frost-free garage, but is definitely not mollycoddled!
Richard


paul 300358
Minor Fan
Posts: 467
Joined: Thu May 11, 2017 8:23 pm
Location: South Cheshire
MMOC Member: Yes

Re: Metal thickness

Post by paul 300358 »

The problem with co2 is that you need a heater or the regulator will freeze. The main problems people have is trying to mig weld in a draught, standing on the main lead, kinking the lead or using outside in the breeze, all of which will remove the gas shield. Gasless requires the filler wire to be kept dry.
When purchasing welding equipment, its like purchasing any other tools, you often get what you pay for. I have a R-Tech tig welder and its excellent for both tig and arc. My head shield cost over £80 and the filter is adjustable.
There are some interesting videos on the R-Tech web site.
mogbob
Minor Legend
Posts: 1280
Joined: Thu Apr 02, 2009 3:43 pm
Location: Esher
MMOC Member: No

Re: Metal thickness

Post by mogbob »

Unless you feel you have a real need for " gasless " , I would opt for gas MIG welding every time for car body work.Argon mix gas will deliver the cleaner weld.
I wore out my old SIP gas / gasless Mig welder after 25 years and had to retire it after sterling service. I did replace it with another gas / no gas welder but only because I sometimes have to do some outdoor " heavy
metal " welding repairs e.g. large steel gates / large metal fire escapes / building's vehicle protection corner
metal cages. ( There are some car drivers who try to demolish the brickwork as they attempt short cuts , driving around ).
Fantastic for thick metal , when you can crank up the power but much more difficult using gasless for car panels. I always switch my welder back to "gas ". Much more subtle and with practice , good results every time.
Bob
cadetchris
Minor Legend
Posts: 1182
Joined: Wed Aug 12, 2009 7:38 pm
MMOC Member: Yes

Re: Metal thickness

Post by cadetchris »

Well, after reading all the very helpful posts, it’s obvious that I’m out of my depth so I’ve gripped the bull motif by the wing mirrors and enrolled on an 8 week (Thursday evenings) welding course. But if a hike every Thursday, but I know it will be worth it
IslipMinor
Minor Legend
Posts: 2147
Joined: Mon May 10, 2004 9:10 pm
Location: Oxford, UK
MMOC Member: Yes

Re: Metal thickness

Post by IslipMinor »

Where is the course being held? I bought a TIG welder a little while ago, and have been trying to find a part-time TIG welding course somewhere near(ish) to Oxford, but no luck so far.
Richard


Post Reply