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Author: Subject: 1mm sheet butt weld practice
nick205

posted on 7/2/14 at 09:16 AM Reply With Quote
1mm sheet butt weld practice

Hi All,

Been practicing butt welding some 1mm sheet in preparation for my 205 restoration project. Photos show front, then back. I'm quite pleased with the look of the welds using the stop/start method. It certainly feels strong enough and bends the surrounding metal before the weld.

Any feedback or tips would be welcome please.










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DW100

posted on 7/2/14 at 09:37 AM Reply With Quote
Better cleaning of the metal would help, you want bright shiny metal.

When doing panels place a few spot welds along one edge, tap into shape for a good fit and continue until it is spot welded at about 1 inch gaps all round, then fill in the gaps a bit at a time. Don't get too much heat into it or you will distort the panel.

[Edited on 7/2/14 by DW100]

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nick205

posted on 7/2/14 at 09:40 AM Reply With Quote
The metal is Zintec and I've had conflicting advice about grinding it clean before welding. Some say yes others say no! Logic says leave the Zintec coating in place for the best corrosion protection. Might have a go at grinding it clean tonight.






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Davey D

posted on 7/2/14 at 10:09 AM Reply With Quote
Looking at the name Zintec, i presume it has a zinc/galv coating on it? if so, then you want to grind it off to get the best weld penetration, and finish. Also welding zinc plated/galv steel risk getting metal gas poisoning from the burning zinc fumes as you weld.

You can see the zinc burning off around the weld you have done ( the white deposits at the side of the weld). Did you weld that with CO2 gas? as the weld looks quite dark, and there is a lot of brown scorching around the weld too

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Minicooper

posted on 7/2/14 at 11:25 AM Reply With Quote
There is no problem welding zinctec without removing the coating, the coating is incredibly thin unlike galvanizing. I have welded through that stuff for 30 years plus.

Zinctec has the same fume exposure levels as steel, use milk as it protects you from any excess zinc exposure, as with any welding make sure the job is well ventilated

Cheers
David

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nick205

posted on 7/2/14 at 11:47 AM Reply With Quote
Two contrasting views on the grinding issue ^^^ similar story on the MIG welding forum too.

Speaking again with our metalwork supplier this morning, their operators don't grind off the coating, just weld through it. They have fume extraction, but nothing over and above what they have for plain mild steel.

I'm going to continue with the coating left in place.

Welding with Argoshield at around 10l/m - worht trying a higher flow rate perhaps?






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DW100

posted on 7/2/14 at 12:08 PM Reply With Quote
The answer then is what you are happy with, try a few practise welds after cleaning the metal and a few without. The key to preventing future rust is proper prep and priming, the zinc coat is already burnt off near the weld so is not going to protect that area. I have seen plenty of weld repairs where the patches have rusted through after 12 months due to poor protection from the elements.
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JAG

posted on 7/2/14 at 12:39 PM Reply With Quote
I was warned about this issue when an Apprentice...

quote:

gas poisoning from the burning zinc fumes as you weld



You'll see Yellow fumes coming off during welding - don't breath them in!

[Edited on 7/2/14 by JAG]





Justin


Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!

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owelly

posted on 7/2/14 at 12:47 PM Reply With Quote
+1 for not grinding the coating off. Welding galv'd material is very different to this stuff. If you weld galvanised steel without cleaning back to bright metal, you get the whispy fluff coming off and the fumes make your fillings taste funny. Then you fall over and die. Probably.





http://www.ppcmag.co.uk

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r1_pete

posted on 7/2/14 at 01:23 PM Reply With Quote
I'm not getting into the weld through coating debate,
but,
You'll find the car tin is less than 1mm, to help prevent distortion and burn through, try clamping a strip of scrap aluminium sheet on the back of the weld, it will soak away excess heat. I've welded outer body panels using this method and have needed next to no filler to correct the finish. See my E Type pics for the type of welds I've had to do.

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Mark Allanson

posted on 7/2/14 at 02:26 PM Reply With Quote
quote:
Originally posted by owelly
+1 for not grinding the coating off. Welding galv'd material is very different to this stuff. If you weld galvanised steel without cleaning back to bright metal, you get the whispy fluff coming off and the fumes make your fillings taste funny. Then you fall over and die. Probably.


You get zinc fever, like a really nasty cold - instantly. The cure is to drink 2 pints of milk.

Zintec coating is so thin that it won't make any difference to the weld or your health





If you can keep you head, whilst all others around you are losing theirs, you are not fully aware of the situation

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907

posted on 7/2/14 at 06:05 PM Reply With Quote
IMHO

Breathing in zinc dust while grinding is just as bad as breathing in zinc fume while welding.


There seems to be a belief that if you grind it off you are safe.


ventilation ventilation ventilation

Paul G

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nick205

posted on 7/2/14 at 06:26 PM Reply With Quote
quote:
Originally posted by r1_pete
I'm not getting into the weld through coating debate,
but,
You'll find the car tin is less than 1mm, to help prevent distortion and burn through, try clamping a strip of scrap aluminium sheet on the back of the weld, it will soak away excess heat. I've welded outer body panels using this method and have needed next to no filler to correct the finish. See my E Type pics for the type of welds I've had to do.



The ally trick certainly helps. That's what I was welding on last night and you can see whee it draws away heat straight after the weld.






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jacko

posted on 7/2/14 at 07:36 PM Reply With Quote
quote:
Originally posted by 907
Breathing in zinc dust while grinding is just as bad as breathing in zinc fume while welding.


There seems to be a belief that if you grind it off you are safe.


ventilation ventilation ventilation

Paul G

+1 Ventilation
I had to weld a lot of galv steel years ago and was very sick and off work for a few days, drink milk and use a face mask
jacko

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GRRR

posted on 7/2/14 at 09:17 PM Reply With Quote
quote:
Originally posted by nick205

Welding with Argoshield at around 10l/m - worht trying a higher flow rate perhaps?


I'm doing a restoration course at the moment, suggested flow rate for MIG is 12-14lpm as a guide

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Minicooper

posted on 8/2/14 at 12:36 PM Reply With Quote
Here is a health and safety data sheet for zintec sheets


http://www.insulationgiant.co.uk/webimage/500000/530000/535000/535316-C-535316.pdf


Cheers
David

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hkp57

posted on 8/2/14 at 01:15 PM Reply With Quote
Another note away from Zinc

I noticed in your picture some of the filler metal on the reverse side was flat, this would make me think you had the test piece flat and on a metal surface.

Being flat against a big metal surface (heat sink) will give you false hope.

Try the same test piece held in a vice in various positions from flat through 45deg to verticle.

Then do it from underneath to simulate overhead welding, you will have to deal with all positions welding a car.

Results may surprise you.

For welding thin material see if you can find a piece of heavy copper flat bar like used in high voltage terminal boxes.

Where possible when welding your car, clamp it behind your weld area.

Makes a great heat sink and stablises the metal when welding in awkward positions, above all don't try to weld to much in one pull of the trigger, it will end in tears and ultimately inaminate objects being thrown at high speed accross your workshop.


Edit :- Just notice the bit back up your thread about using a piece of Alloy as a heat sink.

[Edited on 8/2/14 by hkp57]

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