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.
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]
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.
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
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
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?
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.
I was warned about this issue when an Apprentice...
quote:
gas poisoning from the burning zinc fumes as you weld
+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.
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.
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.
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
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.
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
quote:
Originally posted by nick205
Welding with Argoshield at around 10l/m - worht trying a higher flow rate perhaps?
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
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]