Chassis Welding - Methods

[gtipping]

As part of my preparation for that time when I can start on my chassis, I have signed up to a welding evening class which will cover gas, arc, MIG and TIG.

From what I have read here and on other forums its seems that for a lot of self builders MIG is very popular. I was wondering what methods folk on here have used for welding their chassis and the reasons for their choice?

Cheers
Geoff.

[alga]

Besides MIG, people use TIG (neat, slow, expensive) and MMA (cheap, tricky).

[shh120m]

MIG,
Its easy to learn, and easy to get what i call sexy welds, where the weld looks clean and tidy with nice swirly patterns.
I would recconmend that when your learning you practice welding at difficult angles because the chassis is full of awkward nooks and crannies. I believed i could weld pretty well until i started fully welding my chassis, its kinda hard at first to weld around corners without stopping.

Arc welding is a little agricultural for the roadster chassis, but i believe one or two of the guys on here have done it succesfully. Theres loads of advice regarding welding on the forum, just have a search about.

Cheers

Nathan

[Enoch]

I did mine with arc. I have a 200 amp inverter that I used at about 85-100 amps for the chassis tubes and at about 130 ish for the largest job ie rear uprights. I had never welded before, I practiced loads before I started. I have never done mig so don't know which is easier. Mig probably does a neater job, I think arc seems to penetrate better and give a very strong weld.
Enoch
www.deepfolly.co.uk

[mark]

Done properly and on the correct setting all methods will give good penetration

In my opinion mig is definately the easiest to master then mma then tig, they all have their upsides and downsides but this is a can of worms best left with the top firmly on!

Whichever method you choose they are all perfectly suitable but mig is the quickest method and the easiest to learn.

[Talonmotorsport]

MIG Pros: reasonably clean weld,medium spatter, looks good if done well, quick, machine is reasonable in cost.
Cons: welds may look good but with out understanding of weld prep or no penetration can be weak, gas can be exspensive.

TIG Pros: very neat welds, no spatter ,penetration can be seen,no clean up needed of welds.
Cons: machine not cheap, slow,akward in tight spaces, may need 3 hands for tacking,gas not cheap.

MMA/arc/stick Pros: very strong ,cheap machines,can be used outside.
Cons: very messy, lots of spatter, slag on welds,damp rods if not stored correctly,easy to blow holes in tight gauge material.

[alga]

What about gas? Is it even theoretically possible to weld a chassis with oxy-acetylene?

[Talonmotorsport]

You could gas weld the chassis I don't see why not, might get alot of heat distortion. The other thing is if you have a wooden build table you may have trouble building the base frame.

[locostkiwi]

from what i have seen in books the original lotus 7 where brazed up using gas and im sure the older catermans are brazed also
great skill is need to do this

[Bonzo]

Originally Posted by Talonmotorsport

MIG Pros: reasonably clean weld,medium spatter, looks good if done well, quick, machine is reasonable in cost.
Cons: welds may look good but with out understanding of weld prep or no penetration can be weak, gas can be exspensive.

TIG Pros: very neat welds, no spatter ,penetration can be seen,no clean up needed of welds.
Cons: machine not cheap, slow,akward in tight spaces, may need 3 hands for tacking,gas not cheap.

MMA/arc/stick Pros: very strong ,cheap machines,can be used outside.
Cons: very messy, lots of spatter, slag on welds,damp rods if not stored correctly,easy to blow holes in tight gauge material.

That's well put together Phil

I agree, out of all weld procedures, MIG welding if not done correctly will produce a very weak weld .... The MIG can & will weld cold if not enough welding current is used. ( This is easier to detect in other welding methods )
The weld will look neat but will lack penetration

The original Lotus 7 chassis was indeed brazed, Bronze welded with Oxy/Accet & Nickle/Bronze filler rods.
A good Nickle/Bronze weld should produce a very strong weld, equal or better strength than the parent metal.

Not too much distortion as a lot less heat is used whilst brazing ( When compared to mild steel welding with Oxy/Accet )

The cost of renting & filling Oxy/Accet bottles has gone through the roof .... At least with MIG or TIG, you only need to pay rental on one bottle if you have to