Spacing of spot / plug welds

[Penguin45]

30mm is the accepted spacing.

P45.

[Luxobarge]

30mm is the accepted spacing.

P45.

Yeah, I was going to say I normally go for around an inch, and sometimes less depending on how structurally strong and rigid I want it to be. My welder has a special spot-welding gas shroud, which stands the welder head off the surface just the right amount, so you just turn it up high, point and squirt on each weld, you soon get the hang of how long to hold the welder going in order to fill up the plug hole just right, so it's fully welded but not a huge blob that needs grinding down. Getting the two surfaces as tight together as possible is key too, so a good selection of welding clamps is well worth while, although it sounds like you've got that angle covered pretty well.

All the best with it mate - hats off to you once again for sticking with this one.

[TerryG]

Wow, my poor MIG is going to need a holiday! The boot floor panel is about 1400 long, 1150 wide so one spot every 30mm means 132(ish) welds plus either a seam or 38 spots along the rear edge.
I may do that over several sessions with other jobs mixed in for the sake of my sanity!

Thanks for letting me know, I would much rather get it right first time and only have to do the job once

edit: I just thought, I am going to have to punch 132+ holes to weld through all by hand.

I really do need to update my project thread!

[TerryG]

Just a thought,
I have been using an 8mm spot weld drill to remove old spot welds, so would it be a reasonable guess to use a 6mm punch to make the holes to plug weld through?

[Penguin45]

Correct. Spiral MiG action to fill if you're plugging. The 30mm applies to spot resistance welding only - get them too close together and the nearest weld is a better circuit than welding the metal together where you're at.

I have approximately 140 to do on the Austin 1800, but I gave in and bought a spot welding machine from the US. Even with duty and shipping it's under half the price of buyin one in the UK.

P45.

[TerryG]

I did toy with the idea of trimming the boot floor so it butted up against the flanges and seam welding it. I assumed (possibly incorrectly) that flanged and spot welded panels with the extra ribs and thickness was stronger so am going to rather more trouble to do it the "factory" way.
Hopefully it will be dry at the weekend so I can take my angle grinder / wire brush to the chassis, clear off the crud and paint it so I can put this advice to use and fit my new floor!

[arceye]

I was scratching my head reading this, as I thought the Rangy floor was pop riveted aluminium, and that only Discos had the welded steel boot floor.

But no, I was wrong, post 93 Rangys had the same steel section as the Discos, which only goes to show you learn something new everyday, anyway, I agree that somewhere between an inch and inch and half should be about right.

[TerryG]

My RR is an odd one as it is "MA" (95 model year). Construction wise it is Discovery 300 V8. A royal pain in the bum to get the specific parts for often requiring silly bits of fabrication as nobody produces the spares needed for only 2 production years (one model year).