Hi all,
Tomorrow's the day to finally lay down my first seam weld. I've built a rotisserie, stripped 9/10ths of the underbody deadener (I'm sick of it... The last bit can wait!) and cleaned off the paint around the front rails where they connect to the floor. I've been reading as much about it on this site as possible (thanks heaps everyone) and practicing on some spare sheet metal and i think I'm ready to start doing it for real.

Tonight i've been searching the net outside ozdat and I've come across a lot of sites that warn of seam welding without a chassis jig due to the risk of warping the chassis. This makes me a little apprehensive. Is it ok to seam weld on a ritisserie without a chassis jig? The body will be rotated at various angles on the rotisserie during welding to get the best access (not necessarily upright or at 180 degrees) and I just want to make sure I'm not going to kill my shell! Obviously I'll be pulsing the trigger and waiting for the redness of the precious weld bead/ spot to die off a bit before hitting it with another.

I was planning on welding the stitches in a sort-of random sequence, eg weld the first stitch on a seam then jump a few to like the fourth then back to the second etc, in an effort to reduce heat generation. Is this a good idea or not necessary. Im also assuming i can make the full 30mm weld via multiple sequential spots without needing to move the gun to a new position after every single spot? This would make my welds a lot messier due to constantly changing positions.

I'm also planning on welding 30mm, leaving 60mm to all seams that have been recommended in other posts. I've also heard of others using 25 on, 50 off but assume theres not much difference.. Any recommendations?

Finally (sorry, this started out as one question) did others grind back the weld on other side of the panel after welding? I've got the welder set up as good as I can (no expert) and am getting a bit of weld still building on the back side of the panel due to penetration. I'm assuming this is ok? If so, wondering if people bothered grinding it back on not? And assume paint on the back surface won't create porosity as long as the front faces are wire brushed?

Still so many questions (hence the aprehension) but if I don't start welding tomorrow it will never happen!

Thanks heaps for any info you can provide and im looking forward to checking back here and then starting the process tomorrow morning. Hopefully I don't check again in the arvo to find someone warning me not to do it without a jig!

Cheers,

Chris

im no expert but i had a panel beater do mine while i watched/helped and he didnt use a "jig" he just estimated distances and did one weld after another, and nothing bad has happened to the chassis, and i havnt heard that it will to be honest, you should be alright, what i noticed was 4 beads then stop and move your estimated 50 or whatever you decide, someone else might have more experience but this is how i did mine and im confident in it

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Its not that i have no money, i just have a huge investment in my datsuns!

Hey Chris,

No expert as well, I did mine and there doesnt seem to be any issues.

Only thing is your welder settings are a funny, seems there isnt enough control with the voltage, if you can spare the $$ it might be worth investing in one with a little more control. There penetration on the test welds were borderline too much. It might be hard to get some consistency out of that welder.

Cheers,

Trent

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1600 Build: http://ozdat.com/forum/viewtopic.php?f=59&t=22694

Hey guys, thanks for the feedback. Im now the proud owner of some seam welds! I managed to get through the lower sections of the front rails and also did the rear rails rear rails and the transverse seam between the boot and the rear floor. It's time consuming stuff with having to clean the paint off and getting all the sealer out. I'm taking the paint off both sides of the panel to ensure a clean weld (not sure if this is actually necessary to control perosity?) so its slow going. Great to see some progress though!

As you mentioned Trent, I am getting quite a bit of weld build up on the rear of the panel but it's not blowing through so I'm assuming I can just grind this back. Were you guys getting much on the back side and if so, did you bother grinding it back? Trent, I assume you probably dialed your welder down to reduce / eliminate it all together? I think a new welder is not really an option at the moment.

Anyway thanks again,

Chris