New Build Firewall

Mon Apr 25, 2005 2:09 pm

Hello Folks:

Thinking about building a new firewall for my project using some of the old stiffeners, and was wondering if anyone knows how to remove spot welded stiffeners?

Thanks,

Chris

Mon Apr 25, 2005 6:17 pm

I have used several methods. You can get spot weld cutters from auto restoration places. They are kinda real small hole saws that pilots thru both layers. Or you could just drill a small pilot hole thru both layers and use large drill to cut thru one layer. Then pop them apart with a putty knife.No matter what you can only save one piece of the two welded together. And that one will have atleast a #30 hole thru the weld nugget.
Before you even start look at the weld pattern, That is what your rivet pattern will look like. Spot weld layout varies from nice to erratic. I swear you can tell how much the operator had to drink the night before by how the welds are done.
So even if you get them apart nice and the layout will make a nice rivet pattern. The welding distorts the saved metal.
Being that its stainless you could propably weld up the holes, But that just adds to the mess of the whole thing. Your time and money may be better spent trying to find a better firewall or making all the pieces new. That way you can have them spot welded together and not lose points with the judges.

Mon Apr 25, 2005 6:56 pm

Very good explanation, Vanguard:

How about heating the spot welds with a spot welder, and prying them off while hot? Is that doable too? If not, I may try the automotive too or the other techniquel you mentioned. Thanks!

Chris

Mon Apr 25, 2005 9:43 pm

[quote="HarvardIV"]Very good explanation, Vanguard:

How about heating the spot welds with a spot welder, and prying them off while hot?

Cant say as I have ever tried that. One other way I have used was to grind away on the panel to be replaced with a 1/4 dia rotary file in a die grinder. Grind a spot the size of the weld nugget until your almost thru and the pop it off.It took forever. And you can double that when its stainless.

Mon Apr 25, 2005 10:22 pm

I swear you can tell how much the operator had to drink the night before by how the welds are done.
So even if you get them apart nice and the layout will make a nice rivet pattern

I see what you mean here, Vanguard. I bought a stress panel from someone to replace one original from the Harvard I noticed the one I bought had rivets that were neat at first, and they progressively got a little sloppier!

Anyway, vanguard, what have you rebuilt thus far?

Mon Apr 25, 2005 10:59 pm

vanguard wrote:Being that its stainless you could propably weld up the holes, But that just adds to the mess of the whole thing.

Danger Will Robinson! Welding thin stainless leads to distortion, especially on large flat panels... Spot welding is much better. I would recommend the spot weld cutter and just live with the small pilot hole when you spot weld the pieces back on.

Mon Apr 25, 2005 11:07 pm

Actually, I think you could probably fill in the pilot holes with a tiny "secondary" weld

Website · Tue Apr 26, 2005 7:46 am

Hi

If you can get a very fine flat chisel between both sheets you are seperating you can use an air chisel from a few different angles so as not to tear it apart - I have done that a few times. You can never heat a spot weld up enough to seperate it without virtually destroying it in my opinion.

Regards
John P

Tue Apr 26, 2005 12:54 pm

Hi John:

I've heard about people using your method before too.

Thanks,

Chris

Fri Apr 29, 2005 6:06 pm

I just discovered another way is to drill out all the welds with the Automotive spot weld drill, debur, and then rivet it back.

Fri Apr 29, 2005 10:16 pm

IF TIME WAS MONEY YOU WOULD BE WAY AHEAD TO FIND A NICE USED ONE, THE WORK AND MATERIALS WILL COST YOU ALOT MORE.THANKS MIKE

Fri Apr 29, 2005 11:07 pm

No way Helldivers:

I'll log the time, and if I spend less than 15 hours, give me 50 bucks.

Also, all firwalls have dings if they're not NOS, so my standard is higher too.

Fri Apr 29, 2005 11:39 pm

HI YOUR TIME MUST BE WORTH NOTHING!AS FAR AS THE FIFTY BUCKS I ALREADY SPENT IT ON THE A-25 MIKE

Fri Apr 29, 2005 11:44 pm

HI YOUR TIME MUST BE WORTH NOTHING

So 15 hours at $20/hr=$300, NOS firewall=$2500, Nothing=0

0 not equal $300 not equal to $2500 logic does not compute, math error.

Sat Apr 30, 2005 12:11 am

IF YOU CAN MAKE THEM FOR $300.00 WHY NOT MAKE 20 OR SO AND CORNER THE MARKET?IF YOU CAN DO ONE IN 15 HOURS YOU SHOULD QUIT YOUR DAY JOB AND JUMP ON THE BAND WAGON WE ALL NEED CHEAP PARTS RIGHT?DONT FORGET THE PRICE OF THE MATERIALS,IVE BUILT SEVERAL FIREWALLS FOR MANY DIFFERENT A/C AND STAINLESS IS NOT EASY TO WORK WITH.A T-6 FIREWALL HAS LOTS N LOTS OF LITTLE PARTS AND TO DRILL ALL THE SPOTWELDS OUT AND REUSE THE PARTS WILL TAKE YOU WAY MORE THAN 15 HOURS.ID LOVE TO SEE YOUR $300.00 FIREWALL WHEN YOUR DONE YOU WILL PROBLY USE THAT MANY DOLLARS WORTH OF DRILL BITS.GOOD LUCK MIKE