Rosette (Plug) Welds On Sheet Metal

[JimRussell]

Hi Pugsy,

RodDoc posted a while back on using a tig to spot weld. It might work O.K. for you on these mounts.

[TheRodDoc]

For sure the best way is with NO holes.

[123pugsy]

The 7/32" holes that I tested were harder to break apart than the 3/16" hole welds. The key is to hold the torch in the middle and really get the puddle started in the base material before giving it some rod. It's gonna be a little nerve-wracking when the base material is the front of the car.

I used a backer on the scrap and distortion didn't seem too bad.

[John Buchtenkirch]

I have to agree with Marty, if you plug weld mounting brackets for the nose to the fenders as shown you will see ghosts of the plug welds through the paint work in no time at all. I would suggest mounting to the flanges around the grill opening or flanges at the top of the fenders. Or maybe make up inner fender skirts and a radiator support, bolt them to your outer skins and put mounting brackets on the radiator support. I'm not trying to wish extra work on you , just trying to help before you make a mistake.

I know your professional tig welder but mig welding rules on plug welds IMO. ~ John Buchtenkirch

[123pugsy]

Originally Posted by John Buchtenkirch

I have to agree with Marty, if you plug weld mounting brackets for the nose to the fenders as shown you will see ghosts of the plug welds through the paintwork in no time at all. I would suggest mounting to the flanges around the grill opening or flanges at the top of the fenders. Or maybe make up inner fender skirts and a radiator support, bolt them to your outer skins and put mounting brackets on the radiator support. I'm not trying to wish extra work on you , just trying to help before you make a mistake.

I know your professional tig welder but mig welding rules on plug welds IMO. ~ John Buchtenkirch

Thanks John.

I'm working on two more channels for body mounts right now.
I will also have inner fenders on both sides of the engine compartment bolted to the frame with isolators as well.

I agree with the MIG for plug welds also. I just don't have one.

[TheRodDoc]

I didn't realize what this was for. I went to your other thread and looked at the front end pic's.

You should not weld the mounts to the skin. Only weld things to the lips of the grill opening, top lip where hood latch plate might be put so forth.

You first should mount the radiator. block front in place. Note where inner fenders will have to go. Then build something as in this VERY quick drawing. Very hard to tell you on the net.

Then when that sheet metal work is added design your mounts to weld to that.

By the way, That front looks very good. You did well on the design and shaping.

frontmount.jpg

[Essexmetal]

Our method for faking real spot welds with a TIG is to punch a 1/8" hole. Filler rod ready and hit the arc in the center of the lower panel with a reasonable amount of heat. Soon as it wets out add filler with enough to make he puddle flush. The hole's wall burns out to 3/16" dia. and the center drops slightly. They look very similar to a resistance weld. Acts similar during a nugget pull test as well.

[123pugsy]

Originally Posted by Marty Comstock

This is on your finished surface? The entire nose working flexing and hanging off it? are there no other mounting choices?

That being said I have toyed with a 1/4 inch hole, a very TIGHT gap, and a high heat/wire (say, factory set for 3/16") and very little trigger time. Less time on the trigger meand less HAZ means less warpage.

Marty

Originally Posted by John Buchtenkirch

I have to agree with Marty, if you plug weld mounting brackets for the nose to the fenders as shown you will see ghosts of the plug welds through the paint work in no time at all. I would suggest mounting to the flanges around the grill opening or flanges at the top of the fenders. Or maybe make up inner fender skirts and a radiator support, bolt them to your outer skins and put mounting brackets on the radiator support. I'm not trying to wish extra work on you , just trying to help before you make a mistake.

I know your professional tig welder but mig welding rules on plug welds IMO. ~ John Buchtenkirch

Originally Posted by TheRodDoc

I didn't realize what this was for. I went to your other thread and looked at the front end pic's.

You should not weld the mounts to the skin. Only weld things to the lips of the grill opening, top lip where hood latch plate might be put so forth.

You first should mount the radiator. block front in place. Note where inner fenders will have to go. Then build something as in this VERY quick drawing. Very hard to tell you on the net.

Then when that sheet metal work is added design your mounts to weld to that.

By the way, That front looks very good. You did well on the design and shaping.

Thanks Richard/John/Marty.

I'll consider other mounting methods.
I figured by spreading the spots over a wide area that it would be fine. It sure would be a bummer if the spots showed thru the paint later.

I'll see what I can come up with. The rad is already mounted and tough to work around.

This shape will prove to be challenging to mount to without using the skin.

So any brace touching the skin should only be welded at edges/rims. Would panel adhesive between a top hat channel and the skin be advisable?

Thanks,

[barry larson]

I would take 2 2x6 19 ga samples and clamp them up....Set the tig at 100 amps and just burn a spot about 1/4 in and do this every inch........then try to separate the parts.... i am sure you will destroy the sample befor it comes apart...big spot welds..just make sure you clamp it tight..Barrry

[John Buchtenkirch]

Originally Posted by 123pugsy

Thanks Richard/John/Marty.

I'll consider other mounting methods.
I figured by spreading the spots over a wide area that it would be fine. It sure would be a bummer if the spots showed thru the paint later.

I'll see what I can come up with. The rad is already mounted and tough to work around.

This shape will prove to be challenging to mount to without using the skin.

So any brace touching the skin should only be welded at edges/rims. Would panel adhesive between a top hat channel and the skin be advisable?

Thanks,

Anyone who has done structural body work for a living soon realizes that all the attachment welds on outer skins are hidden on flanges or on hems that aren't readily viewable from the outside of the vehicle. The only exception I can think of is that van side panels are spot welded to the vans floor and those spot welds always show through the paint. Back in the days of the custom van craze some guys would actually tap those spot welds inward to the point of being slightly low, then Bondo up and block out the sides of the van to perfection. In many cases ghosts of the spot welds would still actually show up through the paint & Bondo at a later date, particularly if they drove the vans a lot.



Most people don't realize how much car bodies twist when they hit bumps, potholes, railroad tracks and when driving diagonally across gutters when exiting the roadway. All that twisting and vibration will cause perfectly finished spot welds show through the paint. It is only a matter of time if the vehicle is actually driven. Show cars or racecars that get trailered around obviously operate under different conditions so they might be able to get away with it. Possibly if those inner brackets were glued on with structural adhesive you might be able to get away with it but I wouldn't be totally surprised if an outline of where the adhesive is didn't show up on the face of the fender after driving for some time. In a certain sense I'm an old-school body man, I've never glued a quarter panel on a car in my life, so I don't trust structural adhesive like I do when welding parts together. I believe structural adhesive is only for skins but I think it's only a matter of time before some nit-wit glues in a uni-body rail and kills someone because of it.



Just some thoughts….you might be able to make an inner structure type cross-member by attaching to the lower flanges for the grills and going back several inches where you would make a right angle turn down to the very back edge of the lower pan. Then attach braces to the side flanges for the grills and tie those braces into the lower cross-member just mentioned. At that point you would have something pretty substantial to attach to but there should also be flanges at the top of the fenders that would take some of the road stresses too. I feel little guilty, like I'm dumping a bunch of work on you, but better now than after everything is painted. Also, I agree with the Rod Doc, you have done an excellent job of restyling the nose of that car. ~ John Buchtenkirch