Stud welding (also suitable for mig)

[optima21]

on the boot lid of my Triumph Herald, I need to secure a new supporting frame to it made from 16mm steel tubing, so I decided I will use 16mm P clips to hold it in place. to secure the P clips in place I need some M5 studs welding to the boot lid, but I need minimal distortion due to heat. I came up with the following idea.

get a bit of steel bar, tap it M5 (in my case) and then countersink the end to use as die for flaring a hole in the sheet metal and use a countersunk screw to form the flare (as shown on the hole above the screw)

turn most of the head off some more countersunk screws

and put them into the flared hole with a copper heatsink (I used a thor copper hammer blank) with a threaded and countersunk hole as the steel die.

then tig or mig weld the screw to the steel sheet. (tig in my case and after wire brushing) and with minimal distortion

and the reverse,with minimal distortion due to the heatsink. its is tapered around the base of the thread due to the flaring of the sheet metal

and assembled with a p clip and washers

just need to do about 20 of these around the edge of the boot lid now

 

[J.B. Welding]

Nice. labour intensive, but nice.

 

[awemawson]

Or you could use this stud gun - no need to drill holes then

 

[Wallace]

Nice neat solution. I did something similar in stainless, load spreading stud plates to go through a floorpan on a Jensen for the sill to floorpan supports and bonded them in with Sikaflex.......

 

[optima21]

it would have been nice to have a stud gun but I don't so this was the next best option.

Nice neat solution. I did something similar in stainless, load spreading stud plates to go through a floorpan on a Jensen for the sill to floorpan supports and bonded them in with Sikaflex.......

I was thinking of welding bolt to a repair washer and bonding that to the boot lid, but wan't sure if it would have had enough strength. If I'd known you'd have gone that was I might have done that too, with perforated holes like bighead fasteners

http://www.bighead.co.uk/index.html

another option was to turn the end of a bolt down so there was a pip on the end (like a weldstud) and use a tig welder to try and weld that using an home made adaptor and either a guessed time or pulse at upto 160amps...it was a bit of a failure, and as they say, you learn by your mistakes.

 

[Wallace]

Nice effort on the stud weld experiment, is that Zintec sheet you have used? I made those stud plates up to avoid welding to the floorpan inside the car as the interior is still in and I wanted to avoid a bulge under the carpet, they are M6. The Sikaflex is more than capable of holding the plate to stop it spinning when tightened/loosened and squeezes though the drilled hole sealing it nicely from the elements.

 

[Justme]

Could the same not be achieved by just drilling a hole, put a nut on the end of the stud so the stud is half way through the thickness of the hole & then a small spot weld on the stud allowing to to spread to the sheet from the non nut side, remove nut & job done?

 

[langy]

Checkout big head fasteners & polyurethane adhesieve sealant, would of saved you a lot of work

 

[optima21]

Could the same not be achieved by just drilling a hole, put a nut on the end of the stud so the stud is half way through the thickness of the hole & then a small spot weld on the stud allowing to to spread to the sheet from the non nut side, remove nut & job done?

yeah but knowing my luck either I'd have ended up with a wonky thread or managed to weld the nut to the stud

and yes I was using zintec on my test pieces, I guess the white deposits from the zinc oxide give the game away

 

[Robotstar5]

It may look simple, but the stud welding process is quite complex.
The "pip" is used to initiate the arc then the stud is lifted and the current melts the parent metal, the stud is then plunged into the molten pool to form the bond. The ones I worked on were made even more complex with auto stud feed using a breech mechanism inside the gun.

 

[Justme]

How fast would you have to spin then to use friction welding as a method?

 

[J.B. Welding]

When I did some destructive testing on some stud welder studs, I found it was beneficial to run the tig around the wee flange at the base to get the max strength possible. The stud would hammer off unless it was blended in with the tig, then it would bend. That was with M8 studs onto 6mm mild plate.
Friction welding studs must require a really abrupt stop or surely the weld will twist and shear off during cooling.

 

[awemawson]

When I got my stud welder, which is a capacitor discharge type, I did some testing, and if set right the stud would always shear off before the weld broke. That was both on repeated bending and shearing tests.

 

[RaceDiagnostics]

I had a problem with the nut shearing off the threaded part of this stud on my soft top mechanism, the replacement part was about £150 so repairted it

Drilled and taped.

Put a bolt in and cut off the head.

Welded it up and filed it down.

Cut the bolt to length and fitted it back together with a nyloc nut