Cowl Spot Welding Drill Out

[Darren 72]

Hey Guys,

Can anyone give some advice about drilling out the spot welds on the cowl of my 72. When I drill it goes through the lower cowl and the fire wall flange also. Is this OK. Trying to get through just the upper cowl is hard to do. What is the acceptable practice?

Also what is the best way to get the upper cowl to peel off after drilling? The firewall lip is directly in the way so a flat chisel can't be put into the front seam w/o bending the snot out of the firewall flange.

 

[72HCODE]

are you using a spot weld drill bit?

you don't want to drill straight through the the spot welds you just want to drill out the top of the cowl because when your ready to plug weld the cowl top back to the bottom you need a surface for the plug weld to sit on. when you drill completely through the top and bottom of the cowl you have no base to start the weld pool on to fill the hole back up.

also depending on where you went totally threw both the upper and lower cowl you will have water getting in.

now you can get magnetic copper sheets, you can place that under the bottom cowl where you drilled through completely and the copper will not stick to the weld wire so you can built up a weld pool and then slowly fill the empty space up and then the top will fuse back with the bottom cowl, and you clean up with a grinder so it looks factory again.

another option is cutting out coins of sheet steel to fit into the holes you made then butt welding the seam around the coin to the hole, then grind that flat, put the top of the cowl in place and then plug weld on top of the coin area. this is more labor and you will need to prep the lower cowl to get rid off all incorrect holes on the seams.

basically a spot weld drill bit is sort of like the cutter used when drill out a door to install a knob or a lock its a larger hollow tube with saw teeth, with a drill in the center and you set the depth of the cut, the center drill bit keeps the larger cutter on track. the larger hallow tube cutter then cuts around the spot weld, once your through the top layer of sheet metal you stop, and continue to the next spot weld. when you done the top can be separated from the bottom.

you can use a chisel, or a gasket scrapper or trowel, you just want to separate the seam try not to deform the metal if possible, but its going to happen anyway so don't worry try to get all the spot welds first then you man try working from the windshield frame forward instead of the the front flange back.

 

[Darren 72]

are you using a spot weld drill bit?

you don't want to drill straight through the the spot welds you just want to drill out the top of the cowl because when your ready to plug weld the cowl top back to the bottom you need a surface for the plug weld to sit on. when you drill completely through the top and bottom of the cowl you have no base to start the weld pool on to fill the hole back up.

also depending on where you went totally threw both the upper and lower cowl you will have water getting in.

now you can get magnetic copper sheets, you can place that under the bottom cowl where you drilled through completely and the copper will not stick to the weld wire so you can built up a weld pool and then slowly fill the empty space up and then the top will fuse back with the bottom cowl, and you clean up with a grinder so it looks factory again.

another option is cutting out coins of sheet steel to fit into the holes you made then butt welding the seam around the coin to the hole, then grind that flat, put the top of the cowl in place and then plug weld on top of the coin area. this is more labor and you will need to prep the lower cowl to get rid off all incorrect holes on the seams.

basically a spot weld drill bit is sort of like the cutter used when drill out a door to install a knob or a lock its a larger hollow tube with saw teeth, with a drill in the center and you set the depth of the cut, the center drill bit keeps the larger cutter on track. the larger hallow tube cutter then cuts around the spot weld, once your through the top layer of sheet metal you stop, and continue to the next spot weld. when you done the top can be separated from the bottom.

you can use a chisel, or a gasket scrapper or trowel, you just want to separate the seam try not to deform the metal if possible, but its going to happen anyway so don't worry try to get all the spot welds first then you man try working from the windshield frame forward instead of the the front flange back.

Only drilled 4 out completely through. I am using the 3/8" spot weld drill bit. Looks just like a hole saw. Got it at Harbor Freight. It works good..... too good..lol. I got it. Makes sense what your saying. I knew it wasn't right so I stopped.

 

[Qcode351mach]

Only drilled 4 out completely through. I am using the 3/8" spot weld drill bit. Looks just like a hole saw. Got it at Harbor Freight. It works good..... too good..lol. I got it. Makes sense what your saying. I knew it wasn't right so I stopped.

Heres how to drill out spot welds & remove the metal as 72 hc stated u can use a spot weld driller or I sometimes use a brad point bit depends on what your doing

 

[Darren 72]

Only drilled 4 out completely through. I am using the 3/8" spot weld drill bit. Looks just like a hole saw. Got it at Harbor Freight. It works good..... too good..lol. I got it. Makes sense what your saying. I knew it wasn't right so I stopped.

Heres how to drill out spot welds & remove the metal as 72 hc stated u can use a spot weld driller or I sometimes use a brad point bit depends on what your doing




Thanks.. The copper piece of metal attached to the open hole is what 72HCode was talking about. I need to do this when its time to button up the cowl. Good stuff. Gives me more confidence seeing it. Thanks for all your help.

 

[machman_73]

Great vids Qcode.

 

[71_badmach]

Excellent work... thanks for sharing. I'll be looking to remove my upper cowl and maybe replace the right pillar on mine. Seeing this kind of work kind of helps me get over my fear a little. Can you reference the rust preventative you are using?

 

[Qcode351mach]

Excellent work... thanks for sharing. I'll be looking to remove my upper cowl and maybe replace the right pillar on mine. Seeing this kind of work kind of helps me get over my fear a little. Can you reference the rust preventative you are using?

Thanks ! Heres the products used

 

[canadian_red_maple_leaf]

great work Qcode351mach!!! you're putting a lot of love into that mach1 of yours. keep up the good work.

best regards from vienna

abudi

 

[Qcode351mach]

great work Qcode351mach!!! you're putting a lot of love into that mach1 of yours. keep up the good work.

best regards from vienna

abudi

Abudi..Thanks ! Yes lots of love ! The reason being is this car is very special to me...It's the first car I ever bought..I've owned it since 1979 ! Alot of history & sentimental value ! Met my wife (of 24 years) with that car & we shared lots of good memories with that car( Ya gotta admit these cars are chick magnets! at least back in the day & it snagged the love of my life & soul mate, Interesting story I will post up one day but it was all about "do you want to take a ride in my mustang") I don't know who's more excited to see it done Her or Me ! and it helps that she is so supportive .. thanks for subscribing to my you tube channel. I think you be impressed when you see it done !

Scott

 

[PAPPY HAROLD]

TWO TID BITS. WHEN USING A SPOT WELD CUTTER, I LIKE TO USE A VARIBLE SPEED DRILL. WHEN YOU TURN IT SLOWER YOU CAN USUALLY FEEL A VIBRATION WHEN YOUR BIT GOES THRU THE TOP LAYER OF METAL AND STARTS THE SECONED ONE. DOESNT ALWAYS WORK BUT SAVES ME ALOT OF HOLES TO PATCH IF I GO SLOW. THEN AS I AM OF AN AGE WHERE I STILL REMEMBER USING LEAD INSTEAD OF PUTTY, BEFORE MIG WELDERS WE HAD TO WELD WITH A TORCH, IF YOU HAVE ACCESS YOU MIGHT FIND THAT BRAZING AT A LOW FIRE TEMP YOU CAN FILL HOLES PRETTY EASY AND ITS FAIRLY EASY TO GRIND SMOOTH.