Drill size?

heddrik

Well Known Member
What drill bit size do I need to drill out the spot welds on a 62 firewall? Thank you for your experienced response(s).
 

Phil Reed

Well Seasoned Member
Supporting Member 10
They make one that makes a pilot hole and steps up to the correct size. Paul will help you!!!
 

heddrik

Well Known Member
Thank you, esteemed Mr. Phil. Kinda like a center drill .? Do they make it in carbide? We have a grinder at work with a wheel to grind carbide so I could resharpen it.
 

heddrik

Well Known Member
Thank you for the link sir. Looks more complicated than I thought. But that is the best way to remove body panels without damage I believe. Thanks again everyone. Anyone know the size for the firewall?
 

bobs409

 
Administrator
Harbor Freight sells the same thing that Ron posted for a LOT less! Around $5 bucks I think.

There is more than 1 kind of spot weld cutter. The one shown is ok if the side of the part your drilling into is the part you'll be throwing out. If not, your going to a have a 3/8" hole to fill. That's a bit more than desired to weld up sometimes. (especially if it goes beyond the new part)

I use a combination of that type spot weld cutter and a regular 1/4 inch drill bit to go part way thru. Sometimes that's all you need. Carbide would be the ultimate if you go that way.
 

heddrik

Well Known Member
I'm a machinist so I have access to some carbide drills. I want to have the correct tools that will last long enough to get the job done without trips to get more tools when they wear out. Guess I wll check out harbor freight too. Thank you for the suggestions.
 

heddrik

Well Known Member
That makes sense, high surface footage kills tool steel on tougher parts. What speed do you use, 200 rpm or so? Do you use any cutting oil? That s what I have thot to use. Thank you for the tip sir. Seems like the spot welds go on forever on some places on these cars.
 

heddrik

Well Known Member
thank you Mr black 63, that also makes sense. I have a #3 carbide center drill, pilot is .125, body .3125 I may use for this application. Thanks again for all this information from all the wonderful people on this site.
 

heddrik

Well Known Member
Cool. What s the center drill bit size, 1/4? I want to drill out the a c part of a firewall. How do u best preserve the side you are drilling out? Thank you Mr L A for the pic and suggestion. :ty
 

La Hot Rods

Well Seasoned Member
Supporting Member 15
1/8 inch center drill, with this you work on the waste panel side. It leaves a small hole in the save part. Drill tell you see the dark ring showing up.
The outside is 3/8. You can buy replacement center drill's, and can sharpen the cutter.
 

blkblk63ss

Well Seasoned Member
Supporting Member 5
1/8 inch center drill, with this you work on the waste panel side. It leaves a small hole in the save part. Drill tell you see the dark ring showing up.
The outside is 3/8. You can buy replacement center drill's, and can sharpen the cutter.
Yep.....
 
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