70 Grill

[Lee McGlamery]

Hi - I was tapping a parking lens mounting hole in my new original 1970 grill and the tap broke. I have been unable to drill it out and have tried carbide bits and a diamond Dremel engraving tool. The bits will not begin to drill in the hardened steel of the tap. I do not have enough depth available in the screw hole to fill it and drill it.

Does anyone have a solution on getting the tap drilled out of the screw hole?

Thanks

Lee

[Craig S.]

Re: 70 Grill

Lee - this is a really tough problem...and I have been there a time or two. It is virtually impossible to drill out a tap. I had some luck with a special set of broken tap extractors, basically, a tool with 4 pins that slide in a body and the pins engage the flutes in the tap body that normally allow chip clearance. I was successful once using this method. However, for a very smal tap, this may not work. What size tap are you working with...is it a small one like 8-32 or 10-32?

[jim34671]

Re: 70 Grill

Lee,

Firstly..If you claim it is a NEW '70 grille...STOP RIGHT THERE!
Chances are you will do more damage to a very rare piece.
I've often left these untouched and simply cut the lens attach screw at head and adhered it to grille.
There is no real reason to remove lens as bulb fitment is from rear side of grille.
Some of these grilles get so corroded that the pot-metal gives and they break.
If the grille is in fact NEW...How did the screw break to begin with?
FYI...Original early '70 grilles have 3 rear side attach studs...Not the front face screw holes.
Go easy.
Jim

[Edward McComas]

Re: 70 Grill

I would recommend that you find a competent machine shop and let them deal with it. They have all of the special tools and the special knowledge to deal with problems like this. It will be a lot cheaper than replacing an original 70 grill.

[Lee McGlamery]

Re: 70 Grill

The tap size is 8-32. Also I was not clear when I stated that the grill was new. The grills are restored show condition grills with the correct three studs along the bottom of the grills. The lens were not on the grills when I purchased them. I successfully extracted the two broken screws in the left grill but the tap broke in the bottom hole.

The lesson I learned on this experience is never use your high torque low speed drill to tap threads!

Thanks

Lee

[Craig S.]

Re: 70 Grill

Lee - even hand tapping you must be very careful with clearing chips by backing up every quarter turn or so. Power tapping is always a disaster unless you do it correctly as in an industrial process with flushing tapping fluids etc. Good luck with the Walton tap extractor....Craig