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-   -   Trouble drilling out screws on 409 (http://www.bristolcars.info/forums/restoration-repair-non-specific/1756-trouble-drilling-out-screws-409-a.html)

LarryW 06-04-20 12:46 AM

Trouble drilling out screws on 409
 
The screws attaching the plated brass window frame are hopelessly corroded and many will need to be drilled out. The ones I can access from behind aren't a problem but the others won't budge. I've tried titanium and cobalt drill bits but nothing appears to penetrate whatever alloy was used on these. Has anyone else had to deal with this issue?

PEU186F 15-04-20 02:34 PM

You have got the drill rotating in the right direction, haven't you? I've seem it done!

I have very slowly learnt over the years that drills are a bit like wood chisels. You buy them new and assume they are sharp, but they aren't and, moreover, the shape and angles of the cutting edges are only an approximate mean of the whole range of angles that are required to deal with different materials.

I have also very slowly learnt that words like titanium and cobalt are merely a diversion. They may be hard but that counts for nothing if the drill isn't sharp, they just skate about on the surface without getting on with the job.

The best material for cutting most materials is tool steel, which is what ordinary, black, jobbing drills are made of.

So get your drill.

Then sharpen it. Since you possibly are a bit too senior to enrol as an apprentice in an engineering workshop you'll have to turn to other learning opportunities. Fortunately there's the Internet -so try searching on a phrase like "drill point angle chart" and start learning. Putting your new knowledge into practice will need concentration, good eyesight, dedication and steady hands, not to say a suitable fairly fine grindstone and patience. But the plus is, even if you only arraign a grade 1 out of 10, like me, it will stand you in good stead.

You say " rusty" , so you are almost certainly only facing thinly plated mild steel so match your drill angles to that.

A perfectly sharpened drill will take itself into the material. You won't achieve that very often if ever but,believe me, it's a revelation to even get close to it.

A final tip. Centre pointing the material to be drilled out achieves two plus points. The first is centring the drill where you want it to be. The second is the provision of a suitable starting profile for the drill to bite into in its inexorable downward path.

Good luck

Roger

LarryW 19-04-20 03:45 PM

Drilling out screws
 
Good point. I'll try sharpening the drill bits. Thanks. Larry


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