I've probably got the right size tungsten carbide. Bought a load off a workshop that closed down - including the ancient but very good PCB drill press.
I'd say there's a very real chance of breaking a small tungsten carbide used hand held.
I could cut a cross with a Dremel to provide the centre?
Luckily the bit the screws go into is in pretty good nick. And I want to keep it that way.
If you can do that why not just cut a slot and use a parallel sided (not wedge shaped) straight screwdriver after the soak with PlusGas/Diesel? Gentle use of a powered impact driver might be better than a hand held tool. How much pressure can you apply to stop any driver turning out without distorting the bit you want to keep?
That's how I broke them off flush in the first place. ;-)
Only if it is used in a pistol grip power drill. I also make PCB's but I use HSS steel drill bits in a 12 Volt mini drill. (I have no problem with regrinding them at this diam.). It has a body of about 35mm diam, that contains the DC motor, with a very small chuck at the end. It is very difficult to put any side force on it, unlike a pistol grip drill. Just let the bit do the cutting without using too much force to make the bit cut. The only problem you might encounter, is if you you do break the bit and part of it stays in the screw, you might be stuffed at getting the broken part out.
That could shatter the bit, due to the cutting edge ramping up and down over the cut cross. I wouldn't tackle it that way.
As an aside, many years ago, I had a series of Austin Minis and they were notorious for the brake adjusters to seize up. One was so bad I used an easy out to try and get it to move. Needless to say, the easy out snapped. The tungsten carbide drill I had, drilled it as if it was butter. After that, it was out with the blow torch and use heat to release it. That never failed. :-)
Some years ago, I bought some tungsten rotary files, one was a ball cutter, only about 3mm in diam. Something like that would be far better to give you a centre.
Thinking about that, why not find what used to be a Fred Aldous shop and see if they are still available? Our local one was closed down some years ago and it was the only place I had ever seen them. They used to be based in Manchester.
Good luck
Dave
sided
better
Ah.
How thick is the surrounding sheet? Could you punch the remnant through?
Well yes. I have a similar one. And if drilling the odd PCB hole with that I too use HSS drills. Because the tungsten carbide ones break too easily. So I only use them in the drill press.
I'm wary about using force in case I damage the panel. Think I'll have a go with a small pointed grindstone to give a centre for a tungsten carbide drill.
I had a similar experience with the door handle screws on a Golf. In the end there was a combination of plus gas, time, cutting slots with a dremel and a drill. I think the slots and plus gas eventually did it. I find using a torque limited cheap electric screwdriver useful for these sorts of things - set them to a low torque setting and high speed and you get a very light impact driver effect that tends to get things moving. Drilling was something of a waste of time - the screw must have been made of something tough as it blunted drills like crazy. The heat may have helped a little though - couldn't use a blowtorch due to the still attached plastic handle.
The problem of drilling something hard is down to the very tip of the drill, the chisel point. If this is not hard enough to create a hole then all effort is wasted. Once you get a hole in the metal, known as a pilot hole, you might find that standard HSS drills will be OK to open it up. Obviously the twist drill must be freshly sharpened and run at a slow speed.
Dave
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