Broken drill bit soaked in Alum : it is not working

At least with non ferrous metals it is possible to remove these offending bits and pieces, where as if you have something made of steel or cast iron you either have to ditch the part, or some mechanical method of removal or modification has to be done. Ian S C

True enough ! (If you don't know someone with a spark erosion machine).

Try to scrounge used sharp-pointed diamond burrs from your dentist and use 'em in a high-speed mini drill. (Only genuine dental burrs are any good with HSS). It is relatively easy to eat away at a broken tap or drill in a ferrous part without doing much, if any, damage to the hole or thread providing the broken bit isn't too long. Once the centre part is ground down, you can usually break up the remaining bit with a hammer and carpet pin. (Carpet pins are invaluable in the workshop & can often be "found" lying around in carpet stores. Grind off the round top and they make very tough, small pin punches).

Speaking of all this drilling, does anyone here still use "core drills" , as opposed to stepping up diameters of drills as it apparently tends to result in lobed holes?

I know it's a teeny bit off topic. But hey...drills y'know?

Michael W

Ps. I did a quick google of this and it doesn't actually come up with the type of drill i'm thinking of (the results are more down the alley of circular saws) I'm thinking of a drill bit thats flat bottomed and has 4 or 5 cutting flutes or there abouts. 

Edited By Michael Walters on 10/06/2016 23:15:25

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The search result seems reasonable, Michael ...

Core drills are for cutting cores [like they do for rock, or ice, etc.]

... What you're describing would disintegrate the core.

MichaelG.

Edited By Michael Gilligan on 10/06/2016 23:31:21

You're missing the point, the idea of the core drill is to follow a previously drilled hole. As drilling through a previously drilled hole with a bigger drill will encourage a lobed hole to be formed. It's simply called that because it can't drill a virgin hole so to speak.

It's all there, clear as crystal, black and white. 

**LINK**

"Oh you mean THAT core drill...."  

Michael W

Edited By Michael Walters on 11/06/2016 00:26:46

Cor blimey !!

An ambiguity

I find it hard enough to buy stub drill bits (sometimes known as screw machine drill bits) let alone core drill bits ! I am usually met with a blank stare or ''What are they ?'' when I make enquiries.

Edited By Brian John on 11/06/2016 02:00:30