What the??

[whatknot]

..heck is this ?

I bought a load of stuff this morning but don't recognise this at all

Its about 52mm long x 12mm

Its like a short double ended drill bit but am unsure what it is

Anyone seen one before?

 

[MusicMan]

I think it is a screw extractor. Note that you would put it in a drill and drive in reverse to drill a wood screw head then unscrew it.

Keith

 

[whatknot]

Thanks for that, but I don't think so, its a clockwise cutting face, so that would drive a wood screw in further

I hadn't noticed before but both ends appear to be damaged, ie the very end seems to be snapped off

I was wondering if it was a lathe bit ?

Now I see its broken its likely to be bin fodder unfortunately

 

[CHJ]

Broken Centre Drill ?

 

[whatknot]

Yes that looks like the man

Odd I have never come across one before

Its a shame its no use but at least I know what it was for ;-)

 

[MusicMan]

ah yes, broken centre drill it is. Metal recycling.

 

[Ttrees]

I have used these in a mill and a lathe before, absolutly delicious to use in bright mild steel.
Does anyone use these in a drill press, or even a hand drill ?
I had pondered about buying one before.
Tom

 

[AndyT]

Before you bin it... It might well be hard enough to use as a burnisher to sharpen card scrapers, if you don't already have something better. Just epoxy one end into a handle.

 

[whatknot]

I confess to being guilty as charged, I rarely throw anything out ;-)

And when I do I then find a week later I wanted it

 

[Lons]

I have at least half a dozen of those in different sizes and use them regularly. Most common use for me is a starter prior to drilling out a pen blank.

They're cheap and useful, wouldn't be without them unfortunately though when broken like yours they aren't much cop.

 

[Rorschach]

Broken centre drill as others have said. Never understand why people break them soo much, I use them almost every day in sizes from 1mm up to 4mm and have never broken one yet.

 

[whatknot]

Thanks for the replies

I am fairly sure there are a few more odd things in this lot which I may post tomorrow as I don't know what some of them are

Its a real mixed bag this lot ;-)

 

[ED65]

Even once broken don't these make an acceptable countersink? Assuming the cutting edge is still sharp of course.

This doesn't look like it was broken, or just broken, it looks like the tips were ground flat. Maybe it was converted to a countersink so it wouldn't go to waste?

 

[whatknot]

No on close inspection the tips are snapped off

I feel sure they will come in useful for something ;-)

 

[CHJ]

No on close inspection the tips are snapped off

The mind boggles as to how someone managed to 'snap off' the pilot tips.
They are robust cutters that usually last a lifetime.


On a slightly different tack, if you have various diameter versions, they can with care be used to make very accurately dimensioned full diameter holes, their short stiff design means they don't wander off or cut oversize or follow the grain if used on wood.

 

[Cheshirechappie]

If you do plan to use a centre drill as a countersink, bear in mind that the cone angle is 60 degrees, not the near 90 degrees more normal in woodwork for screw heads and the like.

Their 'proper' job is to sink the sink the holes into which a metalworking lathe centre seats, when turning between centres or when using tailstock support. The pilot part of the drill allows clearance for the centre's point, thus reducing the chances of damaging it and allowing the job to sit on the slightly larger diameter further up the cone. It also provides a small oil reservoir to keep the centre lubricated - not such a problem with a rotating centre, but sensible when using a dead (non-rotating) centre.

They're used in all manner of machine tools to start drills, too. Lathes, drilling machines, jig borers, milling machines doing jig drilling, and in cylindrical grinders and some inspection equipment, and so on. You can use them in a hand drill, but any wobble does tend to break the pilot off, especially if the operator is a bit 'cack-handed', so it's not really regarded as good practice - that's probably what happened to the OP's example. They break much more easily when hand-drilling hard materials such as steels than they do in wood.

 

[hodsdonr]

A blow hole just below the surface snaps the tips off faster than anything. Also a non flat surface, too fast a speed etc work just as well.

 

[whatknot]

Thanks for all the replies, its been educational ;-)

Just to add that a further search through the oodles of stuff I picked up and I found something rather familiar (well now it is)

This chap obviously had a wide number of interests, mechanical, lathe, plumbing, carpentry, upholstery etc

The larger item I assume is some sort of milling drill/bit, you can't see from the photo but it has end teeth rather like a tap seat cutter

 

[CHJ]

The larger item I assume is some sort of milling drill/bit,

Clarkson Milling Cutter.

 

[whatknot]

Thanks for the clarification

Crumbs, not cheap are they