hello welcome to Enots engineering Im Alan in today's video I'll be sharpening a
center drill for the first time using a tool and
cutter grinder and an ER 20 collet adapter which we made earlier
As I didn't know the angles of centre drills I looked it up on the internet and I
couldn't find much information about cutting angles clearance angles for the
tip of the center drill so I've had to try and pick it up from the center drill
I'm sharpening let's see how we did So how many times does this happen to
you when you've got the center drill drilling away and the tip is breaks off
it's more often in the lathe and the pillar drill and that's because when your
using the tail stock in the lathe you haven't got a feedback of the force
you're putting on and the first thing you know is when the drill just snaps
that's why I made the ER 20 collet adapter to fit the cutter grinder. If you keep
the center drill sharp you'll be less likely to break off the first thing is
to set the center drill at Center height just blacken the ends so I can see were
I've ground
now we'll try to do is use this I've built this little magnet with a washer
on the top which I've built up to the center height and we're using a little
washer on the top I can turn the drill until the flat is just under that washer
which puts it on center line and now I tighten up the screw here.
The next thing I'm going to do is turn the center drill around give me an angle.
I think it would be about forty degrees make it 39.
I will set the angle of the table at ten degrees what I'm trying to do is do a
grind at ten degrees then move it down to about six seven and do another grind
so I've got a 10 degree clearance Turn the wheel one. Bring the tool in till it
just touches
so now if I lift the table up
you see see then the light lights just reflecting off the face that I've cut and
it's cleaned up the whole face so now I'll turn it round 180 degree and do
the other face on the same settings. Just take the tool out turn it round 180
degrees put the tool back in lock it up drop it down set this to zero here I
haven't moved this and black it off
you can see you might just be able to see the reflection there where the edges are
ground off I'm changing the angle from 10 to about 7 I'm not sure what angles
these are ground it so I'm just guessing really. This the wheel is going that
direction it's pushing down so that it's pushing the tool down onto the table not
the opposite way when it will lift it off
Bring it over feed it in
By the hand screw until it touches.
you can just see there where it's cleaned up
so those have got two angles cutting edge and clearance.
I've done that at 10 degree and 7 degree. Put the centre drill in the tailstock and Jacobs
Chuck and see how that cuts just put a spot of oil this is just car engine oil.
now if you look closely you can still see the black felt-tip marks on the
clearance cut
I hope you found that interesting and hope to see you next time
on Enots engineering