cobalt drills

[roofman]

Whats the best way to sharpen these 100% cobalt bits then please Chaps...my regular HSS stones wont touch them

 

[brightspark]

Whats the best way to sharpen these 100% cobalt bits then please Chaps...my regular HSS stones wont touch them

a green silicon carbide stone or a diamond and u can sharpen your masonary bits with them as well and carbide lathe tip tools

 

[roofman]

a green silicon carbide stone or a diamond and u can sharpen your masonary bits with them as well and carbide lathe tip tools

Ahhh great stuff,cheers for that

 

[mfletch]

I think you will find there 5% cobalt

 

[roofman]

I think you will find there 5% cobalt

Really..what i meant was there not the pretend Cobalt then.LOL. They are about 3 times the weight of a normal drill bit so i persumed they were solid cobalt.

 

[awemawson]

Some are 5% and some are 7.5%

 

[premmington]

Cobalt drills are hard (even at 5-8%).

Biggest problem with them is not sharpening them, it is breaking them in use! They are so brittle....!

 

[awemawson]

I first started using them in earnest only a few months back when I had a cap screw rusted off in a machine tool. Brand new Dormer HSS drills just wouldn't touch it, but a cobalt one went though like butter Soon went out and bought a full set for emergency use!

Many cobalt drills have a sharper (135 degree) tip angle than the standard 118 degrees, and this can make them self starting and not needing a centre punch in some materials.

 

[premmington]

I first started using them in earnest only a few months back when I had a cap screw rusted off in a machine tool. Brand new Dormer HSS drills just wouldn't touch it, but a cobalt one went though like butter Soon went out and bought a full set for emergency use!

Many cobalt drills have a sharper (135 degree) tip angle than the standard 118 degrees, and this can make them self starting and not needing a centre punch in some materials.

I have a left hand set of cobalt drills for drilling out snapped bolts. Yes they are mostly 135degrees (which makes no difference to me as I cannot sharpen any drill whatever the angle)

 

[500e]

Thought it was only me

 

[premmington]

Thought it was only me

I am an absolute failure at the task!

 

[brightspark]

I am an absolute failure at the task!

watch a few vids on u tube. get some old drills and have a go on the grinder .practice and more practice and it will come to u .most people just put themselves off if its not happening the 1st time . have another go

 

[500e]

Have been shown so often it really
Still trying to get that dash for you to look at he keeps saying it does not work "will get you to take it out, give you a call when we are not using the tractor," & every time I see him the same result must get it done

 

[premmington]

watch a few vids on u tube. get some old drills and have a go on the grinder .practice and more practice and it will come to u .most people just put themselves off if its not happening the 1st time . have another go

I have been working for myself for 32years (which means buying my own drill bits).

I have tried so many times. I can just about do a big ish drill. But a small one is a non starter. They just skate everywhere!

 

[brightspark]

drills smaller than 6mm are best done on a jig as its dificult to get the flutes even

 

[premmington]

drills smaller than 6mm are best done on a jig as its dificult to get the flutes even

But the lad who works for me! Can turn them out like new! He even asks "what you gonna drill with it" before he takes the drill to the bench grinder!

When he hands it back, you use it and it cuts swarf that comes out all in one bit!

 

[brightspark]

But the lad who works for me! Can turn them out like new! He even asks "what you gonna drill with it" before he takes the drill to the bench grinder!

When he hands it back, you use it and it cuts swarf that comes out all in one bit!

best go watch him then .then do one in front of him and he should tell u where your going wrong .if he wont show u make his life a misery

 

[premmington]

Just explain to me how I am going to make a six foot tall fit 17 stone Russian "who was a prison guard in Russia" life a misery?

 

[brightspark]

Just explain to me how I am going to make a six foot tall fit 17 stone Russian "who was a prison guard in Russia" life a misery?

give him a few sh...it jobs but do it sneakily theres more than one way to skin a cat

 

[500e]

Got a few years on you Pete Started in 1963 with a small garage finished with 3 then went back to one, lost interest & went back to RF electronics did my time in that the motor trade was just a mistake, then I discovered Helicopters should retire or so here indoors says, but what would I do.
We also had a lad 60+ who could sharpen drills, lathe tools, etc they always seemed to keep their edge as well, nothing smaller than 1\8 he used to say