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Re: Are there better drill bits than cobalt?

Posted: Sat Sep 04, 2010 10:48 am
by Roy Gavin
Diamond lapping tools and knife sharpeners are not hard to find, Mine cost $10 around 20 years ago and still cuts OK.

On a larger drill it would probably do a good job cleaning up the undercut -better than I could do on a grinder anyway.

Re: Are there better drill bits than cobalt?

Posted: Sat Sep 04, 2010 11:28 am
by Ken in Oklahoma
Roy Gavin wrote:Diamond lapping tools and knife sharpeners are not hard to find, Mine cost $10 around 20 years ago and still cuts OK.

On a larger drill it would probably do a good job cleaning up the undercut -better than I could do on a grinder anyway.

I'm a big fan of diamond abrasives. I have a fine (sorry) assortment of whetstones, dremel cutters of various shapes, needle files, and even a bit of diamond paste which I'm looking forward to using if I ever discover a need great enough to actually use it. I've even got a diamond grindstone fitted to one of my bench grinders that I love for sharpening drill bits. But I've never found diamond abrasives very useful for removing "significant" amounts of metal. I suppose that's because "significantly" large diamonds are too expensive to use for coarse abrasives.

I'll be a happy camper when I find a large 200 grit and even coarser diamond whetstone (that I'm willing to pony up the bucks for). How wonderful it would be to do significant resharpening of things like planer or jointer blades without removing them from the machine. For smaller curved surfaces, like router bits, diamond wheels for a dremel work fairly well.



Ken

Re: Are there better drill bits than cobalt?

Posted: Sat Sep 04, 2010 1:52 pm
by Zombie Master
The Veg wrote:
Zombie Master wrote:I can't seem to get a year out of a toaster oven anymore!
I never knew I could get so enthusiastic about a toaster oven! :D
Yea, bu let's face it Veg, you are easily amused!

Re: Are there better drill bits than cobalt?

Posted: Sat Sep 04, 2010 3:21 pm
by Major Softie
Ken in Oklahoma wrote: I have a fine (sorry) assortment of whetstones, dremel cutters of various shapes...
Ken
I'm (sorry), but does that mean you really have "a sorry assortment of whetstones,...) :mrgreen:

Re: Are there better drill bits than cobalt?

Posted: Sat Sep 04, 2010 10:58 pm
by Chuey
Ken's (sorry) was an apology to the women of the world for having bought diamond sharpening devices and depriving them of their best friends.

Chuey

Re: Are there better drill bits than cobalt?

Posted: Sun Sep 05, 2010 12:23 am
by Ken in Oklahoma
Major Softie wrote:I'm (sorry), but does that mean you really have "a sorry assortment of whetstones,...)

You know I'm not sure now. It made a lot of sense when I posted hours ago and the thought was fresh in my head. I seem to remember being concerned about a pun involving fine grit and whetstones.

Ken, fogged in in Oklahoma

Re: Are there better drill bits than cobalt?

Posted: Sun Sep 05, 2010 7:03 pm
by Sunbeem
I was lucky a while back, and came across a large stash of stones, covering a wide range of grades, and centre holes...
Most of my drill-bits will be over twenty year old, many much older.
After sharpening a drill-bit on my bench grinder, I usually dress it on the side of one of these, stone in one hand, bit in the other, holding it to the light, then finish off with a slip, (stone wedge) of very fine carborundum.
Sunlight and a jeweler's loop, or lens, makes life easier.

A two stone grinder will get you from a badly chipped bit, to a fairly sharp one, if you get the grades right, and quench repeatedly. The outer edge is very easy to overheat, and it takes all the pain.
If it turns red, you need to cut the end off square with an angle grinder, try again, and fail again ... but this time - fail better.

Blunt drills are freely available at car boot sales and garage sales. The older the better is not always the case, but I find disappointments are very rare.
If you're starting from scratch, have one sharp half inch/12mm to copy, and begin with your largest.
As I'm right handed, I hold the end in my left hand and with my right, guide the tip through a circular motion as I lift the end, all at the correct angle seen from above, and the side.


Look out for triple fluted bits, as well as being nice to use, they are invariably good steel. Check the flutes on used bits, the tip condition is immaterial.

Buying bits with heavy advertising behind them, and bold ingredients to the fore, should set alarm bells ringing.
Just avoid wasting money on new drill-bits, when the world is full of blunt ones that just need bloody sharpening.
It's not about what they are made of, it's more about what you are made of.

Sunbeem.

Re: Are there better drill bits than cobalt?

Posted: Mon Sep 06, 2010 2:04 am
by Zombie Master
If you're starting from scratch, have one sharp half inch/12mm to copy, and begin with your largest.
As I'm right handed, I hold the end in my left hand and with my right, guide the tip through a circular motion as I lift the end, all at the correct angle seen from above, and the side.

Great description!

Re: Are there better drill bits than cobalt?

Posted: Mon Sep 06, 2010 2:33 am
by Max Headroom
Sunbeem wrote:I hold the end in my left hand and with my right, guide the tip through a circular motion as I lift the end, all at the correct angle seen from above, and the side.
Funnily enough, I'm left-handed yet I hold drills the same way as you when sharpening. Probably comes from years of using equipment and machinery designed for right-handers . . .

Re: Are there better drill bits than cobalt?

Posted: Mon Sep 06, 2010 3:52 am
by ME 109
Max Headroom wrote:
Sunbeem wrote:I hold the end in my left hand and with my right, guide the tip through a circular motion as I lift the end, all at the correct angle seen from above, and the side.
Funnily enough, I'm left-handed yet I hold drills the same way as you when sharpening. Probably comes from years of using equipment and machinery designed for right-handers . . .

I'd like to see someone sharpen a drill bit holding the 'blunt' end in their right hand! :shock: