Yep, they work. It won't be super ultra sharp, but it'll work for general sharpening.

For very similar money you could get a real grinder and for not much more you could get one with a good enough tool rest your could just use that. You just need to git gud.

>>970234

I already have a grinder, so I'm game to do it by hand if it's not too hard. Is there some kind of jig you use, or can it be done freehand?

Oh yeah, and will this work on carbide bits? I was under the impression that they have only a thin coating of hard stuff and once they're gone, they're gone.

>>970230
>Are these things any good?
the high-end Drill Doctor is as good as you can get (at least in the USA) without spending a lot more money.

The company that makes Drill Doctors also makes an industrial-grade line of drill sharpeners named Darex. Drill Doctors are essentially small/plastic/babby versions of the Darex machines.

The "low-end" Darex is the model V390. It costs around $1500 retail.
The next-up model of Darex costs around $3200. (this is still a totally-manual model, mind you)

>>970234
>For very similar money you could get a real grinder and for not much more you could get one with a good enough tool rest your could just use that.
You won't ever get drills sharp & even doing them by hand. Especially if you want stuff like split points.
It works, and if you step drill and ream to final size it is decent accuracy,,, but it's not as fast or smooth as using a properly sharpened drill bit.

~~~~~~

The "olde-fashioned" way of grinding drills correctly was to use universal cutter grinders like the Quorn
https://www.google.com/webhp#q=quorn+tool+and+cutter+grinder
I dunno if anyone really builds (manual!) grinders like this now.
To build your own, there are places that sell the rough castings that you must finish yourself.

>>970255

This is pure gold, thank you.

>>970254
>Oh yeah, and will this work on carbide bits? I was under the impression that they have only a thin coating of hard stuff and once they're gone, they're gone.
nope.
There's two kinds of carbide bits: brazed tips and solid carbide.

Masonary bits are an example of brazed carbide tips. You can see that the tip is a separate piece of metal that is attached to the rest of the drill bit. If you use these too hard the tip heats up enough to melt the braze and the cutting tit falls off. Thats why they say to use masonary drill bits with water if possible.

Solid carbide drills look just like regular drill bits, they are all one-piece. The main difference is the price. A decent HSS 1/4-inch drill might cost $1 each, where a carbide drill the same size would cost $20 each.

------

If you want to buy drill bits from 'normal' hardware stores and you want to get good bits, then buy the cobalt bits.
Cobalt is harder than HSS and will stay sharp longer (and they cost more!) but cobalt is still pretty tough. (like HSS--it can withstand being flexed and bent a little bit without breaking....)

Carbide is way harder than cobalt and stays sharp much longer, but carbide is very brittle and can't be used in a hand-held drill. You need a drill press or a milling machine to use them. The reason is because if you bend a solid carbide drill bit just a *tiny* amount, it snaps and breaks in two.

Got one of these at a yard sale for $5
works great

>>970279

OK, sounds good. The cobalt bits are fine for my purposes, and those are what I have been using so far (if I needed real carbide, I would probably know what I'm doing). Do I need a diamond wheel for cobalt bits?

>>970289
>Do I need a diamond wheel for cobalt bits?
no.
you can grind cobalt bits on a bench grinder with a regular aluminum oxide wheel but you will notice that they grind away slower than HSS does.

the Drill Doctors have a diamond grinding wheel in them anyway.

You do need a diamond wheel to grind solid carbide.

-------

I should point out that I sharpen drills on a bench grinder by hand too--after the original split point is dull. But I know they drill oversized holes from then on, because the cutting edges and tip aren't on-center if they were hand-ground.

If I had to drill a perfect 1/2" hole through metal, I would normally use a good split-point bit of 31/64ths and then ream the hole to 1/2". A drill with a factory-ground split-point will make the exact hole it says it should, and it will plunge straight as well.

If I did not have a good-condition split point but only had hand-sharpened drills, then I would drill a 1/4" hole, then a 3/8" hole, then a 7/16" hole, and finally a 15/32 hole, and then ream to size.
The 1/4" hole might not drill straight, but every larger size would result in a more-straight hole, since each larger size is making a smaller and smaller cut than the drill bit before it. But the bits may still be cutting off-center, so I'd leave the final hole smaller before reaming.

........

I've not seen anyone build a CNC 5-axis grinder rig yet just for sharpening drills and mill bits, but I think the age is near.
It's a perfect job for a little CNC setup: the work envelope (and so the machine's range needed) is very small, and the cutting geometry is a colossal pain in the ass to perform manually.

By the way, carbide and cobalt dust is not good for you. Carbide is a sensitizing agent when exposed to skin, which may cause irritation. Breathing it in can cause asthma like symptoms (hard metal lung I think it was called). Chromium and cobalt to begin with are not things you want to breath in, which carbide tools contain. Research the proper precautions. The tool grinders at work have dust collecting systems, for example, on the open manual machines. Obviously the NC grinders are enclosed and the dust is evacuated along with coolant.

>>970230
https://www.youtube.com/watch?v=xDOlPMEC7IU

>>971152
this review is worthless, the guy is a retard.