DocsMachine
Well-known member
- Joined
- Sep 16, 2006
- Messages
- 1,864
Just picked up a new drill grinder, one I hadn't heard of until just a week or two ago. Came in yesterday and I finally had a chance to try it today.
Quick opinion? Worth every penny. It's basically a Drill Doctor that actually works, without having to hold your tongue just right, or sacrifice the correct color chicken.
I had been taught years ago how to grind my own drills, as any decent machinist should, and while I'm passable at it, it's time consuming and a little fiddly. I've wanted a good grinder for a while, but the typical fare has either been $2,500 Darex machines, Lisle machines that take three wrenches and twenty minutes to adjust, or $100 Drill Doctors that only work if you got a "good one", and the gods smiled on you that day.
I recently had a need for a good, accurate grind, and to be able to split the point, which I've never been able to do by hand. One of my readers pointed me towards this kind of machine:
I hadn't seen that style before, but a couple of YT videos praised them. They "just work". They're easy to set, easy to grind, and do an accurate job of splitting the point. The biggest takeaway I got was that none of them ever mentioned getting a bad grind- and all the ones I watched were people that bought the machines themselves, not "paid promoters".
This isn't going to be a full review. If you're interested, there's a dozen or more reviews and how-tos on YouTube. This is just my impression.
First, they use ER-20 collets, as most machinists are familiar with. They appear to be standard collets, save for the two smallest, which have a special tail end specifically for this grinder:
Normally the marked end- on the left- is the nose- that's where the tool comes out. On these, the small end is the working end, so on the smallest-diameter two, they're machined for clearance at the "front" and to the working bore at the "back".
Not an issue, of course, just don't get 'em mixed up with your regular ER-20s.
I had a little basket of dull drills, and to start with, picked a .264" with worn points:
I set it, ground it and split it- all of which took less than two minutes:
A note on the finish: The CBN (cubic boron nitride) wheel these things come with is maybe a bit coarse. It's a blance between finish and grinding time- a finer wheel would take longer to grind the tip, and maybe overheat it. Really, the finish looks rougher than it is, and it produces a smooth finish when drilling.
After that, I picked one that was a bit more badly damaged...
And still ended up with a nearly perfect grind.
It's worth noting that this bit was the only one that gave me- for a moment- a "less than perfect" grind. The initial tip was pretty bad- it had been badly ground at some point in its life, with the edges mismatched and almost rounded. That must have caused a small issue when setting the drill in the holder, and after splitting the point, the cutting faces were clearly uneven.
But I simply re-set the drill, ground it back a little more, and the result was nearly perfect.
Most of the videos show the user grinding a big drill- around 1/2"- simply so it can be seen better on camera. I wanted to see how it could do smaller drills, like 1/8", and while I didn't try splitting the points, they worked quite well. This one is a .106" drill, and seems to have worked just fine.
The only real issue I've found is in the length. I have some "stub" length drills- and point in fact, wanting to custom-grind a very short, stiff drill was one of the reasons for wanting a machine like this- and unfortunately, anything shorter than about 2" is very difficult to do, simply becasue you can't reach in and hold the drill in place while tightening the fixture. There may be ways around that, I plan to experiment a bit.
But anyway, I was able to sharpen fully half of what was in the dull-drill tub, in about half an hour.
The ones in the trough at the left are badly damaged enough they need to be cut back or heavily ground down before they can be properly sharpened.
Bottom line: I've been wanting a machine like this for most of my career. It takes about two minutes at most to set and grind a drill, including splitting a point. Better yet, it "just works". You don't have to fiddle or tweak or hold your mouth just so. You set it, grind it, and go back to work.
One bit of warning: The grinding wheel has a fan on it, which helps keep both it and the drill bit cool. But this thing makes a LOT of dust in a short period, and blows it pretty much everywhere. I recommend using it in a ventilated area, and/or with a dust mask. The CBN wheel can supposedly do carbide, and tungsten carbide generally contains cobalt as a binder, so you definitely want breathing protection for that.
Since I have a shop crowded with machines that I'd rather not get grinding grit on, and half the year I can't take it outside and grind, I'm toying with the idea of making a new sheetmetal cover for the working end, that has a connection for a shop-vac.
Doc.
Quick opinion? Worth every penny. It's basically a Drill Doctor that actually works, without having to hold your tongue just right, or sacrifice the correct color chicken.
I had been taught years ago how to grind my own drills, as any decent machinist should, and while I'm passable at it, it's time consuming and a little fiddly. I've wanted a good grinder for a while, but the typical fare has either been $2,500 Darex machines, Lisle machines that take three wrenches and twenty minutes to adjust, or $100 Drill Doctors that only work if you got a "good one", and the gods smiled on you that day.
I recently had a need for a good, accurate grind, and to be able to split the point, which I've never been able to do by hand. One of my readers pointed me towards this kind of machine:
I hadn't seen that style before, but a couple of YT videos praised them. They "just work". They're easy to set, easy to grind, and do an accurate job of splitting the point. The biggest takeaway I got was that none of them ever mentioned getting a bad grind- and all the ones I watched were people that bought the machines themselves, not "paid promoters".
This isn't going to be a full review. If you're interested, there's a dozen or more reviews and how-tos on YouTube. This is just my impression.
First, they use ER-20 collets, as most machinists are familiar with. They appear to be standard collets, save for the two smallest, which have a special tail end specifically for this grinder:
Normally the marked end- on the left- is the nose- that's where the tool comes out. On these, the small end is the working end, so on the smallest-diameter two, they're machined for clearance at the "front" and to the working bore at the "back".
Not an issue, of course, just don't get 'em mixed up with your regular ER-20s.
I had a little basket of dull drills, and to start with, picked a .264" with worn points:
I set it, ground it and split it- all of which took less than two minutes:
A note on the finish: The CBN (cubic boron nitride) wheel these things come with is maybe a bit coarse. It's a blance between finish and grinding time- a finer wheel would take longer to grind the tip, and maybe overheat it. Really, the finish looks rougher than it is, and it produces a smooth finish when drilling.
After that, I picked one that was a bit more badly damaged...
And still ended up with a nearly perfect grind.
It's worth noting that this bit was the only one that gave me- for a moment- a "less than perfect" grind. The initial tip was pretty bad- it had been badly ground at some point in its life, with the edges mismatched and almost rounded. That must have caused a small issue when setting the drill in the holder, and after splitting the point, the cutting faces were clearly uneven.
But I simply re-set the drill, ground it back a little more, and the result was nearly perfect.
Most of the videos show the user grinding a big drill- around 1/2"- simply so it can be seen better on camera. I wanted to see how it could do smaller drills, like 1/8", and while I didn't try splitting the points, they worked quite well. This one is a .106" drill, and seems to have worked just fine.
The only real issue I've found is in the length. I have some "stub" length drills- and point in fact, wanting to custom-grind a very short, stiff drill was one of the reasons for wanting a machine like this- and unfortunately, anything shorter than about 2" is very difficult to do, simply becasue you can't reach in and hold the drill in place while tightening the fixture. There may be ways around that, I plan to experiment a bit.
But anyway, I was able to sharpen fully half of what was in the dull-drill tub, in about half an hour.
The ones in the trough at the left are badly damaged enough they need to be cut back or heavily ground down before they can be properly sharpened.
Bottom line: I've been wanting a machine like this for most of my career.
It takes about two minutes at most to set and grind a drill, including splitting a point. Better yet, it "just works". You don't have to fiddle or tweak or hold your mouth just so. You set it, grind it, and go back to work.One bit of warning: The grinding wheel has a fan on it, which helps keep both it and the drill bit cool. But this thing makes a LOT of dust in a short period, and blows it pretty much everywhere. I recommend using it in a ventilated area, and/or with a dust mask. The CBN wheel can supposedly do carbide, and tungsten carbide generally contains cobalt as a binder, so you definitely want breathing protection for that.
Since I have a shop crowded with machines that I'd rather not get grinding grit on, and half the year I can't take it outside and grind, I'm toying with the idea of making a new sheetmetal cover for the working end, that has a connection for a shop-vac.
Doc.
