Drill Doctor 750 review

Taking a break from more onerous tasks, I got out a Christmas present for the first time to see if would perform better than my skepticism predicted. Yup. My rotten grandlings got tired of listening to me bellyache about not being able to see well enough to sharpen drills free hand so they got me a Drill Doctor 750 for Christmas.

First impressions.

Neat compact kit in a blow molded case with all accessories, two chuck/cam arrangements, a little wrench for changing the grinding wheel, and finally a video tape in case my famous instant mastery of all things mechanical suddenly lapsed. Everything made sense and went together in a logical sequence. The instructions were crystal clear with plenty of illustrations to guide each step. There are numbers on the case of the Drill Doctor to follow so you don't mix up any steps.

Performance

This gadget performs as advertised. Follow the steps and you can sharpen a drill as well as I could in my prime (which is pretty damn good if I do say so). You have a choice of conventional grind or split point and it will sharpen masonry bits should you ever need to, The 750's two chucks are cheap looking affairs having hardened sheet metal jaws. The rest of the machine is stout plastic and I don't mean this in a joking way. Many plastics are capable of withstanding the rigors of the open shop better then metal if the application is selected with the material's characteristics in mind.

I have plenty of dull drills so I did not lack for demonstration material. The Drill Doctor sharpened a ½" drill spot-on and split the point precisely. I then used it to drill a 0.503 hole in mild steel and it did so with two full width chips spiraling out of the flutes—a perfect textbook grind.

The ¼" drill didn't fare as well. It took some fiddling around to get the Drill Doctor to grind a symmetrical point with cutting edges of equal length. I diagnosed the problem as being with the chuck and its six wimpy, wobbly sheet metal jaws. They would not get an even concentric grab on the drill—one jaw was always splayed off to the side a bit. The chuck was correctly assembled and functioning normally. It would grip a piece of ¼" drill rod okay and centered within 0.002" of the chuck's (plastic) registration surfaces but the interruptions of a fluted drill's diameter seemed to defeat it.

1/8" drills were hopeless. An utter PITA. By the time I got the chuck working right and the drill properly gripped for sharpening I could have sharpened it with a hand stone—my usual method for sharpening small drills anyway.

I sharpened my ¾" and under drills with the larger chuck without trouble and they drilled on-sized holes.

Follow Up

A call to the Drill Doctor people and a conversation with Denise, their tech person, failed to resolve the problem. She walked me through several scenarios none of which corrected the problem of unpredictably poor centering of small drills in their drill chuck/cam unit.

Afterwards I carefully checked the chuck until I discovered it was incorrectly assembled...twice. Once from the factory and once by me. There are shallow guides molded into the chuck barrel that the jaws must engage in order to correctly align with the axis. This is tricky because the jaws are merely hardened sheet metal and dangle from a hairpin spring. The insertion of the jaws simultaneously in their guide slots has to be verified as it's assembled. A judicious nudge with a scribe helps the process. Once properly engaged the jaws stay put and accurately center.

Usage Tips

Ensure the Drill Doctor chuck/cam units are correctly assembled so the jaws engage the slots in the thrust collar as well as the slots in the barrel. Mine were not and when I disassembled it for inspection and diagnosis I incorrectly reassembled it in the same way it came from the factory. Without correct assembly it will not sharpen smaller drills so the point is correctly centered.

With the chuck assembly corrected per these steps—not mentioned in the manual—the machine will sharpen drills down to the 3/32" minimum so the points are accurately centered.

The spring jaws inside the alignment port sometimes hang up. Be sure to wiggle the drill while it's a bit loose in the chuck so the spring jaws in the alignment port index the drill in time with the cam in the chuck. Only then do you snug up the chuck.

Closely examine the clearance angle on smaller drills. I discovered on my unit the smaller the drills got the closer the as-ground clearance got to zero. While they cut they were slow to feed. I set the alignment adjustment lever to "+" to gain a bit more clearance and the drills cut better. This lever needs some intermediate positions.

Suitability

The manual gives you clear instruction on maintenance and what signs to look for to determine wheel wear and how to flip the wheel over when the abrasive poops out. The manual goes on to say the little diamond wheel it comes with is good for maybe 200 drills. Only 200? In a busy five man shop 200 drills accumulate in the sharpen me coffee can in a week or two. Given that the replacement wheels cost $40, that alone brings into question whether the Drill Doctor is adequate for any but the small home shop. Well, that's how it's advertised and that's where I'd place it.

This is one machine that could benefit from double angle collets but that would triple the price. So we got sheet metal and plastic. The chucks could be better designed to grip small drills. Dammit, the Drill Doctor should grind all sizes from 1/16" to its max rated size without a fuss.

Small commercial shop owners better get the Drill Doctor's larger cousins because replacing the little diamond wheels will bust the economics justifying its purchase.

Additional Remarks From Other Users

Derek Lent agreed:

I don't own one, but I used a friend's for quite a few drills. It worked very well for me for small drills after I played with it for a while. As I recall, I had to align the metal fingers to the inside edges of the drill flutes to get it to center symmetrically. Then the small drill came out as symmetric as I could see under a magnifier (I did not make test hole in metal though).

My impression was the replacement grinding wheels are about $20, not $40. I should get one for my friend because I sharpened a lot of bits, but it was still grinding just fine.

John Lucas cautiously dissented:

I will look at my Drill Doctor and check it out when I get home. I thought everything was aligned in the chuck. I called them and they walked me through the process but I didn't have any better success. I've been very unhappy with mine. I often get funny grinds and the angle it grinds is a poor angle for thin woods and plastics.

Small drill bits tend to have the backside of the clearance angle ground incorrectly. I can sharpen better by hand. I will try again and see what happens.