Woodworker's Central Woodworker's Gazette Gazette Archive 2/7/04

Tool Review: Drill Doctor 400 by Bob Bradley I had no prior knowledge of the Drill Doctor so upon receiving the tool it was an experience to set it up for a test. The instruction manual was quite good; I was ready within fifteen minutes to test my first sharpening of a dull drill bit. The test bit I selected was a 5/16 Titanium coated twist drill bit which would not cut through a 1/8" steel plate. I first sharpened it on my Makita wet wheel sharpening system using the built-in drill bit guide. After my best attempt at sharpening, the drill bit still would not cut through the steel plate even with a punched starter hole. I then sharpened it on the Drill Doctor and made a split-point on the bit. It wandered a bit without a punched starter hole but then cut through the steel plate without too much pressure and in a good time. I was somewhat surprised because I had dulled the bit cutting steel and did not think it could be brought back to good use. Then, I punched a starter hole and drilled another hole through the steel plate and this time it cut right in and went through the plate with an almost perfectly circular hole. THE BIT WAS SHARP! Next I used the bit to cut through some 2" Red Oak. No problem - like cutting through a soft wood--I mean it cut through fast. So, the next test was a 15/64" standard twist drill bit which would just barely cut into the steel plate with a lot of pressure on the drill. After sharpening on the Makita, it would not cut at all. So, on to the Drill Doctor. After sharpening on the Drill Doctor and after cutting a split point, the drill bit went through the steel as if it were wood. AMAZING! Now the real test - a masonry bit. I selected a 1/8" bit with a carbide tip that would not cut through a piece of concrete. I was really hesitant to even try sharpening it on the Drill Doctor for fear of ruining the sharpening wheel. Did not even attempt to sharpen on the Makita. Well the alignment of the bit in the sharpening chuck is not very precise. However, I did sharpen it with just two turns and it cut right through the concrete. It really does work and with very little skill. I decided this was enough testing. My sons and I will be sharpening all of our drill bits over the winter. I have already purchased a replacement grinding wheel because this machine will stay in my shop for a long time. Thanks to the developers for a great machine that any "shop guy" would like to have. Bob Bradley ************** Drill Doctor Quick Impressions by Jim Mattson Before sending the Drill Doctor off to Bob, I pulled it out of it's really nice case and played around with it a bit. I needed to take some pictures and more importantly, I needed to know if it works! I learned how to sharpen twist drills from an old German craftsman nearly thirty years ago using nothing but a grinding wheel and a deft hand. Over the years I've become pretty good at the medium size bits - the really small ones and really big ones are still a challenge. To sharpen these bits by hand, you have to get the point centered and perform a half-twisting roll against the grinding wheel which sharpens the leading edge and determines the relief angle. Did I mention both sides need the same angle? It's not easy and I might spend a couple trips back and forth to the grinder to get it right. Almost immediately, you realize the Drill Doctor performs all these 3D acrobatics for you. First you set the bit loosely but not too loosely in the chuck, then slide it in the side hole to align the drill flutes to the chuck and then tighten. Then you plug the chuck/drill into the end hole and rotate to sharpen the bit. A couple cams and a swivel move the bit precisely through the proper motions making the operation fool-proof. There is even another access hole on the far side to cut split-points on your bits. This can be really handy for eliminating the need to center-punch your holes since split-points don't skate around as much! ( I can't do split-points by hand...:() Along with the Drill Doctor is a simply great video explaining how to operate the machine. After one viewing, I was off to the shop - no need to open the manual. (But I'm sure there is some important safety and maintenance stuff in there so you better read it! ;)) Anyway, I decided to test the machine by clamping a 1/4" thick bar of aluminum to the drill press table and drilling the first hole with a brand new bit - a Hansen 1/4". I wanted to see how close the Drill Doctor came to re-creating that just new sharpness. In the picture above, the new hole is the one on the right. I then de-sharpened the bit by grinding a flat on the point, (Picture Left) and then sharpened the bit using the Drill Doctor. It took about 12 revolutions of the chuck to get the bit sharp again, and then I mounted the bit in the drill press to drill the hole just to the left of the new hole. Then I repeated the desharpening/resharpening routine to drill another hole. As you can see from the picture above, the Drill Doctor holes are indistinguishable from the hole drilled when the bit was brand new - even down to the spiral groove cut in the hole side!!! Just for kicks, I desharpened the bit again and sharpened it by hand. The two holes on the far left are the result and boy, do they look good! How did I do it? Beats me, but my best guess is the relief angle I ground on the bit was much shallower so the bit fed less aggressively through the soft aluminum. This is born out by the fact those two holes on the left took three times longer to drill and lots of downward pressure on the drill press handle. The main impression I got from the Drill Doctor is really favorable. It has a diamond grinding wheel for longevity and the unit itself has a very solid feel. The motor seems plenty strong and the whole operation couldn't be more straightforward. Once you get a couple bits under your belt, from dull to sharp takes about two minutes - certainly far better than trudging to the hardware store for a new bit; and most of the time, better than my hit-and-miss method of grinding them by hand. All things considered, the Drill Doctor is a winner and I'm kind of sorry I mailed it off to Bob! Jim Mattson ********************* The Drill Doctor 400 costs about $150 and is available from the manufacturer's website.