Drill Doctor 750X
Pro-level drill bit sharpening in your shop- when you need it!
Text, photos and video by Tom Hintz
Posted – 2-27-2011
Anyone with even a basic workshop uses drill bits. Nearly all of them have thrown away bits that have gone dull or damaged and buy new ones because they do not have a reliable way to sharpen the old bits. Some try freehand sharpening on a grinder or use one of the jigs available. However, the happiest of the drill bit users that I was hearing from were consistently using the Drill Doctor. It didn’t take long for me to get very interested in this little machine. This review focuses on the Drill Doctor Model 750X, the most capable of the models available because I just cannot see going halfway with such a useful capability. Now I also am one happy drill bit user!
The Drill Doctor 750X shop model uses patented technology developed by the parent company, Darex who leads the field in designing and building high-end industrial drill bit sharpeners. Being able to access that kind of in house engineering expertise is a major reason that the Drill Doctor is so effective and has sold over 3-million units!
The 750X can sharpen a huge range of drill sizes from 3/32” to ¾” using the chuck included in the Drill Doctor 750X kit. This machine sharpens high-speed steel, carbide, cobalt, TiN-coated and masonry bits. It also handles reverse-twist (left hand) bits from 3/32” – 1/2”-diameters with an optional chuck. The design of the Drill Doctor 750X lets you create bits with custom angles between 115 and 140-degrees.
The included chuck has long jaws that hold the bit precisely for dead-on accurate sharpening. That includes all common drill bits including split point and carbide-tipped masonry bits. You can even resurrect a broken bit by sharpening the stub if it is long enough! A separate “Push to Stop” port lets you split points cleanly and precisely with no guessing.
The chuck has a cam shape built into its outer edge that interacts with a pin on the machine at the sharpening port. The cam moves the bit through a very specific motion that produces properly ground cutting edges. You simply press inwards while giving the chuck ½-turn then repeat a number of times to complete sharpening. The chuck has white markers that make it easy to insert the chuck correctly and then take accurate half turns. The manual suggests the number of turns usually needed to sharpen common drill sizes.
The sharpening port itself is on an adjustable plate that lets you select drill angles of 115 to 140-degrees. Most bits are 118-degrees and some have a shallower 135-degree angle but you can custom design your bits angle very precisely if you have the need or just want to explore the possibilities.
The Drill Doctor 750X has a dial that lets you control the amount of material being removed. Since most bits do not require extensive grinding this material control means that you can sharpen your bits many times without sacrificing significant amounts of the overall length. Keeping the amount of material removed to a minimum also prevents excessive loading of the diamond-encrusted grinding wheel. When that grinding wheel does eventually wear out you can replace it easily in your shop.
A special port makes setting up the bit in the chuck very easy yet ultra precise. The chuck has indexing wings that engage the port walls and a set of arms hold the bit in the perfect position for grinding. You simply let those arms close on the bit and then turn it until they grasp the bit at the narrowest point. That insures that the grinding action shapes the drill points perfectly.
The Drill Doctor uses a permanent magnet motor that assures consistent power during use. That also makes getting a clean, even set of cutting edges much easier.
Busted to Un-Busted
Another thing the Drill Doctor is very good at is resurrecting chipped or broken bits. Obviously the remaining bit has to be long enough to use before it is worth saving. I had a couple broken bits that fit the criteria so decided to fix them. The first one that I repaired on the Drill Doctor is in the video found later on this page.
The first step in repairing a broken bit is to use a bench grinder to rough in a taper on the drill point. That just allows the point to register against the depth stop to reduce the amount of grinding the Drill Doctor has to do. This bit of pre-grinding saves excessive wear and tear on the Drill Doctor diamond wheel and speeds the process in a big way.
After roughing in the taper you set the bit in the chuck exactly as you would with any bit. The only difference might be using more turns in the sharpening port to fully shape and sharpen the bit. The bit that I repaired in the video needed about 10 full turns to attain a finished tip. Incidentally that bit cut better after being repaired on the Drill Doctor than before it broke!
In the Shop
I suspect that many of you will discover a bunch of old drill bits that were tossed in a drawer when they stopped cutting well, just as I did. Since getting the Drill Doctor in my shop I have “resurrected” those bits and improved some of my current A-list bits. If you appreciate sharp drill bits the Drill Doctor is amazing.
The Drill Doctor is very simple and the hardest part of learning to use it is getting that through your head. Turning the bit in the sharpening port takes a little getting used to but after sharpening two or three bits I was accustomed to just pressing it in and turning the chuck through half turns while letting the cam do the rocking motion part of it. Here again, the Drill Doctor handles the geometry, you just have to get used to letting it do it!
All of the Drill Doctor parts are well made and appear to be very accurate. The adjustments necessary to sharpen bits properly are fast, simple and easy to master. Within an hour of getting the Drill Doctor in my shop I was happily making great bits out of duds. In fact, after following the instructions to sharpen a couple bits I was thinking that I might have missed a step or two. Sharpening bits just seemed to easy and straight forward. For once the real world really is that easy!
In addition to doing its work quickly, the Drill Doctor is very easy to use. Being able to add split points so quickly and easily lets you fine-tune a bit for a job that tends to induce walking of the bit. You don’t have to go anywhere or buy anything, just tweak the bits you already have.
I know that in some situations hard cases are becoming more of a marketing afterthought but with the Drill Doctor, it is a very good idea. For most of us the Drill Doctor won’t be used all day, every day. The included case makes sure it stays clean and all of the related pieces are where you can find them. That is no small point of convenience.
It is hard to imagine anyone that uses drills not finding the Drill Doctor to be one of the better machine values on the planet. With the cost of drills these days the street price for the Drill Doctor 750X shown here of $150.00 (2-27-2011) owning this machine makes lots of fiscal sense. Just being able to keep your bits sharp rather than replacing them will more than pay for the Drill Doctor in a short time. The convenience of being able to touch up a bit or add split points to one in my shop, at any hour is worth the expense.
If you work with metal, drilling is part of your skill set. The Drill Doctor 750X should be part of your in-shop machine set so that you can work more easily and smarter. Anything that lets you be more precise or reduces frustration (or both) is a valid expense my world.
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