As mentioned above, a replaceable diamond wheel performs all the sharpening tasks. The wheel supplied should be good for many hundreds of drill bit sharpenings, but should you require a replacement wheel, these are readily available and can easily be changed by the user. All instructions supplied in the included manual.

Before you get started, it is a good idea to read the included manual, and perhaps more importantly, to watch the instructional DVD that is included in the 750X kit. This is a nice inclusion and shows you how to correctly use the tool. You will grasp the concepts much better by seeing them on screen rather than reading about them in the manual.

The Process
Ok, let me walk you through the process of sharpening the various drill bits using the Drill Doctor 750X, and along the way I'll explain the feature of the tool as well.

I will be sharpening a 1/4" (6.5mm) standard twist drill bit to begin with, but the process is basically the same for any sized twist drill bit.

To begin with, you have the option with the Drill Doctor to sharpen the cutting tips to the standard 118 degree angle, or to use a flatter 135 degree angle for drilling into more difficult materials. Sheet metal drilling bits often have this flatter 135 degree angle to allow the bit to engage the surface more fully during the initial drilling process, and hence speed up drilling operation, and generally with less bit wandering on start too. This angle can be switched between the two options via the Drill Doctor's Point Angle Adjustment Plate. Tip geometry can also be adjusted with this sharpening device.

To sharpen a bit there are two basic steps. First you need to align the bit correctly in the drill bit chuck supplied with the Drill Doctor. What this does is align the bit correctly with the specially designed chuck so that when you come to sharpen the bit on the diamond wheel, the bit geometry and angles are correctly matched to the same angles already on the drill bit. The alignment process also allows you to control how much material is removed from the cutting tips. This is a great adjustment feature because it allows you to either quickly touch-up the edges of a bit that has just started to lose its cutting edge/sharpness, or take off more material from a very dull bit, or one with damaged cutting tips. The adjustable Material Take Off screw (MTO) allows this adjustment feature. With the drill bit loosely secured in the supplied chuck, the chuck gets inserted into the Drill Doctor's alignment port. There are a number of notches in the alignment port ring which engage into the chuck "finger" at the different angle settings. 118 degrees and 135 degrees are marked on this notched ring, so first you align the finger on the chuck with the correct angle notch on the ring. Two metal fingers (called clamp arms) in the Alignment port do the job of aligning the drill bit correctly in relation to the chuck. They are positioned into the narrowest section of the flutes on the drill bit just before the tip, which in turn rotates the drill bit into correct alignment in the chuck for sharpening (you may need to rotate the drill bit manually to this point, hence why you don't fully tighten the drill bit in the chuck initially). Once this alignment is made, the chuck is tightened while still engaged in the alignment port, then the chuck is removed and further tightened ready for sharpening. The bit is now secured in the chuck and correctly aligned to begin the sharpening action.

Step 1 is probably the hardest, but in saying that, its still very easy. Step 2 is a breeze. Simply plug in the Drill Doctor to a circuit and switch it on. The diamond coated sharpening drill spins up to 15,000 RPM, although it is far quieter than a router or a rotary tool. Take the chuck, and with its white markings, line one of those up with the cam guide on the Drill Doctor's sharpening point. Plunge the chuck in until is doesn't go any further, than start rotating the chuck in half turns, ensuring light pressure is directed into the port direction and that the chuck rides against the cam guide as you rotate. This causes the whole port to rock up and down as you turn, which is normal and how it is designed to move. The action of the cams will provide the continuous changing angle by the port needed to sharpen twist drill cutting tips. It is hard to describe this action, so have a look at the Drill Doctor video supplied here to see exactly how it works. Basically, all you need to do is rotate the chuck in half turns about three of four times (or more if removing larger amount of surface material) and ensure the chuck is seated adequately in the port as you rotate it. A few seconds later and the bit is now sharpened. It's terribly easy, in a good way of course. It makes other methods of drill bit sharpening seem somewhat prehistoric, and definitely mundane and slow. Now the 1/4" dull bit I had has a noticeably sharp tip by look and feel. And in practice it seems as sharp as it was the day it came out of the pack off the shelf. I just saved myself a few dollars there.

Creating a 135 Degree Drilling Tip
This is done in the same manner as 118 degree tips, however, the sharpening port is raised to the 135 degree position and secured, and when you align the drill bit in the chuck using the Alignment Port, you seat the finger in the 135 degree notch of the Alignment Port instead of the 118 degree notch. Everything else is the same.

Creating Other Angle Tips
The Drill Doctor is also capable of sharpening other angles in the 115 - 140 degree range. The sharpening port angle is variable between these angles, and there are a few extra notches in the Alignment Port to cover other angles (although these are not marked with degree notations. However, there is flexibility here to achieve different angle grinds. I don't personally have a need for anything other than 118 degree or 135 degree grinds myself, but who knows, your situation might be different.

Creating a Back-Cut/Split-Point Tip
The back-cut or split-point tip is a popular drill bit tip profile for metal workers or wherever a more aggressive cut start is required. The Drill Doctor 750X allows you to create these tip grinds very quickly and easily. To create a split point tip you start by sharpening the drill bit as stated above. Now, with the drill bit remaining in the tightened chuck, you use the splitting port on the lateral side of the machine. You simply align the white mark on the chuck with the mark on the splitting port and plunge the chuck (and secured bit) straight into the port. Split the other side by aligning the second white mark on the chuck with the mark on the splitting port and plunge. Withdraw the chuck and bit and check it. You should now have a split-point drill bit. Again, very quick and easy.

I would say that to sharpen a smaller dull bit from scratch to a sharp edge with a split point design will take no more than 30 seconds, and probably less once you have the process figured out. It's easy, don't worry. I had it licked after just one or two attempts, and the first attempt was perfectly successful. It is hard (almost impossible) to mess it up if you have ensured the sharpening port is set for the correct angle and that you have aligned the bit correctly in the chuck.

Factors Affecting Sharpening Speed
The major factor affecting speed at which a bit can be sharpened is the bit's size. Basically, the larger the bit, the more sharpening rotations are required to sharpen the bit correctly. The whole cutting face needs to be treated, and this can take a few turns. For example, a 1/2" bit can take up to 20 half rotations of the chuck in the sharpening port. A 3/4" bit (which is the largest the 750X can handle) might take up to 40 rotations for a very dull bit. Obviously the more material that needs to be removed, the longer it will take, and very small bits only need a couple turns and light pressure on the chuck. The type of material the drill bit is made from might also affect sharpening time. Naturally, harder materials will take slightly longer than softer metals. The diamond wheel (180 grit equiv) is the hardest of all of course, and should last quite a long time according to the manufacturers. Spares are readily available and fairly inexpensive. I cannot say at this point how long the diamond drum will last. I haven't owned the Drill Doctor long enough yet. It is still grinding very fast after about 50 or so bit sharpenings. I expect it to suffer through many hundreds based on my experience with other diamond sharpening tools. If you regularly sharpen larger bits of 1/2" or larger you can buy a coarser 100 grit diamond wheel to increase the sharpening speed for these bits.

Regardless of these factors, I can't imagine any faster way of sharpening twist drill bits that can be done at home and without spending thousands on sophisticated machines.

Sharpening Masonry Bits
The other type of bit the Drill Doctor can sharpen is the masonry bit (used for drilling brick/concrete, and you guessed it, other masonry products). Sharpening masonry bits is even easier than twist bits on the Drill Doctor because the alignment process is a little simpler. On the end of the drill chuck and two marks opposite each other. Insert the masonry bit in the chuck and line up the cutting tips to be parallel to the marks on the end of the chuck. That's all you need to do for alignment. You set the cutting depth by lining up the white mark on the chuck with the cam guide on the sharpening port. Insert the chuck in the port until the cutting tip of the bit touches the diamond wheel. At this stage the machine is turned OFF. Now with the bit touching the wheel, slightly move the chuck backwards on the drill bit (essentially projecting the drill bit further out from the chuck) so material will be removed when sharpening action is undertaken. Secure the bit in the chuck, again ensuring the cutting tips are parallel to the mark lines on the end of the chuck. Switch on the Drill Doctor, align the white line on the chuck with the cam guide and plunge the chuck straight in to engage the diamond wheel. NO rotation is necessary for masonry bits. It is just a straight plunge and withdrawal. Turn the chuck 180 degrees to line up the second white mark with the cam guide and plunge again to sharpen the second tip of the masonry bit. Switch off the Drill Doctor and inspect the tips. If further sharpening is required, readjust the depth of cut of the bit and sharpen more. Note that you cannot split the point of a masonry bit as you can do with a twist drill bit.

Needless to say, sharpening masonry bits is simple to do as well with the Drill Doctor.

Drill Doctor Maintenance
There is not a lot to maintain on the tool. Basically you need to keep it clean for best performance by removing any accumulated grinding dust or debris from the ports, chuck, and around the diamond wheel enclosure. This can be done with a dry cloth, small brush, or vacuum. But perhaps it is easiest with compressed air. A blast of air seems to get rid of pretty much all the accumulated material on the tool. Be sure to wear safety gear when cleaning with compressed air however as debris does get blown in all directions. Doing it outdoors is also better than in a small enclosed area.

The diamond wheel will eventually require replacement as the surface wears down. You should get many hundreds of bits sharpened from a single wheel, but if cutting speed starts to slow or there are visual signs of strong wear, grab a new wheel and replace the original. The wheel is held on by a securing plate and two screws. Simply use the arbor wrench supplied to hold the arbor steady and unscrew the two screws. Remove the old wheel, add the new wheel, add the plate, re-insert and tighten the screws and you are ready to go again. It only takes roughly 1-2 minutes max to change wheels.

There is no other real maintenance needed on the Drill Doctor. Just keep it clean, don't overload the motor by pushing excessively hard against the diamond wheel when sharpening and it should deliver great service for many years. I can't claim this on my own unit yet but I have read other owners comments in the past and most of them seem to have little or no trouble with their units. The motor does seem to deliver consistent speed despite variable load.

Left Hand Bits
The 750X can sharpen 3/32” – 1/2” reverse-twist (left-hand) drill bits, however, this requires an optional left hand chuck accessory that does not come with the kit. I haven't seen or used it so I can't comment further at this stage.

Conclusion
Well, the basic conclusion is that I now have a shop full of sharp drill bits. I had a stack of dull bits I had kept over the years that I have been meaning to sharpen, and this collection had grown quite a bit because of my lack of time or lack of faith in other sharpening products to do the job properly. Now with the Drill Doctor, this large collection of bits are back in a useable condition and will be cutting wood and other materials once more.

The Drill Doctor is not the cheapest drill bit sharpening device on the market, retailing at around US$130 street price, however, if you use twist and masonry drill bits a lot, and particularly the larger, more expensive ones, you will find you can recover the cost of the unit relatively quickly in savings on new bits from the store or having your existing bits sent out to be professionally sharpened. The Drill Doctor allows you to sharpen your drill bits quickly, easily, and right at home, or on the jobsite (if power is available) meaning there is very little or no down time. And it is far superior to the cheaper sharpening devices which often do not replicate the correct tip angles or curves that make the drill bit a practical, clean, and efficient cutting tool. 

I consider this a very useful and worthwhile tool, but you have to be using your bits fairly often or require very sharp bits to get the best value for money out of the tool considering its initial purchase price. But as I have found, recovering the cost shouldn't take so long if you are a keen woodworker using your drill bits on a regular basis. I expect some of my drill bits to service me for a very long time now I have this particular sharpening device in the shop, and I will always have sharp bits ready to go when I need them, which is a big plus!

Available to Order Online through these companies... Click graphic to go to their direct product page for this item
Amazon.com (USA)
DD750X As reviewed above... Full featured Pro model	DD500X Cheaper model. 1/2" max bit capacity
Rockler.com (USA)
Drill Doctor® 750X Bit Sharpener Don’t let dull drill bits slow you down! Top-of-the-line professional bit sharpener from Drill Doctor is built to handle larger drill bits — up to 3/4" — and offers additional custom flexibility. .. Drill Doctor® 750X Bit Sharpener
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