Just checked to see if reversing the diamond drum would work. My drill doctor is the 500 - so good up to 1/2in bits.
Both a 1/4 and 1/2 in. bit reach to the rear of the sharpening drum so reversing it should work. Mine needs a change although visually it looks good compared to the new drum. Feeling it reveals that it is now very smooth at the back and less so near the front.
It's not easy to see however this is a 1/4 in. drill bit reaching near the back of the drum - this is similar whether set up for 118 deg. or 135 deg.
Have any of you used it for split pointing bits? I've never tried that and would have to look at the instructions to see how.
John, I have been loaned a drill doctor on long term. My mate has acquired a proper Union tool and cutter grinder so doesn't use the drill doctor these days.
I sharpened a couple of old sets of drills with it and was quite pleasantly surprised at how decent a job it can do.
I did split the points on the drills over 4 mm dia up to 13mm and it does that very well also.
In essence there can be a bit of fiddling about to get the drill set up and indexed properly,but for the price of the unit they do a good job. Most certainly a huge improvement over the old Martek that I used to own.. As a couple of others have said previously,be gentle when feeding the drill into the wheel and don't lean on it or the wheel life will be dramatically reduced.
I do wonder whether the wheel might also benefit from being occasionally de-clogged by using a diamond wheel cleansing stick.......OZ.
ETA: I also meant to say that small diameter drills(1-4mm) are often so cheap to buy in packs of 10 that they aren't worth the hassle of re-sharpening