Thread: drill doctor

I have an old "General" sharpening jig that works well for largish drills (say >6mm):
s-l1600.jpg
except for split pointing or web thinning.


(I'm also trying to work out a ZB drill grinder, but it is doing my head in )



So, I borrowed a "Drill Doctor XP" to try and sharpen some small drills (3-4mm), and am horrified by this thing..

• Surface finish of the grind looks like the drill bit had been towed behind the car over gravel for a few miles
• Drill gripping chuck/vice/thingy is flimsy, doesn't centre drills consistently
• Depth and flute position setting guide seems to be even flimsier - too far back from the face

However, I haven't tried the "split point" feature yet. It might slightly redeem itself.

Originally Posted by nigelpearson

So, I borrowed a "Drill Doctor XP" to try and sharpen some small drills (3-4mm), and am horrified by this thing..

• Surface finish of the grind looks like the drill bit had been towed behind the car over gravel for a few miles
• Drill gripping chuck/vice/thingy is flimsy, doesn't centre drills consistently
• Depth and flute position setting guide seems to be even flimsier - too far back from the face.

The one I bought from H&F recently for $79 has a small CBN wheel inside it and also has the first problem, but so far seem OK on the other two.
I sharpen manually but I bought the sharpener mainly for bits <6m because my eyesight is not so good on small bits.
For other sizes Ive been using it mainly to get damaged/broken bits back into shape but then I end up doing the final sharpening manually.

I bought a 750 Drill Doctor and found it's particularly good at putting negative relief on the cutting edge - has the benefit of massively reducing the load on the drill, as it's no longer actually drilling.

I find the finish is pretty damn good. The main benefit for me, once the relief is being ground correctly, is that it accurately resets the geometry. For 6mm drills and larger, I then just touch up the edges on the grinder as needed.

With the current state of play regards being in lockdowns, it may be beneficial to some members to look at hand sharpening their smaller drills by hand.

If at all possible I-would recommend a good light source above your pedestal/ bench grinder, and if eye sight/vision is an issue to try and obtain a suitable means of magnification.

I would also suggest that you have or find a suitable dressing means for your grinding wheel/wheels.

I would also recommend that you look on line for a reputable source for grinding your drills by hand.

Manually grinding in my opinion can not be that difficult, as it has been learnt by many apprentices and others over many years, it may take time to achieve workable results but once mastered or understood what needs to be achieved in regards to drill shape and cutting clearances resharpening becomes quite a quick task, depending on the drill size, some drills will require longer to achieve the desired cutting profile, ( negative rake, flat bottom, sheet metal, thin material ) .

Most of what I have said is achievable on a home bench grinder, depending on HP of grinder and the type of wheel being used .

But in this current climate it would seem to me to be the ideal environment to practice.

No real out lay apart from a dresser and grinding wheel required, the latter which most would already have.

Stefan Gotteswinter on utube demonstrates his simple method of free hand grinding of drills under 4mm . I tried his method and it does do a nice job , it's not so complicated . He uses a push upwards method , it is very effective. Stefan has so many utube lessons, not easy to find the drill sharpening one ! He starts at the 3 min mark

https://www.youtube.com/watch?v=dPlsEMY_HZ8

1) Peter is right, reasonable hand sharpening isn't that hard.
Bright light, some extra magnification,
and maybe an angle starting guide,
or a round bar to roll the drill over, are also helpful.


2) Perfectly sized hole drilling, however, needs perfectly ground drills ?



Here is a 7/16" that was previously sharpened on my General jig against a fine wheel,
re-sharpened, and split, on the Drill Doctor:
IMG_1882.jpg
The cutting edge texture seems quite rough to me. Like a 40 or 60 grit wheel.
Reasonable little split and outer corner removal, though.


Here are some 7/64" attempts. Left two are Drill Doctor, right was hand sharpened at about 100° point angle.
IMG_1880.jpg

Split from the Drill Doctor at this size is minimal, and outer corner removal is a little excessive.



Of course, the proof of the pudding is always how they drill. Haven't tested that yet.

Originally Posted by nigelpearson

Here is a 7/16" that was previously sharpened on my General jig against a fine wheel,
re-sharpened, and split, on the Drill Doctor:
IMG_1882.jpg

Hmm, that does look considerably rougher than the finish I get on mine - I wonder if it's a different grade diamond wheel?

The main challenge I have with hand grinding is maintaining symmetry, particularly of cutting edge length. For touch-ups, I try to make sure I do the same number of passes with the same pressure on both edges, but I know that after a couple of times doing this, I'm going to have the point going off to one side, and the angles are going to start to differ, hence the attraction of the Drill Doctor to reset all that.

Hi, new member here - Chris.

I'm not a machinist, but am a semi-retired tradesman.

I found when I was sharpening drills by hand often, it did take me quite a while to get the knack of it, but then didn't have the need to sharpen any for some time, then it felt like starting from square 1 again, when trying, only, worse as 'I can do this, why isn't it working' set in and I gave up. This was some time back.

I saw a Drill Doctor being demoed at a Blackwoods Trade Show (do they still have them ?) and was impressed, it seemed fairly priced and the Representative gave me quite a few tip on setting angles and that some of the 'settings' were more of a guide than a setting. The machine I have is not the current model, it maybe 2 or 3 models back (?), I'd have to check.

I read (and see !!) here the trouble others are having and while I'm not expert, it looks like the diamond wheel (if that's what they still use ?) is damaged or dirty or clogged with something ??

I won't say 'I love' mine, but I do find it quite good, I don't think I've ever had a poor result from it.

I'll look later at what model it is.

Originally Posted by pipeclay

With the current state of play regards being in lockdowns, it may be beneficial to some members to look at hand sharpening their smaller drills by hand.

If at all possible I-would recommend a good light source above your pedestal/ bench grinder, and if eye sight/vision is an issue to try and obtain a suitable means of magnification.

I would also suggest that you have or find a suitable dressing means for your grinding wheel/wheels.

I would also recommend that you look on line for a reputable source for grinding your drills by hand.

Manually grinding in my opinion can not be that difficult, as it has been learnt by many apprentices and others over many years, it may take time to achieve workable results but once mastered or understood what needs to be achieved in regards to drill shape and cutting clearances resharpening becomes quite a quick task, depending on the drill size, some drills will require longer to achieve the desired cutting profile, ( negative rake, flat bottom, sheet metal, thin material ) .

Most of what I have said is achievable on a home bench grinder, depending on HP of grinder and the type of wheel being used .

But in this current climate it would seem to me to be the ideal environment to practice.

No real out lay apart from a dresser and grinding wheel required, the latter which most would already have.

Pipeclay,

I agree with every word.

From there its not very hard to progressing to grinding your own HSS lathe tool.
Hell of a lot better than buying specialist carbide tooling you may not use from one year to the rest. Applications like circlip grooves.

Grahame

The biggest challenge I find with hand grinding/sharpening drill bits is ensuring that both cutting edges are at the same height so that both sides cut.

Second to the above is ensuring the centre of the drill is in fact centralised.

I'm 50:50 between using my DD and hand grinding.

A fitter/turner once showed me his test jig (for want of a better term) which was nothing more than a scrap piece of steel bent in an unequal U shape.

The short part is where the base of the drill rested, the longer part had dye or colouring. You rested the drill bit on the short U base and rubbed/scratched the drill bit against the longer part with the dye.

The two cutting edges left a witness mark through the dye and you could check to see if both cutting edges were the same height.

Not sure if this jig was also used to check that the bit was centralised.

Simon

Sent from my SM-G970F using Tapatalk

Originally Posted by simonl

The biggest challenge I find with hand grinding/sharpening drill bits is ensuring that both cutting edges are at the same height so that both sides cut.

Second to the above is ensuring the center of the drill is in fact centralised.

There is a gauge you can buy or even make from a piece of sheet.
It will check for point on center and for angle of cutting edges at the same time.

Yes drill grinding takes some practice but really is not that difficult- even I can do it.

Below is a commercial copy but the diy version works every bit as well.

Grahame

drill gauge.com.jpg

Simon, that was the method we used ( the u shape steel) ours was more like a flat bar with a pointed hook on the bottom that fitted in the centre of the drill - mainly used for the larger drills/morse taper drills.

smaller drills we just free hand ground.

I had a look at the Model of mine, it's a 750 SR. I have had it about 25 years now (gee time flies!)

Originally Posted by Snapey

Can these drill doctors be set up to sharpen sheet metal & flat bottom drills or are you limited to the usual angles?

The particular one I have, no, it will a wide variety of angles but not 'specials' like these.