Drill Sharpening Jigs – Advice please.

[John ShepherdParticipant @johnshepherd38883]

Can anyone help me with a decision on which way to go to achieve conistant and accurate drill sharpening please.

 

I have built  a grinding rest and 4 facet jig to the design by Harold Hall and when used with some slight modifications to the rest and a diamond cup wheel, I get what I consider to be good results on drills above  6mm.

 

 However I would also like to achieve ‘normal’ 2 facet sharpening across the range from  3mm 12 mm or so with the same repeatability as I get with the above set up. I would also like to be able to sharpen dills at different angles to suit the material from time to time

 

I have tried one of the inexpensive commercial jigs that swing the drill on the side of the gringing wheel but I have put this in the scrap bin as I find it impossible to get the repeatability I am looking for. The uncertainty of the alignment to get both edges ground evenly, the effect on geometry  by the amount the drill projects from the jig, the feed arrangement and a general lack of rigidity make it unacceptable for me.

 

The options I have considered are:

1. Buy a Drill Doctor – gets good reviews, claims to split points also but costs about £100.00 – only seen reviews and have not heard comments of a ‘real’ user.

 

2. Buy the Hemmingway kit and build a Potts – The end cost not much less than the Drill Doctor and will take up some time to make.

 

3. Build one to Ian Bradley’s design from the Hobbystore plans – again an investment in time (not sure of material cost).

 

(Although I have included cost this is not an overriding factor and  I consider the above options to be within reason . Anything much above that would not make it viable for me – it would probably be cheaper to buy a stock of new drills!&nbsp

 

The options I have rejected are:

1.The ‘toys’ that connect to a portable drill.

 

2. The motorised sharpeners sold by Siverline and Machine Mart – I have not tried one but I cannot see that they will provide what I am looking for.

 

3. Hand sharpening – yes I can do it on larger drills but I want the precision of a well designed jig.

 

Would welcome suggestions of other reasonable options and any comments that help reach a decision.

 

John Shepherd

 

 

 

[John ShepherdParticipant @johnshepherd38883]

[Anonymous]

Can’t say I’ve ever used a Drill Doctor, but the professionals don’t seem to think much of them:

 

http://www.practicalmachinist.com/vb/cnc-machining/drill-sharpener-183618/ 

 

The cheap add-ons to bench grinders are useless. Other than that, I haven’t tried much. Strange as it may seem I don’t seem to need to sharpen drills that often. In the longer term I expect I’ll either build some sort of jig for the surface grinder, or keep looking a Clarkson drill and tap grinding attachment.

 

Regards,

 

Andrew

[John ShepherdParticipant @johnshepherd38883]

Andrew

Thanks

 

Judging from the comments in the link, that looks like option 1 out then – I am not totally surprised.

[adyParticipant @ady]

You might be better learning to do it by hand, using a finger tip sensitive jig.

 

The micro drills on pultra micro lathes used a  finger powered quill type arrangement because the human hand is more sensitive with a good sense of feel.

(p218 Newnes Lathework)

[Gordon WParticipant @gordonw]

I’m no expert on drill sharpening, but. I’ve used a swing type cheap jig for years, it’s ok when you get the hang of it, does from 3mm up to about 15mm. Not precision but pretty good. Also, just bought a self contained (silverline?) sharpener, the tips look dreadfull after grinding, but they do cut well, use it for general purpose drilling, pop rivets etc. For accurate drilling I buy a new drill, sure it works out cheaper.

[adyParticipant @ady]

I got a cheapo diy shop sharpener years ago which was great until the grinding wheel got too worn.

 

The product is poorly made, but until it fails it does do a really good job.

 

http://www.amazon.co.uk/gp/product/images/B0001P0GIU/ref=dp_image_0?ie=UTF8&n=79903031&s=diy

 

http://www.amazon.co.uk/Martek-Drill-Sharpener-Handy-Dhstd/dp/B0001P0GIU

Edited By ady on 24/09/2010 10:53:02

[Steve GarnettParticipant @stevegarnett62550]

Posted by John Shepherd 1 on 24/09/2010 08:45:38:

 

The options I have considered are:

1. Buy a Drill Doctor – gets good reviews, claims to split points also but costs about £100.00 – only seen reviews and have not heard comments of a ‘real’ user.

 

One of the ex-partners at work bought one of these several years ago, and had a lot of problems getting any sort of consistent results from it at all. We all looked at it, he took it to bits, and nobody ever bothered to put it back together. When he left, we invited him to take it with him!

 

I have been contemplating the whole business of small drill sharpening myself recently, and come to the conclusion that finding some means of achieving this on my Clarkson Mk1 is the answer as far as I’m concerned. Yes, there’s the wonderful drill and tap sharpening attachment that Andrew mentioned – but that’s going to cost me several times what the Clarkson cost in the first place – assuming that I can even find one. So ultimately I’m going to make something that effectively does the same thing, I think, unless a miracle occurs. Yeah…

 

At least if you take this approach, you get to find out what the real problems with repeatability on small drills actually are, and hopefully get to find a way of resolving them. Yes, I will probably end up reinventing the wheel. Does that matter? If it takes my mind off everything else for a while, then probably not. So even if you are slightly that way inclined, I’d recommend it as a process, rather than just buying something. If, on the other hand, you just want to use the drills, then either reconcile yourself to purchasing new ones, or get a really posh sharpener. Your choice, really!

[Ian S CParticipant @iansc]

Its almost exactly a year since this subject came up in the beginers section (22/09/09). I’v got a cheap swing type one thas OK for1/8″ to 3/4″ as long as the larger drills are short enough. Go a plastic thing with ecsentricly mounted wheels, the drill clips on the front and you just roll it back and forth on a strip of carborundum cloth, Found it in dads tool box, it actually works quite well 1/8″ to3/8″. I tend to sharpen free hand. I’v got one of those idiot things that fits on a portable drill, we spent hours seeing if it would work, then gave up, at least it did’nt cost me anything. Ian S C

[Clive FosterParticipant @clivefoster55965]

Far as I can see the Potts has the same set of fundamental problems that afflict all the simple swing jigs.  It seems asking for trouble necessitate simultaneous setting of angle and projection separately to do both edges.  Given the space available effective accurate stops are probably impossible to achieve.  The complex geometry involved, which is never explained, doesn’t help.  Its take me about 1/4 of a century to finally twig WTHIGO with the common Picador / General et clones and why one has the edge at an angle and one has it vertical.  These days I can get decent results from my Picador although I still need to put a screw depth of cut adjustment on my improved base mount.

 

I suspect this http://www.practicalmachinist.com/vb/general/who-makes-drill-sharpening-jig-210357/ is about the best type for the home shop, at least it has a calibrated adjustment.  If you are careful the PlasPlugs device works unreasonably well for cheap and plastic.  At least they have made an effort to give you projection and edge angle gauging as well as providing a flip over drill holder so you only have to set it once.  I suspect that improved versions of the setting gauge and drill holder made accurately in metal would transform the performance of the swing systems.  Prolly need about three holders tho’.

 

Clive

[TigermothParticipant @tigermoth]

I have one of the cheapo swing jigs (Draper). It works if you’re careful and certainly sharpens drills. This is a lot better than trying to do it freehand and does give you a sharp drill. Care is needed when turning over from the first face to the second. It is better than using a blunt drill or throwing away a drill which can be re-sharpened.

Bob

[Robin KingParticipant @robinking15611]

I can endorse the views on the Drill Doctor from experience of trying to use mine – with practice it can produce a good point but I could never get it to produce the correct included angle, and the back off was too shallow an angle, despite endless experiments. I talked to a fellow club member who had one and he reported similar problems. Result – both of us have discarded them.

 

My next task is to build a 4 facet jig as described by Dave Lammas many years ago in M.E. – by all accounts it works well.

Robin

[John Wood1Participant @johnwood1]

The cheapo swing jig certainly works well enough although it won’t do the small drills.  I have made a decent base for mine with a single reamed mounting hole as the original simply pressed the mounting shaft against a vee channel with a flat metal plate, this meant that the whole thing could be pushed out of upright quite easily.

 

I have a 4-facet jig for use on the Worden cutter grinder (not tried yet) and I would have thought some bright lad might have designed a simple two facet one for similar grinders, just an idea.

Otherwise sharpening by hand is surprisingly accurate for most purposes.

 

Cheers

John

[WALLACEParticipant @wallace]

It’s a real shame that no one does a ‘quality’  version of the cheapo swing jig.  .  .something like the Reliant one.

 

W.  

[Sub MandrelParticipant @submandrel]

I have a plasplugs 4 in1 sharpener which seems to be similar to the Drill Doctor.

 

It can take a couple of goes to get a decent result, but after getting a manual (it was a bootsale bargain)  it is usable. It gives better results than my useless ‘clamp and swing’ device, though I can’t see it sharpening hundreds of drills before needing a new wheel.

 

Over 1/4″ I usually put a 4-facet point on by eye – I did a 1/2″ drill and then drilled a 0.502″ hole with it. As long as the cutting edges are even, all that matters with the angles and the second pair of facets is decent clearance. I will make a proper jig one day!

 

I am building up a pile of blunt <3/16″ drills though, and I think I’ll have a go at one of the wishbone sharpeners.

 

Neil

[John ShepherdParticipant @johnshepherd38883]

I am surprised that there has been no comment from anyone using a Potts jig or one made to the  Ian Bradley design. Are there any users that can comment on how well (or otherwise) they work? 

 

Clive

 Can you explain further why ‘one has the edge vertical and one at an angle’. It is something I have noticed and would also like to know WTHIGO without waiting 25 years. I ask because I may add another option to my list – Make a clone of the swing jig but try and eliminate or improve on some of the problems like aligment etc and do something with the base as mentioned by John Wood. 

 

John Shepherd

[Bill StarlingParticipant @billstarling10428]

I’m very much a novice at all aspects of model engineering, let alone the ‘black art’ of drill sharpening. As I have inherited/scrounged a serious collection of blunt drills and an old swing-type Reliance jig – which I’m relieved to find others have difficulty with – I’m very interested in this thread. However no one has mentioned drills less than 1/8 ins dia, except for Stub Mandrel’s passing reference to wishbone sharpeners. What are these please? Also have you any other advice and guidance re small drills? Thanks very much. Bill.

[Richard ParsonsParticipant @richardparsons61721]

 

Drill sharpening on an offhand grinder is very much a skill. Until I built a tool grinder I used a Picador ‘Swing jig’ (I still have it). The trick is setting the drill in it in the danged thing. For drills under 3.2 mm (1/8&#8221 I used to use and often still do a block of square steel with ‘V’s files across the diagonals and a front clamp to hold the drill. It is then rubbed on a diamond plate. I know it is not exactly correct but the drills cut! I also built a 4 facet hone which was written up in Model Engineer somewhere in the late 70’s to 80’s. Again the problem is setting the drill in it. I saw a ‘wishbone’ sharpener but it was beyond my skills to use.  Over here I often make and use diamond pointed drills which I make with an old lump of ‘hex’ sawn at 64 degrees across the diagonals and rubbed on a diamond plate. I think I saw this at an ME exhibition at Wembley on the SMAEE stand. These drills are very good for sheet metal as they do not ‘pick up’

[Sub MandrelParticipant @submandrel]

A wishbone sharpener, is a v-shaped holder with a wheel on each side. Originally produced by Eclipse iot holds the drill in a collet or between two plates so its tip just protrudes from the V. You roll the device with the drill trailing across a slipstone, allowing it to gently fall to the side to back off the point.

 

I must admit I’ve been known to sharpen such small drills just by ‘filing’ the tips with a diamond slip.

 

Neil

[Clive FosterParticipant @clivefoster55965]

John

 

My take as to WTHIGO with the two different varieties of the Picador / General and clone swing type drill grinding jigs goes like this :-

 

1) The clearance angle behind the cutting edge of standard point drill runs circumferential at all radii of cut.  The natural way to generate this clearance angle is by twisting the drill during the grinding process.  Correctly timing and synchronising this twist with the basic grind is the hard bit of learning to do it by hand.

 

2) Swing grinders move around a single axis.  The clearance angle runs straight across the drill at right angles to the swing axis so the grinding depth at the trailing edge of the land is less than when the drill is correctly twisted whilst grinding.  When correctly set up a swing jig generates an increasing depth of cut  to produce the circumferential clearance angle by geometrical means.

 

3) Consider the vertical spindle Picador type jig.  If the drill cutting edge were also vertical and aligned with the pivot axis the swing would grind a circular arc shaped face across the drill, the radius being set by the projection of the drill relative to the pivot point.  Having no clearance  angle the drill won’t cut.  Offsetting the cutting edge so it trails behind the pivot axis grinds a clearance angle so the drill can cut.  This offset also increases the effective depth of grind as the swing proceeds giving a better approximation to the desired circumferential clearance angle.  Clearly if the swing were 90 degrees the increased grinding depth would equal the offset of the drill cutting edge relative to the pivot.  It appears that in practice offset alone doesn’t increase the depth of cut sufficiently as the grind moves across the land.  By rotating the drill cutting edge away from the vertical the trailing edge of the land is effectively put further behind the cutting edge increasing the grind swing angle and therefore the depth of cut.  This rotation effectively reduces the offset of the drill point relative to the swing axis so clearly there is a pretty fine balance between offset and rotation angle if clearance is to be ground along the whole cutting edge.  The grinding swing is no longer at right angles to the cutting edge which makes it harder to follow.

 

4) The spindle of the General type jig is angled back away from the grinding wheel.  Effectively the lower edge of the drill is closer to the grinding wheel than the point so it travels on a slightly smaller radius during the swing thereby increasing the depth of cut at the trailing edge of the land despite the cutting edge being vertical.

 

Clive 

[John ShepherdParticipant @johnshepherd38883]

Many thanks for that explnation Clive it makes sense.

 

The clone of the Picador I bought has the anged pivot but the instructions also show that the cutting edge shouldalso  be set at an angle. I suspect that this is perhaps a case of copying one design and another set of instructions!

 

In light of what you have pointed out I will resurect the jig and do some experiments now I understand a bit more on how it is supposed to work. The reason me an others have indifferent results from these jigs, other than some of their manufacturing shortcomings, probably has more to do with the poor and confusing  instructions?

[Clive FosterParticipant @clivefoster55965]

John

 

I’m glad you think that will be helpful.

 

Of course its possible that your jig uses a combination of pivot angle and drill angle to get the required extra grind depth.  If I recall things correctly the angle of drill edge rotation from the vertical used by the Picador type and the pivot angle of the General type are both about 15 degrees.  I measured them a few years back but can’t find the results, somewhere lost in computer space.  I guess a combination of around 7.5° each should work and has some point positional advantages relative to the grinding wheel.

 

Worst point is that the grind is damnably sensitive to drill point projection.  The further the point projects the greater the “cone” radius, the smaller the clearance angle and the less the geometrical increase in depth with swing angle.  It takes very little extra projection to destroy the geometry.  The standard design is barely able to cope with the small projection possible at the bottom end of the range.  Ages back I looked into creating an offset pivot position to allow a bit more projection, say 50 thou or so but decided it was  too much work for something I didn’t really understand.  Plan was to fit an offset end to the pivot pin, might have done it if the pin had been screwed in rather than cast in.

 

I suspect the American Delta and Atlas types with their horizontal pivot pins do operate with a little more drill projection.  These more complex versions seem a bit more effectively engineered but apparently are too costly for the market.

 

Clive 

[John OlsenParticipant @johnolsen79199]

I have used a rather “cheap and cheerful” die cast one with quite good sucess, it is better than I could do by eye for sure. Anything below about 5mm does get a bit small for it. Some of the guys locally have built one of the published designs, with good results, nbut I;m not sure which it is. They would be better than mine, especially at the smaller end of the range.

 

I inherited a lot of drills that my Dad had sharpened by eye, and he had a lot of practice at it. These would be typically larger drills, 3/8″ and up, and even the cheap jig can improve on the way they cut.

 

regards

John

[Michael Cox 1Participant @michaelcox1]

Small drills (<6 mm) are relatively cheap that it is hardly worth the effort of regrinding them. On the other hand larger drills rapidly become more expensive with increasing size and these are relatively easy to resharpen using the cheap swing sharpeners and these are definitely worth re sharpening.

Mike

[Eric LougheedParticipant @ericlougheed54619]

Clive’s narrative is most helpful – especially the conclusion at ‘4’: I shall now try ‘leaning back a little’ on my el cheapo jig. Incidentally I’ve used that to sharpen 20mm drills – setting the rotation of the drill by eye.

Eric L 

[Author]

Posts