Thread: Lubrication for & sharpening of metal drill bits

Originally Posted by seanlark

Thanks all, plenty of wise counsel and ideas above which will be handy to many others in learner mode like me.

Regards Sean

One thing that doesn't seem to have been touched on is the importance of not overheating the drill and job when drilling steel when using a spray to apply the lube/coolant.

If the drill bit gets really hot and you spray intermittently you can actually work harden the steel (localised hardening) and have all sorts of issues as a result - eg if you then try to tap a thread in the hole you will find the steel is too hard.

If the lube is steaming/vaporising significantly then you're going too fast.

I just use engine oil kero mix at 1:4 ratio.

Rob

I use a commercial threading oil for all steel cutting ops O007 | High Grade Threading Oil | machineryhouse.com.au and it works very well. You don't need to go crazy with it, just brush a little on the work and brush some more on the drill shank and gravity will pull it down to the cutting face. An easier to find alternative is Tapmatic or similar tapping fluids. I've never seen any warning on either of these regarding over-heating, and given that industrial threading machines do so at high speed, would expect they would warn if there was a health risk with them.

If your drill bits are becoming excessively hot when run at recommended speeds I'd suggest they're probably blunt. You really shouldn't need to be running any form of coolant for this type of non-production drilling. A lubricant on the other hand often seems to make a big difference.

With regards the drill sharpness, I use a drill doctor 750x I bought from Enco for a fraction of the local asking price. Despite their reputation I find it perfectly acceptable for home workshop use. They're not idiot proof however, and some drills can be sharpened with insufficient relief (they will rub instead of cutting, and also get excessively hot if you persisted with trying) if you're not careful. I notice a big difference between drill brands in regard to how long they will maintain a keen edge, with the better brands holding an edge much longer. Conversely it's quite surprising how often my "hack" drills that I use every day need touching up. Learn to read the chips/swarf coming off the flutes as a guide to how sharp your drills are, it will depend on the material you're drilling so there's no definitive answer to what it should look like, but you should normally definitely see the drill drill bit cutting. Think of it like a lathe tool that is going around in circles, although the actual mechanics of drill bits is remarkably complicated.

If you don't have access to a drill sharpening jig or machine, it's possible to learn how to freehand sharpen drills to a reasonable level. A very good friend of mine is quite good at it, but I must admit I gave up practicing before I became especially good and tried various jigs and machines instead. The 750 is fine by me, and I've seen little incentive to upgrade. Be aware that freehanding will never get the two cutting faces identical, despite what some may like to claim. It's why large large production shops buy drill sharpening machines costing many tens of thousands of dollars instead of some old bloke with a fag hanging out the corner of his mouth and a hanky with knots in the corners draped over his head who answers to the name of Guido! If a drill doesn't have nearly identical cutting surfaces it won't drill round or straight holes, end of story. Sorry Guido. Not that twist drills are especially good in that role anyway ... but that's another story.

Hopefully a few things to consider.

Pete

Originally Posted by Pete F

Be aware that freehanding will never get the two cutting faces identical, despite what some may like to claim.
It's why large large production shops buy drill sharpening machines

Pete

Hi Pete,
on Wednesday I freehand ground a 1/2" drill bit ending up with two cutting faces identical. Equal swarf scrolling off both edges. Not one edge heavy and one light. Not one cutting and the other not, both pieces of swarf were equal.
I can also do this with surprising frequency. Why? Because I can. Never say never Pete.
Large production shops also buy sharpeners for time management due to the fact that the skill has all but gone now. Although, I can have a broken drill bit sharpened quicker than an apprentice can get the appropriate collets out of the box.
Just ignore me Pete, I am an over the top fan of the old skills.

Guido

Agreed SW - hand sharpening is an all but forgotten art, and with a bit of finesse can produce bits that cut plenty well for all but the most precise of jobs. Just a shame it's not a skill taught these days, and the convenience of a jig seems all too luring.

On topic, I've always run with a bit of thick, mineral based engine oil. All sorts of companies make cutting and drilling fluids - and they do stellar work, at a cost. For a lot of home use oil will do the trick. TiN bits can usually get away without much lube as the TiN is super slippery as is, but it certainly wont hurt on larger holes. As raised earlier, if things are just too hot, slow down. In thicker pieces the heat can cause the bit to expand and seize in the hole, causing a crack down the web of the drill. Then it really is knackered - which hurts the wallet when buying bigger drills which are more prone to this happening.

Guido Jr.

Yes I knew it would create a reaction and sorry to say that considerable research has been conducted into the field and everyone is free to believe what they like, but it is a fact that the research has found freehand sharpening will NEVER produce perfectly identical lips. In skilled hands, close yes, but identical no. Never. It's not hard to imagine why not either. The point is "close" is probably close enough for most purposes and hats off to those who have obtained the skills to get that close. If you honestly think you can get it close, do your best, then stick the bit in a quality machine and see how you fared, be prepared for a bit of disappointment.

Freehand sharpening was (and I presume still is) also a skill that was always taught as part of any apprenticeship in this area, so it's not like nobody knows how to do it. In my experience it's FAR quicker to freehand grind a drill bit versus setting it up in a jig or machine, so the time management argument makes no sense, it's the way most guys I've worked with sharpen their drills. Indeed, as most people in a home workshop don't have any form of machine or jig at all, I think it's a skill that is worth acquiring if someone can't afford a machine or the time to acquire the skills to freehand to an acceptable level. However it's always worth pointing out that this is the reality of the situation. Sorry but they're just the facts

Anyway, the point of all this was not to generate an OT argument, it's one I've seen many MANY times before on the net, and some will never believe their efforts aren't every bit as good as a good machine's so I see little point in pursuing it further. The point was it doesn't matter how you get there, just don't use blunt drills! I think there's always the temptation to say "I'll just throw them out when blunt", but it seems invariably they aren't thrown out and continue to get used, even when clearly in need of sharpening.

Pete

Originally Posted by Pete F

Yes I knew it would create a reaction and sorry to say that considerable research has been conducted into the field and everyone is free to believe what they like, but it is a fact that the research has found freehand sharpening will NEVER produce perfectly identical conical chisel points. In skilled hands, close yes, but identical no. Never. It's not hard to imagine why not either. The point is "close" is probably close enough for most purposes and hats off to those who have obtained the skills to get that close. If you honestly think you can get it close, do your best, then stick the bit in a quality machine and see how you fared, be prepared for a bit of disappointment.

Freehand sharpening was (and I presume still is) also a skill that was always taught as part of any apprenticeship in this area, so it's not like nobody knows how to do it. In my experience it's FAR quicker to freehand grind a drill bit versus setting it up in a jig or machine, so the time management argument makes no sense, it's the way most guys I've worked with sharpen their drills. Indeed, as most people in a home workshop don't have any form of machine or jig at all, I think it's a skill that is worth acquiring if someone can't afford a machine or the time to acquire the skills to freehand to an acceptable level. However it's always worth pointing out that this is the reality of the situation. Sorry but they're just the facts

Anyway, the point of all this was not to generate an OT argument, it's one I've seen many MANY times before on the net, and some will never believe their efforts aren't every bit as good as a good machine's so I see little point in pursuing it further. The point was it doesn't matter how you get there, just don't use blunt drills! I think there's always the temptation to say "I'll just throw them out when blunt", but it seems invariably they aren't thrown out and continue to get used, even when clearly in need of sharpening.

Pete

No worries Pete, you win
though I would love to read the research. Purely to check out the control parameters used so that I can make an informed decision on this one.

Horribly off topic for which I apologise Sean.

Phil

Yes sorry for the digression. Also not something I'm trying to "win", as I've said it's not like I'm against offhand sharpening, hats off to those, like yourself, who can do it well. But just raising the awareness of the limitations. It's a bit like taking a hand saw and ripping down a panel. A skilled craftsman will be able to rip a very straight cut close to the line. But it will never be as straight as a quality panel saw can do the same cut. Sad, but just a fact I think most would acknowledge.

I thought I saved one of the papers on this very subject, and was going to post it, but if I did save it I've now lost it. My main machine lost a hard drive last week and with it went a lot of my data like this. Yes I know I should have had backups

Pete

Edit: Phil this wasn't the reference that I had in mind, but it definitely echoes other things I've seen. Unfortunately I need to go back to work but just quickly found this link Audel Machine Shop Basics - Rex Miller, Mark Richard Miller - Google Books it seems as if I can't get the missing pages up, but it should convey the idea. References begin on p138

Originally Posted by Steamwhisperer

No worries Pete, you win
though I would love to read the research. Purely to check out the control parameters used so that I can make an informed decision on this one.

Horribly off topic for which I apologise Sean.

Phil

Pete's right about the impossibility of getting the flutes the same but IME wrong about hand-sharpened drills not drilling straight. They certainly will if not grossly out of symmetry, however they will almost certainly drill slightly oversize. Not a problem IME as I rarely to never trust a drill to be exactly on size anyway.

I use Trefolex as a drill lube, or soluble oil, or whatever else is handy. Often don't bother UNLESS I'm drilling holes in 304 or 316. Then it's always worth the trouble to touch up the cutting end on the wheel and use lube, especially if you've lots of holes to drill and the material is over 12mm thick.

PDW

Originally Posted by Pete F

Yes sorry for the digression. Also not something I'm trying to "win", as I've said it's not like I'm against offhand sharpening, hats off to those, like yourself, who can do it well. But just raising the awareness of the limitations. It's a bit like taking a hand saw and ripping down a panel. A skilled craftsman will be able to rip a very straight cut close to the line. But it will never be as straight as a quality panel saw can do the same cut. Sad, but just a fact I think most would acknowledge.

I thought I saved one of the papers on this very subject, and was going to post it, but if I did save it I've now lost it. My main machine lost a hard drive last week and with it went a lot of my data like this. Yes I know I should have had backups

Pete

Edit: Phil this wasn't the reference that I had in mind, but it definitely echoes other things I've seen. Unfortunately I need to go back to work but just quickly found this link Audel Machine Shop Basics - Rex Miller, Mark Richard Miller - Google Books it seems as if I can't get the missing pages up, but it should convey the idea. References begin on p138

Thanks Pete,
I have that book (or the boss does)
I'll see if I can locate it.

Phil

Thanks, handy about drill sharpening - have been wondering about that after some good success with a chainsaw sharpener - my drill bits have never been sharpened!

Originally Posted by Steamwhisperer

Hi Pete,
on Wednesday I freehand ground a 1/2" drill bit ending up with two cutting faces identical. Equal swarf scrolling off both edges. Not one edge heavy and one light. Not one cutting and the other not, both pieces of swarf were equal.
I can also do this with surprising frequency. Why? Because I can. Never say never Pete.
Large production shops also buy sharpeners for time management due to the fact that the skill has all but gone now. Although, I can have a broken drill bit sharpened quicker than an apprentice can get the appropriate collets out of the box.
Just ignore me Pete, I am an over the top fan of the old skills.

Guido

The crusty crafty old ''jock that showed me the finer points of free hand drilling.He weren't no Guido.In fact when he went to the grinder to give tapered shank drills a lick he always took his secret weapon with him,nothing flash a 2 ft piece of inch and a half x 3/16'' flat bar with a turned up end in the form of a u side,that end had a point that fitted into the centre hole in the drill tang. On this the surface was chalked and with the fag in the mouth would grind up his drill then check by scribing each cutting face in an arc on the fresh chalked surface. he served his time on the Cyde brown's ship yard pre war.and they were grim hard as nails places duly and equally served by hard doing workers assaults fights mysterious accidents prevailed.Our work places are palaces compared to these hard days.Story after story used issue about the old days. he was a very competent marine engineer and a precise machinist.Lived for his rollie weed and ''mothers milk'' as he called his whiskey.
I am a time served motor mechanic,and the majority of mechanics I have encountered over the years cant sharpen a drill or oxy weld. Braze yes but wire weld no.I also sat the Victorian automobile Chamber of commerce A grade certificate 13 subjects written and practical with a pass of 80 per cent.One of the practical tests was to be given a drill a piece of steel a sketch and measuring tools the request was to drill a hole in the piece of metal.There was one catch the drill had had the cutting tips ground off . the test was to sharpen the drill, drill the hole and present it to the examiner along with the drill and the test piece he then checked both and pass or fail accordingly.
Like Phil i have no problem free hand grinding drills although with smaller ones i need good natural light. Cheers.John.

Just some of the things that work for me,

Keep a spray bottle with a 50/50 mix of kero and ATF, use as drill lube, penetrating oil, machine cleaner on a rag,
not perfect, but will replace 3 or 4 spraycans at very small cost.

Drill speed, very important. For quick reckoning say 0.500" drill runs 500rpm max. Half that size, 0.25 =1000rpm
A quarter that size runs 2000rpm. By this rule a 1" drill is 250rpm.

Hand grinding drills is a skill worth perfecting, but to get holes near size, drill a pilot hole half or three quarters
finished size then enlarge with correct size. Again, not perfect but much better. Reamers are made for accuracy.

Use a medium diamond stick to put a good finish on a reground drill. Stand it in the vise under good light and
finish the edge. It will now feel sharp.

Put a scrap of hardwood under the job so the drill breaks through gently with no grabbing or jamming. Saves
edge chipping or breakage. On a drillpress tighten the quill clamp so it does not drop suddenly on break through.

A keyed chuck has 3 key holes so you can tighten each position progressively, and a good chuck will stay tight
and will not slip and ruin the drill shank or the chuck jaws. Just a few points from hard experience,

Combustor.

I'll add my 2 c worth.

Keep a spray bottle with a 50/50 mix of kero and ATF

Marvel Mystery Oil - true story - marvel mystery Oil was sold all over the USA and western world for a generation making millions for its inventor in his own lifetime.

Only when it became law to provide a MDS (Material data Sheet) when shipping products, that had to include the ingediaents did anyone learn the old Marvel Mystery Oil, 57 different herbs and spices secret recipe.....

You guessed it - ATF and Kero!

The end of a great company!

Now as to the cutting oil.

Chlor Parafin.

Chlor Parafin is industrial cutting oil.

It has a rather unique quality that makes it suited to use as a cutting oil.

With most oils (except chlor parafin) if you ever watch a timkin friction test for oil (a lever drag on a spinning bearing immersed in oil applied until it stops the bearing spinning, the heat generated from the friction causes the oil to run AWAY from the heat (friction) source.

Not so Chlor Parafin.

When friction causes heat - with chlor parafin - it actually attracts the lubricant to the heat source thus lubricating it better 7 better reducing friction!

Its an amazing chemical property -= on a relatively cheap chemical (in bulk about $2 a liter).

So you get all these chemical snake oil salesmen add it to gear oil and call it fancy names like "Bitron" and a 500 mm bottle to add to your diff is only 40 bucks! (800% profit).

Heck they even say on the Bitron web site that you can add the crap to your sump oil to protect your engine, but I beg to differ, because the gasses of combustion that byapss the rings in into the sump react with the chlor - paraffin to create hydrochloric acid - which ain't good for the metal internals of your engine... in long term use.

For hole drilling but, nothing beats chlor - paraffin - known as 'cutting oil' in the machining game due to its propensity to be attracted to the source of heat and not repelled like most oils.

Chlorinated Paraffins in Cutting Oil : Products Finishing

Your welcome.

Thanks for tips - the last point on chlorinated paraffin makes interesting reading - I am learning of things I never knew existed. In the article however it talks of it leaving a residue which makes it difficult to coat. Would this mean if you drilled pieces of steel you then welded and wanted to spray with Gal paint that it may not adhere?

There have been so many useful ideas coming through on this thread it may be worth summarising them for future reference for other readers?