Thread: Lubrication for & sharpening of metal drill bits

Originally Posted by seanlark

is ATF 'Automatic Transmission Fluid'?

Hi Sean,
yep it is and like you, I am learning a lot too. Great thread.

Phil

Originally Posted by j.ashburn

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.

I've seen that too except instead of chalk, layout blue was used. Simply brilliant idea. Sadly I'm hopeless at such an art and have grown to accept it. I'm the proud owner of a Drill Doctor. Love it, perfect results every time. I have a "to sharpen" bin for blunt bits. When it piles up, I spend 15 - 20 mins sharpening them. Very relaxing!

Oops sorry. OT again. I'll give myself an upper cut!

Simon

Originally Posted by Combustor

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.

Combustor.

I was taught to grind drills by hand as a kid by my father who was a motor mechanic, and it's never been an issue getting them even.

The trouble with drill sharpeners (inexpensive ones) is that they don't put any back relief on the flutes. You can however do that after by hand, so they're not a total loss - they do grind the flutes uniformly.

I often finish off the cutting egde on the linisher.

Rob

If Bunnings is your only choice, they sell Sutton cutting oil, and nobody know it is there you have to look hard its usually near the drill bits away from other lubes, placed high on the shelves.

While not strictly related the the initial question, I think all the responses are in reference to drilling, and hopefully useful in their own right.

Anyone who has done any reading or has specific education through their trade in regard drill geometry I'm sure appreciates that this is an extremely complex area. Indeed the humble conically ground twist drill is the most complex cutting tool we have in our workshop. Given that the two cutting edges need to be ground to precisely the same angle (ie better than fractions of a degree) and precisely the same length (ie tenths or better of a millimetre) it's no surprise that it can't be done truly accurately freehand. However most of the time we aren't necessarily required to produce "perfect" holes, and a good hand can produce very good drill grinds using simply his skill, a good eye, and a grinder. Just in regard reading the chips, I believe if the cutting edges are ground to slightly different lengths, but accurate angles, similar looking chips will be produced off each flute, but the drill is in fact still not ground correctly and is not cutting properly.

I think the skill is a little like the (increasing rare) skill of being able to drive a manual transmission car. Now personally I believe everyone should learn to drive in a manual car, even if it's for no other reason than to weed out those without the motor skills to be taking to the road in the first place. But I digress. The reality is that even something as common as manual transmission is becoming the minority in sales, and many new drivers will never have a need to drive one in their life, so why learn it? I think a similar situation applies to grinding drills by hand. It's a great skill to have, mainly because it's fast and can be good enough, but more because there's no upward limit to the size of the drills that can be ground (indeed it becomes easier). One would also hope that it develops a much better understanding of the geometry that is being sought, rather than popping a drill in a machine and watching the results pop out a few seconds later. However we now live in an era where (relatively) cheap machines are readily available and can do an excellent job, so there's no actual strict requirement to actually learn anymore.

On that note, with regard the Drill Doctor (or any machine grinder), don't necessarily presume they will produce perfect results, and the results should always be inspected, preferably with an understanding of what to look for! I know I have problems with mine of it not producing sufficient clearance on some drill bits when set up at "standard" settings in the machine. The result was the bits would just rub and not cut at all. It led to a lot of head scratching as to why they were grinding that way, and the only answer I could come up with that made any sense was the helix angle of the drills varied between each other, and the finger that registered in the helix was actually spinning the drill point to a different angle with each drill bit. These were all bits from the same set BTW. An interesting situation. Anyway, the point is, always look at the results!

Phil I think the reason I couldn't find that resource I had in mind is that I probably came across it after researching about 4 and 6 facet drill point sharpening a couple of years back, and I really have no idea how I'd find it again. I'm keen to try 4 facet sharpening as from what I've read it is a far superior cutting process. Many of my drills are split point, and I've seen the advantages first hand of doing away with the chisel point where accurate location on a punch mark and easy of drilling is desired. I'm not sure if 4 facet geometry last as well between grinds, but I'm certainly curious enough to want to try it. From what I've read, the only good reason for traditional conical grinding is because the process is a one step grind, and therefore fast (read cheap) to produce. Over the last 2 days I've gone through and sharpened about a dozen end mills on the Darex, and the results were excellent. Given that it's a similar process (albeit different angles) for 4 facet drill sharpening, it will be interesting to see if I can achieve equally good results on the T&C grinder with drill bits, possibly using a similar setup.

Pete

Originally Posted by seanlark

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?

In adding to these threads some years ago used to use a product from Wurth used to be a universal tapping drilling threading solution was in an aerosol can .Haven't bought it for ages as been using atf diesel kero mix. For penetrating oil mix of kero diesel atf and acetone topped up with some carbolic acid [wheelie bin cleaner] dont ask me the ratio as i just mix it to what i think is right but acetone diesel mix is good on its own for really stuck frozen stuff. dont ask me how it works but it does. Wurth make another expensive product too that works Rost Off. John.ps atf is a small amount for colour..ps if you tapping threading or drilling and you have a steel bench an old metal tin with some fluid in it and small brush pop a magnet out of an old micro wave in bottom of the can stops it getting knocked over easy and picks up any ferrous swarf out of the brush.Handy to stick one on the lathe saddle too or mill table. J

Continuing on the OT meanderings about all things drills, here is a brief description of the 4 facet geometry that is gaining popularity within some circles, and also a jig with which to produce it. I hadn't seen this jig until now and presume it's quite pricey but would be interested if anyone has tried it or has one?
Drill bit sharpening attachment DBS-22
Tormek DBS-22 Drill Bit Sharpener - YouTube

Originally Posted by j.ashburn

In adding to these threads some years ago used to use a product from Wurth used to be a universal tapping drilling threading solution was in an aerosol can .Haven't bought it for ages as been using atf diesel kero mix. For penetrating oil mix of kero diesel atf and acetone topped up with some carbolic acid [wheelie bin cleaner] dont ask me the ratio as i just mix it to what i think is right but acetone diesel mix is good on its own for really stuck frozen stuff. dont ask me how it works but it does. Wurth make another expensive product too that works Rost Off. John.ps atf is a small amount for colour..ps if you tapping threading or drilling and you have a steel bench an old metal tin with some fluid in it and small brush pop a magnet out of an old micro wave in bottom of the can stops it getting knocked over easy and picks up any ferrous swarf out of the brush.Handy to stick one on the lathe saddle too or mill table. J

I did some research on net some time ago re penetrating oil. I read about tests (not to lab specs) done by a magazine, 4WD I think, that concluded that ATF and acetone was the best of what they had tried. Not all of the mixes mentioned here were tested. The theory with ATF and acetone is that the acetone is a liquid that gets into tiny cracks etc (low surface tension) taking the ATF with it. It then evaporates and leaves the ATF behind.

Dean

Originally Posted by Oldneweng

I did some research on net some time ago re penetrating oil. I read about tests (not to lab specs) done by a magazine, 4WD I think, that concluded that ATF and acetone was the best of what they had tried. Not all of the mixes mentioned here were tested. The theory with ATF and acetone is that the acetone is a liquid that gets into tiny cracks etc (low surface tension) taking the ATF with it. It then evaporates and leaves the ATF behind.

Dean

Just have to try it now Dean it works.

Till the her majesty indoors finds her stash of ''nail polish remover'' gone!

Probably better stuff out there then ATF to mix with acetone....

My thoughts is ATF is not a super slippery oil... Automatic transmissions relying on wet clutch plates to transmit power means they need friction to work..... Oil is supposed to reduce friction, so ATF oil has to be a balance between slipperiness to reduce friction not not too slippery that the clutch plates slip..

I theorise why ATF is used in the home brew recipes is because people had it on hand in their home shops and it is a lighter grade oil then plain engine oil...

Well that is my theory anyway....

Originally Posted by Pete F

On that note, with regard the Drill Doctor (or any machine grinder), don't necessarily presume they will produce perfect results, and the results should always be inspected, preferably with an understanding of what to look for! I know I have problems with mine of it not producing sufficient clearance on some drill bits when set up at "standard" settings in the machine. The result was the bits would just rub and not cut at all.

Pete

Hi Pete,

I have experienced the same results. Some drill bits require the relief angle set to the next "notch" to produce sufficient relief not to rub. I'm happy with the results overall. I think the DD is probably the best of the "cheaper" drilling jigs and still probably the cheaper of the very, very good tool room setups. It consistently achieves better results than I ever did!

PS I love my 6 speed manual!

Simon

ATF is a base grade sae 40 with colour and an anti oxidant additive for seal longevity. Heat is the biggest killer of all automatic transmissions big or small.SAE40 is the grade for hydraulic use. John.

Originally Posted by simonl

Hi Pete,

I have experienced the same results. Some drill bits require the relief angle set to the next "notch" to produce sufficient relief not to rub. I'm happy with the results overall. I think the DD is probably the best of the "cheaper" drilling jigs and still probably the cheaper of the very, very good tool room setups. It consistently achieves better results than I ever did!

PS I love my 6 speed manual!

Simon

Yes I have a few that need to be set several notches around. The reason I emphasise to always check the results was because at first I, well, didn't . I pulled the bit out and at casual glance it looked glance just fine. The problem was of course it wouldn't cut. "Well that's odd" I said (or words to that effect), but then I saw why.

As mentioned I bought my DD 750 through Enco in the US and it was not expensive. I'm not sure I'd consider it worth what the local distributer asks for them, but that sounds like the usual story. I agree, for home workshop use I think it's ideal and the less expensive commercial grinders are a big step up in price, while I don't believe offer much more in terms of performance and are simply more robustly built. I did come very close to buying something like this D111 | PP-13C Precision Drill Sharpener | machineryhouse.com.au except it was a Vertex and much better than the POS shown in that photo (complete with rust, a nice sales touch). However in the end it was difficult to justify the additional expense. I do however feel that many of the factory grinds I use are better than results off the DD, so there's definitely some upside to be had if one's pockets are deeper than mine.

Pete
VERTEX-MILLING-GRINDING-TOOLING-CNC-LATHE-GRINDER