How can I drill a deep, non-standard, small diameter, hole?

[duncan webster 1Participant @duncanwebster1]

now I'm confused, I thought the problem was to drill a 0.3mm hole, in which case why are you turning silver steel down? If you are talking about drilling it, why use silver steel, EN1A would be plenty strong enough and drill/turn a lot more easily.

[pgk pgkParticipant @pgkpgk17461]

This chap did a vid on turning small diameters and also stated that one hefty cut was the way to go.

https://youtu.be/X-TkuQDWdbA

You can get fine arthrodesis wires down to 0.6mm – one end pointed, one blunt and the trocar point happily drills bone .. so apart from perhaps blunting one or two it'd drill most things.

**LINK**

As for syringe needles they do go down very small. I've used 23g to hand drill bone just twirling it by it's hub although you do get through a few making any depth. Worst patient had a skull fracture like a dried river bed of fragments needing careful drilling and wiring all the bits together.

pgk

[SillyOldDufferModerator @sillyoldduffer]

Posted by duncan webster on 09/07/2018 10:30:51:

now I'm confused, I thought the problem was to drill a 0.3mm hole, in which case why are you turning silver steel down? If you are talking about drilling it, why use silver steel, EN1A would be plenty strong enough and drill/turn a lot more easily.

Requirement drift. My original problem was to drill a 0.28mm diameter hole, when I didn't know that 0.3mm twist drills are easy and cheap to buy. So the plan was to turn a 0.28mm diameter rod in silver steel, put a diagonal flat on the end, and then harden it to make a fine drill.

My failure to turn silver steel down to 0.28mm has become the priority problem because Jason did it without fuss. So why can't I? Failure is not an option.

This mornings attempt with an aggressive cut using a smaller HSS knife, not very sharp, but not blunt, at least when I started:

I'm starting to think the Silver Steel might be the problem. As you say, mild-steel would be OK for drilling brass: I'll give it a try.

This is a bit of a blow to my self esteem. No genius in the workshop but I'm not a beginner either. If the steel is OK, something else must be wrong and I'm running out of ideas. Hottest day so far this summer. Might be an obvious mistake due to heat related brain fade!

Meanwhile, Amazon are winging me a pack of 0.3 drills.

Dave

[SillyOldDufferModerator @sillyoldduffer]

Posted by pgk pgk on 09/07/2018 10:40:04:

T

…

Worst patient had a skull fracture like a dried river bed of fragments needing careful drilling and wiring all the bits together.

…

Lucky I wasn't "helping". Delicate work isn't my forte!

Dave

[JasonBModerator @jasonb]

Dave, don't try and do it all in one length, get the end down to dia and then another two cuts to bring the rest down the same

[HopperParticipant @hopper]

SOD, the tool bit in your photo has "blunt" geometry. IE, even when it's sharp, it's not sharp. The side rake on the top surface is not very great, maybe 5 or 10 degrees. It would cut better if that top surface were angled at closer to 20 or 25 degrees to make a really sharp knife tool profile. A bit of back rake on the top surface would help cutting action too.

[duncan webster 1Participant @duncanwebster1]

and I thought I got easily distracted!

Just had a go with some indeterminate mild steel with my tangent turning tool. Found I needed to set the approach angle to deflect the swarf away from the tiny little bit left, otherwise the swarf wiped it out. As others have said, sharp, plenty of rake and bang on centre height. Reduced from 1/4 diameter in 2 passes.

Edited By duncan webster on 09/07/2018 16:50:21

[SillyOldDufferModerator @sillyoldduffer]

Well I'm improving. Too hot to grind a better tool but with care I got down to 0.5mm x 10mm in Silver Steel. Some of my trouble was due to the rod being slightly bent, the rest was poor technique. The finish is dreadful, but I hope sharper HSS will fix that.

However, I'm still not happy. As Duncan says, swarf breaks the rod – it's very delicate. Be interesting to see if heat treating makes the steel stronger. As it is I'm not impressed by slim silver steel because it's nowhere near as strong as a needle. Not sure it will stand up to drilling.

Too hot to do anything. I may collapse with a book and cider in the shady part of my garden and have a nap.

Dave

[duncan webster 1Participant @duncanwebster1]

Going back to SOD's original, I've often wondered how you strike a centre for a 0.3mm drill? Do centre drills go down that small?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by duncan webster on 09/07/2018 17:52:16:

Going back to SOD's original, I've often wondered how you strike a centre for a 0.3mm drill?

.

With a graver.

MichaelG.

[JasonBModerator @jasonb]

Posted by duncan webster on 09/07/2018 17:52:16:

Going back to SOD's original, I've often wondered how you strike a centre for a 0.3mm drill?

1/8" Spotting drill worked OK for me on that hole I posted on the first page

[SillyOldDufferModerator @sillyoldduffer]

Despite assistance I think I'm out of my depth on this one!

Made progress cutting thin rods, my technique has improved. The material matters. Not difficult in brass, tricky in mild-steel, awkward in silver-steel. I can turn down to 0.5mm without too much bother, less than that and the rod becomes fragile and breaks easily. Photo has dressmaking pin for scale.

I haven't tried a specially sharpened HSS tool yet and hope that will fix the poor finish.

So far so good except I now need to drill deep holes through brass with one of those spindly rods. The plan was to make a spade or spoon bit drill as per Sparey:

Seems simple enough, and Sparey says "easily made by the amateur". With help from Michael Gilligan (thanks) I was able to make a crude drill on this pattern from 3/32" (2.4mm) steel, and to drill a hole in brass with it. Hard work, about 10% as efficient as a twist drill. No doubt the cutting rate could be improved by more careful grinding but this type of drill needs more force than a twist drill, doesn't clear swarf at all, and I despair of drilling a hole 0.3mm diameter hole 10mm deep with one.

More bad news, I struggled to produce a decent drill tip at 2.4mm diameter. My fat fingers and poor eye-sight made heavy weather of the job. Now I've tried it, I've no idea how to scale the process down to 0.3mm. I have to heat the rod without melting it, flatten the end, and then grind a pair of relieved cutting edges without breaking a delicate sliver of metal. I am intimidated!

Final blow, I dropped the prototype drill and it's joined my missing Biros in another dimension. Woe is me.

Making fine drills in a home workshop must be possible, any ideas?

Dave

PS Jason's suggestion that Neil cover this in 'Lathework for Beginners' is excellent. Full of good advice though 'be prepared to use your ingenuity' didn't work for me as I've lost it. Neither did 'Turn off your phone!', though at least I managed that without breaking anything…

[Anonymous]

Posted by SillyOldDuffer on 12/07/2018 17:19:11:

Making fine drills in a home workshop must be possible, any ideas?

Stop messing about and buy one! Drill Service have a range of 0.3mm twist drills to suit all budgets.

Andrew

[SillyOldDufferModerator @sillyoldduffer]

Posted by Andrew Johnston on 12/07/2018 17:29:15:

Posted by SillyOldDuffer on 12/07/2018 17:19:11:

Making fine drills in a home workshop must be possible, any ideas?

Stop messing about and buy one! Drill Service have a range of 0.3mm twist drills to suit all budgets.

Andrew

Fair cop guv. I have a packet of ten on the way for less than £8. Meanwhile, I love a challenge!

[Michael GilliganParticipant @michaelgilligan61133]

Some options here: **LINK**

https://watchmaking.weebly.com/drill-bits.html

MichaelG.

.

[quote] Another type of drill that may be useful in horological work are pivot drills.  Very small diameters are available, and are a simple spade type drill made from carbon steel.  It is the type of drill that one can make from drill rod relatively easily.  The set shown is offered by Bergeon (No. 1713) among other sets, and includes 0.10 to 0.28mm. [/quote]

 Checking the Bergeon price is likely to supercharge your enthusiasm for DIY, Dave

Edited By Michael Gilligan on 12/07/2018 18:06:09

[JasonBModerator @jasonb]

Also read what was suggested early on. You were not supposed to be making a drill but a reamer to put down a 0.25mm hole that just required an oblique cut across the end of your 0.28mm ish embrio reamer.

[pgk pgkParticipant @pgkpgk17461]

Aged eyesight folk need to stick together

If you can get as far as producing the spaded end in your challenge then in your position (and thankfully I'm not) I'd have to cheat and make a small honing guide (like the ones sold for sharpening chisels) and run the edge on a fine stone with plenty of reference through an eyeglass.

Two bearings of different sizes spaced appropriately should give the wanted angle under a sledge and tape/glue/clamp drill blank to it.

pgk

[SillyOldDufferModerator @sillyoldduffer]

Posted by JasonB on 12/07/2018 17:55:18:

… You were not supposed to be making a drill but a reamer to put down a 0.25mm hole that just required an oblique cut across the end of your 0.28mm ish embrio reamer.

Ah no, sorry if I gave that impression. The requirement is as stated in the title, "How can I drill a deep, non-standard, small diameter, hole?"

Where I'm at now with the real job is to use commercial 0.3mm twist drills when they arrive. But for the moment I've been distracted by the challenge of rolling my own. Yes it is daft.

Thanks to pgk pgk for suggesting honing guide, eyeglass and bearings. It looks very much as if I will have to make tools to do this, if I get that far.

The Japanese Gameshow was interesting and ended to my surprise with the manual lathe man beating EDM comprehensively. Both EDM and drilling faced serious difficulties. I thought the best of the programme was seeing how they worked around their various problems. Thanks to Richard for the link.

Dave

[Michael GilliganParticipant @michaelgilligan61133]

Posted by SillyOldDuffer on 12/07/2018 17:19:11:

 

So far so good except I now need to drill deepThe plan was to make a spade or spoon bit drill as per Sparey:

Seems simple enough, and Sparey says "easily made by the amateur".

[ … ]

More bad news, I struggled to produce a decent drill tip at 2.4mm diameter. My fat fingers and poor eye-sight made heavy weather of the job. Now I've tried it, I've no idea how to scale the process down to 0.3mm. I have to heat the rod without melting it, flatten the end, and then grind a pair of relieved cutting edges without breaking a delicate sliver of metal. I am intimidated!

 

.

It's perhaps worth noting that the Bergeon-style drills look like this:

Image adapted from the catalogue of H S Walsh: **LINK**

https://www.hswalsh.com/product/bergeon-1712-pivot-drills-010-015mm-hd11a

Sparey's design is, I think, better suited to larger sizes.

MichaelG.

Edited By Michael Gilligan on 12/07/2018 21:04:22

[Michael GilliganParticipant @michaelgilligan61133]

I have been struggling to find a definitive design for a pivot drill [i.e. the optimum rake angles and proportions of the blade], but along the way, I discovered Shor International: **LINK**

https://www.ishor.com/flat-pivot-drills

Their offering looks useful, and reasonably priced.

… Any comments regarding Shor and its products would be welcome.

MichaelG.

[JasonBModerator @jasonb]

Michael. are those "flat" drill bits a rectangular section at the end or just flat on the top much like a D bit, can't easily tell from the angle of the photos.

J

[Michael GilliganParticipant @michaelgilligan61133]

Posted by JasonB on 13/07/2018 07:00:21:

Michael. are those "flat" drill bits a rectangular section at the end or just flat on the top much like a D bit, can't easily tell from the angle of the photos.

J

.

Effectively they are flat blades, slightly 'lozenged' in section.

… Still struggling to find a decent photo of a commercial one

MichaelG.

[SillyOldDufferModerator @sillyoldduffer]

Ho hum, commercial twist drills arrived today with mixed results.

With a gentle touch and many withdrawals to clear swarf I was able to drill a 0.5mm hole 10mm deep with my screw-type tailstock without too much trouble.

Not managed to drill a deep 0.3mm hole though. Drill started OK then seemed to hit a hard spot in the brass rod. I can't feel if the drill is making progress or not and the first warning of trouble is the drill whipping.

The drills are tiny and they bend and break easily:

My lathe has a top speed of about 2500 rpm. Seems this is a little on the slow side – one website recommends 40,000rpm for 0.3mm HSS and 'if available' more than 100,000 rpm for carbide.

All my home made drills are now broken. Thank goodness I didn't give up my day job!

Dave

Edited By SillyOldDuffer on 13/07/2018 19:12:35

[JasonBModerator @jasonb]

I did that one I posted earlier without even shifting to the fast belt so about 1100rpm

Try holding as much of the drill as possible in your chuck to help prevent whipping, even if it means cutting down the shank and having some of the flutes in the jaws.

[Anonymous]

I've drilled down to 1/32", in brass, on my lathe. But TBH I don't like the combination of small drills and large lathes. It's difficult to get the drill started. Spot drills are better than centre drills, but not perfect. And the small drills, although held in a pin chuck, have a tendency to wander. Must get the Pultra up and running, 6000rpm and a lever tailstock should be better!

Using smallish drills on the Bridgeport is much easier. I've drilled a load of 0.7mm holes 10mm deep in brass without a problem. I didn't bother with spotting first. Just a light touch enables the drill to make it's own mark and then one can drill normally. The modus operandi is to peck frequently, every few drill diameters, and to make the drill work. Even for small drills the feedrates can be surprisingly high. With slightly larger drills I've successfully drilled 1.2mm holes 10mm deep. Normally that would be yawn territory but it was in a tungsten alloy with a slow helix carbide drill.

To summarise, bin the lathe and try the vertical mill.

Andrew

Postscript: I was recently given a high speed (10000rpm) PCB drilling machine which I shall be using in future for small holes.

[Author]

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