High speed drilling, sensitive drills?

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WisJim

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What do folks do for drilling very small holes in various metals? The higher speeds specified for small bits aren't usually in the range of available speeds for the average drill press, and drill presses made for those speeds (maybe 10,000 rpm and up) are expensive. I'm not sure if the run out on my older Craftsman drill press is small enough to make it worth adapting the drill for the higher speeds needed. What do you do when drilling very small holes that need to be positioned accurately?
 

HennieL

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Hi WisJim,
I don't think you NEED the very high speeds recommended for industry. In fact, I do a lot of drilling into titanium and into high alloy and normal high carbon tool steel (annealed, of course), and even into 300 series stainless (303, 304 and 316) whilst making pocket knives - making holes to tap for 0-80UNF screws, and that's pretty small :). I use both HSS-Co and solid tungsten drills, and only run them at around 2000RPM on my little mill/drill... have only broken 4 of these small drills in the last 3 years... I do use a good quality soluble oil cutting fluid on all my drilling, and "black magic" tapping compound on the taps.
I suspect a bigger risk/problem will be that these small drills break just as the drill exits the hole. This is normally as a result of play in the drill press spindle, and can be largely eliminated by adding two coil springs to keep the chuck/spindle in tension even as the drill passes through the hole. I will have to post a sketch if this is not clear and if you cannot find anything on the 'net - just give me a shout.

Hope this helps.
HennieL
 

jack620

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I have one of these: proxxon
I made a holder to mount it on my lathe toolpost for cross-drilling holes. It's extremely smooth and has very little runout. Eventually I will buy the drill stand for it for drilling holes in circuit boards, etc.

I also have one of these: Sensitive Drill Feed | 1/8" Keyless Drill Chuck - LittleMachineShop.com

It allows a more delicate touch when drilling with very small drill bits on a lathe or pedestal drill.
 

RM-MN

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The high speed listed for small drills is more of a maximum for the fasted drilling. If making the hole in the least amount of time is critical you want a fast drill. Slower works pretty well. One of the downsides of the slower drilling is that the bit may not evacuate chips as well so peck drilling becomes more of a necessity. Get the bit into the material just a little, then back out to clear chips. Failing to do this can fill the drill flutes and jam the bit and the small bits break very easily. I have proof.
 

Steamchick

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I make gas jets and find drilling 0.25mm (about 0.10") a bit of a pain on my lathe. The biggest problem is striking a centre to start the drill. If off centre by even a "thou" or 2. the drill will cut a large hole and/or just break. So I have about 3 holes per drill before the edge goes and I expect a break. And only 1 in 3 jet holes is "on size" - the others just save me making larger jets.
My latest idea is to use a "broken" drill - with maybe 0.5~1mm of drill bit left attached to the 3mm shank... and use this to strike the centre - as regular centre drills etc. are just bigger (on the blunt end before the cutting edge at the flutes!) than the holes I'm drilling. When I have a centre (maybe only a few thou deep) that I like, I then drill with the proper drill bit. But I am unsure of speed. My lathe is currently set to go to 1600rpm, but I drill at around 800rpm as this seems to be OK... I'm only drilling through about 3mm of brass to make the jet so don't need to "Peck" at it - although when I have tried to drill deeper even pecking doesn't get me past the 5mm depth before a breakage. Feeding the tailstock is very difficult - "old" muscles sometimes don't work perfectly. - Too fast and the drill breaks. The lathe is far too large to have any sensitivity so I can feel the drill pressure. Maybe I need a sensitive drill chuck? Does it need a special adapter for a no 2 Morse taper?
Any suggestions to help me improve?
Thanks,
K2
 

Jules

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Steamchick, have you tried PCB drills ?
They are usually very short and have 3.2mm shanks.
A sensitive drill chuck will also help no end.
I would also try using a very small carbide stubby drill to give you a centre. They are very ridged and should cut at the correct angle to start your small bits.
 

Steamchick

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I'm using drills with a 3.2mm shank. The 0.25mm. bit is only about 10mm long. A centre-drill would need the central web to be less than 0.25mm. thick. I'll stick with the 'broken 0.25 drills" for centring until I can find a super small centre drill.
I just don't know what speed I should be using? Or how to get better control? I'll try and find out more about the Sensitive Drill chuck..
K2
Thanks.
 

Jules

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Steamchick,
You can easily make a sensitive drilling tool.
I would get an MT2 blank with a short stub. Drill and ream to 10mm.
Make a disc approx 40mm dia x 8mm and drill out 10mm.
Drill and tap for a locking grub screw and then knurl the outside.
Then lock that onto an ER11 parallel shank collet holder.
Put the drill into the ER11 collet and the MT2 in your tailstock. The collet holder should slide smoothly into the tailstock.
Just hold the knurled disc and feed in your drill.
Take care of the chuck. (Much better with a collet)
 

Richard Hed

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I make gas jets and find drilling 0.25mm (about 0.10") a bit of a pain on my lathe. The biggest problem is striking a centre to start the drill. If off centre by even a "thou" or 2. the drill will cut a large hole and/or just break. So I have about 3 holes per drill before the edge goes and I expect a break. And only 1 in 3 jet holes is "on size" - the others just save me making larger jets.
My latest idea is to use a "broken" drill - with maybe 0.5~1mm of drill bit left attached to the 3mm shank... and use this to strike the centre - as regular centre drills etc. are just bigger (on the blunt end before the cutting edge at the flutes!) than the holes I'm drilling. When I have a centre (maybe only a few thou deep) that I like, I then drill with the proper drill bit. But I am unsure of speed. My lathe is currently set to go to 1600rpm, but I drill at around 800rpm as this seems to be OK... I'm only drilling through about 3mm of brass to make the jet so don't need to "Peck" at it - although when I have tried to drill deeper even pecking doesn't get me past the 5mm depth before a breakage. Feeding the tailstock is very difficult - "old" muscles sometimes don't work perfectly. - Too fast and the drill breaks. The lathe is far too large to have any sensitivity so I can feel the drill pressure. Maybe I need a sensitive drill chuck? Does it need a special adapter for a no 2 Morse taper?
Any suggestions to help me improve?
Thanks,
K2
Let me be sure that I understand you. You say you are drilling a .25mm hole with a lathe? your lathe is a toy lathe? I would thimpfk even a toy lathe would be too clumsy to try this with. I would thimpfk a dremel type tool would be needed. You could set that up in your lathe but to use the lathe itself would be like hunting mosquitos with a 500lb bomb. A dremel style tool, (I thimpfk), would give you far more control over a tiny operation like this. Is there any other possibilities? a local water jet? Laser? acid etching? EDM? If you have a small enough hole, (as you do), you might be able to construct a tiny EDM machine particulalry since you have only a few mm to go thru.
 

geo

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I make gas jets and find drilling 0.25mm (about 0.10") a bit of a pain on my lathe. The biggest problem is striking a centre to start the drill. If off centre by even a "thou" or 2. the drill will cut a large hole and/or just break. So I have about 3 holes per drill before the edge goes and I expect a break. And only 1 in 3 jet holes is "on size" - the others just save me making larger jets.
My latest idea is to use a "broken" drill - with maybe 0.5~1mm of drill bit left attached to the 3mm shank... and use this to strike the centre - as regular centre drills etc. are just bigger (on the blunt end before the cutting edge at the flutes!) than the holes I'm drilling. When I have a centre (maybe only a few thou deep) that I like, I then drill with the proper drill bit. But I am unsure of speed. My lathe is currently set to go to 1600rpm, but I drill at around 800rpm as this seems to be OK... I'm only drilling through about 3mm of brass to make the jet so don't need to "Peck" at it - although when I have tried to drill deeper even pecking doesn't get me past the 5mm depth before a breakage. Feeding the tailstock is very difficult - "old" muscles sometimes don't work perfectly. - Too fast and the drill breaks. The lathe is far too large to have any sensitivity so I can feel the drill pressure. Maybe I need a sensitive drill chuck? Does it need a special adapter for a no 2 Morse taper?
Any suggestions to help me improve?
Thanks,
K2
I have 1 .8 and .5 mm centre drills they are not expensive and very good joe pieczynski on you tube does a good sensitive drill feed
 

Ken I

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WisJim,
These are what I use for very small holes :-
drillhead.jpg

The upper one uses a DC motor, Dremmel collets or chuck (5/16" 40 ME thread) - the whole thing floats in that it is free to rotate and slide in the MT3 shank. It uses a Mabuchi motor running off a DC power supply, all the mechanical bits are home made - I scavenged the chuck end of an old Dremmel accessory.
You hold it and feed by hand - this gives you "feel" for the torque - I keep the other hand on the on/off switch.

The lower one is a similar sliding pin chuck that I use held in a conventional chuck in the lathe - again you feed it manually and you can feel the torque - if the drill snatches, you just simply let go and it spins harmlessly. Obviously it doesn't work for the mill - apart from using it for M3 or smaller thread tapping by hand.

The motorised unit works on my mill or lathe - on the lathe you can rotate the part as well as in gun drilling which is suppose to held keep it running true.

I use a spotting drill rather than a centre drill to make the start point.

Regards, Ken
 

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Drawfiler

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For lathe work I use a pin chuck. You put the shaft into the normal tailstock Chuck just loose enough to turn, almost as though the shaft is running in a bearing, you then get the lathe going and feed the pin Chuck forward by gently holding it between your two forefingers with the rest of your hands holding the tailstock Chuck, if the dill jams or bends, the pin Chuck will turn between your fingers.
 

MRA

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I do some volunteering at a place which collects industrial engines (Anson Engine Museum), amongst which are many diesels. We have a display case containing some photos and a drill bit with a small shank, out the end of which protrudes the bit itself which looks like a hair - how the **** they formed and sharpened it, I don't know. I think it came from Gardners. Attached is a label hand-written in ancient copperplate, saying something like 'this bit was used to drill 14,245 injectors for type 'xx' engine. It is now undersize, but may be used for type 'yy' engine'.

The photos show the rig - much like your ideas above, but on a small cast iron bed about a foot long on top of a bench with a strong light immediately above, operator sat next to it, and driven by pulleys and a round belt to get the speed.

I regularly break bits up to about 1/8". I've even sheared an M10 tap, once :cool:
 

Steamchick

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Richard, Ken 1 'n all. Thanks. Being fair, I have probably only made a couple of dozen jets all told. The 6" (Chinese) lathe is more accurate than my Unimat SL. (Which I guess must date from 1960s or earlier?). The Unimat must be at least 1 diameter off-centre for the 0.25mm drills. And trying to align the headstock with the tail-stock tells me the Unimat lathe just isn't true after a long life. I have had best results on the 6" lathe by threading the jet, drilling the "gas-side" 1mm dia for all bar 3mm of length - then parting-off. Reverse the jet in the chuck, face then strike a centre for the 0.25mm drill and do the drilling with tail-stock chuck holding the drill. On the Unimat, I have to swap the chuck and tail-stock (drill-chuck) so the drill is rotating, as I just can't find a true centre the conventional route with the drill in the tail-stock. - Through the magnifying glass you can see the drill bending as it wobbles off-centre. If I get a hole it is somewhere around 0.27~0.28mm I guess (smaller than my 0.30mm drills). I buy sets of 10 drills of E$@y for £2.50, so cheap enough, and I have a dozen or so shanks from broken drills - some with a mm or 2mm of drill left unbroken. I use these to strike the centre now, as nothing else is small enough in my collection of centre drills and spot-drills. When I get a true centre, the jet gives a gas flame exactly the same size as a commercial jet (cost £3.). I'm just a sucker for making it myself, rather than buying "mass-produced stuff at 10 times the cost". When commercially practical - I buy! - Then spend my time making the more unique stuff.
I would just like advice on the best speed for drilling? The drills are so femur that high speed definitely doesn't work for me. I seem to do best at 800rpm... but when you talk about it you seem to be at Dremmel high speeds of over 10,000rpm? (If I read you correctly?). When I tried that the drill bit simply broke-off the shank "to meet its maker". Glad I was wearing glasses! Perhaps you are drilling >0.5mm when the drills are strong enough for the speed? When I have tried simply holding drills with a steadied chuck that has less than a 70% chance of success, as my hands are not "stiff" enough. You can't feel the snatch - there isn't enough torque on such a small drill. But you can feel the drilling pressure, holding the chuck lightly 'tween finger and thumb mostly supported by the tail-stock, but without the taper jammed... (like Drawfiler's method). - I don't need pin chucks (mine are not accurate enough anyway) as the drill shanks are 3.2mm dia. I'll make a tail-stock sliding holder for a small chuck I have, and try that. It really does need the alignment from the larger lathe, but with the feel I guess I'll achieve with the sliding chuck arrangement? - I'm much like MRA with my hand skills, so need the machine to compensate! (Breaking 10mm taps is easy for me! - For hand tapping, my Push and Pull are not in-sinc most of the time! ;) ).
Cheers lads! If I achieve more than 1 in 3 true jets I'll let you know... or if I ever reach more than 5 true holes with 1 drill-bit. My real challenge will be to buy some 0.2mm drills...
Did someone recount the tale that after WW2 the Americans sent the British a tube with a machined-hole that was smaller than anything supposedly available? - So the British sent it back with a tube inside it? Here's the latest! - Smallest 'test tube' scoops world record

At work, we needed oil-spray bars for valve cam lubrication (400,000/year)... 0.5mm holes specified. The Japanese had very clever checking devices an cameras to check for broken drills, blocked or badly drilled holes, etc. and a 5% part reject rate. To make these in the UK I specified Laser drilling - 100% OK parts - and cheaper! (High capital cost recuperated in months).

I'll try not to stress you with my "simple" queries again!
K2
 

goldstar31

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Ken
The holes in holes dates back to the Japanese- and the Tyne which built Japananese battleships.

My eyesight is more than rough but drilling holes correctly on a round object demands a milled surface PRIOR to attemps at drilling. Here were go again, but I hit problems at the age of 14/15 trying to drill reheat holes in a baby athodyd jet engine ex Aerodeller and Cpl Henwood. The metering was made on an old pre-war Myford.
Skipping( he jis joking at 90), I wood then make up tiny D bits that the local nurse had made(. Vickers Armstrongs and Metal Box yet agai) to release trapped blood in crushed finger nails.

You and I discussed a possible workshop from an even old bloke and he was a Geoege Daniels and George Thomas fan. Both were also wath,akers and it took Daniels a year to make a wrist watch.
Contraast this to me haggling over a £10 Rolex diving watch in the Ladies Market in HongKong.

So my thoughts of an ancient old git is to buy a set of turns with a set of 6mm collets. Shut the door on the metal butchery department here and start thinking about watchmaking.

Incidentally, this 10 milllie Pultra 10 had a microscope! More words of dismay but the chairman of the British Horological Society of old- has an empty shop in in Byker. OK he does Mason's time[ieces from time to time(!) but he is maintaining instruments for the NHS.
Damn, another bloody Quorn e-mail but if you had on ----- say no more

Cheers


N
 

Steamchick

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Thanks for that Norman. I bought the Unimat SL 20 years ago for small stuff. Just my luck the lathe I bought isn't so good. (It has been well used and is worn).
I have ordered a different pin vice with multiple collet and a shaft to run in a hole I'll ream in a tapered sleeve in the tailstock. Maybe it will work? Not sure I can make that quality of precision.
Keep well,
K2
 

goldstar31

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When Noah and I were lads, I had a SL and r ecall the late Rex Tingey( he was. same age as me) did some overhauls and put in silver steel bed bars and I recall the gibs were plastic. FYI and I ithen had a mk3/4 clone= which I recentltly( ?????) sold. Vagely, I have Making the Most of the Unimat on file somewhere. Thonkiing of Quorns, I recall someone using the little motor as ubit for a sort of Quorn.
My Mk3/4 had ER14 collets. I think.

Off topic( really OFF0 the Quorn guys are prattling on about microscopes and eye aids. Bright set of enthusiasts. How I got in is a mystery of science.

This 6" Chinese lathe has made me curios. I had no idea abut one. Details please, of you can.
Meantime, I have just driven myself nuts on rebuilding my garden shredder and am off to run a series of tailstock tests until a couple of us are going to devour a remaing half bottle of Scotch.


Cheers everyone and stay safe

Norman
 

DickG

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I'm using drills with a 3.2mm shank. The 0.25mm. bit is only about 10mm long. A centre-drill would need the central web to be less than 0.25mm. thick. I'll stick with the 'broken 0.25 drills" for centring until I can find a super small centre drill.
I just don't know what speed I should be using? Or how to get better control? I'll try and find out more about the Sensitive Drill chuck..
K2
Thanks.
I often need to drill a 0.010” dia hole in silver steel. This is for the anvils used in my “Graskop” Rivet Tool. I do have an advantage in that I can use the tool to centre pop the blank anvil. I can drill with very small drills in my Myford S7. This has a rack feed tailstock and a 1HP 3-phase motor. I wind the VFD up to 100 Hz to get the spindle turning at around 5k RPM. However, I prefer to use my small Pultra as the spindle turns at around 8k RPM, still a bit slow for a 0.010” drill. The Pultra has a lever feed tailstock so peck drilling is easy.
I do have some ‘micro’ centre drills for starting in a plain bit of material.
 

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