What's new
What's new

Drilling a .004" hole.

Do listen to the speeds here.



You are going to need to turn that drill bit around 10'000 at the slowest. 25'000 would be better.

If you can find an air powered, spindle mounted grinder head, you might get close to the RPM you need. Balance and runout becomes critical at those speeds.

You may just try to mount a pin vise in your BP with a spring type dead center and try drilling those by hand.

That's the way I would go, if it's still in brass, like you said.
 
I would send the customer to the local drug dealer or a psychiatrist as that kind of a sick joke is an indication of a nasty problem... 0.004 hole... thats what, x2.514 in civilizationsville, 0.01mm hole... Tell them to piss off or to spit out more cash than they earn in a year, per hole... Or if you have a jig grinder-borer, do it, but still, price that shit up properly... Asking for a hole that small is just rude and uncivilized... Also, if you are doing it, lock every axis of movement apart from the down/up feed... Those drills indeed are a breath away from becoming a good dowel pin...
 
I do a lot of sub 1mm holes because I repair & restore antique clocks and I usually do it with a pin vice in my hand, and I know it sounds off using a hand held pin vice but once you have found centre ( I use a small carbide spot drill ) the bit will find it’s own way on centre, and if drilling brass stone the leading edge off the bit otherwise it can bind and snap the bit , also drill a bit remove drill a bit more.
The smallest I have done is 0.2mm.
 
While having a lot or rpm helps, it's not critical. Most important is the drill runs concentrically. The biggest issue (aside from concentricity) is feeding correctly. If you calculate the chipload needed you will be surprised how fast you need to feed at 10k rpm to avoid rubbing the lips dull. Chipload for a drill this size would be about half a tenth per lip, or 0.0015mm. Even at 3k it's one second for 0.006", which I guess is around the "few thousandths" the OP needs to drill.


What Screwmachine said....he's one guy that would have experience with this. Not sure where the idea that you have to have fantastic speeds comes from. The guys who do it, watchmakers, use a few thousand rpm or less

What you need is concentricity and sensitivity. I've got fancy little drill presses, but better is the following table. Its very simple to make, you could do so from the photos. It has a shoulder bolt as the pivot, and is counter balanced so you can zero out all other forces. Best one I've seen, came out of Home Shop Machinist a gazillion years ago. If you have a way to spin them concentrically, this what you need. A bit of masking tape is the usual 'work holding' device lol

KakwzaE.jpg


OiIZXKm.jpg
 
Not sure where the idea that you have to have fantastic speeds comes from. The guys who do it, watchmakers, use a few thousand rpm or less

It comes from the theoretically correct surface speed. If we take the middle of the road surface speed for brass at about 500 sfm with a 0.004" drill, you need almost 475,000 rpm. Thus the mentality of "as much as you can possibly get".

At a more realistic spindle speed that one might have on a small purpose made drill press like a Servo, 20k, sfm is a small fraction of the "correct" sfm, at about 20. Still have to feed at 2 ipm, which doesn't sound like much, but is still 0.033" per second (getting close to a millimeter per second). The downside of underfeeding and killing the drill's cutting edges, and then breaking it, is far worse than having an even slower sfm and being able to feed at a reasonable rate (and clear chips etc.).

In a CNC where the feed is very well controlled absolutely use as much rpm as you can on the little stuff, it's definitely better and welcome. For manual feeding, lower rpm is better.
 
Whenever I see tiny holes used as orifices, I have to wonder how long they will stay orifices. Whatever they are flowing had better be reeeaaallly free of dirt, grit, or just about anything else.
 
At a more realistic spindle speed that one might have on a small purpose made drill press like a Servo, 20k, sfm is a small fraction of the "correct" sfm, at about 20.

I've got a Servo, nice machine, but between its speed and the simple rig I post above (giving great sensitivity), one would be better with the rig than the speed imo. The ultimate set up might be the sensitive table coupled with a collet headstock like the Levin shown above....perfect sensitive and as good as it gets concentricity. I may do that with a spare headstock....after I get the other 800 years worth of projects done. I have a Rivett DP head somewhere (only different I can see between it and the lathe version is the oil cups are upturned to receive oil in the vertical position)
 
When I drill sub 1mm I find the slower the better at high speed it binds and snaps the drill bit before you have time to react but at slow speed at least you have a chance .
 
When I drill sub 1mm I find the slower the better at high speed it binds and snaps the drill bit before you have time to react but at slow speed at least you have a chance .
If I'm repivoting a frighteningly small hard to replace part like a tiny LeCoultre escape pinion I actually like to use a hand powered lathe where I can go _really_ slow. Usually with hand ground spade drills, hand held, with a bit of a "waist" so if there _is_ a problem (breakage) the drill falls out.

But otherwise if in the lathe it's drill in tailstock, or if spinning the drill in the drill press or jig borer it's a pleasure drilling at 1500-2000 rpm. With a micrometer stop you can guesstimate and turn it while feeding to get the feed close. There's not a lot of "feel" at 0.004"/0.10mm, haha.
 
If I'm repivoting a frighteningly small hard to replace part like a tiny LeCoultre escape pinion I actually like to use a hand powered lathe where I can go _really_ slow. Usually with hand ground spade drills, hand held, with a bit of a "waist" so if there _is_ a problem (breakage) the drill falls out.

But otherwise if in the lathe it's drill in tailstock, or if spinning the drill in the drill press or jig borer it's a pleasure drilling at 1500-2000 rpm. With a micrometer stop you can guesstimate and turn it while feeding to get the feed close. There's not a lot of "feel" at 0.004"/0.10mm, haha.

A lot of machinists will not know what a spade drill is, so I will post pictures. Spade drills are for drilling in metal and were the normal sort of drill bit before the twist drill became popular in the mid-1800's. The large bits in the picture were hand made by blacksmiths and usually turned by hand with a brace. The shanks are tapered squares and you can see the shanks are not all the same size. Note that most have a taper behind the cutting edge. The two boxes contain sets of carbon steel watchmaker pivot drills with spade ends in sizes from .004 to .050 inch in .002 increments. Back in the 1960's when I worked on watches these sets were a buck or two each. I also have some more expensive Swiss-made twist-type HSS pivot drills in various sizes. In watch or clock talk, a pivot is the reduced diameter cylindrical end of a rotating shaft that rides in a drilled hole in the metal plate, or in a hole in a jewel.

Repivoting is a repair process done after a pivot is broken off or damaged. You have to face the end of the shaft and start a center hole with a hand-held pointed graver (chisel). Then you drill a hole in the shaft and insert a hard steel pin (sewing needles have been used) and polish it down to the diameter required to fit the pivot hole in the plate or jewel. I do not do watches anymore, but I still do repivoting on Hardinge feed screws with the 9/32" crank end broken off. Pretty much the same job, but the parts are big enough for arthritic fingers to cope.

Larry

Flatbits 1.JPG Flatbits 2.JPG Hardinge slide rest 19Jan06.JPG DSC00129.jpg DSC00136.jpg
 
That's a Boley lathe, with a story behind it. I was able to purchase all the parts from Manhattan Supply (this was before they became MSC!) Also purchased a set of WW collets and the WW-mount precision albrect chuck as well. So I had the headstock, tailstock, toolmakers compound, a motor, pulleys and belts.

They would NOT sell me the bed. So I went and was grousing to one of the model makers at work, and he said "what they heck, I can make that for you easy."

And he did. So the bed is custom length, custom size part. We seldom use that machine, but when you need it, it's invaluable. It would drill 0.004 holes all day long.

When G. Boley was still in business, the USA jewelry supply houses sold complete G. Boley WW pattern lathes, collets and accessories. At one time, possibly in the 1930's, G. Boley made an actual drill press based upon their WW lathe. I have only seen one example, which I own. Note the lever feed tailstock that holds WW collets is the same on the lathe and the drill. I have a WW shank drilling pad in my drill tailstock.

DSC02862 (2).jpg

Levin is still in business, though their machines are priced for customers indifferent to cost. They make a nifty micro drilling machine said to easily drill holes smaller than .004 inch. It is a lathe with a live tool tailstock that can be adjusted for concentricity with the headstock. They rotate in opposite directions so the two max spindle speeds (each is 5000 RPM) add up to 10,000 RPM. There is a hand lever feed for pecking, a hand crank stop and a depth dial indicator.

LevinLathe.com: MICRO-DRILLING MACHINE Complete drilling machines $29,280 or less (choice of 3C or D headstock).
LevinLathe.com: MICRO-DRILLING ATTACHMENT Drilling tailstock to retrofit a lathe $10,140 plus you need a motor and idler pulley assembly to drive the drilling spindle.
LevinLathe.com: INDIVIDUAL SIZES OF LEVIN PRECISION COLLETS WITH DECIMAL EQUIVALENTS 89 piece set of WW or D collets $41,000 A collet with a .1 mm (.004") order hole is $3500.

Larry
 








 
Back
Top