Small Drill Bit Question

50 years ago I remember lines of girls drilling .20 mm holes in diesel fuel injectors at a rate the was a wonder to see
all done on tiny bench drilling machines.
No man was able to do this job, they just could not match the sensitivity.of the girls. needles to say they where well paid.
The same for the men hand lapping the pumping elements to get a 3 micron fit, the company just did not mess with this group of workers.

Brian.
 
I usually resort to a "Pin Vice" and manual. Time consuming but effective. Usually I only need a small hole in a thin plate or to enlarge a slightly smaller hole.

Steve
 
you can get them in 1/8" shanks at harbour freight but take a magnifier some in the sets are end mills that small
I was just playing around once to see if i could do it and drilled 3 holes in the head of a pin in my cnc mill. they were so small i would break them if i even drop them . I made it to show my friend who owns a machine shop how accurate my little mill is
i'd hate to have to work with them all day and i'm sure thats why that company brian was talking about paid the girls well.
what i would like to see is the machine that makes them
steve
 
I was involved in the production of rubber molds for many years and small drills of this type were used to put in the sprues through which the rubber was forced into the cavities. The smallest drill I recall using was 1/64 there are drill chucks made to hold these tiny drills however I felt there was less breakage if they were held in a collet, if you have all your ducks in a row, as to feeds,speeds depth of cut, and using cutting oil rather than coolant there was generally not much of a problem. Most of the sprues were .031/.040/.046 also speeder attachments were used in the spindles to get enough RPM.
:cool:
frankie
 
I just had a dig around in the small drill box and came up with these.

P1011734.JPG

the large drill is 1/8" for referance.
the 3 on the left are.028" I use these when making lantern pinions, the stub drill I use as a centre drill to make a ding just to start the small one on its way.

This is the drill I use when drilling in the lathe.

P1011733.JPG

I have 2 different chuck attachments for it and a wood carving attachment a very handy tool.

P1011638.JPG

This shows it in use as a tool post drill making pinions.

If I need to ease the hole a little I use a 5 sided tapered broach,

P1011735.JPG

These go down to .028"

Happy Drillin---Brian.

P1011734.JPG P1011733.JPG P1011638.JPG P1011735.JPG
 
The big problem with these tiny drills is that you need SPEED,or they will break off VERY easily. We now have a Servo brand mini drill press. I think it goes to about 30,000 RPM,with variable speed.

I have one of those sensitive drill chuck attachments as pictured,but,unless your regular drill press has VERY high speeds,the drills can still break right off.
 
Very true, George. There is a great need for speed with these small drills. I've broken a few, but usually just a bit of nerve twitch on the drill. Wide open on a BP is really too slow, but with care, is enough to get by. Certainly not for production, but with the hobbyist in mind, it works well enough if careful.

I usually pull up a lit magnifier if I have to drill small holes. I can't see the chips well enough to know how it is doing, and feel isn't what it used to be.
 
I plan to make a high speed attachment for my Bridgy. I will take a piece of 1" thick aluminum plate. On one end,I'll bore a hole that fits around the spindle of the mill. About 6" away,on the other end,I'll bore a hole that fits the front end of my 10,000 RPM Dumore hand grinder. Both holes slit for adjustability,w/screw for tightening. I can use a router speed control unit on the hand grinder.

If I try to use a 1/32" end mill on this mill,it usually breaks right off on steel,from not enough speed. I saw some guy make such a unit with a Dremel tool for a motor,and a belt from it to a small spindle.
 
Thanks to all for the great information. I will put the small drills aside until I have the correct tooling and a need to use them. I don't have the skill level yet for them. I usually break any drill smaller than 1/8 inch.

Thanks,
Benny
 
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