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gilessim
04-07-2007, 04:37 AM
Hi there,I have to drill several rows of 1mm holes ,5mm deep in brass and no matter how well I set up the piece in the mill (with a lazer center finder) the drill bit wanders!. I need to somehow centerpunch my marks ,I guess I could use a finely ground punch in the mill ,and just press down lightly ,but does anyone know of an easier way? by the way, check out this guy! http://www.barryjordan.freeola.com/

Stepper Monkey
04-07-2007, 05:57 AM
If not a centerpunch, try a ball mill or bur to start the hole. If you don't think they make 0.9mm, 0.7mm, 0.5mm and smaller ball mills, go ask your dentist for his old ones. They used to sterilize and reuse bits until they got dull, but they aren't allowed to reuse on patients anymore. Every little cavity and a new 3/32" shank carbide bit goes in the trash with only seconds of use on it.
Ask him to save up and autoclave (sterilize) his old ones for you instead of trashing them and a week or two later you should have a lifetime supply to play with, even if you live a very long time!

bogstandard
04-07-2007, 09:33 AM
Just buy yourself the smallest centre drill (slocombe drill) and just touch on, this will give you a detent to start your drill. The reason you want to touch on is I think that the smallest tip point is 1.6mm, you just need to create a small detent to keep your drill straight. Also at this size you need to have your drill press or miller running the fastest it will go otherwise you might find you are breaking drills. Using this method I have no problems drilling as small as 0.2mm.

2muchstuff
04-07-2007, 02:26 PM
They used to sterilize and reuse bits until they got dull, but they aren't allowed to reuse on patients anymore. Every little cavity and a new 3/32" shank carbide bit goes in the trash with only seconds of use on it.


Lab burrs have a 3/32" shank diameter, high speed handpiece burr shanks are 1/16" in diameter. I work in the dental field and dentists still sterize and re-use thier burrs until they get too dull to cut thru tooth enamel, then they throw them away. I see it done day after day in numerous offices. They are still plenty sharp enough to do what you want them to do. You can get new ones for about a dollar each thru a dental supply.

drk
04-07-2007, 02:36 PM
You could always try some carbide pcb drills, the shank would be 1/8 inch and sizes start from 0.3mm

gilessim
05-23-2007, 12:33 PM
Thanks guys, I did find some centre bits with 0.9 mm points on them ,I bought them from some polish people who sometimes sell stuff on the side of the road here in Italy, they seem to be solid carbide ,and I already broke one tip!, they have resolved my problem ,and luckily I bought a few (50 cents a piece!) they have 5 mm shanks and must be made in Russia ,but do the job!....thanks again..Giles

AMCjeepCJ
05-26-2009, 05:03 PM
I think NASA used to just have tiny holes put in using EDM machines, no tool pressure and perfect holes, just make the trode undersized!

AMCjeepCJ
05-26-2009, 06:04 PM
I should add that these holes were in the .003"-.006" range and they made the electrodes by using the EDM too. No tool pressure, no bending~ I only remembered this because the guy who had the job made a bundle of money because no one could figure out how he made such perfect, tiny holes exactly on location... Now the whole world will know, lol... He's retired now and out of the machine industry so it's not a big deal to share anymore and besides, this was several decades ago and those types of holes aren't a big deal any longer but it is a cool way to make tiny shallow holes precisely if you are having trouble drilling them~