Drilling small holes with a vertical mill

[Mr Ron]

What would be the best way to drill number size holes on a vertical mil?. I'm thinking an R-8 collet, holding an Albrecht15 keyless chuck with an adapter. Would this give me a rigid setup to minimize drill breakage? https://www.penntoolco.com/royal-produc ... C%20%24325
I don't think the typical drill press would be rigid enough to drill small holes

[GlennW]

I use a 0-1/8" Albrecht chuck with a 3/8" shank in the lathe and mill for small drills down to #80. Works fine.

[whateg0]

I've used my 8" harbor freight dp for drilling pcb holes with tiny carbide drills before. It's just a matter of eliminating the runout in the Chuck. You won't be applying a lot of pressure so it's more about runout than rigidity.

[Harold_V]

Aside from a concentric running drill, the most important feature I can think of is feel. If you use a drill press, they tend to have rather strong quill retraction, which takes away from the feel. A drop spindle mill (Bridgeport type vertical mill) tends to have lighter spring pressure and often has excellent feel. On my BP, the weight of the stock quill handle is enough to overcome the spring pressure, and I keep the quill well wiped and oiled. It has excellent feel. Like Glenn, I use a 0-1/8" Albrecht chuck, but mine sports a ½" shank.

It pays to do the math when using small drills, as running them too slowly is an invitation to broken drills. When you run them at the prescribed speed, they actually cut quite nicely, especially when you can feel them. Clear chips often, and be mindful to NOT drag old chips in to the hole when you peck. That is a recipe for broken drills.

Tiny drills are easily broken by an air stream. If you don't use air on your machine, no problem, but if you do, use caution.

H

[Bill Shields]

Define small...

[whateg0]

Define small...

If op is going to use a 15, then less than 1.5mm. granted, there's a big difference between 1/16" and 0.025"!

[rmac]

FWIW, Joe Pieczynski describes a homebrew accessory for drilling small holes that doesn't cost $450. Here's a link:

https://www.youtube.com/watch?v=PqU5wS0J4MU

-- Russell Mac

[Mr Ron]

Thanks all. I need to get a small Albrecht chuck and make a sliding adapter.

[NP317]

Do an online search for "Sensitive drill chuck images"
Questiones answered.
RussN

[pete]

Depending on your part size there's another out side the box method. Sometime I think in the 1980's HSM magazine published an article and drawings for what was in effect a small stand with a sub table maybe 1"-1.5" in diameter all made from aluminum plate for lightness and to get that feel for how the drill is cutting. The tables lift mechanism was basically a piece of drill rod with a tiny key to prevent table rotation through a vertical dead straight bored and reamed hole in that stand, and the end of the drill rod was moved up and down with pretty much a wood router bearing placed eccentrically on a round disc with a short operating rod for the operators fingers. It also had a steel weight that could be moved on the handle to get a neutral balance on the table and work piece weight, so any forces your feeling are all from the amount of drilling feed pressure being used. Pull the handle down and the router bearing makes a partial arc lifting drill rod and the table upward. If I recall the details correctly, the author meant it for drill press use, so it's table was plain without any method of holding the parts in place. To me holes that small usually indicate that a fair amount of accuracy in there positioning might be required. Adding a method of clamping or holding the parts on that table rigidly and then using standard mill practice of edge finding, indicating an already known feature on the part and then using standard off set coordinate positioning for your hole locations would be a lot better.

There wasn't much travel on that table, maybe about 1/4", but holes that small aren't usually all that deep. And that table still doesn't solve how to accurately hold drills or even reamers in those sizes. Not impossible if you can work accurately enough to drill and use a small set screw or even loctite to hold the drill inside a shop made larger arbor that can be held in a larger drill chuck or collet though. A Dremel has most of the speed and could be attached as a sub spindle to a drill press or mill spindle. But any I've used have garbage run out because of the price there built down to. I recently ran across a deal on a hardly used Foredom unit, but haven't yet checked it's run out. There supposed to be pretty good, but until I personally check that's only a rumor I don't know is true.

[Mr Ron]

Define small...

If op is going to use a 15, then less than 1.5mm. granted, there's a big difference between 1/16" and 0.025"!

I don't know where the "15" came from? I mean to use an Albrecht chuck that will go down to a #80 drill.

[TomB]

I use to work for IBM in the manufacture of MultiLayer Printed Circuit boards. The boards we were making had tiny embedded via holes to carry the circuits from one internal layer to another. We had a custom made heavy duty drilled hole machine that used drills with a .125" shank diameter a taper down section and finally a normal twist drill profile. The tool supplier we used could seemingly come up with any drill diameter we ordered. It seems to me that it would be more effective to look for a source of that type twist drill than to try and mount some sort of custom chuck or collet to hold a very small straight shank drill bit. The one limitation of those small drill bits is they did not come with a lot of hole depth capability. The thickest PC board I ever saw produced was less the .250" thick and that was about the limit of the drill bits hole depth. But withing the limits of that drilling technology we made an awful lot of drilled holes.