• MMS Youtube
  • MMS Facebook
  • MMS Linkedin
  • MMS Twitter
10/1/2009 | 1 MINUTE READ

Does Small-Hole Drilling Demand a Fast Spindle?

Facebook Share Icon LinkedIn Share Icon Twitter Share Icon Share by EMail icon Print Icon

A reader with a 10,000-rpm drill press can drill a 0.019-inch hole in stainless, as long as all the contributors to runout are controlled.


Facebook Share Icon LinkedIn Share Icon Twitter Share Icon Share by EMail icon Print Icon

A reader recently used the “Ask an Expert” feature of our Micromachining Zone to ask the following question.


I'm trying to drill a 0.019-inch hole in 316 stainless steel that will need to be 0.092 inch deep. I have a drill press with a top speed of 10,000 rpm. I have tried solid carbide circuit board drills and out-of-the-book high speed drills. I'm breaking drills and have not drilled one good hole. I can adjust the feed slower, but this doen't help. We are holding the drill in a pin vise in an ER collet. Is there a better drill to use? What do you think?

Response from John Bradford, micromachining R&D team leader for Makino

I certainly recommend that you investigate drills from Union Tools.

However, for micro drilling, our main focus is not necessarily on the drill itself, but rather on the total accumulated runout that occurs in actual operation. Accumulating factors include: spindle runout at actual rpm, tool holder and collet runout, and flute runout relative to the drill bit shank.

Additionally, I would recommend spotting the hole with a spot drill that gets you a seated diameter that is 5% larger than your drill bit diameter.

After these items are taken care of, then you can start tuning in your actual machining process.

I have a feeling that, in this case, your culprit is likely the runout created by the accumulation of items starting at the spindle downward.

Here is an example of drilling that I recently completed in stainless steel, with a 0.002-inch drill going 0.020 inch deep. It is a very stable process, and much easier if you have negligible runout.

You will note from our specific part that we were using a speed above 30,000 rpm, but this is not a requirement. You can effectively drill holes as small as 0.005 inch with 10,000 rpm, as long as you minimize runout and vibration.


Hand holding a crystal ball

We’d rather send you $15 than rely on our crystal ball…

It’s Capital Spending Survey season and the manufacturing industry is counting on you to participate! Odds are that you received our 5-minute Metalworking survey from Modern Machine Shop in your mail or email. Fill it out and we’ll email you $15 to exchange for your choice of gift card or charitable donation. Are you in the U.S. and not sure you received the survey? Contact us to access it.

Help us inform the industry and everybody benefits.


  • The Challenges of Machining Glass-Filled Plastics

    Plastics reinforced with glass present more machining variables to manage than conventional metals. This shop has developed a process to overcome those challenges and has become more adroit at short-run work along the way.

  • Where Dry Milling Makes Sense

    Liquid coolant offers advantages unrelated to temperature. Forced air is the fluid of choice in this shop...but even so, conventional coolant can't be eliminated entirely.

  • Drill And Bore With A Face Mill

    Cutting holes by interpolating a face milling cutter may be a better process choice for many rough and even finish boring operations. Software improvements and better cutter designs allow expanding use of the versatile face mill for hole making.