2

I have a drill press with variable speed adjustment. It is provided with a graph showing the maximum rotation speed for aluminium and steel based on drilling diameter. I can get the wood graph by guessing.

I remember that sometimes old belt-driven drill presses were left on the slowest speed (which brings the maximum torque), and that was it.

Obviously faster rotation corresponds to faster drilling. Assuming I'm not in a hurry, when should I aim at the fastest I can get, and when should I reduce it? what are the disadvantages of either choice?

Improve this question
1
  • "I can get the wood graph by guessing." Well, as you've gotten a peek at already below, there sort of isn't one for wood since in practice you can drill practically everything at the one speed you set the press at and generally not notice any issues. Certainly you won't typically experience any scorching at the low / medium speed that most presses are left at! The published numbers are a guide only, and really geared more towards a production environment than a typical weekend warrior. And if you think about it those speeds are all essentially irrelevant WRT hand-drilling holes. – Graphus Sep 28 '20 at 23:33
3

Optimal drill speed involves maximizing how fast you can drill through a substance while getting a smooth hole and not damaging the drill bit by over heating. The correct speed will allow the drill bit to cut the material without getting too hot. Too slow will "chew" or tear the material. Too fast will cause excessive heat. Spade bits are especially problematic if run too slow.

The best rotational speed depends on the type of drill bit and the material being drilled through.

As a general rule:

  • The larger the drill bit diameter the slower the speed.
  • The harder the material being drilled the slower the speed.

Here is a chart for a twist drill bit:
enter image description here

Note: Hardwood ratings are for hardwood species with a Janka number below 1500. For hardwoods with a Janka number above 1500 use slower speeds.

Renovation Headquarters

There are other tables for other drill bit types at the link above.
You can find a variety of tables with similar information at other sites.

If you are drilling at a recommended speed and find that things aren't working well you may need to do some experimenting to arrive at the best speed for your situation.

Speed charts assume that you have a sharp drill bit.

Improve this answer
8
  • My question "assuming I'm not in a hurry, when should I aim at the fastest I can get, and when should I reduce it?" is not clearly answered, or the answer is hidden. So you are saying that if I reduce the speed the hole won't be as smooth? in other words, lower speeds have disadvantage? I know about drilling speed tables, it's not clear to me whether they are for "max speed" or for "optimal speed". – FarO Sep 28 '20 at 16:08
  • @FarO Thanks for clarifying. I have edited my answer to add: The correct speed will allow the drill bit to cut the material without getting too hot. Too slow will "chew" or tear the material. Too fast will cause excessive heat. – David D Sep 28 '20 at 16:45
  • Interesting. I've got a full speed chart label inside the top of my drill press. I think I adjusted it once or twice when I first got it, but it's been set on its lowest speed (~650 RPM) ever since and I've used bits from 1/16" to 2" through pine, aluminum and steel and never changed it. I've never experienced (to my recollection) any tearing in wood with any bit size. I know I should change the belt, but... lazy and it works... – FreeMan Sep 28 '20 at 17:07
  • 1
    @FreeMan I'm a big fan of doing what works. – David D Sep 28 '20 at 17:09
  • 2
    The problem with drilling too slow is that to maintain a clean cut you would also have to correspondingly slow the feed rate, and with manually controlled tools this is basically impossible. The factor that determines how clean the hole will be is how much material you're removing with each pass. Like most of woodworking, the less you remove with each pass the cleaner your result will be. When a bit is spinning fast each pass removes a very small amount of material. – SaSSafraS1232 Sep 28 '20 at 17:36

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.