Importance of Using Correct Drill Speed

[LCHIEN]

Posted a while back, reposted by request.

(see attached pic, click it to enlarge)

These are like 1/4 or 3/8" bit drilled through 3/4 whitewood pine.
Numbers are RPMs. Cut the piece in half after drilling on a D.P.
Looks like the slow speed tears the wood and the higher speeds cut the wood.
Conclusion is to look up and set the correct speed each time I change bits and or wood.

Here's a chart of recommended speeds for different bit types and materials, from Wood Magazine:
www.ibiblio.org/twa/info/drillSpeedChart.pdf

[Stan]

Excellent 'visualization' of the effects of different speeds. Did you notice any difference with the bits ability to clear itself at the different speed settings?

[Tom Miller]

Loring,

Did you make a note of the quill advance rate, or at least try to keep it constant for each hole? I would think that would make a big difference.

It'd be interesting to compare the 3100 rpm and 620 rpm, but with 1/5 the advance rate for the 620 rpm.

Great pic, and info, BTW!

Regards,
Tom

[JR]

Good one, Loring. I'd bet you'd get a reverse picture if the material were steel. But then again, what I don't know about operating a drill press would fill a book.

JR

[Jim Boyd]

I don't remember the last time I changed speeds on my drill press.

[leehljp]

Jim,

In the past I only used one drill speed most of the time, but after Loring's picts a couple of years ago and a recent note on a pen turning forum about the correct speed causes better ejection of the chips, (as compared to a slower speed) I started changing speeds with the need.

With pen turning blanks on some rare woods and woods with that crack with heat, I used to go slow to keep the heat down. But realizing that the flutes clog up easily and knowing that sometimes the slow speeds do cause what Loring's slow speed pict shows, I figured I needed to make some adjustments.

Slow speeds catch and tear more and I think that is what causes "blowouts" on some pen blanks.

[LCHIEN]

there's been a couple of comments about feed rate.
It was a while back but I'm sure I fed at an appropriate rate, that is, not so fast as to bog down the drill but fast as it would comfortably feed. That probably means I fed a bit faster at the higher RPM rates. If it loaded up with chips I would raise the bit to clear them but I don't think in this case it did.

Basically I ran the test trying to optimize cutting in the best way I knew how given the characteristics at that speed. So whatever the feed rate, it's what felt right at the time, how I would have done it making a hole for any other reason other than a speed test.
Therefore the results are what I would get if I set that speed and tried to drill a hole.

So the test is realistic in that I drill better holes, given my normal drilling habits, at the correct speed (which is 3000 RPM incidentally, for that combination of bit and wood).

P.S. If you feed too slow with a high RPM, you can burn the wood, just like going too slow with a saw or Router.

[Jim Boyd]

Jim,

In the past I only used one drill speed most of the time, but after Loring's picts a couple of years ago and a recent note on a pen turning forum about the correct speed causes better ejection of the chips, (as compared to a slower speed) I started changing speeds with the need.

With pen turning blanks on some rare woods and woods with that crack with heat, I used to go slow to keep the heat down. But realizing that the flutes clog up easily and knowing that sometimes the slow speeds do cause what Loring's slow speed pict shows, I figured I needed to make some adjustments.

Slow speeds catch and tear more and I think that is what causes "blowouts" on some pen blanks.

Hank, I never said the speed was slow. Just that I never change it Maybe I will with snakewood

[LCHIEN]

more than one speed?

It's officially not funny. I'll bet there are some people who don't know you can change the speed of a drill press... and even more who don't know how.

maybe the topic of my next poll...

At least I've demonstrated I'm not one of them!

[leehljp]

Hank, I never said the speed was slow. Just that I never change it Maybe I will with snakewood

I was wondering if you were going to use the same "generic" speed on "snakewood". Are you getting a little "unsure" of yourself? Paranoia with all the snakewood cracking setting in?

I hear some people are puttin' a lot pressure on you with that snakewood. You better come through. From what I hear of how fragile that wood is - maybe use a glass cuttin bit and some oil will help prevent the cracking.

[Raymonator]

Great illustration, and I will definitely make note of this thread. I know I can change the speed of my DP by using different pully's, I'll have to take a look as see what rpm I'm set at. Thanks, this has been very informative.

[LCHIEN]

Everyone with a drill press should read this. So, ba-buuuump!

[cgallery]

A very good PSA (Public Service Announcement).

I'm lucky because my Ryobi drill press has a continuously variable speed. And a speed chart for different bit sizes and materials printed right on front.

[ragswl4]

Everyone with a drill press should read this. So, ba-buuuump!

Absolutely correct, I did, I printed out the PDF chart and most of all Thanks for posting, great information that was missing from my limited knowledge. That's what so great about this forum. It's my woodworking college.

[gwyneth]

The inside of the lid on many Deltas (and possibly other brands) has a chart that shows which pulleys make which speed.

Anybody who still needs to be convinced should reflect on the fact that the most efficient way to start a fire without matches or magnifying glass is a fire-drill.