I am trying to understand a little better, how to drill stuff with
CNC.

My current approach amounts to "winging it" and deciding something
like "it oughta be good enough at 2 IPM".

Well, I think that I can do better than that.

I looked and have not found a decent drilling calculator.

My feeling is that the drilling feed rate in any given material is
calculated as inches per revolution, and IPR is proportional to drill
diameter.

Does anyone know of some good tables for this sort of thing?


i

On Fri, 15 Apr 2011 19:25:08 -0500, the renowned Ignoramus1116
wrote:

I am trying to understand a little better, how to drill stuff with
CNC.

My current approach amounts to "winging it" and deciding something
like "it oughta be good enough at 2 IPM".

Well, I think that I can do better than that.

I looked and have not found a decent drilling calculator.

My feeling is that the drilling feed rate in any given material is
calculated as inches per revolution, and IPR is proportional to drill
diameter.

Other way 'round. You start with the recommended speed in SFM (surface
feet per minute at the drill diameter) to get the RPM, then the feed
drops out from the inches per revolution feed rate.

Does anyone know of some good tables for this sort of thing?


i

Here's one, but there are lots:-
http://vikingdrill.com/Feed_Speed_Face.html (HSS)




Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

On Fri, 15 Apr 2011 19:25:08 -0500, Ignoramus1116
wrote:

I am trying to understand a little better, how to drill stuff with
CNC.

My current approach amounts to "winging it" and deciding something
like "it oughta be good enough at 2 IPM".

Well, I think that I can do better than that.

I looked and have not found a decent drilling calculator.

My feeling is that the drilling feed rate in any given material is
calculated as inches per revolution, and IPR is proportional to drill
diameter.

Does anyone know of some good tables for this sort of thing?

http://goo.gl/YoYyW Hey, wait a minute. That's not a table. It's a
sideboard, and I think it wasn't wearing protection when it went into
that House of Ill Repute.

--
Some people hear voices. Some see invisible people.
Others have no imagination whatsoever.

"Ignoramus1116" wrote in message
...
I am trying to understand a little better, how to drill stuff with
CNC.

My current approach amounts to "winging it" and deciding something
like "it oughta be good enough at 2 IPM".

Well, I think that I can do better than that.

I looked and have not found a decent drilling calculator.

My feeling is that the drilling feed rate in any given material is
calculated as inches per revolution, and IPR is proportional to drill
diameter.

Does anyone know of some good tables for this sort of thing?


i

I go by looks. As long as I'm getting nice looking chips or spirals without
a lot of coloration indicating high temperature, I'll settle for a speed
that cuts and doesn't have me changing bits frequently.

On 2011-04-16, Steve B wrote:

"Ignoramus1116" wrote in message
...
I am trying to understand a little better, how to drill stuff with
CNC.

My current approach amounts to "winging it" and deciding something
like "it oughta be good enough at 2 IPM".

Well, I think that I can do better than that.

I looked and have not found a decent drilling calculator.

My feeling is that the drilling feed rate in any given material is
calculated as inches per revolution, and IPR is proportional to drill
diameter.

Does anyone know of some good tables for this sort of thing?


i

I go by looks. As long as I'm getting nice looking chips or spirals without
a lot of coloration indicating high temperature, I'll settle for a speed
that cuts and doesn't have me changing bits frequently.




I sort of do the same thing, too. With a manual mill, the operator is
pushing on the quill by hand and the feedrate is easy to change. With
a CNC, the rate is in the program. It may be easier to break the drill
in case of a mistake.

i

Ignoramus1116 wrote:

On 2011-04-16, Steve B wrote:

"Ignoramus1116" wrote in message
...
I am trying to understand a little better, how to drill stuff with
CNC.

My current approach amounts to "winging it" and deciding something
like "it oughta be good enough at 2 IPM".

Well, I think that I can do better than that.

I looked and have not found a decent drilling calculator.

My feeling is that the drilling feed rate in any given material is
calculated as inches per revolution, and IPR is proportional to drill
diameter.

Does anyone know of some good tables for this sort of thing?


i

I go by looks. As long as I'm getting nice looking chips or spirals without
a lot of coloration indicating high temperature, I'll settle for a speed
that cuts and doesn't have me changing bits frequently.




I sort of do the same thing, too. With a manual mill, the operator is
pushing on the quill by hand and the feedrate is easy to change. With
a CNC, the rate is in the program. It may be easier to break the drill
in case of a mistake.

This is why essentially all commercial CNC controls have nice simple
override knobs for feed rate and usually spindle RPM, so the operator
can readily fine tune the operation to match the actual cutting
conditions interactively without having to recode the program.

"Ignoramus1116" wrote in message
...
I am trying to understand a little better, how to drill stuff with
CNC.

My current approach amounts to "winging it" and deciding something
like "it oughta be good enough at 2 IPM".

Well, I think that I can do better than that.

I looked and have not found a decent drilling calculator.

My feeling is that the drilling feed rate in any given material is
calculated as inches per revolution, and IPR is proportional to drill
diameter.

Does anyone know of some good tables for this sort of thing?


2% dia per rev

--

On 2011-04-16, PrecisionmachinisT wrote:

"Ignoramus1116" wrote in message
...
I am trying to understand a little better, how to drill stuff with
CNC.

My current approach amounts to "winging it" and deciding something
like "it oughta be good enough at 2 IPM".

Well, I think that I can do better than that.

I looked and have not found a decent drilling calculator.

My feeling is that the drilling feed rate in any given material is
calculated as inches per revolution, and IPR is proportional to drill
diameter.

Does anyone know of some good tables for this sort of thing?


2% dia per rev

--



That seems easy enough! I can remember that. Thanks

i