PDA

View Full Version : Standard woodworking router bits for Mill?



Russ Kaiser
12-23-2010, 11:05 AM
I am just getting started and need to buy tooling for 3D wood carving. My mill will only be able to handle feed rates up to 80 IPM and my top spindle speed is 4500 RPM until I work on making a router or high speed spindle attachment.

I will not be cutting out parts, rather carving curved pieces of solid hardwood, no MDF, no plywood. My question is will router bits designed for a hand router survive in my CNC world with my current speed limitations?

Specifically, can I substitute a core box or round nose carbide tipped router bit instead of a solid carbide round nose mill? If so, my tooling costs can be reduced.

The finishing pass programs I have been creating will be taking shallow cuts but will run in excess of 1 hour. I would really like to hear from someone with some experience with longer wood cutting jobs like this.

Thanks,

Russ

ger21
12-23-2010, 11:44 AM
The rpm may be an issue, but I'd recommend trying it. You'll probably need to lower the feedrate to compensate for the lower rpm.
I use core box bits on a $100K router all the time. They work fine. But they're not designed for 4500 rpm, so I'm not sure what the cut quality will be like.

Russ Kaiser
12-23-2010, 11:59 AM
Thanks for responding Gerry.

The 80 IPM is a max, I am certainly willing to slow down.

In regards to slowing down, I have been looking at a bunch of threads, getting bits and pieces here and there, but getting lost at the same time. I think in one thread you mentioned an "optimum bite range" for lack of a better phrase when machining wood.

That figure could be used for calculating a feed rate for a given spindle speed and a given number of flutes. For the last few minutes I have been trying to find my way back to that information. Can you help?

Russ

ger21
12-23-2010, 12:09 PM
Chip load, but it's specific to each individual tool, and even diameter. I'd just crank it up to 4500 rpm, start at 30-40ipm, and increase feedrate until quality starts to decrease.

Russ Kaiser
12-23-2010, 02:49 PM
Gerry,

As for ball mill or router bit diameter, I am assuming that a better finish is going to be achieved with the largest bit that will fit the geometry of what I am carving out. Unfortunately the shape is somewhat complex.

This is the top profile of what I am cutting. This will be two-sided milling.


http://salemband.org/images/worm1.jpg

This is about 19 inches X, 4 inches Y, and 1.5 inches Z

ger21
12-23-2010, 06:01 PM
I am assuming that a better finish is going to be achieved with the largest bit that will fit the geometry of what I am carving out.

Yes and no. You can get a better finish with a larger stepover, resulting in much faster cut times. However, you can also get a glass smooth finish with a 1/16" dia. bit, if you use a small enough stepover. I use a 1/16" bit with a .005 stepover and get really good results. But you'll need a larger bit to get deeper.