Feeds and speeds for very small Router bits

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WallyM
Posts: 4
Joined: Mon Apr 15, 2013 10:26 am

Feeds and speeds for very small Router bits

Post by WallyM »

Recently I purchased some very small bits for my Shark 2.0 HD from Rockler, I called Rockler Customer Service to get some idea of factory recommended feeds and RPM but they were of no help.
I realized that these bits (0.25mm and 0.5mm) resembled dental drills, and dental drills run 250,000 to 420,000 RPM !!!
I want to use these bits for a very fine detail on Basswood and Oak.
I found one website, toolstoday.com and using their calculations for wood and Solid Carbite bits I'm getting unrealistically high RPMs.
For example, 1/32" or 0.313" comes to 262,140 RPM
I sure could use some help understanding this.
What is the proper RPM and Feed rate to enter in the Tool Database for use with these tiny router bits ?, please help.

Danwood
Posts: 44
Joined: Sun Nov 17, 2013 9:46 am

Re: Feeds and speeds for very small Router bits

Post by Danwood »

Cutting wood with small bits is a balancing act.
If your machine travel is to slow the bit will burn the wood and if it is too fast your cut will not be clean and you risk breaking the bit.
There are chip loading charts such as found here. http://robbjack.com/technical/formulas.
these are designed mostly for metal cutting.

Select a pattern you want to cut.
Here is what I recommend set your router to turn at it's maxim RPM.
Start with a shallow depth cut and a slow feed rate.
Make few passes and examine the results.
Gradually increase the feed rate until the results are satisfactory to you.
Good Luck
Danwood

WallyM
Posts: 4
Joined: Mon Apr 15, 2013 10:26 am

Re: Feeds and speeds for very small Router bits

Post by WallyM »

Thank you Danwood,
That's the kind of practical info that I was looking for.
WM

Danwood
Posts: 44
Joined: Sun Nov 17, 2013 9:46 am

Re: Feeds and speeds for very small Router bits

Post by Danwood »

SOME FURTHER THOUGHTS ON RELIEF CARVING.
The configuration of the project you are carving has a lot to do with how you set up and run your program.
I do a lot of relief carving on cabinet doors. The usual configuration is a some animal or flowers placed in a recessed dish.
I use Aspire software so I can control all the configuration variables. The recess is usually a circle or oval with sloping sides and relatively flat bottom. the 3D art work is then placed in the dish and adjusted for depth (relief) and position.
Most of my carvings are done with a 0.125 ball nose cutter with a 1.0 inch Length of cut and 10% step over. This allows me to cut the job in one run If the job is 1.0 inch or shallower. I do not have to do a roughing out cut with a larger bit.
The first pass is always on the edge of the recess and is about 0.5 long and 0.01 deep. With a 10% step over the cut is only 0.0125 wide on each cut allowing me to run at 100 IPM for the whole job.
A word of caution, If for some reason your first cut is very deep it is wise to edit the program so the first cut is at a slower feed rate.
50 IPM usually works for me.
Attachments
Grapes on panel.JPG

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