Lazy Cam and Involute Gear Generator

[John Tribe]

Originally Posted by Alonzo Hello John I am trying to learn to build wooden geared clocks. I have the gear g code generator you mentioned and a trial version of mach3. The smallest router bit I can find is 1/8 inch. Every gear I enter in involute ,the program tells me the cutter is to big. I have not been able to figure out if the information I give the program is wrong or if there is a work around some where. Can you tell me how you would cut a gear with-# of teeth=10,Diametral Pitch=11,Pitch Circle= 23.09,Base Diameter=22.35,Outside Diameter=27.71,Root Diameter=17.55,Tooth Thickness=3.2,Face Rad=5.0. Any help would be much appreciated. Thanks Alonzo

Hi Alonzo,
I fed your parameters into my gear generator and you're absolutely right using a 1/8" bit to cut a 1" gear will give a problem. The root of the gear would be undercut however if that's the smallest bit you have and the stress on the pinion isn't too great then you could cut the pinion and it would work because there is no contact at the root of the gear. Having said that there are other options:
I don't normally use "router" bits I use drill bits since my cut per pass is usually around the 0.07 " cuts. There is a huge supply of micro bits at

Metric Drill Bits Resharpened 5 Pack

So I will search for the bit size I want at:

drill bit, drill bits,shop tool, drill bits,carbide drill bits, pcb drill bit, pcb drill bits, optical drill bits,small diameter drill bits, High Speed drill bits,carbide router bits,carbide end mills, PCB carbide drill bits, CNC drill bit, hobby too

the big advantage is that these are the cheapest that I have found and you can get "resharpened" ones further reducing the price. I usually buy in quantity (10 to 50) because at the small diameters they do break easily. I try a 1.95 mm bit first on the design because this is a fairly strong size.
or

Microcut Carbide Micro End Mills

these are really good bits and available in the sizes I want however they are more expensive sometimes as much as 10 times - but if that is the only one I can find i'll get a couple.
or finally

Engraving Cutters | End Mills | Tools for Milling Wax

These bits are more aimed at engraving which I also do some. They also have nice round end bits that are great for 2.5 D carving (bass relief)

If you are new to all this I would recommend starting at
Metric Drill Bits Resharpened 5 Pack
since breaking bits won't break the bank. The rule for me is take shallow cuts and go fast enough not to burn the material.

Hope this helps a little
John
You can't fail as long as you keep trying!