Best practices for cutter definitions in MeshCAM

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I picked up a 1/64" end mill from McMaster (http://www.mcmaster.com/#3066a53/=vcau4n) for doing some fine finishing work on molds for resin casting (gears and such).

I used the information from that McMaster page to populate the values in the MeshCAM tool editor like this:

I am assuming that length of cut should correspond to flute length and that helix angle is the same as taper angle?

What are the rules of thumb for figuring out appropriate spindle speeds? Is it based on the material of the tool only (this is a carbide endmill)? Something else?

What about the default feedrates, plunge, stepover, and depth per pass? Are there good rules of thumb for these values based on cutter dimensions? Does anyone have a handy reference?

When I tried to use the tool definition above, I ran into a bug in MeshCAM:

Assertion failed: (“ERROR in drop_cutter() Flute Length <= 0” && 0), function drop_cutter, file /Users/robert/projects/meshcamapp/libs/camlib/src/cl.cpp, line 496.

Robert, did I do something wrong, or am beyond a typical use case with a cutter this small?

-James

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The Shapeoko community has tried to gather together all the information on this sort of thing which we can find, and share values on the wiki:

http://www.shapeoko.com/wiki/index.php/Materials

You might find some of the reference material of interest and helpful in informing your populating that dialog.

While they (Nomad883 and Shapeoko) are different machines, the underlying principles are similar, and it would be nice if we could add to that all the values for feeds and speeds which have thus far been worked up for the Nomad.

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That’s a great resource. Thanks, Will!

@robgrz any thoughts on the assertion issue (led to a hard crash, and I haven’t been able to generate gcode with these cutter settings)?

-James

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Hey Mitchell-

The assertion shouldn’t be there so I’ll look into that.

For the taper angle, you should leave that at 0 for your cutter. The taper angle is used for cutters that have an overall “V” shape like this:

The rest of the dimensions look good and should be fine if that taper angle is 0.

-Rob

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Sounds good, Rob. What’s the process for getting updates? Will you just release a new beta build on the main MeshCAM site and let us know?

-James

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MeshCAM will check for updates every 10 runs or you can run the Help->Check for Updates command.

-Rob

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Thanks, Rob. Have you had a chance to look into that assertion error and produce a build? I’m excited to try milling some really small gears.

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@robgrz - any ETA on a new MeshCAM build addressing that assertion bug?