Can MeshCAM be made to do roughing and finishing Waterline passes?

[MrHume (Joshua Hume)]

I have another thread about how to do this in Carbide Create, but I think I might need the added control MeshCAM gives one over climb vs conventional milling. I’m making round picture frames out of wood. They are extremely simple, as you can see below. Using G-wizard and Carbide Create, I have a pretty good cutting program for them, but it’s leaving a LOT of tear-out on certain parts of the frames, because, you know, wood sucks.

I think the solution is to do a roughing pass, and then a finish pass where I use climb cutting. I know CC can be made to do the roughing vs finishing paths, but I don’t seem to be able to set climb vs conventional.

I don’t want to use MeshCAM’s regular 3d roughing, as it will make a way bigger hole than is necessary and take a great deal longer than I’d like. So is there some way to make it run several Waterline passes, leaving a larger margin the first time and then cutting to size the second?

I know I’ll have to make multiple jobs, which is fine, but how do I make it leave material when I do the first Waterline “roughing” pass?

Also, any general advice for achieving the best possible finish on vertical surfaces? Especially as it pertains to wood? I know normally you want to go in the direction of the grain, but as you can see below that’s not really possible for the full circle. Any thoughts?

Note that in these shots the frame is face down, so you can see the rabbet that holds the artwork.

[Randy (Randy Gordon-Gilmore)]

@MrHume, first of all MeshCAM won’t take the cutter centerline out of the defined stock, so you need to make your stock at least a cutter radius larger on all sides of your geometry.

There is no reason that roughing needs to make a kerf much larger than the cutter diameter. You generally want a little more kerf to clear chips. But under Global Paramaters set Machine geometry only. Under Roughing make sure Use parallel roughing is unchecked, and set a little stock to leave. Back up in Global Parameters set the Machining margin to (your cutter radius plus the stock to leave) times 1.1. Use a close tolerance–I always use .0001" for actual toolpaths.

You should get a roughing kerf on the inside and outside of the part just a little larger than your cutter, and there will be just a little material left for your finishing pass.

But to directly answer your question, no, the only way to use multiple waterline passes is to lie to MC about the cutter size so it thinks the cutter is a little larger than it really is. That has been discussed on the MeshCAM forum, always a good resource.

Randy