Trick I figure out today!

I have a 3-axis machine, but often want to make cylindrical objects. So, I cut half of it, then flip it and cut the other half. Using the planar finishing toolpath I get rough spots at the lower edges. Using Z Level Finish I get roughness at the top of the object. Here I am making a tool handle. I chose to do a planar finish first, then a Z Level Finish for the bottom few mm. It was easy to select a height range for the Z Level Finish, but when I tried to reduce the depth of the Planar toolpath things went awry. So, I just let it cut to the full depth. I also wonder why I have a lot of unnecessary paths in the planar run, which I don't usually encounter. A lot of cutting in air, but it works. This is v27. Maybe some of this is no longer a problem in newer versions?

Dang Lathe works great,,just sayin

Other than that,,,if the part is small,,put the part in the tool changer and the cutter in the vice,,,,,and think backwards inside out,,,,no kidding

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Originally Posted by jrmach

Dang Lathe works great,,just sayin

Other than that,,,if the part is small,,put the part in the tool changer and the cutter in the vice,,,,,and think backwards inside out,,,,no kidding

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Ha! That's a good idea, but my collet is 7mm max and the handle is 28Dx100mm. I do turn wood on my machine lathe, but I find scraping a contour into hardwood quite time consuming. I also work with bamboo plywood, and that stuff is very difficult to turn. What I do is cut half of the surface, then reverse it in the drawing and mill a depression into a block, then tape the cut side into the depression and carve the other side. Works really well, although much slower than if I had a cnc lathe.

Robobass;
Two thoughts here:

You could use a manual rotary indexer and tail stock while still using a 3 axis mill and 3 axis software.

Also, not clear from your post, but you can use the planar tool path near what you call the top of the part, and use Z level finish for the bottom few mm's. Yes, there can be issues with the tool path seeming to try to cut both sides of the surface, so you have to be careful with which surfaces you select, or use a boundary/ depth of cut to exclude the path from trying to get to the other side of the surface.

Good luck.

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Originally Posted by ShortTrack

Robobass;
Two thoughts here:

You could use a manual rotary indexer and tail stock while still using a 3 axis mill and 3 axis software.

you can use the planar tool path near what you call the top of the part, and use Z level finish for the bottom few mm's.

Good luck.

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I do plan on grabbing an indexer. A lot of the parts I make would still need the trough approach, though, and it's a gantry router without a terrible amount of Z height.

Yes, Planar on top and Z-Level-Finish on the bottom is what just I figured out and thought I was so clever. I was having trouble setting the Z range on the planar path, but finally got it worked out. I'm still having trouble with the planar sometimes cutting in air though. Not understanding that the roughing pass has already removed the material. Maybe I have to import a STL file for the stock.

Robobass;

Yes, Z axis height can be a problem. I know several folks that mount an indexer IN the router table to allow for clearance. Re STL file to stop cutting air: There is a tutorial out there somewhere that shows how to 1) use one tool path then 2) save the cut stock as an STL, 3) import that STL as NEW stock, use a second tool path, then 4) save that cut stock as an STL, then continue... This stops some versions/ strategies in BBCD from cutting so much "air". I have been known to cut a lot of air as the methodology I just described is itself consuming time, and more difficult to modify/ understand if you ever need to change the model, etc.

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Originally Posted by ShortTrack

Robobass;

Yes, Z axis height can be a problem. I know several folks that mount an indexer IN the router table to allow for clearance. Re STL file to stop cutting air: There is a tutorial out there somewhere that shows how to 1) use one tool path then 2) save the cut stock as an STL, 3) import that STL as NEW stock, use a second tool path, then 4) save that cut stock as an STL, then continue... This stops some versions/ strategies in BBCD from cutting so much "air". I have been known to cut a lot of air as the methodology I just described is itself consuming time, and more difficult to modify/ understand if you ever need to change the model, etc.

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Yes on both counts. 1. My table is MDF anyway, so no big sad cutting a hole in it. 2. I have so much finishing work in my operation that there isn't normally a queue of jobs waiting to get on the machine, so cutting some air doesn't cost anything. And, right about overcomplicating the drawing/CAM file.I sometimes come back to a part I did a half year ago and lose an hour trying to figure out what the heck I did!

I'd do that kind of shape using the equidistant command, should give a constant stepover regardless the angle of the wall. Just set it top to bottom and make sure the bottom of the job is the bottom plus the radius of the cutter.

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Originally Posted by shaunwil

I'd do that kind of shape using the equidistant command, should give a constant stepover regardless the angle of the wall. Just set it top to bottom and make sure the bottom of the job is the bottom plus the radius of the cutter.

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Ah! That's perfect! Wish I had tried that before. I haven't explored the "Pro" toolpaths much.

Doesn't always work as a faster option than the planer option. It does give a constant cut though.