Restmill and Leftover toolpath

[jcnewbie]

What is the difference between the surface rough restmill toolpath and the surface finish leftover toolpath ? Don't they both clean up material left from previous operations, so why have 2 operations that do the same thing ?

[thebowman]

I'm by no means an expert in surfacing toolpath. Both of these toolpaths are the older style surfacing toolpaths and from the little experimenting I've done Surface Finish Leftover takes much longer to calculate than Surface Rough Rest.

[Matt Berube]

Surface Rough Restmill will pocket away all remaining material making as many "stepovers" as necessary to get all the stock out.

Surface Finish Leftover will only finish the outer edges of the piece and does not add "stepovers" to the toolpath.

I still use Surf Rough Restmill at times but the Leftover path is something I don't use much at all anymore. The newer High-Speed toolpaths are more efficient especially now that we have Multi-Threading to get those toolpaths crunched with incredible speed.

[thebowman]

Here is a file I just did that contains the Surface Finish Leftover toolpath. The Surface Finish Leftover toolpath certainly appears to "stepover" to me and in this file it's used to clean up the fillets which are not on the outer edges of the part. This file is from a tutorial I worked though and it appears the part came out pretty decent to me. Since I do almost no surface toolpathing, I'm sure it can be improved. I'd love to see someone do this file with the new style of surfacing toolpaths.

[Matt Berube]

I'll comment more on this tomorrow. No HASP at home today.

[Matt Berube]

In your file the surface finish leftover does step over but along the surface being cut.

The way that Surface Rough Restmill differs from this is that restmill will pocket out any remaining stock according to the max stepover/stepdown in your operation's parameters. This effect could be more or less obvious depending upon the size difference between your roughing tool and your rest-roughing tool...

Added operation 5 to your file to demonstrate Surface rough restmill (restricted depths to make processing faster). It's just a quick and dirty toolpath but I think you'll be able to see the multiple passes along the internal radii (similar to "multipasses" in a 2-D contour operation).

That's all I have time for at the moment but perhaps another day I'll make those HS toolpaths you requested.

[thebowman]

Hi Matt,

I appreciate your efforts and your follow through. When I get home from work I look forward to downloading the file and seeing what you came up with to improve what I had.

[thebowman]

Matt,

"Surface Rough Restmill will pocket away all remaining material making as many "stepovers" as necessary to get all the stock out."

Would I be correct in saying the only practical way to machine with the older style toolpaths for most parts is to remove almost all of the material with pocket style, contour style, parallel style and project blend with flowline for very simple surfaces (usually single surfaces)? The rest are only for special cases... scallop, radial, finish leftover?

I got rid of the holes in the part by rolling back the solid. I changed to a 1/4" ball end mill. If what I wrote above is something you agree with then for the first time I see how to machine the fillet radius's on this part so they look good. I was going about it completely wrong if I have what you said right.

"I still use Surf Rough Restmill at times but the Leftover path is something I don't use much at all anymore."

Because it's not efficient and is too slow? It's only practical use is as a last resort for very small amounts of material?

Do you ever use the old Finish Pencil? Do you remove the fillets when you use Finish Pencil and use a sharp corner to drive the tool around?

[Matt Berube]

First let me say that I'll share my opinion about these questions but if you were to ask other MC users the same questions you could get very different answers. It all boils down to user preference.

Would I be correct in saying the only practical way to machine with the older style toolpaths for most parts is to remove almost all of the material with pocket style, contour style, parallel style and project blend with flowline for very simple surfaces (usually single surfaces)? The rest are only for special cases... scallop, radial, finish leftover?

Yeah I suppose you're pretty accurate with that although it really doesn't matter much regarding new toolpaths vs old toolpaths... For me pretty much every part starts with pocketing of some sort...

Because it's not efficient and is too slow? It's only practical use is as a last resort for very small amounts of material? Do you ever use the old Finish Pencil? Do you remove the fillets when you use Finish Pencil and use a sharp corner to drive the tool around?

I don't like the tool motion from the old surface finish leftover and I think I recall that it was difficult to get the toolpath to cut all desired areas. The "rest machining" features available in many of the newer Surface High Speed toolpaths is superior to the old surface finish leftover in many ways... Most notable is the smooth lead-ins and lead-outs and the calculation time is dramatically reduced due to the new multi-threading feature.

I haven't had much use for "pencil" over the years but I have had greater success with the newer one in the limited times I've needed it. The times I've needed pencil I have left the radii intact and configured Mastercam to make multiple passes along the remaining stock of the internal radii areas.