[MFchief]

Hi All,

I know this is a little off topic, but kind of generic, so here goes.

Does anyone have any knowledge of how CAM packages choose the order of making cuts? I don't mean the order of operations, that's determined by the way you set up the various operations. I mean inside of a particular tool path. Yesterday I did some engraving using Vcarve Pro, it was 5 lines of text on a small piece of brass, and I was struck by the odd way it chose to do the letters. For example, it did the bottom edge of the first two letters on the last line, then jumped up a line and did a few letters, but after that it was all over the map. It cut the last letter of the first line last, after everything else was done.

Now I'm not actually complaining, it did exactly what I asked it to do, and everything came out fine, it was just odd watching it do the job, and it's not unique to Vcarve, I see the same behavior in Sprut and HSM.

If anyone has a idea how this is planned, or knows of a reference that explains it, I'd love to hear about it.

Terry

[popspipes]

Terry,

I am only familiar with Sprut but there is an option in some of the ops to select how the selected items are machined called "optimal" or by "list", I use the list function for my parts as I like all of them machined the same way to kind of get around the backlash in the machine.

How some of the machining ops could be optimal makes a guy wonder sometimes how that could be the case??

I also use the transform function for multiple parts, that assures that it machines the same way for each part I believe.

[MFchief]

Hi Mike,

I'm not really looking to optimize or anything, most of my stuff is one-off, so time isn't often an issue, just curious how the heck they come up with the patterns.

You might have seen the post I put up recently about Fusion 360, with a jpg of the tool path it calculated in HSM, what the heck is that. LOL The semicircle was made by trimming a circle, so I have no clue why it decided to cut it in 2 quarter circles.

[popspipes]

I saw that post,

In Sprut if you have curve segments or edges, I just select one of them then hold shift and double click (2d contour op), that will select the whole curve "usually" ha.........
I am just a hobbyist as well and make short runs of various small parts, I usually machine 4 or 5 parts at a time out of a single piece of stock, so I have gotten pretty good with the transform function .......This eliminates the jumping around and machines as selected.

Sprut has a mind of its own sometimes thats for sure.

At my age I dont think I will try to learn another cad cam package but the F360 looks good as the cam is incorporated into it.

[MFchief]

Yes, very similar steps, after some help on the forum, I was able to select the arc section, but it selected as one semicircle, not half's, still resulted in the tool path shown ???

I'm liking fusion, I believe it, with the HSM CAM, is easier to use than Sprut, but that may just be me. I probably wouldn't have started using it, except it's free for hobbyist, at least so far. But I'm a spring chicken (69), so lots of time to learn. Lol

Terry

[Tormachmaster]

Have you thought of using another cad cam package? There are a lot out there some not too expensive depending on what you are doing maybe a simple 3 axis cam package would work. What type of work are you doing?

[popspipes]

Yes, very similar steps, after some help on the forum, I was able to select the arc section, but it selected as one semicircle, not half's, still resulted in the tool path shown ???

I'm liking fusion, I believe it, with the HSM CAM, is easier to use than Sprut, but that may just be me. I probably wouldn't have started using it, except it's free for hobbyist, at least so far. But I'm a spring chicken (69), so lots of time to learn. Lol

Terry

I was curious so I downloaded the free trial, the first thing it says is I need to up date my video drivers. I tried to import an .igs file to check out the cam, there is a semblance of the file, so I guess the video driver is maybe the hangup or at least part of it. It may not like my igs files either as they were created in Rhino.
I will play with it for awhile as the price was right..........

Just a spring chicken here too, 76 and hopefully a few good years left...........

[SCzEngrgGroup]

Hi All,

I know this is a little off topic, but kind of generic, so here goes.

Does anyone have any knowledge of how CAM packages choose the order of making cuts? I don't mean the order of operations, that's determined by the way you set up the various operations. I mean inside of a particular tool path. Yesterday I did some engraving using Vcarve Pro, it was 5 lines of text on a small piece of brass, and I was struck by the odd way it chose to do the letters. For example, it did the bottom edge of the first two letters on the last line, then jumped up a line and did a few letters, but after that it was all over the map. It cut the last letter of the first line last, after everything else was done.

Now I'm not actually complaining, it did exactly what I asked it to do, and everything came out fine, it was just odd watching it do the job, and it's not unique to Vcarve, I see the same behavior in Sprut and HSM.

If anyone has a idea how this is planned, or knows of a reference that explains it, I'd love to hear about it.

Terry

There is no single answer to that question - each CAM package has its own algorithms, and they're all different. There are countless different ways of doing it, each with its own strengths and weaknesses.

Regards,
Ray L.

[bevinp]

Yes, very similar steps, after some help on the forum, I was able to select the arc section, but it selected as one semicircle, not half's, still resulted in the tool path shown ???

I'm liking fusion, I believe it, with the HSM CAM, is easier to use than Sprut, but that may just be me. I probably wouldn't have started using it, except it's free for hobbyist, at least so far. But I'm a spring chicken (69), so lots of time to learn. Lol

Terry

MFchief,
I beat you, I'm 71 and still learning. I wonder about you saying you're a Spring Chicken... maybe that's a sign of... I know I want to say but I can't remember what it's called..
Bevin

[Routerfiend]

Hi
And who knows why it chooses the path it does ?? I use alphacam and the way it chooses the order of things if left to it`s own devices is a mystery to me ,even after 15 years of use ?? If my OCD kicks in I can set the order either by geometry or by toolpath or another option is to pick each letter as a separate operation. It bugged me for ever watching the gantry track 8ft to carve the smallest cut but there are ways around almost everything.

[mountaindew]

There is no single answer to that question - each CAM package has its own algorithms, and they're all different. There are countless different ways of doing it, each with its own strengths and weaknesses.

Regards,
Ray L.

And don't forget the hundreds of settings that can be changed and many effect how those countless different algorithms generate tool paths. I use sprutcam "Russian" and like others mentioned its hard to get exactly what you want unless you do mostly 2d type operations. These are easy to set edged, depth and direction for tool and generate paths they look much like you would expect. Use a 3d type operation and tool paths are all over the place and many times baffling why it does what it does. I don't do production so this is no big deal and its even fun to see just what it does generate. Could be frustrating if your doing production cam and parts.

[Spinnetti]

I find paths from various cam to be bizzare too. The "easy" answer is to just code it yourself. For non-3D stuff you can often get more efficient results anyway, and have it cut just what you expect. I typically run stuff through CAM, then hand edit out the dumbness, giving best of both worlds (for me anyway).

[MFchief]

I think the consensus is it's a great flamin' mystery and we will probably never know! Lol
Bevin, you're on to me.....

Terry

[shred]

FWIW, Optimal tool paths for non-simple things turn into a "Travelling Salesman" NP-hard problem, so the software has to pick something "close enough" and go with it (some form of closed-chains first, or longest-cuts first or nearest-neighbor and so on). The more expensive software spends more money on algorithms for various cases and conditions.