[Shaune]

Ok so I setup a wee engraving job cutting some tracks in some pcb board. It's basically a whole series of parallel small cuts with 1mm between them. When I run the job it cuts one slot then travels back to the other end and cuts the next and so on.

now I will be real happy to hear this is a setup issue but my problem is this. As the small cuts are the same size as the tool it makes no difference which direction you cut in, so why doesn't the toolpath remove all of the travels and cut in both directions. This would cut the machine time in half.

i have looked but cannot see any configurable options that could correct this but would be happy to know there is one


thanks
shaune

[jrmach]

Ok so I setup a wee engraving job cutting some tracks in some pcb board. It's basically a whole series of parallel small cuts with 1mm between them. When I run the job it cuts one slot then travels back to the other end and cuts the next and so on.

now I will be real happy to hear this is a setup issue but my problem is this. As the small cuts are the same size as the tool it makes no difference which direction you cut in, so why doesn't the toolpath remove all of the travels and cut in both directions. This would cut the machine time in half.

i have looked but cannot see any configurable options that could correct this but would be happy to know there is one


thanks
shaune

Use the profile feature for more control.
Can you post a file ? Dummy
It is all about learning the software,no dis-respect intended

[Shaune]

Cheers JR, I should just pm you directly, lol.
i can post a file at the mo, on iPad, don't ask!

to be perfectly honest I should have had the board etched but it's just so much fun cncing stuff. It took around 9 hours to cut, I did BO sides so 18 hours run time, looks fantastic.

i had hoped that bobcad etch would be smart enough to optimise this type of cut by working in any direction.

i will try a profile path as see what happens


thanks

[Shaune]

Ok JR, I just did a test.

With profile I tried all the sorting options x,y and closest. Different tool paths but still the return trip as a travel move.

So I drew a new drawing. The first line I drew from x0 to x50, then went up in the y direction 5 and drew the next line x50 to x0. I then arrayed these lineage so there was a bunch of them all evenly spaced. Now when I use engrave it machines in both directions with just a small travel to jump from line to line in y.
It seems like there is some legacy left from my drawing package (rhino) that means lines have a definite direction in which they were drawn. I have noticed this before, say for example you are drilling a series of holes. No matter what order you select them in or optimise them they will always be drilled in the same order, the order in which they were drawn.

Ok I don't use bobcad for drawing but it's weird how these residual direction properties remain and transfer into bob.

I wonder if anyone else has noticed this? Found a solution?

Shaune

[jrmach]

Mr.Burr can probably answer those questions the best.

When picking your geometry,pick in the order you want (1 at a time,,not window pick)and check the no sorting box.

And of course,no system compensation.

[Shaune]

Yes compensation off.

I picked them with a window as on the actual product there are around 200 lines, on my test dummy I only have 10 us much easier to select one at a time.

Will give it a try later on.


Thanks
Shaune

[BurrMan]

Lines have a direction. That's geometry! Select a line and choose "entity modify" to read it...

Direction can be directed by "shift clicking" in BobCad. But there is also sorting and picking and order in the features...

You will need to do 2 things in BobCad. Shift click all your entities (get to clickin) And then in the Profile feature, there is also a modification for "default chain start point", which if you select modify, you can click every other entity to change the direction the feature has created....

This is also the same as "creating contours" out of your geometry, which will be much faster process. Just choose other-contour and window select your lines to create contours. Then choose utilities-reverse contours and go down the line and reverse every other one....

The BEST thing to do, is think about it a bit before hand and do the array from 2 entities to start. Array the first entity at X2, then create a new layer and array the second entity at X2... Now you can window select each group as a whole.

[mmoe]

When doing circuit boards, I like to draw the circuit as closed loop regions and then use a profile to cut them out. I've never really been taught how to do it, so maybe that's not ideal, but it works well for me and I can create geometry and program for a board like this in a couple hours (assuming I know what I want). The tool then stays down most of the time with only short rapids between contiguous regions. Here's an example of how I typically draw a circuit and the resulting board. Cuts pretty fast and I don't get random motion. Some of the geometry is not for machining, but rather for graphics, but you'll notice that I keep things generally color coded for easier selection. You can also see there was a design revision between the diagram and the part, mostly because I wanted to accommodate a 25 pin connection.

ControlPanelPCB by mmoe5150, on Flickr

_1020833 by mmoe5150, on Flickr

https://www.youtube.com/watch?v=Dq1QgEa7wbo

[Shaune]

Nice work mmoe, it's always great to put the drawing alongside an exact copy in the real world.

I see exactly what you mean about the tracks, yes a good way to do this. I will be aware of the way bobcad works in the future and make my drawings to suit.

Thanks
Shaune

[Shaune]

Hi burrman, someone, jrmach I think, said you would be the man to ask.

yes you are right abouth the geometry but given these are simply lines (2d) I assumed that bobcad would have no need or interest in the direction of lines as decisions as to the direction of cutting is specified when you generate the tool path. It just seems like an anomaly that despite defining all of the cutting conditions you want they are overridden by simple geometry from the drawing.

am I oversimplifying this? Just seems a bit crazy to have an engraving option that can't optimise cutting unless the line directions suit. Aarrgghh


shaune

[jrmach]

Worth a repeat,,,"pick the lines in the order you want to cut,,check the box for no sorting." This should get you close.
Now,however,,looking at mmoe's example,that is more than just lines,,they are arcs and lines than form loops.For these I would use Contours.Contours are powerful.

Burr was suggesting you can "Modify" the behavior too with the shift/click and or using contours.

The question I was suggesting Burr answer is the one about lines having retained order from drawing in Rhino.

Maybe tonight,if your still confused,I can show you on an actual drawing of yours.Upload the .bbcd if you can,

[BurrMan]

The question I was suggesting Burr answer is the one about lines having retained order from drawing in rhino

Rhino a very powerful cad app useing opennurbs format. Entities have all kinds of info attached to them, like parents and children etc and are written into the file (inside a rhino file has the Nurbs written out by definition. (Knots, vectors, coords, normals etc etc...)

i wouldnt want my importer to "clean off" any of that info. Just get what "i want"... you could bet bobcad didmt write the importer, just licensed one. (Most likely integritywares)...

What you are referring to is some type of "rebuild" imside of bobcad...

[BurrMan]

yes you are right abouth the geometry but given these are simply lines (2d) I assumed that bobcad would have no need or interest in the direction of lines as decisions as to the direction of cutting is specified when you generate the toolpath

well, you have entities with direction (something thats needed) and a toolpath which needs direction. It does a pretty good job of creating a direction, but needs help when it comes to order AND direction AND method.

The engrave IS a pretty simplistic path. Profile is a bit better (you would use engrave when you want to avoid toolsize interfering with anything). We meed to direct things sometimes..

I do agree they can beef things up a bit with it though.

[Shaune]

Lesson learned. I need to use a bit more finesse when drawing. I normally just crash right in and fix things as I go as needed otherwise it can do your head in. It still seems crazy to me to have all of these different tool path options and configurable settings (like sort, closest) when they are overridden by unimportant details associated with the geometry. At the end of the day a line is a line and when you machine it who cares what direction it goes in, that why we set the machine offset.

Thanks for the feedback and banter.

Anyway the heater is now finished and works like a charm. It's double sided to ensure a very even output. 196w of power over the build area will make sure the prints stick withour curling. Now I can get back to printing some stuff for my cnc machine. Picture attached

Thanks
Shaune

[mmoe]

I've spent a little more time trying out the engraving feature the way you are using it, and I have to agree that it simply doesn't behave quite as I'd expect it to. When I draw my 2d lines, I always know what direction they are since the software I use for the CAD side of things uses the start point of a line as the anchor and the end point as the direction that a line expands when changing the length. Knowing that, the direction always goes from start to end. If I create a group of lines and plan for the specific path I'd want the engrave to follow, it does so some of the time, but not all of the time. I can consistently get it to follow the direction for simple things, and even to some degree more complex drawings where it follows the directions as I'd expect. However, if the tool starts somewhere other than zero (as in a second operation/feature), it seems to cause the engrave feature to be more random. It will still cut the lines out in the directions I've drawn them, as it should, but it will definitely skip around and even do them out of order (I know the order they were drawn in, and this is far more random).

I really can't say what the logic it's using is, as it's obviously something beyond the line direction and order of creation, which to me means it's simply random. Profile seems to be more constricted to order, but you also have the additional options to control that in a profile routine, so that's not surprising. In the past, I've only used engrave for some very special 3d toolpaths where I've literally drawn a motion that I know is harder to get out of the software than it is to just draw the path itself and use engrave, and it works fantastic for that purpose (I do very customized spiral entries that go tangent to a wall right when reaching the final depth). For actual engraving, it seems to me that profile is more robust unless it's on a 3d surface, in which case the engrave feature probably is the only solution. Hopefully they will improve the engrave feature at some point.

[jrmach]

Shaune,if you would of uploaded a file....................that looks to be fairly easy to cut in a productive manner.Next time.

when they are overridden by unimportant details associated with the geometry.
Ha,,there is a lot more to CAD than what you or me even have a clue about.Burr could probably write a whole page on it,but we would not understand it.But that is pretty funny


I can't help but think my points did not come across clear so here is a video

https://www.youtube.com/watch?v=iTYa...ature=youtu.be


Later tonight I will make another one and show you some real power with contours,,,,,

[jrmach]

Here is Power.Absolute control.


https://www.youtube.com/watch?v=6C7j...ature=youtu.be


There are yet still MORE things one could do to speed up/optimize that simple Heater.Burr hinted on an array.

[mmoe]

Here is Power.Absolute control.


https://www.youtube.com/watch?v=6C7j...ature=youtu.be


There are yet still MORE things one could do to speed up/optimize that simple Heater.Burr hinted on an array.

You can also just change the direction of the geometry from the CAM tree without making them contours. Here's a quick video showing that. Also, when I drew the geometry for the video, I started in the lower left then worked in a path that you can see connected one line to the next. The start and end of each line should be opposite that of the previous line as you work your way up. As you will see, by window selecting the whole lot, the directions are as they should be. However, the engrave feature does not pick them in the most obvious path. I think this has something to do with window selecting moving the first selection to the end of the list, or something of the sort. If you pick the lines individually without making them contours, you can influence which direction they are by which end of the line you click on during the geometry selection process, just the same as you can change it later. The only difference is that you just can't see the arrows during the selection process. It used to be, back in V21 and earlier (not sure about V22/V23), that you could see the direction while selecting, so I got in the habit of selecting in a way that always puts the direction how I want it initially. Just paying attention to whether you click to the left or the right of the center of a segment makes all the difference.

The window select does not influence the direction of the lines and will use their default as created direction. As you can see in the video, this held true. Once you get to more complex window selections with the engrave feature, particularly as a second op, the random-ness starts to creep in, never in the direction of the cut, but in the order they are performed. Any window selection is going to use the default direction.

Link to video:
https://files.secureserver.net/0sEVnCKliH4R7A