Machine Along Vector toolpath

[KenC]

I would most appricate some help here.

I need to add a spline right at the centre of this example figure. 11440
I failed to do it with Acad so... :o

After some search, I found the ShopBot software has the feature that can generate the tool path which I need. The ShopBot people call it "Machine Along Vector toolpath" Which I don't have...

I need to know if there is/are any alternative(s) to generate the centreline spline? Or which other CAD or CAM software that can do it?

[Alan_c]

You have to actually draw the vector(line) down the centre of the item so that the cam program can generate the toolth path. There must be a line for machining along a vector pathe to follow. You may have to fiddle a bit to get the line exactly where you want it.

Here is a quick one I tried 11441

[Gerald D]

Ken, it is more commonly called V-carving.

See http://www.vectric.com/WebSite/Vectric/vcp/vcp_vcarving.htm

[KenC]

Thanks for the heads up.

Alan,
Thousand thanks that is exactly what I need. but how did you do it? I tried using offset & it gets tired just halfway through of just one of the 33 shapes... & more coming....

Gerald,
Not exactly what the job call for. The job only requires a constant 2mm deep V grove around on the figure which Alan did.
Using the V carving in VCPro, it will cut through the 9mm sheet stock... Not to mention time consuming... I love the V carving, but it will be even better if there is an option of not making 2 passes on one carving... that is another subject..

[Alan_c]

Using an offset wont give you you what you want as the distance between the outside lines is constantly varying. They way I did it will take some time but is the quickest way I could think of: I started by connecting approximate opposite sides of the main shape with straight lines, I then drew a curve line (term used in DesignCAD 17) through all the centers of these lines, giving me a line that would follow the center of the shape. As I said some tweaking was necessary to get the line to "flow" nicely to give a clean result.

11447

[KenC]

Alan, Thanks for elaborating, I had a go at it & with lots of tweaks, it works as prescribed...
Now, all I have to do is to burn through the night to get this done...:(

*ps,
I really hope to find a lazy way to go about this...:o

[danilom]

I fount THIS (http://cnc.rs/mechmate/rolling_ball_method.lsp) lisp function for AUTOCAD which could serve for centerline creation with open curves, maybe it can be adapted to work with closed shapes like these. Save the file with .lsp extension

It is rolling ball method, it starts with circle and enlarges it till it can fit between curves, moves the increment given and draws again, all the time remembering the circle center points and connecting them, so you can get pretty accurate centerline. It must be the method used for V-carving but has to be tweaked a little bit.

p.s.
here is how to start lisp from autocad
http://www.cadtutor.net/forum/showthread.php?1390-How-to-use-the-LISP-routines-in-this-archive

[Gerald D]

. . . .Using the V carving in VCPro, it will cut through the 9mm sheet stock. .. ..

If you output the V carve file to dxf, then you can "flatten" the file by removing all the z values. (make it 2D only)

[KenC]

Can it be done? please elaborate.

[KenC]

Had a go at the suggestion, generated the tool path & ticked the "Show 2D Preview" option in the toolpath screen (the right hand side menu)
No matter what I did, I can not select the the V-carving path line (in red)...
Export disregard & I can only export the figure without the centreline. :(

[danilom]

Toolpath can be exported from Artcam to dxf, but the vector which is created for toolpath has two lines as the created toolpath is not single line.

Here it is
centerlined.dxf (cnc.rs/mechmate/centerlined.dxf)

If you have drawings of what you need to do, it is no problem to convert them like this. But it needs cleanup as there are two lines overlapping.

[KenC]

danilo, I some how missed you previous post, will have a go at the lisp function.
I really hope V-Carve Pro will have the same function as Artcam. Maybe someone who know will show me the light .

Thanks & many more thanks

[KenC]

Installing the "Rolling_ball.lsp" is beyond me for now... Will return for another crack at this after a good night sleep.
Thanks again Danilo.

[danilom]

Just load it from Autocad
open AutoCAD and select Tools->AutoLISP->Load... from the pull-down menu

and type ROLLIN or ROLLIN2 to start command

[KenC]

It works like a charm! :D
Is a bit slow at first but it gets better time after tweaking with the increments. Surely take the strain off my eye. Fantastic!

This LISP thingy is real fun! and the fun don't stop here... there are loads of toys to play with here :D Danilo, you just open up another playground...:D

What I learnt,

Instead of using the MENU, you can also load the LSP by typing "APPLOAD" in the command line.

It doesn't work with a single polyline loop, what I did was to break the loop using "trim" command into 2 open spline. occasionally require to PEDIT the line to Spline

Require some "remodelling" so that the LSP app can will track along the anticipated centreline.

It will deactivate "OSNAP"

Thousand thanks!

[danilom]

Every day its something new, I am glad it works for you :)

I too learned something new. Thats why we are here.