[Griwa]

When generating an engraving toolpath, for some reason aspire(or vcarve) decides to do a multipass. Is there a way to restrict engraving to a single pass? The depth is shallow and I do not believe it to be a factor.

The idea is I have halftone image which is really complex all done in linear lines. It takes around 4 hours to carve using a halftone software (point to point acceleration 15-30 IPM), but if I annalize the halftone vectors as lines I reduce the cut time in half (curve progression 30-70 IPM). Unfortunately Aspire decides to do them as a double pass returning the process back to 4 hours.

I do a lot of these and the timeframe reduction would be a huge plus.

[ger21]

Can you post your Aspire file? Are you sure there aren't duplicate vectors?

[Griwa]

I had to zip the crv file (The file(s) uploaded were too large to process.), and also attached 2 images. One of the toolpath going both directions and the other of the toolpath settings. I am used to using RhinoCam, but unfortunatly Rhino overestimates the cuts and splits them into fragments causing too many lift points.

[victorofga]

vcarving works this way only..
no single pass vcarving exist..

very roughly vcarving is a profilecut on a closed curve.. where depth is not preset

if you were working with halftone.. then you can reduce the toollifting, to set the minimal grey 12 percent or more, and black also can be filtered to 85 percent or less

one solution could be, convert your halftone to heightmap.. or say relief.. and create a reliefmachining toolpath with v bit.. like 60 deg bit.. set stepover that the deepest point where bit going still leave between toolpath some very small gap..

this is the way othervise as photovcarve create toolpath..

this way you have only single pas on each point..

[Griwa]

The lift off only happens in RhinoCAM, not Vcarve. That is why I thought Vcarve might be better. The result is good, but since it does a double pass my time is the same as doing the cut dot by dot. Is there another software perhaps which could analize the vector image in order to produce single straight cuts?

[fixtureman1]

Have you looked at Photo vcarve

[victorofga]

griwa

:-)
if youre using vectors and vcarving, then all program makes same toolpath..
if you convert halftone to heightmap or model or relief what ever you know, then you get the continuous machining..

this is what I wrote earlier to answer.. for your mentioning, for 1 million small island as you vectorizing a haltone image theres no any program calculate continuous toolpath

repeating, the vcarving process, in rhinocam, in vcarve in mastercam and all known cam works exactly same way..

for you need to convert the halftone to heightmap.. postscript makes bitmap and vector same time.. use the bitmap of..

[victorofga]

also theres a method used, the ""photocut"" what actually was the base for the photo v carving..

in photocut you cut the vynil with variable width and those programs can adjust the lowest and highest value..
means the 8 bit grey picture will be limited to from 18 to 243 approximately..

with this settings you get continuous lines across the bitmap..

================================================== ==========

you might say you don't understand a word of all.. then sorry just go and study what possible to make with vector, and what possible make with bitmap..

[Griwa]

I do not want a 3d Relief. The whole point of what I am doing is that it is not a 3d image. I can post some pictures of my work later. Using Rhinocam i can generate single passes through vector halftones done in algorithmic ways, therefore reducing the cut time of my halftones. Unfortunately when the vectors get longer, and more intricate, Rhinocam splits the job into sections causing lift ups in the z axis. This slows the process down. It is still doing single passes and is faster than machining by coordinate system.

I'm amazed that with how simple the job is, and how difficult it is for the toolpath to be generated.

Theoretically if I chose to bevel the vectors down at the angle of my bit, the intersection of the bevel would be my toolpath line. Unfortunately some of the larger images I do (around 4'x4') this method is impractical. And trust me when cutting several hundreds of thousand lines, 30-60 IPM is a huge advantage over 15-30 IPM. Some projects can take 8 hours to cut at this rate.

Reason I like Aspire (Vcarve) is that it generates very smooth path with no lift offs. However for some dumb reason it is omnidirectional cut. Where RhinoCAM does single direction cut in multiple segments, and when you make the machine lift off and move over it is a time increase.

Two completely different calculation techniques. Neither offering what is best. I am sure there are justifications for both, but neither is optimal in the time factor.

[victorofga]

griwa

you simply don't see when your v bit follows two vawy vector, and moving up n down you practically follow as the ""color"" changing..
this practically same when your vbit follow a relief..

difference is, with vector you go forth n back on same path, with relief you go on one way
================================================== =======================

white is zero black is 256 or backward..

no you don't have to make relief..

each bitmap contain a database where in the file header defined the number of rows and columns..

after header you just need to associate each pixel value with a heightvalue..
it is dead easy.. unless if you never made before....

so, your tool need to follow these values.. for you, whos not a programmer, the simplest is creating a heightmap with a program, and that heightmap leads your vbit..
in each row only one times, no forth n back..

as I wrote you might don't understand it.. that's fine.. I don't want to push you to learn or understand..

I made this in 1997 before anyone see photovcarve or any similar program..
reason why? because we wanted to paint with airbrushes controlled with cnc.. so we had to find how we can control how much need to open the airbrush on each pixel..

making a photo on a white pvc sheet this was the way as you make today with different programs.... we didn't made relief.. we simply generated two vector on each pixel row..
preventing to closing, we limited the light to 18 and up... and dark was limited around 235-240 so curves were continuous..

on one side they were connected and after cut vynil we could pull back ((weed)) the vynil in one piece

so again, if you go with vectors, vbit will go forth n back in same track..

and my guessing , you wont find any program that makes single pass between vectors with vbit..


you can program each pixel as a drill path.. also slow

those values will make photovcarving or lithopane..

[Griwa]

I understand completely, thank you for your response. I do program (mostly java and c++), but was hoping it would not come to that. PhotoVcarve is a good software but very limited in its capabilities. The reason I like to generate vectors is that it is easy to do so with almost any software. I might not be making my purpose clear enough. But anyhow thank you for your input. I will continue cutting the way I was previously, and maybe start on a simple script to generate my own toolpath if I get the time. If I do, I will certainly post it as freeware for all to use. Thank you again.

[victorofga]

ok.. we getting closer...

the most important you see I try to saying..
youre seeing, there are several program will do you try to achieve..

the issue you encountering, that bitmap is for more human than vectors..
what I mean?

a simple mes or pointcloud no shading used gives no or little ""feedback"" for human eye..

that's the reason so many folks looking to working from bitmaps.. but from here, you can let computer works or translate the pixels to a toolpath..

what program you will use that pending on your ""taste"" because what is on the market they already working solutions..

the program what one of our friend made a little 40 kb assembly program inputed *.raw fileformat and outputted the necessary vectors..
I going to ask them if program exist somewhere yet..
it made in assembly, because that was that worked on the fastest way..

your issue also that bitmaps used for this purpose 8 or 16 bit..

either way you need to limit the picture, or modify in photoshop.. when I say limit you can change pixelvalues as from zero to 18 overwrite to 18 and from 235 to up overwrite to 235..

why these values, because from 0-18 or you can go down to 10 ... these values within a picture almost same for the human eye.. however it will prevent lines are closing and generating insulated islands..

just for interesting.. we made experiment breaking down to 4 color the bitmap, and with this method cutted 4 vynil mask.. in different angles to eliminating moire..

painting with these four masks the four color the picture came back.. so with 4 basic color we painted ""photo""
certain way when you can buy a large format printer, this method already not affordable..

but in 1997 vutek machines were on market with 8-12 dpi!!!
the Michelangelo named piezoprinter -painter came up later..

look for the F-engrave program.. it is present on the cnczone.. scorch made an incredible work, using the voronoi algorithm..
he might has idea to using it as generating single vectors instead loops, what you can see on your preview..

heres is scorch link on cnczone..

http://www.cnczone.com/forums/openso...arving-20.html

for those readers who weren't sure about F-engrave, this program not simply makes engraving or vcarving.. this program creates profile cuts and pocketing too..

a complete program for starting to cut on your cnc router

all is this for free..

[victorofga]

just make sure you don't misunderstand me


1st for continuous toolpath no halftone

convert to greyscale

the greyscale pic need to convert to ""lines"" .. lines here means a variable width line where line width associated to the actual area pixelvalue..

those lines can be used as vbit just going on one way..

seeing how voronoi generate the fillup, I think your idea is very viable