Vector line length measuring

[Pete Andrew]

Imagine a silhouette of a bird in a cage with lots of flowers round about, then using the outline of the silhouette as a vector path to cut it out of a piece of thin black card, letter or A4 size. The whole cutting process might take about 2 minutes.

My job is to cut this complicated design out of 5 mm black acrylic, sized 650mm x 450mm. So I can price the job appropriately, I want to know how long it will take, so I set my machine up to run the job with the lid up so no laser was firing, and now 40 minutes later it is still going.

Has anyone found a way, in either Adobe Illustrator or Corel Draw, to find out the combined length of all the vector lines in a file? If there was a way of doing that, I could have an idea of how long each job might take, before having to do the dry run.

[Joe Pelonio]

I still haven't heard of any such tool.

I've gotten to be pretty accurate estimating based on what you are doing. In other words, let it run with the top open but stop at one minute. Estimate what percentage of the cuts is done.

[Rodne Gold]

http://www.oberonplace.com/products/...orks/index.htm
You can use curve statistics
http://www.oberonplace.com/products/...curvestats.htm
Or you can import into Acad and use the "list" function.
Im not sure if either of these will give you an accumulated length of all curves and vector lines in a drawing however

[Andrea Weissenseel]

I don' know if I understand this right. Cutting the same design out of cardboard takes 2 min, and acrylic takes > 40 min ?

Andrea

[Dan Hintz]

Andrea,

You can run cardboard at a significantly faster rate than acrylic, hence the increased runtime.

[Steven Wallace]

Andrea I am sure that you are also looking a one being roughly 280mm x 216mm rather 640mm x 450mm. Which is also greater than 4 times larger

[Doug Griffith]

That can be done in earlier versions of Illustrator using a plug in called pathlength. http://www.telegraphics.com.au/sw/info/pathlength.html

I've got a script working on CS1+ that does the same and also allows laser speed to be entered. It then returns the time it takes to cut the part (and is very accurate!). It uses an array of speeds (ie. 12" @ 5sp = 12sec, 12" @ 10sp = 8sec) that is calculated by physically running the length/speed on the machine and hard coding into the script. Once I create an interface where people can enter those values themselves, it will be ready for release. I will also add a rate per minute field which will make cost calculation easy.

Cheers,
Doug

[Carl Sewell]

Try the attached Macro: CurveLength.gms

Close CorelDraw. Unzip the file. Place the GMS file in your GMS directory (something like: C:\Program Files\Corel\CorelDRAW Graphics Suite 13\Draw\GMS).

Start CorelDraw.
Select one or more curves.
Tools>Visual Basic Play>
Click on the arrow next to "Macros in" for a list of macros.
Run CurveLength

[Andrea Weissenseel]

I just was not sure if he cut both materials, or just ran the acrylic one.

If the whole cutting process took that long, there could be a problem in the design. When automatically vectorized, you should clean up the nodes in Corel - for some designs that decreased the runtime about 60%

Andrea

[Rodne Gold]

Even if you did get the curve length , there are ramping issues to consider
The length at the speed of head travel (like 3" per sec) will not be a constant. IE you cant say 100" at 3" per sec = 33.3 secs. It might well be 3x that if the curves are "curvy" etc.

[James Mooney]

That can be done in earlier versions of Illustrator using a plug in called pathlength. http://www.telegraphics.com.au/sw/info/pathlength.html

I've got a script working on CS1+ that does the same and also allows laser speed to be entered. It then returns the time it takes to cut the part (and is very accurate!). It uses an array of speeds (ie. 12" @ 5sp = 12sec, 12" @ 10sp = 8sec) that is calculated by physically running the length/speed on the machine and hard coding into the script. Once I create an interface where people can enter those values themselves, it will be ready for release. I will also add a rate per minute field which will make cost calculation easy.

Cheers,
Doug

Doug,
I'd really interested in that if it comes together for you.

[Doug Griffith]

I ran 2 files on my Epilog Mini. One consisted of a 12" x 24" rectangle. The other consisted of a curved shape that looked more or less like a scribble. Both line lengths equaled exactly 72". The time to cut both files was within seconds. I think that variation would be acceptable for job estimating.

Also, if you think about it, the material you are cutting doesn't care if its curvy or straight. So theoretically, if speed changes with curves, an oval (not an ellipse) would cut differently on the curves than the straights. If a setting was set where the beam just barely cut through on the curves, it would not cut through on the straights. I've never seen this.

I can see where a lot of sharp directional changes such as a star might have a more radical effect. Rapid moves from shape to shape would be a bigger issue.

I think 2 setting files could be ran for each speed setting. One straight, one curvy/spiky. Then a slider on the "estimator" could be added to help the user guestimate the time/cost. Settings between those manually entered would be dynamically calculated.

Also, I only have experience with Epilog. Other manufacturers may (and probably do) have more variation.

Cheers,
Doug

[Rodne Gold]

Doug , I dont think I made myself that clear , lets say your laser does 40" per sec and you using 50% speed , theoretically it should be 20" per sec , and if you have a 100" curve it should take 5 secs , but the advertised or computed linear speed is not the same as what it actually takes , the linear speed is max speed on a st line.
Lasers slow down on curves and corners and take time to reach their max speed according to your setting of it , most also automatically adjust power in slow sections or corners. Some lasers call it "ramping"

[Michael Simpson Virgina]

Also don't forget you have the time it takes the laser to get from object to object. There is no way to figure this in.

Universal has a real good simulator as it actually runs through the machine without moving the head at several times the speed. From what I have heard and seen it is very accurate.

[Doug Griffith]

Doug , I dont think I made myself that clear , lets say your laser does 40" per sec and you using 50% speed , theoretically it should be 20" per sec , and if you have a 100" curve it should take 5 secs , but the advertised or computed linear speed is not the same as what it actually takes , the linear speed is max speed on a st line.
Lasers slow down on curves and corners and take time to reach their max speed according to your setting of it , most also automatically adjust power in slow sections or corners. Some lasers call it "ramping"

I agree that to mathematically calculate times based on a single speed won't work. There are just too many variables. My work around is to run the same test file at multiple speeds (ie. 10,20,30,40,50...) and enter the time it takes into an array. This array is used as a speed "curve" when calculating cut times. 2 "curves" could be used - one straight and one curvy to give a more accurate result. I know it will never be perfect but close enough to estimate a job.

Attached is a zip file containing 2 eps files. One is straights and one is curves. Both begin and end at the same position. Both have the same path length (within .003 mm). I'm curious if others find a large difference in the time it takes to run.

I did not know lasers automatically adjusted their power to compensate for slowing in curves. Interesting.

Cheers,
Doug