How to set up line drawing order sequence for optimization in laser cutting

[mabloodhound]

I use AS v.9 (on XP) for my 2D drawings that I send to my laser vendor for parts cutting.  After drawing one item that has about 110 lines plus 36 small holes, I then create an array of 12 of these items which my vendor then laser cuts on one sheet.

However, the laser (Epilog) jumps around a lot between various lines with no logical order or sequence.  My vendor requires that I set this up using AS.  He tells me that the laser follows the order in which I drew the lines or modified them.  Although his laser has an optimize option, it does nothing because there are just too many total lines.

My question, can I manually go through the initial drawing and set the order sequence of the lines so the laser will cut them in a logical order and not bounce around?  All of the extra laser carriage movement is time (and money) which I could save considerable by setting up the cut order.

I know I could re-draw the entire item but I was hoping to find a simple 1 or 2 keystrokes that I could mark each line in the order I want cut.  As I have over 30 different items that I have the vendor cut for me this would be valuable time spent.

Thanks.

Dave Mason

[Fred9002]

IMHO what he is telling you is almost certainly false and certainly a faulty system.  

Under "probably false"  you might test it by randomly making 40 marks on a brand new drawing, make separate notes on the sequence, and tell him to tell you what sequence you put them in. 

Plus most elements of an Autosketch drawing are not themselves machinable features, so it couldn't possibly machine based on drawing elements.   For example the corner formed by two intersecting lines.  Let's say line #1 was your 34th element drawn, and line #2 was your 135th element drawn.  The feature didn't even exist until the 135th  element was drawn, so what is supposedly going to happen when he hits feature #34?   

To illustrate that give him a drawing with just one straight  line on it (so it is feature #1) and ask him how he is going to machine that in step 1.

[mabloodhound]

It is not to my advantage to test this vendor.  I have also talked with another vendor who uses the Epilog laser and he says his machine operates the same way.

If I sent him one line on a drawing the laser would just cut the one line.

I had really hoped for an easy method for me to go into the drawing and mark each cut line in a sequence that I would choose.  But I also would like some simple process for marking each line rather than re-drawing the entire part.  I have thought of going in and changing the color of each line in sequence and change the color back and then move on to the next line.  Not sure if this would work.  But that's a bit more tedious than I want.

[StevenMac]

I've never heard of this. Personally I'd go find another laser cutting service.

[Fred9002]

My point is that there is no one-to-one correspondence between drawing elements and machining steps or machined features and so that whole scheme that your vendor described sounds impossible.

My example was to say to just draw a single line on a blank drawing.  You can't possibly machine based on that.  You don't even yet have an object to machine.   And the line will almost certainly be modified or moved or deleted later in the drawing process.         

[mabloodhound]

This is a laser cut part, NOT a "machined" part.  The laser software certainly does read the drawing elements.

Not only does it read the order in which each cut line was drawn it also reads & cuts in the direction it was drawn (l to r or r to l, etc)

If I draw one line, as you suggest, the laser WILL cut that one line in whatever material I specify.

The line does reference off the x,y - 0,0 axis and on the material I specify which is set to my drawing size.  The outside edges of my drawing are also the outside edges of the material I specify.

I have talked to two other Epilog laser users and they have experienced the same operation.  I was just hoping for an easy way to set up my line order sequence easily in AutoSketch without manually going through each line in order.  Not to confuse the issue, but I have attached the .SKF file to maybe help you understand.   OK, guess not?  AutoSketch does NOT allow attaching their own .SKF files.  WTF

[Fred9002]

Sorry I couldn't help.  I can think of a zillion problems with their approach but I guess that that is what you are running into.

[Kevin.Hutch]

Dave I am not sure I am on the right path but you could try using the "layering  process" of placing the individual lines on top of one another by selecting each line then ctrl F to place it "on top".  Thus layering the drawing, I have often used this to provide overlaid filled areas and this may place them in a sequence for his program.

Failing this try "joining" all elements that can be joined with the function "trim join", that would minimise the number of elements.

[mabloodhound]

  That may work.  We are trying my 1st attempt where I went in and changed line color to red and then back to black in a specific order to see if the laser will follow that sequence.  I'll try the ctrl-F next.

Thanks, Dave

[DSubaric]

Hi Dave,

Could you please report back with your findings as I have the same query and there is very little online discussing this problem!

My Epilog cuts in the order drawn and it is such an inefficient way to cut shapes as usually I draw my main shape then I will go and create fillets in each corner and other modifications however when it cuts it's always jumping from one to the next and since it is an old machine the error in positioning can be seen on the final piece, I can tell between edges that were processed in one continuous cut when compared to edges where it finished and then came back later on to continue the cut.

Our 2016 Trotec Speedy 400 at work did the same thing so the guys would have to always consider the order of drawing and then even colour code etc. but to me that sounds like such an inefficient way to design parts as this is something so simple that the driver should be able to calculate the most efficient path automatically.

Regards,

Dejan.

[mabloodhound]

Dejan,

I never found a solution to the problem.  I even completely redrew a part, attempting to keep an order sequence for the lines but that didn't appear to help.  I do the same as you and add my fillets after the lines are drawn. The one thing I do is to make mutual lines on a cutting layout, all one long line.  I have multiples of the same item laid out on the cutting sheet and after laying out I go in and revise all the mutual lines into one long line to avoid the laser jumping around to a bunch of short cuts.

The laser software is supposed to optimize the cut sequence but I'm told with the larger quantity of cut lines in my drawings it can't do that.  So I live with it and pay for the extended cutting time.

Sorry I can't be of more help.

Dave

[Kevin.Hutch]

Dave, I am somewhat perplexed at your comment "I have multiples of the same item laid out on the cutting sheet and after laying out I go in and revise all the mutual lines" by this I assume you mean "trim joining lines". 

Yet you say  "So I live with it and pay for the extended cutting time."

When lines are one continuous line doesn't this solve the issue, or do you mean this extends your drawing time meticulously joining all the lines into one.

[mabloodhound]

Kevin,

Some of my items have up to 200 cut lines per piece.  Many are cut-out areas and cannot be mutual lines with an adjacent part.

I usually have 12 of the same items on each cut sheet so on the cuts that are in-line, I can make these one long line.

It does save a small bit of time but doesn't solve the overall problem of the laser jumping around to the various other cutouts instead of cutting them in a logical orderly sequence.  I added an attachment so maybe it will show what I mean.

Dave

[Kevin.Hutch]

Dave I just reread the thread and see you tried to attach the .skf file all you need do is change the .skf to fool the forum software or simply just add .bmp to the file.

Secondly I have run through similar things intrigued when watching the sequence on a plotting and if I am surprised that the layering function of bringing forward an object or area does not solve the issue. I understand joining could be time consuming, maybe the "Group" function would help and obviously you do it to the original before you copy it 12 times.

Send me a file and I will have a play with it. 

[Kevin.Hutch]

Sorry Dave can't get my head around your drawing there seems to be lines with missing bits and corners that do not join, or am I missing something.

Se if you can open the attached .skf file by just dropping the .bmp.

[Kevin.Hutch]

Whoops the skf file failed to attach try again.

[DSubaric]

Thanks for your reply Dave, it's at least given me some closure! I've been looking everywhere online for solutions but no one is actively discussing this issue.

I guess I will try to be considerate whilst drawing from now on but really this should be something the machines sort out so that we can design freely.

My colleague at my old workplace has been using AutoCAD for a long time and he came to the conclusion that the way the drawing files are created, it's like a serial command of information that the laser reads in chronological order. It has the start and end point of each line you draw so it literally follows the stream of code to cut the shapes.

I am not using Autosketch but this problem seems universal as laser cutters seem to do it with AutoCAD, Inventor and CorelDRAW. I really thought newer machines and newer software versions would compensate for this but clearly not.

Regards,

Dejan.

[Kevin.Hutch]

 Dejan, you are right in the old days NC machines were operated by punched paper tape with the commands sequenced on the tape, this moved to magnetic tape and again the commands were in order on the tape, separating cuts being left until last.

It seems the laser units still follow that same logic, so it only requires to effect the sequence after the drawing is completed as I understand drafting the layout in a specific order would be illogical to a design engineer or draftsman where rounded corners need the sides to be defined first. Parallel lines and duplication functions would also upset a sequence also.

Selecting specific colours or pen thickness map on a plotter to separate pens, so I would expect to see a similar function in a laser even if colour is not an option in the final product. 

However "trim round", "trim bevel", "trim join", "trim corner", "group", and "rubber stamp" functions must surely cause resequencing of a file.

Running a file out on a plotter may well help establish an understanding the sequence without lots of laser trial and error. 

[mabloodhound]

Kevin,

The drawing I attached was a screen shot of the cutting drawing.  It is the frame for a model RR car, cut in 1/8" thick basswood.  The broken lines, etc. are there to hold the piece in place while cutting on the laser table.  There are 12 identical parts of the frame in the cutting drawing.  The fellow who does my cutting, I've worked with for 10 years and has told me that there's nothing that can be done with that many cut lines.  He has a newer Epilog and is very familiar with the machine and software.  I'm not going to worry about it as his cutting charge is fair and affordable.

Thanks for the replies.

Dave

[Kevin.Hutch]

Fine Dave it is just after years of logic thinking it is hard to retire.