Interior Cuts and Perimeter Cuts

qa

#1

I was noticing on a lot of the videos the laser will cut the outside perimeter of the part being cut out first and then the interior cuts. I realize the material doesn’t move during the process but on the latest Valentine’s Day video I saw the paper rolling up as it was cut. Does this cause problems with correct location of cuts and/or is there a way to set the interior to cut or etch before the outline perimeter cut?

Thanks
Jason


#2

You can change the order of what cuts first. So if you want to cut the inside first, you can.

(As the video shows though, apparently it’s not much of a problem.) :relaxed:


#3

This is only true if you set it as a separate group of objects in the SVG. by default if left on the same layer/group it will cut in a somewhat random order and many times end up doing parts from the inside, then outside, then more from the inside.

So yes, if you want to have a specific order as of now, you have to be very deliberate about it before putting it into the glowforge ui.

Also for some mateials like thinner acrylic, if you are doing an engrave over the entire piece you are cutting out, they default to cutting first and then engraving, and recommend that. I however would say if you are doing an engrave over the entire piece you are cutting out and its 1/8 or less thick, to cut last, as the heat will cause the piece to warp upwards.


#4

Yes, it would be part of the design process. (Should be as simple as assigning a different color to the outside vector path, if I understand what we’ve been told so far.)

(Until I see one in action, I won’t be able to tell if the order in which design occurs has anything to do with what cuts first. You know, bottom of the stack cuts first, next up cuts next…that sort of thing. It’s normal to design that way for the digital cutters as well. But I need to see how this one treats the layers, and/or drawing order.) :relaxed:


#5

Ditto @takitus. There are some creative ways to design to allow for material management. This really does encourage me to document a little bit more and test to see how the SVG file is read by the Glowforge. Since it is a text file basically, it comes with an order. Sometimes those sub parts of an object get put in with a strange order as I design. Will have to see how it affects the processing of a particular part/operation.


#6

Since the Glowforge is all about doing things automagically, I’d be surprised if they don’t add an “inside cuts first” option before it’s released.


#7

Particularly as they would need to determine the inside cuts to get the kerf compensation in the right direction.


#8

With a big engrave, do you find it better to different parts of the engrave (rather than link an inkjet printer) to keep the heat buildup or if you leave final cut for last, the heat buildup doesn’t damage the engrave?

When (if ever), do you find heat buildup damages big engrave jobs?


#9

The company, Inventables, which makes the popular X-Carve CNC machine has spent years fine tuning the tool paths and cut order for their S/W. It gets better all the time but will never handle every situation properly. Yeah I know, the cut order might be obvious to our brains and is reasonably well done in a few S/W packages. But if you look at the size and background of the Glowforge S/W team it will be an iterative process.


#10

Usually it’s not an issue if you aren’t engraving on thin acrylic at high power. Those are the only times I’ve had issues. If I know I’m going to be doing that I just don’t cut til afterwards. Never had any other issues. I usually just do engraves in one pass


#11

I have noticed cutting is broken up, for example all text is not cut sequentially, some part of letters cut then some perimeter cut then more text etc.
Seems that would be helpful in not focusing too much heat in one area.
My Son’s CNC plasma rig does that by design.


#12

When I was cutting acrylic spirals I was mesmerized watching the plastic move around. That is one material where heat management will really matter.


#13

Some of that depend on how you combine the text after stroke to path and break up in the design software.


#14

I see, thanks.


#15

At least cutting paper Dan said he didn’t see noticeable differences cutting the inside or outside first.


#16

Since I haven’t done any layering yet, most of this is beyond me for the time being. As far as kerf is concerned, would it work for the UI to just let you select which shapes you want to “protect” and it just cut outside of that?
Again, I’m talking out loud in the language of laser, which I do not speak.


#17

Not quite that simple. :relaxed:

Some of the folks are writing up some step-by-step instructions for dealing with it during the design stage. (It’s pretty easy if you do it then.)


#18

I save every design iteration to a separate art board so I guess I’ll be fine either way. This discussion is a good learning experience.


#19

I need to learn that habit…I wind up reworking an awful lot of stuff. :confounded:


#20

I learned it the hard way. Too many clients after 12+ iterations saying, “You know I think you’re right! That first design you gave us that we told you to throw in the trash is really speaking to me now!” :fearful: