Cutting from the outside in

cutting

#1

In general I want to cut the outside cuts last as the piece is free to move about then and you don’t generally want that.

I have tried all sorts of tricks to reverse the paths and some places the paths are reversed but the “outside in” cut order remains. Of late I have seen many places where part of the design cuts through nicely but large sections are not cut through. It took a while to eliminate all the other possibilities holding the piece down with pins so there is no initial warp. Using clean pieces of wood with no detectable variation in grain and ramping up the amount of cut to a high degree so I know there is power enough to do the job and then some.

However as soon as the outside cut is through all the pins are useless as they are not holding the work. Worse the act of cutting itself warps the wood and if cut through the piece jumps around as the cut is made relaxing only later, so if you are not watching in that moment you have no idea that part was 1 to 3 mm above the outside still being held by the pins. I don’t have a sticky backed surface and there is rarely a place big enough to put a magnet and the back is usually cut as well so there is no way to hold the piece in place cutting from the outside in.

I frequently put the border in a separate layer to be cut last but my last piece I would have needed 30 such layers to get the cuts in the best order! And the result was too delicate for major surgery.

I would think a button to reverse the cut order would not be such a difficult thing.


#2

You can set the order using stroke colors. Lower hex numbers (e.g. black=000000) cut first. :slight_smile:


#3

I use colors for this and have no issues?

You have to plan for it in your source file and think of cut order early if you have lots of parts, but I have yet to have a job too complex for the method and sometimes I’m cutting 500-600 parts in one sheet.

Sometimes I have a design sheet and then a cut sheet so that I can fool with laths and colors without disrupting my original design, but it’s a method that has served me well.


#4

Here’s what I’ve done in the past that seems to help the issue of material warping from the cutting process (which I think is really stress being released from the material)… I’ve cut out certain interior sections of the piece (with their own color designating a separate job) and then used the holddown pins on the interior as well as the exterior.


#5

Also, I have a tutorial here somewhere that shows how to see the path direction and then reverse it if need be, but it’s for Illustrator. I’m not sure how it would translate to Inkscape.


#6

If you use colors that way each one will be a separate layer and need to be addressed separately. Further as it is easy to reorder layers just by dragging them about I have not paid that much attention to what colors come ahead of other colors.

The layers will cut from top to bottom but inside the one color/layer the cuts are outside in if the concept makes any sense in that circumstance, otherwise there is a meander that I am not sure of the properties but it is not relevant to this issue.


#7

Done that, it was the first thing I tried, some bits make a difference but not the draw order. If you copy/paste in the GFUI clockwise cuts will be counterclockwise but the draw order will be unaffected.


#8

No idea what you’re doing, but my most complex designs have only ever needed three, maybe four colors. Post a sample file and I can show you.


#9

I have had many that were well over that for a variety of reasons but if you have stuff nested inside other stuff or need the flexibility to have different thicknesses of engrave as well as the outside cuts that need to be last instead of first as well as stuff like my lamps that sometimes I only need a top or only a bottom, or one of the many engraves was not deep enough etc etc.

However, that base problem remains even when there is a workaround. The lamp screens should only need one layer but need two as if the rectangle is cut first the rest warps and does not cut through and only making it a separate layer will do that.


#10

Well, offer still stands. I’ll illustrate my workflow if you post an svg. I suspect it’ll work but maybe you’re working on things that much more complex than I am.


#11

Not more complex but need control this is an example where there are different levels od engrave and the center of the bottom needs to be flipped over before engraving,

Base%3D2-3x2-6


#12

It rarely takes more than 3 or 4 colors. Engraves and cuts are done separately, so you don’t have to worry about them being the same color. Unless you’re using varying engrave settings, all the engraves can be the same color, because the order generally doesn’t matter.

I usually draw my layout and then look it over and decide which things need to be cut first, and color them all black (there can be black inner cuts on multiple pieces – each piece doesn’t need its own set of colors), then the next bits to be cut are blue. That’s usually enough, but if there are multiple concentric cut lines, I might end up using green and light green, but I rarely have to go as far as aqua.

The example you posted can be done with two colors for cuts – I’d use black for both inner circles, and blue for both outer circles. Each part doesn’t need its own unique set of colors. The engraves don’t either, unless they’re going to be different engrave settings; you only need one color per engrave setting, across the whole file.


#13

Use greyscale for the engraves and vary power. Problem solved there and a single operation so it’s faster.

As for the cuts and flips, it’s kind of hard to see what you mean but like @geek2nurse says you only need a number of colors equal to your embedded pieces. Maybe 5 on the right circle? Kind of hard to tell by looking what you intend to cut.


#14

In those everything is in vectors as I need to change the diameters frequently depending on the final diameter of the screen. The dampness of the screen can have a huge difference in the diameter. I was very confused at first as the width of the wood was all the same at the start but 8" wood can be 8-3\4" at the time of bending only to go back as it dries.

For this reason depth by grayscale does not work, and as both the ears and the space for the ears are engraved at the same time that engrave needs to be just past halfway or the trick does not work as the part with the ears has to flip over and be glued to the piece with the “X” that the legs need to fit the depth of the “X”. Then the part that the screen fits into needs to be the correct depth and often that is different between top and bottom and of course all the cuts have to go all the way through and the bit with the ears will need less cutting than that which is not cut by the engrave first.

Often any of those will need another pass if they were too shallow the first time or even another top or bottom made if the first is ruined. And in either case ignore is a friend that would be a better friend if the setting would survive the ignore.

I do sometimes combine the top cuts and engraves to save time but the rest needs more control.

Currently I am working on a vase that uses 30 concentric cuts, and working from the outside in is causing a lot of warping and the warping is causing a lot of places to not cut all the way through and the bits are thin enough that cutting them out with a razor is not a good solution and 30 colors/layers is not ideal either

this is the current example:
haf2


#15

Agreed, this is a conspicuously absent feature. I have been making something lately that requires many prototypes, and for every round trip from Fusion 360, I need to export to DXF, open in Illustrator, recolor the lines, save as SVG, open in GFUI, and adjust the settings. It’s quite tedious. Inside-out path sorting would at least eliminate one step.


#16

I wonder if breaking the paths in the same “corner” and then changing the color of the innermost “clover” to black would solve the issue? In theory this would force the start/stop point on each concentric cut and force the innermost cut first. Perhaps the GF algorithm would go for each successive ring in order due to proximity?


#17

My experience is that it does each piece in succession and where applicable . each piece from outside in.


#18

Right. But perhaps forcing the first cut to be the innermost would override that? Worth a quick shot maybe.


#19

Yes and not hard to do in about a day by a competent programmer. And before I get shouted down for saying this I actually coded this for my 3D printer in about a day ten years ago but obviously the opposite order as you want to do outlines first when 3D printing.

I make a tree structure of loops which enclose smaller loops.


#20

It just made a liar out of me. I am recutting that design now and it is jumping about a lot the outer first then skipping 3 two more and then a skip and on in picking up the left behinds going back out. Not a solution, but not linear either. And not what was happening yesterday.