How to create a Test Cut

testcut
basicskills
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#1

I know this has been asked before, I’m pretty sure that I’ve asked this question before, but I cannot find it using search, and I don’t think that it had actually been fully answered before.

If I want to use a non-proofgrade material in my laser, how do I create a “test” that will tell me what I should use for engraving vs cutting vs raster?

I’ve never used a laser before and I haven’t had access to a laser before, so I’m interested in all the steps needed, what I should be looking for, and how do I know that my “test” was a good one.

The only thing I can think of is a spreadsheet style grid that increments speed across the top and power down the left side and let it run. But at some point you should hit a combination that will cause more problems than solutions (test cut on paper vs Maple should have VASTLY different results). How do you handle this today with your lasers?

Feel free to “dumb it down” as much as you’d like, I don’t want to miss any steps.


How to generate Test Cuts / import settings
#2

You’ve got the right idea. I have one of those grids for cuts and one for engraves for different materials - paper, chipboard, acrylic, plywood and solid wood. Each of the “cells” (either a cut line box or a raster engrave) is a different color. Then in my laser software I set the power/speed for that color.

The reason for different copies of the calibration files is because paper has radically lower power & higher speeds than wood. I copy one and tweak it for each new material and engrave the material spec on the sample too (e.g. Baltic birch ply 3mm) so I’m not puzzling over it later to figure out what is this material? :slightly_smiling_face:


#3

How big does it need to be to be useful? I doubt 1"x1" squares, but I don’t think a dot for each combination is really useful either. I’ve seen people post pictures that have a specific design or line work to test when the laser makes a corner or turn, how necessary is that?


#4

Here is an appendix from Epilog where they give some recomendations per material and per machine power (30w, 40w, 60w, etc) and by kind of engraving (photo or text) :wink:

And as they say you can start with a lower power then raising it up. And also you can do someting like this once you have the power and speed reference.


#5

This is similar to what I was thinking. But what about those points where the material starts burning? Say I have a material that burns at 40 speed and 80 power. Do you just keep going through all of the other options (essentially just saying “HOW badly does this burn”)?

Do you only print one Column or Row at a time, inspect, and then load up the next Row or Column? That seems like it wastes a lot of time.

I was under the impression that testing a new piece was a simple but necessary step. The more I’m thinking about it, the more it seems like it’s own project (that apparently takes up a lot of space?), the piece in the image you posted looks to be about 6"x10" or so, that is a lot of material to “waste” each time just to check settings. Is this just a new reality of having a laser?


#6

I’m a newbie like you, and I also have never experience with a laser… but what I think we could do, is only use the values in the glowforge, test them, then use this kind of table (but a small one) only with the values near the values saved in the glowforge.


#7

If you are using materials you havent ever used before, its a really good idea to have something like this handy. Otherwise you will want to start a cut/engrave and end up forgetting what is the best level and ultimately ruining the cut/engrave and having to wing it which will be a huge time sink. having a nice point of reference for each material is so incredibly helpful, and prevent so much material and time waste.

This is definitely a reality of laser ownage and something proofgrade was designed to save you the trouble with. Ive really enjoyed the ease of use with proofgrade so far because of this exact reason.


#8

I order the cuts/engraves in ascending order of power delivered. So the first one is the lowest power with highest speed. The last one is the slowest speed & highest power. When it starts burning I open the lid and hit the stop button.


#9

Bookmarking!


#10

Another thing I would highly recommend doing is to do raster gradient engraves on each material. Sometimes these white to black gradients wont be a smooth curve on the material you are using, so you have to adjust for them in photoshop to get it to appear correctly on the material.


#11

ummm, can you explain this more? I’ve heard this around the forum but I’m not following HOW to do this. I realize white is less laser burning the material and Black is the most, with the various shades doing incrementally different burning of the material.

But can you explain HOW you do “raster gradient engraves” for each material?


#12

For the most part you just drop in a gradient image:

and hit engrave with whatever power and speed you want to test. I would do this even on proofgrade with recommended settings.

This can even somewhat take place of the solid black boxes if you just put the black box at the beginning of the gradient. Not all lasers have variable power engrave though, which is why some people just do the squares like in the image above

When I get home Ill see if I can take some photos of some samples and maybe make a little tutorial. I need to do some on some other materials anyways!


#13

that would be immensely helpful. I’m doing what I can to learn, but it’s hard to retain the information when you can’t use it anywhere (use it or lose it!)

So I’ll just be saving it off to reference later.


#14

Do you do this one “square” at a time, re-evaluate, and then engrave or raster or cut the next one?

ok…another stupid question. As far as the laser is concerned, WHAT is the functional difference between engrave, cut, raster, and vector?

I thought vector was just a design element (a vector image can be scaled to whatever size and still look non-pixilated), engrave was just a cut that isn’t all the way through the material, cut was an engrave that went through the material, and I have no idea what a raster is.


#15

At the heart of it,

  • Cutting uses vector (lines) to cut all the way through the material.
  • Scoring uses vector (lines) to cut part way through the material.
  • Engraving uses bitmaps or vectors to cut partway through in a back and forth pattern (raster or rastering). Engraving can be done at one or more power settings to change depth/darkness.

It can be much more complicated (as other posters will elaborate), but this is at the heart of it all.


#16

No. I specify different colors for each power/speed in the file. Then I tell the laser software what order to do those colors. I also tell it what power/speed for each color. Then I send the whole file over to the laser. It takes the first color and engraves. It moves over and ups the speed or power and engraves the next box/color. When it hits one of the boxes where the combo causes it to burn, that’s when I hit the stop button.


#17

huh…scoring. There’s another term to identify.

So Scoring and Cutting are related to each other. Engraving and Rastering are related terms. All of these can be done using Vectors (assigning different colors to different speeds and powers to achieve different things), but bitmaps are usually restricted to Engraving/Rastering functions.

Is that about right?


#18

Do you then go back and resend the file, but only selecting other boxes that haven’t been run but you suspect won’t cause burning?

I’m imagining running my file starting at 10 power and 100% speed and then moving in a diagonal type pattern until I start burning things.

10p-100s, 20p-100s, 10p-90s, 30p-100s, 20p-90s, 10p-80s, etc…(where p=power and s=speed)

Please let me know if I’m not going about this the right way.


#19

You’ve got it…

Scoring is a partial cut, useful for creating fold lines in paper, cardboard, foamcore, etc. Not really a thing when laser cutting/engraving wood, tile, stone, glass, etc. I’d guestimate that 90%+ of GF owners will rarely, if ever, score materials. But I could be very, very wrong.

“Raster” describes the back and forth pattern used to fill in a space. CRT TVs and Montors used electron beams scanning back and forth from top to bottom to “draw” images on the screen phosphors. Now it refers to any process that uses back and forth patterns to fill in a shape.

When you watch the GF videos that show engraving shapes, you’ll see the head move rapidly side-to-side along the X axis and the then entire gantry take a microstep in the Y direction. That’s rastering.

When cutting along a vector line, the head can move in both the X & Y directions at the same time. Think Etch-o-Sketch. :wink:


#20

A bitmap is a raster image.

I know that we are working on making our own tutorial set, but in the meantime, this is a pretty clear breakdown of vector (vector) vs. raster (bitmap):
http://vector-conversions.com/vectorizing/raster_vs_vector.html