Vocabulary

qa

#1

Not necessarily an ask Glowforge so much as anyone willing to help.

I can’t be the only one relatively new to laser cutting/engraving. Anyone want to dump so vocabulary lessons out here or point us at a good resource?

so far I’ve seen kerf, learned that engraving is removing some material from a surface, cutting is removing all the material. That what happens to the surface of a macbook when shot with a laser isn’t called engraving, and that it’s also not engraving when you use a product like cermark to make black marks on metal.

So anyone have a good Primer so I can actually ask intelligent questions?


Contest: Design a replacement part for something that is broken
Beta day - five (Fitted Gauge Box)
The "My First Laser" thread
#2

Awesome request!

Kerf = material removed by the laser.
CO2 = the gas that actually emits the laser light you use. (Other gasses are present to contribute to the reaction and the proportion is important).
CNC = category of machines that includes robotic mills, lasers, 3d printers, etc.
additive = building up a print layer-by-layer (e.g. Makerbot)
subtractive = carving away from material (e.g. othermill, xcarve, glowforge)

Other ideas?

BTW engraving, in common usage, does include marking-but-not-removing, with and without Cermark:
https://www.google.com/search?q=laser+engraving&source=lnms&tbm=isch&sa=X&ved=0CAkQ_AUoA2oVChMIl_7bnPGuyAIVhZSICh0cDw18&biw=1920&bih=1031


#3

CNC Definition: Computer Numerical Control (CNC) is one in which the functions and motions of a machine tool are controlled by means of a prepared program containing coded alphanumeric data.

I also stumbled upon a tree-file e-book with a glossary of a bunch of relatable terms that should give you much more exposure to terms used in the industry

CNC Handbook

Here’s the Wiki for you guessed it…

CNC Laser Cutting Wiki


#4

Thanks for the links! As another laser newbie, are there other good reference materials you suggest I read before getting my GF? I know there is a lot of information out there and I’d like to get right to the verified reliable stuff.


#5

The common usage you refer to is also very specific regarding materials. Take a look at how Epilog markets their CO2 lasers and is careful to specifically list coated metals and anodized aluminum. That would prevent a lot of the understandable confusion among buyers who want to do things like engrave untreated steel. Some people were obviously mislead and thought they could do things a fiber laser is typically used for.


#6

I’d also add in some joinery terms such as “dogbones”, which are useful for preventing cracking in acrylic or if you’re designing objects that include CNC milled joints. Finger joints and T-slot joints (AKA captive nut joints) are also commonly used when laser cutting.


#7

CAD: computer aided design
Swarf: the material that gets ejected from the kerf. I guess that would be vaporized material with a laser.
Parametric: that was a new use for me. I was thinking of the math terms but as it is used in the 3D world, it seems to mean a 3D model that has a 1:1 correspondence in measuring to the finished product.
raster: (taking a shot here, not as a technical definition but as I understand it. Crucial but basic distinction that folks have to make when doing any computer imaging.) X,Y coordinates on a screen to refer to dots or pixels. Bitmaps/rasters represent images or lettering and are saved as specific file types like *.jpeg, *.gif. So this will be used for the engraving, marking function of the Glowforge. Photoshop and Gimp are bitmap/raster playgrounds. When they get the power supplies dialed in and the software setup,
greyscale or the % from pure white to absolute black will correspond to different depths of engraving, at least as I understand it.
vector: Using equations to describes lines to represent an image. Again, I’m not doing a technical definition here, but how I understand it. So 2piR will give you the circumference of a circle. Just fill in the radius. Very efficient way to describe the circle. This enables you to resize the lines/vectors of a file to real big or real small. Illustrator and Inkscape are native vector playgrounds. What is needed for cutting through a material.
Open to corrections and will happily edit this post if necessary.


#8

Minor corrections:

Parametric: based on parameters. So you don’t have one line that you drew twice as long as the other. You have a line that you DEFINED as twice as long as the other. Now when you re-size either line, the definition forces the other one to resize as well. This lets you change the scale of a design while keeping the shape. Definitions are often very complicated (like branching at a 25 degree angle from the midpoint of the intersection of line AB and a tangent from circle H)
Raster: progressive scanning, going from the far left of a single line to the far right, then moving down one line and moving from far left of that line to far right. Repeat until finished.


#9

or as I like to think of it:
Vector:

Raster:

(Old CRT video games could choose to either drive the beam back and forth, blinking on and off to create a bitmap, or from point to point directly. The former gave more options as you could have any arbitrary arrangement of pixels represented; the latter gave more intense bright lines but without the ability to fill. The analogies to lasers are pretty close.)


#10

So many terms, not just here, have the technical meaning and then the common usage meaning and sometimes more than one common usage. So when trying to communicate with someone I have gotten to where I am not bashful about asking what do YOU mean by “X”.
@jacobturner gives several technically correct definitions but I have heard people use parametric to mean closer to what @marmak3261 said.
I think a lot of this happens when technical people start doing art, and artsy types start embracing tech.


#11

Good improvement to the discussion. It made me understand why raster is being discussed in regard to laser cutting and not bitmaps. So the way I understand it, the image file is a bitmap but the laser behaves as a raster projection when it engraves that bitmap, going back and forth, one row at a time. While it is vector cutting, it follows the line vectors of the image. Watch @jacobturner’s demo of cutting my matchbox bin and the way the laser path works.


#12

Well, my videos only show vector for everything (with terrible toolpath on the celtic cross). But the videos of the GlowForge in action doing the hand drawings on acrylic show the difference very nicely. The laser goes back and forth like a dot-matrix printer to etch the interior design, then when done with that it rushes around the perimeter really fast to do the cut work.

The interior stuff is the raster, and the exterior is the vector.

But… you do have your description spot on for what is what, so you probably did know all of that. I wasn’t sure if what you wrote would confuse someone who hadn’t caught up yet when sending them to watch a supposed demonstration of both techniques and seeing only one.


#13

Designer/artist abbreviations that have other meanings too:
AI: Adobe Illustrator (so “you should design this with AI” does not refer to artificial intelligence)
Ps: (adobe)Photoshop (“I made this in PS” does not mean you made it in post-script)

Quick breakdown of formats: (source: ideabook)

@marmak3261 I feel like I should point out that Ps can work with vectors (to a point), and AI can work with bitmaps (to an extent), although you are very, very correct about the “native playground” part of things. Vectors and bitmaps can both be exported from either of the programs. If you make a design as vector in AI and then “export for web” as a jpeg, you have exported a bitmap. If you make a vector shape (or “path”) in photoshop you can “Export > Paths to Illustrator”. If you save something as a PDF or EPS, make sure your save settings match your intent: they are both “wrapper” formats, and the file may contain vectors and/or bitmaps, but that is up to you. Simply saving a bitmap as a pdf or eps does not convert it to vector.
More good info here on Graphic Design Stack Exchange.


#14

Good extension to the fundamental definitions. How the programs we will use play with each other in the work flow is important.


#15

As far as the ‘parametric’ buzzword goes, I like to think I have lots of experience pinning down a definition from it’s use (or maybe overuse) at my university :wink:

As @jacobturner stated, anything parametric means that the final object is derived from a set of rules, or parameters. So instead of modeling a vase with a height of 10" and a width of 5", you would establish input parameters saying height=x and width=y, and that way the values can be changed to give an output form (say a 3Dmodel or svg linework) adapting its shape to the parameters rather than you having to go in and re-model or re-draw all your objects to meet a static set of numbers.
I see the definition @marmak3261 gave about parametric meaning 1:1 scale modelling as more of a result of how parametric modelling works, since when you’re giving your input values (“I want my vase height at 12 inches”) it makes more sense to give the full size you want your final object to be rather than a scaled number. :smile:

edit: just noticed I am 24 days late to the party----whoops! haha


#16

SUPER handy if you’re designing a lot of parts that need to be assembled after being cut… move or change one feature and every other feature that depend on it changes as well.


#17

Yes!! Especially if you have, say, a lot if intertwined gears- it would be way too much of a pain if you end up re-sizing one gear and then have to go and remodel every other piece.
And then from a product design standpoint, parametric modelling allows for you to introduce ‘mass customization’ into your products: instead of selling a single-sized vase (if you haven’t noticed- vases are my go-to examples lol) you can offer buyers custom options, allowing them a sense of contributing to the design and therefore making your product more interesting or attainable if people have size limitations. Then, even if you have 20 differently sized vase orders, all you need is one definition with all of your size inputs- just plug in each customer’s numbers and voila! A new model each time without you having to do all the modelling work over for each new vase.