Thank you!
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Yeah, that was how I was using them long ago…had some pretty lengthy ones written up that personalized name plates.
I’ll get around to playing with it one day, but it’s going to have to take a rear seat to the design at the moment. I want to keep creating while the muse is with me. (And no, not the laser kind.) 
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Ah I see.
This isn’t true. All closed shapes get kerf-adjusted in the exact same way - offset the lines by half the kerf width.
ALL closed shapes. Half the kerf. One process for all shapes for all cutting tools in all materials (that hold their shape after being cut).
I’m probably willing to explain it, again, if you care.
Not in this case. I designed the tabs to extend exactly the width of the material thickness, and didn’t want to adjust the receiving side. (This was in AI so I was working manually to adjust specific tabs.)
I’m also trying to use the slope of the kerf when it’s set at the surface to provide enough resistance to allow for kerf adjusting acrylic for a snug, but not splitting, fit. It’s a bit tricky, but I actually had some success with it this afternoon.
I’d post the project but I’m not happy with the overall concept on the design…it came out a bit clunkier than I like. But the acrylic part of it worked, so I guess it was enough for one day.
I’m just trying different methods to see which one I like best for my own designing.
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If you don’t compensate for the kerf properly, by offsetting the lines of all closed shapes by half the kerf width, your tabs will not be cut to the proper (as-designed) dimensions.
Thankfully, I don’t have to explain it all again, as I did a pretty good job last year.
If you want your tabs to be the exact same lenth as the thickness of the material, and you’ve designed them to that length, you’re going to want to cut them with the kerf-compensating technique that will cut your tabs to the correct, as-designed, length.
Thankfully, the kerf-compensating technique that you will want to use in this instance is the exact same as the technique you’ll want to use for all other instances of cutting out closed shapes, and that is to offset the lines by half the kerf width.
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I’m not adjusting all of the lines, just the tab width. I’ve written about four tutorials on it now. They’re in the Tips and Tricks section. I know the half-kerf offset trick which works for all parts, if applied evenly. I’m trying something else now.
The half-kerf offset “trick” is THE method of compensating for kerf.
Of course, you can offset whatever you want, but unless you’re offsetting closed shapes by half the kerf width, you aren’t…
… you’re just offsetting. And if your goal is for the ends of your tabs to sit flush with the material they’re slotting into, you’re going to want to
A. design them to the proper dimensions and
B. do a proper kerf-adjustment on them (offset the lines of all the closed shapes by half the kerf width)
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It’s been a while since we’ve had a good kerf discussion.
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I’m doing something that works for me quite well. I chose not to use the half-kerf offset this time.
I’ve actually found easier methods of doing things sometimes by not doing the “accepted” thing. It’s just exploring.
Easier than offsetting? So something where you don’t need to…
?
Yes, in this case, since I designed the length of the tabs to be exactly equal to the thickness of the material. Offsetting was expanding the length of the tabs so that they extended just a hair past the flat surface, making it difficult to glue the next piece on, which required a perfectly flat surface. In order to change that, it would have required a complete redesign of the tabs, which would have been more trouble than it was worth.
So I adjusted the width of the tabs only for kerf. Kerf doesn’t appear to be a one-size fits all prospect, although generally, if the tabs are not designed so precisely, the half kerf offset would probably work.
As far as writing the Action for something like that…it would be a bear due to Illustrator limitations, and I haven’t given it any thought yet.
All part of designing these things, and it varies significantly for material. Acrylic is a lot less forgiving than wood.
Nope. You’re obviously breaking reality by doing it wrong. Back to the drawing board and do it all over again.
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I’m sorry. 
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A + B - B = A
MT + HK - HK = MT
MaterialThickness + HalfKerf - HalfKerf = MaterialThickness
MaterialThickness + HalfKerfCompensation - HalfKerfLoss = MaterialThickness
If you know your material thickness and use that for the length of your tabs, then offset that length by half the kerf width, then cut the part out and reduce the tab length by half the kerf width as part of the cutting process, you will be left with tabs that have a length equal to that of the thickness of your material.
If your tabs are coming out longer than the material thickness, part of the equation has not been measured, entered, compensated-for, or cut properly.
Measured - This is pretty straightforward, was the material measured with an accurate instrument? Were all the relivent factors taken into account? (was the material measured with two pieces of thick paper glued onto it?)
Entered - Transcription error? Um… Rounding error?
Compensated for - maybe offset by the full kerf width? I’ve done that.
Improper cut - machine accuracy? Lost steps? Is the actual kerf different than expected? (This relates to measurement errors as well.) Maybe the power or speed of the machine is different than when the kerf was originally measured, or the focus is different, or the lens is dirtier (or cleaner) than before. Inconsistencies in the cut behavior of the material. Who knows.
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The tabs are at a 90 degree angle.
If these 90° “tabs” are being cut by a tool that creates a kerf, they need to be kerf-compensated to be cut to the right size.
If they’re coming out at the right size, and it’s not just a fluke, something is properly compensating them for kerf. Since you aren’t, my best guess is the Glowforge software must be automagically compensating for kerf in the background for some reason.
It sounds like these “tabs” are being cut by raster-engraving. I can believe the raster-engrave routine kerf-compensates. Though, that does make me wonder why two sides apparently still need to be offset for them to work.
The tabs being the right size but in the wrong position is something that I would call a “fluke”.
Not kerf compensating them cuts the length of the tabs half a kerf less that the thickness of the material, which makes them recessed and gives a flat surface when they are inserted into the tab slots at a 90 degree angle. The thickness of the material receiving the tab is not something impacted by kerf.
Two dimensions out of three. I needed to compensate for kerf only on the two sides of the tab, not the depth. And I needed to do it without changing the interior dimensions either.
Anyway, it’s not something that most people are going to run into, and it’s really only necessary for something like acrylics which have zero yield. Definitely not something I plan to spend a lot of time on. Much too limited use.
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I see, you actually want the end of the tab to be recessed below the material and you’re using the kerf loss to create that reduction in tab length.
When you said “flush” above, I interpreted that to mean “of a surface exactly even with an adjoining one, forming the same plane”, but I guess that was just speculation on my part.
I couldn’t seem to get that without leaving the length un kerf-corrected no matter how hard I tried…the acrylic melts unevenly and gets a little rounded. It also slumps towards the base. It’s a fraction of a fraction of a mm, but it still impacts how far above the thickness the end of that tab hits.
In this case, not kerf correcting one dimension is a compensation for the properties of the material.