# The economics of nesting

So it’s that time of the year where I relearn old lessons. Here’s today’s gem:

Be careful how much time you spend messing with arranging parts in a design, it is rarely worth it from a time-money perspective.

Today’s example – take these two layouts of the same parts:

Layout A is a simple grid using the Inkscape grid arrangement tool, layout B was after manually tweaking and arranging.

The Math!

Layout A:
Width: 20.678"
Height: 4.658"
Area: 96.318 in2

Layout B:
Width: 21.285"
Height: 3.833"
Area: 81.585 in2

Differences:

Layout B takes 84.7% of the area of layout B, a savings of 15.3%. This works out to 14.7 in2 savings. This is great!

… except for the fact that the material is 1/8" Baltic birch plywood. Let’s figure out how the cost works out.

I get my baltic for about \$2 per full sized sheet. That’s 240 in2 for \$2, or \$0.0083/in2 Multiplying that by the amount of area saved - \$0.0083/in2 * 14.7 works out to… \$0.12.

Yup, I did all that for twelve cents.

OK so let’s look at it a different way: Maybe this is the deciding factor between fitting it on one sheet versus two. That means I would save setup time etc. And if that were the case, maybe the economics work out based on how much time it will save In this case, nope. It’s about 1.5 sheets of material no matter what I do.

A waste of time, something I occasionally have to relearn.

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The number of times when fitting on already cut pieces I fiddle and fiddle and fiddle, and then smack my forehead and say “Your going to trash the remainder anyway!” is…not small.

Even if I’m not going to trash it, saving a 3"section vs 1" section just isn’t worth anybody’s time!

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There is a certain joy in squeezing extra pieces in sometimes, but I have learned the same lesson more than once and will doubtlessly learn it again.

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i’ll spend a few minutes arranging to save a decent size piece. but i won’t spend a lot of time.

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This is a good example of when it is just not worth while. I’ve developed a “feel” for this over time and if I can save a 1/4 of a sheet in less than a minute then it is well worth it to me.

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What about arrange for straight cuts? Less time on the laser? I tried arranging for shared sides too, but then realized that kerf would be off, and you want more precision.

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Yeah no shared lines for the kerf issues.

Maybe straight lines though. Dunno.

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I have this same disorder. It’s hard to remember that wasting time is the biggest waste of all.

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Also translated as “better is the enemy of good enough.”

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(Me, being the enemy of good here)

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You can make this game more fun by worrying about grain direction, etc.

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That’s the reason! It’s not about the money saved, it’s the intrinsic satisfaction of doing something that’s a little challenging. The satisfaction of solving the little placement puzzle is often worth far more than whatever other mundane thing I might be doing.

I spent 2 hrs getting the CNC to cut a 45 degree ramp on the end of a piece of wood stepping the mill sideways & downwards in the G-code. Someone watching me pointed out that 10 seconds with a table saw & it’d be done. But sometimes it’s not about the efficiency, it’s about the doing in another way.

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Premature optimization is the root of all evil
– Knuth

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Voltaire didn’t know about Deepnest.io !! (https://deepnest.io/)
I haven’t actually tried it out yet, but I came across it awhie ago. Open source, and looks easy to use. Now you can have your cake and eat it too =)

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Deepnest has been discussed here a lot and it hasn’t always gotten great reviews. I remember trying it out once early on and it just didn’t work.

Here we go, early 2018.

Enough time has past that maybe I should give another try, but it had serious issues especially with changing the style and colors in your files.

Also it’s funny that even back in 2018 when I made this post I was already talking about how fiddling too much with nesting was a waste of time. Brings us right back to the beginning of this thread: it’s one of those lessons I just have to keep relearning.

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nesting for one sheet doesn’t make a ton of sense financially.

if you’re cutting 50+ of the same sheets, it starts to make more sense. it’s not really a special tool for crafting, but for commercial production, it starts to make more sense.

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Ok let’s assume your sheet cuts one per half hour. That’s 25 hours of just laser time, not even going into whatever else you have to do for each sheet with the physical products.

50*\$0.12 is \$6. Six dollars.

That’s 24 cents per hour. I’m not sure what your hourly rate is but \$.24 is awfully small.

I stand by the idea that it rarely makes sense economically.

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if you’re cutting the same sheet over and over, nesting will get more product on one sheet. at some point, it makes sense to do that if it saves material. if you nest and it saves 15% of the sheet, you save ~1 board for every 6 you cut. 7 into 50 means saving ~7 boards. if you could run something like deepnest and it was effective, which only takes you a split second of your time to hit “run” and let it go do it’s thing, then a few seconds of your time would save you 7 x \$2 (if it’s cheap BB). if it’s mirror acrylic, it might be 7 x \$10. and if you do that 50 times a year, that’s \$3500 in mirror acrylic savings.

and if that only takes you a few seconds of actual work (while letting the computer do the hard part), i’d do that.

again, keep in mind that i’m talking about doing it at scale, not as a crafter. and i’m not even considering the time savings, just the material cost.

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I almost never do anything on partial sheets.

I make reasonably tightly nested full sheets and don’t screw with partials. Not worth the time with Baltic birch

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