Why I hate box building - The tedium of shaving - why does this happen?

Do the designers provide a way to verify that your design imported at the right size? If there’s a pdf option, I always use that, because it doesn’t have the problem with sizing issues that svg has.


With MDF especially, time and humidity allows it to “dance in the moonlight” and be different the next time you look at it. With humidity it will become thicker than before and that little bit of water will even make the cut thinner and not as deep as the same settings as before.

More often the complaint is that the setting that cut through before now does not. But if the kerf was very tight to start with it might be too tight.

As well, if the total size of some part was changed even a little the the total length could be off even a hair and things will start at one end but get increasingly impossible.

I have a smallish flat file that one edge has teeth and the other edge does not. With the no teeth edge in, it is thin enough to just do the sides of the teeth and usually only need a bit of edge taken so they start after which they compress in tighter and tighter.

If the holes are too small for that file a set of needle files works great.

Also a design set for poplar will be too tight even with fresh MDF.


Explain NERF setting. I am just dropping the design and cutting…

that’s a typo. kerf is the term. that accounts for the amount of material that is lost by burning through. if you make the file have the fingers and the slots the same size, it will always be loose because the laser removes material burning through. so you compensate for the kerf and make either the fingers larger or the slots smaller. that amount can be material dependent, since different materials have different amounts of kerf, since they all burn differently when cut by the laser.


Ahh, so basically, what I am doing, which is manually shaving the “teeth”. I spend the same about of time trying to manipulate the holes in the design, so same amount of time is spent.

If you’re taking long to adjust for kerf you’re doing it “wrong”. There are easy ways and less easy ways to do it, but even the most difficult manual methods should only take a few minutes.

The simplest thing to do is to use a box generator and tell it a kerf value of something like 0.005-0.007”.

Again, though you have yet to tell us a detailed account of how you’re doing this. Until you do we’re just stabbing in the dark which is inefficient all around. Help us help you :slight_smile:


The “detail” is this: I find a box design that says its for 1/8" plywood. I load design in GF, load Medium Draftboard, hit the power button. There is a %90 chance I have to then whittle to make things fit, and/or use a hammer to get the slots to connect.

Yeah but find where Is the key.

If you didn’t generate it you’re gonna have to scale it.

This is where the conversation crosses the threshold from “something that you can help with on the forum” to “something that you need a much longer conversation about” which would be much easier in person.

My advice is to get very familiar with box generation. It’s easier than figuring out scaling at first.


I really like the idea of adjusting for nerf! :wink: Kerf is so boring :yawning_face: If you are in Inkscape you can set the linewidth at the expected nerf then Stroke To Path in the Path pulldown and then Break Apart in the same pulldown, you will have an inside and outside path, just one nerf apart, so if the inside is cut as the outside and vice versa they will fit perfectly (making sure the sizes are equal where nerf is no issue)

However, your problem suggests that the adjustment is too much. If you cannot manipulate the design then you need to cut the approved material it was made for or get that flat file.


The issue is that it is very rare to find plywood that is the thickness that it says it is. 1/8" plywood rarely ever measures 1/8" thick, but some do. I find that even pieces cut from the same 4’ x 8’ sheet of plywood will vary enough from one end of the sheet to the other. This variation has been enough to provide a good fit on one end and have to sand or file fit on the other end of the same sheet. It’s not the file designers fault.


Everything @wilsonpf said is spot on. I’ll add “probably”. It’s probably not the designer’s fault.

This is one of those reasons why I said it’s hard to really thoroughly cover this on the forum, there are things the designer could do that might make the design unworkable at any scale. Covering all of them is not practical in a post… if we were face to face we could talk about kerf and scaling issues for literally hours and not cover it all.

Generating your own boxes will let you sidestep an army of issues.


Yeah, the one where you use what the designer specified - 1/8" plywood. MDF is not plywood. Even though GF uses “Medium” on many materials, the measured thickness is not the same. Medium MDF is pretty consistent batch to batch. Medium basswood plywood is generally the same thickness as medium maple plywood. Neither is necessarily the same thickness as medium MDF or Medium Draftboard (which is what GF’s Proofgrade MDF offering is called).

Try using Medium PG plywood and see if that fixes your issues.


i use a box generator. I lie and tell it my material is 3.2 mm thick. that means I almost never have to fuss with the parts to get them to fit. Yet, many times they fit so well, the glue is not needed.


Looks like the one from here.

If so, it came with the editable file and you could adjust the file before you cut it.


which box generator are you using? the one i use (boxes.py) actually has a kerf setting.

1 Like

I use the same. many good ones there.

if you use boxes.py, you don’t need to change the wood thickness. there’s a kerf box.

1 Like

Yeah lying about material thickness makes your fingers longer. If you’re sanding them flush to get rid of the dark fingers aesthetic then definitely pad the material thickness*.

* again there are exceptions to this. Boxes with dividers don’t like to be lied to about material thickness, etc.

1 Like

yep. in that same dialogue, I set thickness to 3.2 and leave the burn at 0.1

i use the display case generator on boxes.py often. fibbing about thickness makes the tabs go into the holes much more easily
demo box