Cutting a beam, does the kerf matter?

[mikey]

I noticed a comment on one of our YouTube videos, “Made with GridKit: a step stool for Mix and Ziva”.

@AndrewHelgeCox says:

Have you ever had issues from some beams being half a blade kerf short on one or both ends when you cut them after drilling a longer beam? Indoors on flat hard surfaces I mean, or parts touching parts, not beam ends resting on grass.

At least from what I’ve learned, when cutting beams, the kerf doesn’t matter as long as all your beams are cut the same, exactly in between the holes. And yes it’s important to make sure your beams are cut the same, otherwise yes you will have problems with beams touching flat hard surfaces unevenly.

So that’s why I made this cutting jig, to ensure all your cuts are the same:

3d-printable cutting jig for grid beam

A 3d-printable jig to help you accurately and precisely cut grid beams and panels with a standard hand saw. View the OpenJSCAD 3d model (and export 3d-printable file) View the OpenJSCAD source code [hand-saw] [cutting-jig-1] [cutting-jig-2]

So this means the length of a 30gu (30 grid unit, or 30 hole) grid beam is actually 30 * 40mm minus the kerf on each side.

As far as I understand, since it’s not possible to avoid this kerf, it will never be possible to have two beams in a line touch exactly, they will always have the kerf gap in between.

In my mind, the question then becomes, what is the standard kerf size? Standard hand saw kerf, japanese low-kerf hand saw kerf, standard circular saw kerf, or what?

When selling beams, we’d want to match the same kerf that people will have when cutting, so all the beams lengths match up and meet up evenly.

That being said, I think the differences between kerfs are less than the differences between a non-exact cut. So at least if we help make exact cuts, the beams should be much more even.

What do other people think about this?

[incidentist]

It’s a good question. One possibility is just to use the smallest kerf possible, with the understanding that if someone buys a beam and makes a cut with a wider kerf, they can shorten the other end if they need to (by…sanding, I guess?), but they can’t lengthen the end if Village Kit assumes a kerf that’s bigger than theirs.

It’s also worth mentioning that only a fraction of the beams need to be perfectly even in that way – the beams whose ends touch the floor.

That jig is great, by the way. I made a similar one by laser-cutting that pattern into some thin wood a bunch of times, and gluing the layers together.