Crafty new box joint technique

[st_indigo]

This project on the Make Magazine site (http://makezine.com/2015/05/20/custom-tablesaw-blade-revolutionizes-wood-joints-single-cut/) shows a very crafty way to simplify box joints using a specially-made table saw blade. I saw it and immediately thought, hey, we can do that with a CNC router too!

It's easy enough to replicate with a 1/2 inch 90° V-bit and an end mill. That last pass with the V-bit should leave a skin on the bottom face of the plywood so the pieces fold together as shown. Watch the video clip on the Make Zine site to see how it works.

Spend a little time on the lay out your drawers and you'll be able to cut them out all at once with one bit swap. Glue, fold, and off you go.

I'm going to give it a try soon and post my results.

https://farm8.staticflickr.com/7663/17758375979_599132774f_b.jpg

[darren salyer]

Cool.

[Drexel]

Very interesting Philip. I'll be looking for your results.

[darren salyer]

I'm guessing zeroing off the table surface would be an easy way to accomplish this.
Looks interesting.

[Drexel]

I'm new at CNC (just did finish my build of the MechMate) so forgive my ignorance.
If you tell your cad/cam program to zero at the table how would you allow for the fraction of an inch you would want to leave so that the corners would stay intact while folding?

Would telling your cad/cam program that the wood your working with is slightly thicker then it really is work?

[Alan_c]

In your CAM program you would indicate if you are zeroing off the surface of the material or off the table. If the material you are working with is say nominal 18mm, you would set depth of cut at say 17.5mm - by setting you zero on the table surface you can be assured that the cutter will not drop lower than the 0.5mm above the table surface, how ever if you zero off the material surface there is no guarantee that the material is uniformly thick and that your depth of cut would be as accurate.

Of course it is essential that your table surface is accurate and flat over the entire work area so if doing work to this sort of accuracy it may be beneficial to surface the table before starting the job run.

[darren salyer]

Sorry, just checked back in. Exactly what Alan said.

[Drexel]

Thanks Alan, Darren. I've never tried zeroing off of the table. I'll have to play with that a bit.

[servant74]

I saw a YouTube where someone has come up with a table saw blade to add to a dado stack to cut the same profile. ... Interesting. ... They are trolling for a manufacturer or partner is looked like.

[pblackburn]

Zeroing from the table is common when you need an exact height. It usually is done with a zero setter but can be done with a piece of shim and stepping down by the thousandths until the shim will not move under the NOT turning cutter.

[ger21]

I'm new at CNC (just did finish my build of the MechMate) so forgive my ignorance.
If you tell your cad/cam program to zero at the table how would you allow for the fraction of an inch you would want to leave so that the corners would stay intact while folding?

Would telling your cad/cam program that the wood your working with is slightly thicker then it really is work?


For something like this, if your stock is a nominal 3/4", I set Z zero .75" above the table, and program the cut at .74" deep.
If the thickness of the stock varies, it doesn't really matter.

Be aware that you better have a good vacuum table, or there's a good chance that you'll cut through in some places.