View Full Version : Adjusting Box Joints

Linda Creatore
10-09-2005, 2:36 AM

I cut my first box on the laser and the joints are a little loose. I am using 1/4" wood and my joints are 1/4" deep and wide. I know I need to adjust them to get a tighter fit, but am not sure how much I should adjust and whether both male and female joints need to be adjusted. Can someone give me a bit of guidance on how to make the necessary adjustments?

I use an Epilog 45 Watt, but am not sure of the width of the beam.


Shaddy Dedmore
10-09-2005, 4:09 AM
One thing to remember is that different materials will be tighter or looser. For me, Alder and Maple cut pretty good. Walnut isn't as easy for me and char's a little more... so walnut joints will be looser for me. You might keep different files for diff materials.

I use nudge and the shape tool pretty extensively for this type of adjusting. In Corel 12, it's
Change the nudge and micro nudge (maybe .1 then /10) or even less.

I would choose one thing to adj, the slot or the tab, no need to do both. Use the Shape Tool and select certain nodes to move, and press CTRL-Arrows and move it a couple time, and do it the same amount on the opposite edge to keep the tab/slot symmetrical.

If you do it on a few practice pieces and figure out how many key presses it takes to make the fit best, this method doesn't really take all that long.

Let me know if you need more specifics.


Lee DeRaud
10-09-2005, 12:09 PM
Nominal "kerf" width on my 25W ULS machine is 0.005", so that's the starting point. Wood does odd things when you cut it with the laser: sometimes the heat dries out the wood and causes local shrinkage (looser joints), sometimes the heated moisture stays trapped and pushes the wood out (tighter joints). And just like normal wood movement, either effect only changes the crossgrain dimension.

But I normally never use more than 0.003" of adjustment (note: I adjust both pins and sockets, so that's 0.006" total)...that's in 0.2" acrylic, and the resulting joints have to be pressed together in a vise.

I wrote a VBA program that lays out the joints, with an adjustment parameter for the kerf...if I ever figure out how to shrink the file down so it will be "legal" as an attachment (and get some documentation together), I'll put it here.

Linda Creatore
10-09-2005, 12:45 PM
Thanks! I'll do some tests using the nudge method and see what happens.

LOL...I did a "drop test" on my box the other day and it survived, so I guess the glue up went okay and apparently there was not too much space to have to fill! Uh, and yes, I did this test on purpose!

Looking forward to that VBA program!

Take care!