Subtraction – Week #4 CNC Joinery

This week we looked at a lot of different ways to connect two pieces of material using the CNC. The machine gives you a lot of accuracy, but it needs to be well thought, as the CNC machines not that good in creating corners…This project should help us get a better idea on our two weeks CNC project.


I started by thinking about the joints that I can make, and how I can use it…at first I thought to create some sort of a furniture that I can use, like something to put beside my bed, and then I thought maybe to use the joints practice and make letters puzzle so I can sent it to my nieces and maybe they can have fun with it…

I’ll choose after I’ll play around with the joints.

I started to run some ideas on how I can make this joints look more playful, and decided to shape it as a smiley. I can’t actually create a round face, as It will be a cutout and I can’t use it- so I thought about a small tab to hold the round piece of the smiley head:


After the sketches and thinking what should be in which height (and designing it in Illustrator), I measured the material (0.721 Inch) and went to CAM in order to make the orders of operations for this cut. I’m using two bits – one 1/8″inch for the details, and 1/4″inch bit for the outline cut, just in order to save time and using the 1/8″ bit only for what I really need from it, in order to keep it from braking… As you can see I made the last two operations with the 1/4″ inch bit, in order to replace the tool only once.  More over, when I designed both shapes, I made sure to have the part that was meant to be a cut out, to be slightly larger than the other part, actually it was 0.005 bigger.


Shots from the CNC operation:


At this point I see that something is wrong and that I probably applied a wrong depth to this operation, as I wanted it to be only half of the material and not close to the bottom edge.
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I thought I’m hitting the bed, but actually it was something inside the plywood that looks weird and eaten…..

This is how a mistake looks like 🙂

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Nothing like spending time in sanding rather than cutting the whole thing from start..Even with 0.005 inch difference, I had to sand the negative part, to be slightly bigger.

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Mostly sanded part:

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