This weeks assignment to make a joint with the big CNC proved to be a very challenging task. Getting the tolerances right mathematically stumped me a bit and it was hard to conceptualize what was going to happen in a 2D model in Vectorworks. You’d think a simple looking joint like a half lap would be easy to figure out — it wasn’t! I decided upon a half lap joint in order to make a short corner bookshelf. Once I got home though, I realized that the 90 degree angle I had planned to put the furniture was anything but 90 degrees. Now I think I’ll make a short TV stand instead for the midterm.

In Vectorworks I ran into a lot of problems figuring out where I needed to add tolerance and how to go about adding it without ending up with a solid filled shape.

Unfortunately the first attempt to mill didn’t work out because of a common problem placing the X axis all the way forward on the Y axis when zeroing out. The next day the I was able to start milling!

Mastercam was a bit of a nightmare this time around. It wouldn’t let me mill completely around the left square so I had to invididually set each side of the square which is why I think I ended up with a nasty looking edge on one of them. Also the mill didn’t cut all the way through my material even though I set the breakthrough to 0.05 and I rounded up my material thickness. I may chalk that up to the spoil board being pretty wobbly and the position of the wood on the machine was further back to avoid any X axis problems again.
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After having completed my weird looking probably not a real sturdy joint skill exercise I’m a little freaked out about using joints for the midterm. I’ll definitely need some help figuring out how to do the math associated with tolerances and jointery in general.

The big CNC


In the kitchen I find myself using a cutting board a lot, which is not surprising really…there’s one thing I’ve noticed though, about the transportation of the chopped and sliced produce into the pots and pans on the stove — there’s no easy way of doing this without picking up the whole cutting board. I don’t know about you but you I have a pretty hefty chunk of wood as my current board and lifting it over a stove in order to shove the uncooked food into a tiny pot would be a little ridiculous. That’s why having a nice hole in a light, smaller version of the cutting surface would be ideal to avoid making a mess while cooking. But do I make the hole round or rectangular? I don’t want the food to go over the edges so I may make the groove you often find around the edges of a cutting board.

Now that I’m putting together the finalized file in Vectorworks I decided upon a circular shape for the food hole. And the groove will have to be uncurved due to the 1/4 bit not being rounded.

During the milling process there was a brief moment where I thought the cutout circle was going to go flying so I paused the machine. I suppose it was a bit too big and should’ve been screwed down. Noted for next time. Other than that the big CNC definitely has a lot of crazy potential and I enjoyed it more than I thought I would. The most intimidating part by far was using MasterCam. The program was a bit finicky about where to press when selecting a shape and the number of buttons was a bit overwhelming. Haiyi and I both did our separate projects while supervising each other and that helped a lot – as did Ben helping us out when we got stuck with MasterCam. I’d be interested to use a different material with this machine next time. This was the first time I used wood for a skill builder and it turned out to be very satisfying. I’m happy with the results and will probably try making a cutting board with natural wood in the future.

One other thing I realized was the machine was definitely slanted just a little because when I went to take the cutting board our of the remaining plywood, the breakthrough didn’t go through on the farthest side on the X axis. Regardless, I was able to sand down the chipped wood.

For future reference: I used a down bit for this project and went to Prince Lumber for materials. The file was developed in Vectorworks.

CNC Cutting Board from Marco Wylie on Vimeo.