As a group, we did the safety training for the ShopBot in the EDS where Anthony emphasized again how dangerous the machine is, showed us the basics of CAM in Fusion 360, and helped us cut out a test part with different tab sizes with the OSB. I realized that OSB is very ugly and kind of a terrible material, but I guess good for our first attempts at CNC machining since it's cheap. We measured the thickness of the OSB to be 0.459 inches.

I was super excited for this week, and I decided to make a rocking chair! I first designed a small version and laser cut it from cardboard to make sure it was practical and would not collapse. I initially only put one support at the bottom, but Anthony suggested adding two more at the bottom and one more in the back for extra stability. After fixing that, I was ready to design the real thing!

I used a measuring tape to measure the dimensions of one of the chairs in the EDS to get a rough idea of sizing for my design. Then I scaled up all the parts from my cardboard design accordingly and laid them out so that they would fit on two 4 foot by 4 foot boards.

Next, I sent my file to Anthony and we did the CAM together in Fusion 360. An important thing is adding dogbones to all the corners. Since the end mills are round, they can't make square corners, so the standard fix is to use a smaller mill to make dogbones in the corners so that your pieces can still fit together. Anthony used a library in Fusion 360 that automatically creates dogbones in every corner. We also added tabs so that the pieces wouldn't move around once they were cut.

Now I was finally ready to do the machining! The ShopBot is extremely loud, so we had to wear huge earmuffs to protect our ears. We milled one 4 foot by 4 foot board at a time, using the 3/8" end mill first followed by the 1/4" end mill for all the dogbones. It took around 30 minutes to mill each board including setup (nailing down the OSB board to the platform of the machine), changing end mills, and cleanup (sweeping away all the sawdust and prying the board off). Here is the ShopBot in action:

I thought I would be able to assemble everything and finish quickly at this point, but I forgot about postprocessing aka the bane of my existence. Anthony was worried about parts flying out during milling which happened to people earlier in the day so he'd made the tabs thicker, and apparently the first board was slightly bowed, so in some areas the tabs were ultra thick and it was literally SO. HARD. to get my parts out. I had to use an exacto knife to cut all my parts out of the OSB board and then do the typical rasping to smooth out all the edges. We learned our lesson though so for the second board we cut deeper and made the tabs thinner so it was way easier to get the parts out. But overall the thick tabs combined with fact that I am weak and OSB sucks means that it took me ~3 hours to do all the postprocessing :'( But it was all worth it (maybe) because my chair turned out very nicely!

Here is Anthony (aka the best TA) panicking while sitting on my chair because it was making weird noises, but it didn't collapse! Also, as I was bringing the chair back to Maseeh, a bunch of people in the elevator were like "WOAhhHHHHHHH it's so cool!!!!!!!" and now they want to take the class too :) So overall, I'd say it was a pretty successful week!