Computer Controlled Machining

AKA Make Something Big Week!

This week had two parts to two assignment: a group project to test attributes of the CNC and an individual project to make something big using the CNC Mill.

Group Project

The primary goal of the group project this week was to become familiarized with the safety protocols needed when using the CNC, in addition to creating and testing toolpaths, runout, and other aspects of our CNC Machine. Our professor had created a design for a cell phone stand on Vcarve that we used. As you can see, the design contained both drilled holes and cuts. We created a toolpath for each element, than added tabs so the piece wouldn't fly off the CNC.

The small edge of the right-hand piece needed to be able to fit into the slot inside of the left-hand piece. However, the CNC has difficulty making 90 degree interier angles, so we needed to make a dogbone cut, which is essentially using the fillet tool on each of the angles. This allows for there to be a sufficient amount of space for the wood piece to fit.

Then we selected the bit and correct tool settings, then exported it to a USB.

We secured a piece of woog to the bed using screws and double-sided tape. Then we set the X,Y, and Z axis.

Next, we cut the design.

Then we put the two pieces together, and had the final product!

Then we measured everything with calipers. The interior piece was 2.04inches, while the slot it needed to fit into was 2.05 inches, meaning the dogbone cuts did their job, and everything fit perfectly. the drill hole was 0.37 inches, when it was supposed to be 0.25 inches. This may simply be a result of splinters inside of the hole.

Individual Project

The instructions for the individual project were simple: make something big using the Axiom. Each person in out lab got four 48""x24""x0.5"" boards. A group of five people in the lab, including myself, decided to pool resources to make a giant dome out of hexagons and pentagons. We began by making a few sketches of possible designs.

Then we made a paper model to ensure the sizing and angles would actually work out.

To make sure everyone would be able to contribute to each aspect of this assignment, we assigned each person in our group specific shapes that they would have to model in Fusion 360, create a toolpath for, then cut. Because I've written so much about basic CAD functions in the past, I won't waste your time with explaining how to make simple shapes. I made a half hexagon with a hole offset by eight inches. I then used the Rectangular Pattern Tool, which I had just discovered, to replicate that four times. Then I addes another half hexagon, this time with a hole offset by two inches. I made sure each shape was spread out by at least half of an inch, to ensure there was adequate space for the CNC to cut.

The finished design looked like this:

Then it was time to create the toolpaths. I went into manufacture mode, selected 2D, then went to 2D contour.

From there I set the speed, feed rate, plunge rate, and created tabs.

Then I selected the faces I wanted to cut out.

After that, I corrected the clearance and top heights to reflect the size of my board.

Then I selected the 1/4 inch flat end mill. A couple of group members who had cut their board before me mentioned a few of their problems with setting incorrect speeds and feedrates, so I changed mine to the parameters seem in the picture below.

Under the Actions button is a button reading Simulate. I clicked on that and was able to run through the toolpath to make sure that there were no problems. Somehow, miraculously, there weren't any.

Then it was time to cut the boards! I pulled my hair back, put on hearing protection, inserted the USB into the Axium, selected the job, and was ready to go!

We removed the pieces with a saw and put them in stacks according to size.

Then we glued each piece together with woodglue.

After that, is was time to sand.

The group had decided that the easiest way to secure the pieces together was to attach everything with door hinges. After a quick Home Depot run, we had all the supplies to piece the dome together.

The most difficult part of this process was properly orienting the dome so that the screws would go in properly, without letting the rest of the dome cave in. It ended up being a five person process, with one person drilling and the rest securing the sides of the dome.

A couple hours of drilling passed, and then we were done! The dome was a bit smaller than anticipated, but overall it came out quite nicely!

Links

Group Project Design
Fusion 360 Design