Computer-Controlled Machining

Assignments

Make something big

The assignment for this week was to make something big using computer-controlled cnc machines

In our lab we have a Shopbot PRS Alpha 120-60 machine

Me and the the other two interns in the lab wanted to make furnitures for the lab that would come to good use for the lab in the future

The other guys wanted to make computer desks and i decided to make a speech desk

I wanted the front side of the speech desk to include the logo of the Innovation center in Iceland

The innovation center hosts Fab Lab´s in Iceland

The design

I started off by drawing up the desk on a piece of paper in 2d and the dimensions i wanted

After i had an idea of how i wanted my design to look like i started to draw my speech desk in 3d in Fusion 360

I found myself kind of slow doing press fit joints in Fusion. But i was able to sketch up how i wanted my design to look like, apart from the joints

I decided to use Sketch Up instead. I had heard that there were nice tutorials online on how to create decent joints in Sketch Up

Frosti pointed me and the other two interns to a good tutorial on youtube. The video tutorial helped me alot and made me understand the program and how the joints were made alot more.

The video tutorial helped me alot and made me understand the program and how the joints were made

I thought Sketch Up was super handy to make this press fit speech desk and is was fairly quick making it

This is what my design looked like after i finished the design in sketch up and applied a wooden finish to it.

It´s a normal looking speech desk with space for items inside of it

I imported the logo to the design later on in another program that i will talk better about down this page

My next step was to save my sketch up file. I saved the file as a “sketch up version 8” file.

Now the design and i were ready to make and calculate toolpaths for the design

VCarve Pro is the program we use in our lab for cutting parts on a CNC Router

In VCarve Pro there are tools for 2D design and calculation of 2D and 2.5D toolpaths and along with the ability to import and toolpath a single 3D model (STL, OBJ etc.). There is also support to import multiple Vectric Clip Art 3D models (V3M) to create 3D assemblies.

A little text from the softwares website about it:

The software can import 2D designs from other programs but also provides a full set of drawing and editing tools. The toolpath options cover all typical 2D routing operations such as Profiling, Pocketing, Auto-Inlays and Drilling as well as 2.5D strategies such as V-Carving, Prism carving, Fluting and even a decorative Texturing strategy. For 3D you can Rough and Finish the model and there are options to project 2D and 2.5D toolpaths onto the 3D surface. Each toolpath includes appropriate options to customize the settings and provide a high level of control for different types of operation. In addition all toolpaths can be previewed to show just how the part will look when it is actually cut, this allows instant feedback to allow toolpaths to be further optimized.

I was going to use a plywood plate for this project

The size of the plate was 1440x1220mm and the thickness was 15mm

In VCarve Pro i started off by creating new project and set the size of the project the same as the plate i was going to cut

I was lucky that there was enough room for my parts after Arnar cutted out his last parts on the CNC machine

I imported the sketch up file into VCarve and aligned them so they could fit to the plate around Arnar´s parts that were already cut out

My parts are outines with the blue colored lines

After i had aligned my parts to the plate in the software i wanted to create fillets to create clearances in internal corners to make it easier for my parts to fit together

Before i could do that i had to ungroup the parts. I used the “Dog-Bone” fillet and set the radius to 3.12mm

I imported a vector image of the Innovation Center in Iceland to my file and aligned it to the front side of the speech desk

My next step was to create and simulate toolpaths. The end mill i was going to use for this project is 6.5mm

Where i wanted to cut through the material i set the cut depth to 16mm, 1mm more than the thickness of the material

I wanted to cut everything out except the logo

I used the pocket tool on the logo

The Pocket toolpath machines the material away from inside a vector shape. I selected all the vectors defining the shapes i wanted to cut. The program sorted the vectors to identify islands automatically

I used the same end mill on the pocketing and the cut out

After i had created toolpaths for my project and the simulation i let the program calculate the estimated time of the cutting

The program showed that my cut would take about 50 minutes, which i was pleased with

Now my next step was to save my file and the toolpaths with it

After that i could go to our CNC machine and start to cut the parts out

The Shopbot

As i mentioned earlier our Shopbot type is PRS Alpha 120-60

There is a nice tutorial on how to use the shopbot on the fab lab wiki page

English

Icelandic

And here´s also a good video demonstration on how to use the Shopbot software

Arnar had just finished cutting out his project when i started on mine. The plywood was already drilled down on the cnc machine and it was necessary for me to zero the X and Y axes

I did zero the Z axes though to be sure everything would go well

Here´s a good demonstration on how to zero the Z axis

After i had done that i turned on the spindle and warmed it up for about 5 minutes I loaded my file into the shopbot software and started the project

This was the outcome

Now i just needed to smooth the pieces and joints with sand paper and then assembly them together

It went pretty well and this is the outcome

I was pleased with this week and found it very entertaining

Files from week 7

Shopbot files

Sketch Up file

Computer-Controlled Machining in Final Project

I also did Computer-Controlled Machining work in my final project

I made a press fit box that you can read more about it on my final project development page under the "Designs and processes" section (link)