The Shop Bot is a computer guided router or a CNC router. It can cut through most woods and plastics. The one I use has 4ft by 8ft bed size. It takes tool path written in G-code generated from the designs I wanted by a toolpaths, a tool path generating software.
The designs were made in fusion with measurement from the real world. The designs are parametric. Now due to time constraints I had went with a very basic press fit design that didn't involve complex machiningI also added dog bone on the corners to get clearance for the tool. After making a 3D model I made DXF files of each face of the model I needed. And loaded it into the path work for generating tool paths for shopbot to run
First start the shopbot to have access to move the tool head and make way for putting the wood and using clamp or screw fix it into the bed. After that put the required end mill bit into the machine. Remember to not put the mill all the way up as well as not too less as it can become wobbly and come out from the high speed spindle.
Tools that shop bot uses for setting up the bits are1. Two Special wrench. 2. Required size of end mill bits 3. Collet and holder
Now the next step is to set the axis just like in the modela , here also we need to specify the orgin for the machine to start from. To do this we move the X and Y axis using the control in the shopbot software or use the arrow keys in the keyboard to bring the tool head to the corner of the materials to start the cut. Due to the interesting process in operating shopbot I forgot to take screen shots but you get the idea.
The Shop Bot i used, works with part works software but now different software packages are being used called V carve. Using Pathwork to create jobs follow the following steps 1.First open the software and create a new job or open the DXF 2.Enter the dimensions according to how you placed the piece on the board. 3. Set the origin according to how you want it on the machine. 4. Select the required type of cut you need to each vector from various options that is given. 5. Select the right settings and tool types your using into the option windows. 6. Save the tool path and load this file and run the shopbot. And just watch.... but be attentive and look at the machining with safety equipments and some bright smile and also be ready to hit the emergency stop or space bar incase something unwanted happens which might happen
Watching the machine run is a fun experienceThis is the part that has been printed. We have kept to 12000 RPM and kept the depth pass to just once, the cut was not very precise. Since I had to travel far to get this assignment done, I just had to go with it.
Now all I need to do is assemble it.I had to file down a bit from the edges though clearance of 1mm was kept.
After filing for a while, I started hammering and was fitted together. It fit together very tightly which was just what i needed. Though this week is to make some thing big , it was big but not as big as the capability of shopbot so looking forward to make something really big with this amazing machine
For group assignment we took several parameters to check. Like the Alignments of bed Changing bits Various speed of spindle
The bed where we keep the materials should be free from deformities and uneven surfaces as this may affect the cut path and make it irregular so therefore its important to clean it before every new job. Its is also a good idea to check the bed alignment using a spirit level on the work material. There was 1mm to 2mm kerf in machining due to some issues with the alignments of the bed or maybe the machine which lead to cut that was 1mm to 2mm less than the specified size on the design.
We only had access to only one type of end mill which was of size 1/4 " so we only did our work on that same. But there are other interesting tools like the V-bits and Sanding attachments to shopbot which unfortunately we couldn't experiment with. The process of setting the bit is same as mentioned earlier. One must also remember how to properly put the bit into the collet
For checking the affect of spindle speed on the work we took 1. Two Pockets with tools path specified to 11000 rpm and 12000rpm 2. Four profile tool path with different spindle speed of 9000, 10000, 11000, 12000 rpm.
The conclusion I drew from this is that higher spindle speed gives better finishes on the surface as the finish on the 12000 rpm pocket work and the 12000 rpm profile work had softer finish than the lower ones.