7. Computer-Controlled Machining
Assignments
Here you can find a recording of the lecture from the 5th of march.
This week's assignments and learning outcomes, see here:
Group assignment:
- Complete your lab's safety training
- Test runout, alignment, fixturing, speeds, feeds, materials and toolpaths for your machine
- Document your work to the group work page and reflect on your individual page what you learned
You can find the documentation for our group assignments here.
Individual assignment:
- Make (design+mill+assemble) something big
Questions to be answered/from Nueval:
Have you answered these questions?
- Linked to the group assignment page
- Documented how you designed your object (something big)
- Documented how you made your CAM-toolpath
- Documented how you made something BIG (setting up the machine, using fixings, testing joints, adjusting feeds and speeds, depth of cut etc.)
- Described problems and how you fixed them
- Included your design files and 'hero shot' of your final product
Hero shot
Group assignment hero shots
Individual assignment hero shots
Designing in Fusion and fabricating in the Shopbot
I learned so much about designing in Fusion that I would have liked to put many photos of different steps in the design here, but I will let one be enough.
The shelves assembled
Here are hero shots of the shelves assembled.
A sign made in Pre-Fab
This is a video showing a sign that I made in Pre-Fab.
A sign designed and produced in Pre-Fab
Summary
This week we did our lab's safety training and run tests in our Shopbot, as a group assignment. We documented the results on our group page and you can find it here.
As an individual assignment we were supposed to design, mill and assemble something big. It took me far too long to decide what to do, even though I tried to be quick. I thought about different projects and how I could design and produce them. For this reason I only managed to design and mill the parts.
Work process detail
This shelf has been in our Fab Lab since before I began working there. It has bothered me for a long time, so this is a good oppertunity to make a new shelf. You can see that a clamp holds a piece of wood in place, so that the Ultimaker cannot fall of the shelf. It would be better if the new shelf could hold it in place. From the side view you can see that there is very little space between the shelf and the table. I think it would be better if the shelf had a curve on the right side and that would make it much easier to walk around and assist students and guests.
The size and form of shelf
The old shelf is 90cm tall, 90cm wide and 40cm deep. I was wondering if I should make the shelf broader but since I need more space between the shelf and the table, I don't think that's a good idea. It would be better to make it a bit taller with more shelves and then I could make better use of it.
How to design the shelf
I told my instructor, Svavar Konráðsson about my idea and he helped me to begin with the design, showed me how to draw on different planes and how to create a rectangular pattern and the difference between creating a new part or joining new parts with the previous ones. I also used this video about modeling a bookshelf in Fusion as reference.
First attempt in designing the shelves
I designed the shelf in Fusion. I clicked on Create sketch and chose the top view to begin drawing the first shelf. Then I created a new sketch, chose the side plane and drew the side of the shelf on that plane. Then I made the third drawing on the third plane and drew the backide of the shelf on that plane.
By clicking on the shelf and choosing Create, then Create pattern and finally Rectangular pattern, I could multiply the shelves. I chose to multiply bodies and how many of them, chose the axis I wanted to use and then the length of the area that the shelves were supposed to be spread on.
The side and the shelf were one body
When I tried to multiply the shelf the side was also selected when I chose bodies. I had to go back to when I extruded the side in the tree at the bottom, right click on it and choose Edit feature. Then I changed feature from Join to New body.
To move bodies
When I planned on drawing tabs on the shelf I couldn't access the plane on the backside of the shelf. I decided to move the back and the left side away from the shelf while adding tabs. To move the backside and the left side of the shelf I right-clicked on the screen, chose Move/copy and moved it for minus 100mm on the z-axis.
New drawing
I decided to create a new sketch and begin by drawing the lowest shelf first and add the tabs before adding the back and the left side.
Second attempt in designing the shelves
How to create tabs and slots
I found this video about video and used it as reference.
I drew the form of the shelf by using the Line tool. The beginning point was the 0,0. I drew a line for the length, the depth and 500mm along the front side. Then I used the 3 point arch line to close the form with a curved line. When you use this tool you first click on the two points you want to connect, then you move around until you are happy with the form and then you click. Then I extruded it. I set the extrusion to the thickness of the material by writing t. This way I could change the value of the t when I knew the exact thickness of the material.
To create a tab, I drew a rectangle on the left face of the shelf. I set the height of the material as t so that it would adjust to the thickness of the material.
Third attempt to design the shelves
Attempt number three
It took me a long time to design this drawing and I ran into problems when creating tabs and fillets. It was hard to make them fit. I contacted Jón Þór Sigurðsson and he showed me a better way to design the shelf.
First, I created new parameters with, f.ex. t for thickness of material and bit1 for the diameter of the endmill.
I began by drawing the basic form and the tabs on the lowest shelf. I did that the same way as before. I created a new sketch on the backside of the shelf and drew rectangles for tabs. Then I extruded them. The next step was to do the same on the left side. When all tabs were ready, I used the combine tool to make the tabs and the shelf one piece.
Then I right-clicked on the screen and chose the Move/copy tool. I copied the shelf two times and arranged these three shelves with even distribution.
Then I created a new sketch and chose the plane where the back should be. I drew a two-point rectangle on it. Then I extruded it and set the thickness as -t. I had to use the minus for the extrusion to go in the right direction.
Another technique creating tabs and slots
Jón Þór Sigurðsson showed me how I could use the Combine tool for the tabs on the shelves to cut fillets into the backside. So brilliant! I chose the backside as the target tool and the shelves as tool bodies. I used the Cut operation in the middle. It was very important to put a checkmark in Keep tools because otherwise the shelves (tool bodies) would be deleted. By clicking Ok the fillets were created
The side of the shelf
Then I created the side of the shelf exactly the same way as with the back.
The brim on the top shelf
I designed this brim on the top shelf. The purpose of it is to keep a 3D printer in its place. Here you can see the tabs that I designed under the brim.
Fillet for soft corners
Fillet was used to make the corners soft.
Design for new shelf ready
Here you can see the final design for the new shelf.
V-Carve
V-Carve
Jón Þór Sigurðsson assisted me with settings in VCarve and performing the job in the Shopbot.
I exported the design as .dxf and imported it into VCarve. The first thing to do was to set up the job. In these settings you choose between one sided or two sided jobs and write down the size of the material you are using. Then you decide if you want to set the top of the material as a beginning point (z-zero position) or if you want to use the machine bed as z-zero position. I chose the machine bed as a zero point for the z-axis because the material I was using was very uneven. Then I chose the xy-zero point.
Dogbones and T-bones
In Vcarve you can click on the icon for fillets and add dogbones to corners. After choosing which type of bone you want, you have to click on each corner to add the bone.
Settings for toolpath
Before performing the job you have to adjust many settings. You can see that the starting depth was 0.0mm. The thickness of the material varied from around 11.9mm to 12.1mm so I set the cutting depth to 12.3mm and hoped for the best. The path was set on the outside of the toolpath. I added tabs and ramps to toolpath, but I took the screenshot before that, so it doesn't show on the image. Tabs are very important to keep all parts in place so that they would not start flying around when they were cut out.
Pieces breaking off
As you can see, one of the plates I used was a bit too small and I did't give the cut out piece enough room. The edge broke off in some places
The job went well
Everything went well and here you can see all pieces fabricated.
Assembling
Shelf assembled
After sanding the pieces I glued them together. Here you can see what it looks like.
Support
The shelves needs support on the right side, and I did not want to use another side, so I bought these for support. A wooden block will serve as support under the lowest shelf.
Learning outcome
Learning outcome for group assignment
I learned a lot about our Shopbot. I know now how to follow safety procedures and how to use the Shopbot. I also learned more about how to export files from Fusion, import them into Vcarve and how the settings should be.
Learning outcome for the individual assignment
I learned so many details and procedures when designing in Fusion. It was frustrating to spend days on designing the shelves and then realizing that there was a simpler way to do this, but the lessons I learned were so useful.
Fabricating the design in the Shopbot was very useful. I feel more secure about how to control the Shopbot. I was using leftovers from the carpenter students and for that reason I could only cut one part at a time and it was good, because then I had to do the settings again and again.