8. Computer controlled machining¶
THIS WEEK CHECKLIST¶
- [✓] 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’ photos of final object
Group assignment¶
This time, I work with my groupmates together to use the test runout, alignment, speeds, feeds, and toolpaths for our CNC. Since our lab do not have CNC machine yet, so we ask for New Life Psychiatric Rehabilitation Association brrow their lab for using their CNC machine from China. CLICK HERE for the detailing of group assignment page.
Individual assignment¶
The chair design is inspired by Seven CNC Projects. Since my lab use IKEA Frosta as a chair, I feel confortable when I sitting on Frosta. Therefore, my chair design and dimension will base on IKEA Frosta to adjust.
I use Fusion 360 to sketch chair design. Since we need to go to other lab for using their CNC machine, so I finish sketching my chair first and send the file to lab to help to mill first.
There are two different thickness of OBS (12mm and 18mm). I decide to use 18mm OBS as a material for milling my chair because it can thick enough to support my weight.
For making slot, basic on the thickness of material. However, if I make 18mm in my slot design, it will be too tight when I assemble the chair. It means I need to use sander for smoothing the surface and make it the size smaller, so that it can be assembled. However, this is not the perfect way to use CNC mill your work. Therefore, when I making the slot, I consider to make slightly wider. According a advice from the creator of Wilker Do’s, it should be leave 0.007” (0.178mm) for the both side, so it shows 18.356mm. Basic on the testing on CNC Machine that we do before. The slot between 15.30mm - 15.40mm seems not too loose or too tight for assembling the chair.
Draw a Rectangle because the rectangle of size is your material size. It help to check your pirces is that possible to put in the same board for milling. It simulates with CNC working area for arranging the layout for your design. If not, you have to use 2 board for milling.
I am trying to mill in 1 board because it will save my time to unload and load materials. Therefore, I try to change the shape of the seat. I change into octagon. However, it is too close with the leg. For changing into haxagon, I bit the chair is not comfortable. So, I give up to change the shape anymore.
This the way that I adding Dog-bone in my design.
After finishing the design in Fusion 360, I change Fusion 360 From DESIGN to MANUFACTURE for setting the CNC Machine. Click 2D Contour, base on the testing in group assignment, I set Spindle speed: 12000 and Feed rate: 1206. Also, I set the offset of Bottom Height is -1mm because the work piece is really cut out from the OSB.
Last but not least, setting the Endmill before going to mill my work. Here is the setting for my endmill.
Here is the chair design with dog-bone and without dog-bone after milling. Actually, design without dog-bone, I still able to assemble. However, it is too tight for assembly. I need to use tool for smoothing some of the part, so that it can be assemble successfully.
As you can see, after assmbly, design without dog-bone is slighly not flat in jointing part. But, for design with dog-bone do not have the same situration.
Here is the hero shot of my chair.
The chair is strong enough to support my weight (50kg) and a male (75kg).
