Week 7
Computer-controlled Machining
The objective :
This week's assignment is to design and make something BIG!!!
My project for this week is a kids desk, I designed by using onshape.com with a fundamental principle of interlocking.
Tools :
| Name | Uses |
1 | Onshape.com | 2D Designing & 3D Assembly |
2 | Clip art (software) | Preparing the final design to send it to the CNC Machine |
3 | CNC Machine | Cutting |
4 | safety PPE | (glasses, ear plugs,mask, gloves,...) |
5 | wood file | Removing fine amounts of material if needed |
6 | MDF sheets | Material |
7 | Drill and screw | Fixing the MDF sheet for a proper cutting |
A. Designing:
I never dealt with onshpe.com or any of parametric designing tool before I joined Fabacademy. I had a lot of problems in dealing with them in the early stages but now I got use to them especially onshape.com and thats why I made my design by using it.
1.The 1st thing that I started with is a simple design to test and chose the best size for fitting. (18 mm MDF sheet has been used in this project)
2.By using this tool I found the best fitting size is 17.6mm
3.The previous three photos showed my 2D design, you may notes
that I used the best fitting size (17.6mm) for the slots in my design.
4.After completing the design I started assembling the different parts
to each other (3D design) in order to avoid any error that may occur
during the real assembly.
Note : I had one error because of jumping this steep and I will share it in lats part of my report.
B. Preparing for cutting :
The design has been exported as DXF to imported into artcam(software) for the final review and to arrange the different parts along the MDF sheet. In the following photos I will try to give you a quick overview of this very long procedure that need to be followed inorder to have a perfect cutting.
1.Importing file
2.Arranging the design parts and modifying the settings.
2.Identifying the outside and the inside parts of the design before send it to CNC machine for cutting.
3.Profiling setting in this part I adjusted the profiling setting to the ideal settings that suites our CNC machine.
Our CNC settings :
•Tool type end mill
•Diameter 3 mm
•Steover 1.2 mm
•Stepdown 3 mm
•Feed rate 75)
4.In this step I planned the order of cutting to start with all inside lines and then to move to the outside lines (already identified photo #2) this step is very important to have a stable and smooth cutting process .
5.Exporting the the design after the arrangement and the tool setting as PLT file to send it to the CNC machine.
C. Cutting :
After all preparation,sketches,2D design,3D design, reviews and modification on different software I reach the stage in which I can see my product and test it by hand. The coming photos will show you the cutting process from A to Z .
1.CNC machine in Kuwait FABLAB
2.As shows in the previous photo there is an unused half MDF sheet left on the machine. I used it to cut some of project part and for the rest I uesd a new sheet. I set the Home (starting point) manually by using the controller to plot X0 and Y0 in the utilized space. After that I started decreasing Z value until the bit started milling the top most part of the sheet then I used it as Z0 point.
3. After setting the X0, Y0 and Z0 I imported the file to machine and start the cutting process. As you see here the machine started cutting inside lines as per the plan.
4. The first portion of the design is ready.
5. Removing the screw to change the sheet and continue .
6. Collecting all parts to start assembling.
6.Desk legs were perfectly fit each other.
6. filing or removing fine amounts of material to make the assembling process easier. As shown in this photo I use the manual filing tool on the top part of the desk to enlarge the cross slots because there were a bit tinny.
DONE :)
Chalanges that I face :
The closed cross slots that I designed on the top part of the desk was very tinny and on the first attempt even the filing does not fix this issue. Therefore I start searching on the youtube, consulting the local instructor and classmates and finally we found out that I need to increase the allowance which I sat it originally as 0 in order to have extra constant space from all direction. Then I cut a new piece with 0.03 mm allowance and fixed the issue.
Downloads :
Here is onshape.com link for the final design.