This week we learned about Computer-Controlled Machining, creating toolpaths and operating CNC router machine, and testing runout.
In this week we're operating the CNC router Machine and making something big! like any manufacturing technique we have to run some tests to make our design ready for the machine.
We got over the basics which are:
We don't have a CNC Router in our lab but we have a small CNC Milling machine that has a 30*40 working area and, so we made the tests on it first and since it's the same concept we'll make the same test on the CNC Router when we have access to it. We went through the different types of endmills and which is used for which job.
This week we accessed the CNC router on of our community has. His name is Ahmed Hussien and he own the brand called . "Wonder Box". Big Thanks to him. He has a CNC Router machine made by an Egyptian company called "ElMalky". It has dimentisons of 60*90 cm.
Runout is the inaccuracies that cause a tool to spin off the ideal axis. It typically uses dial test indicators to be measured. We didn't have it at our lab so we calculated the runout manually using multiple pieces. We measured the length from the workpiece minus the output piece and divided by two.
on China Router
We used artcam to make the CAM Toolpaths.I'm going to talk about some interesting concepts to me later.Once we calculated the runout which was between 0.04 to 0.1, we made the second test part
Second test part
I'm originally not from Cairo but I'm a small-town girlie. I moved in here last year and I still have minimum amount of furniture and I'm an avid reader so my books are scattered all over the place. I wanted to make a piece that can both hold my laptop, headphone and books. I browesed Pintrest until I found this minimal design. It's a side table with plenty of room for everything. I made the design in Fusion 360. I used these parameters. I started to design the sides then the shelves compartments and finally the top.
To design something to be CNC, you have to put dogbones. This is a helpful videoto know why but basically we're cutting with a spinning round tool so sharp corners will never be sharp and result in problems while assembly, So we add a two . You can either draw them or use a plugin like I did. It's called.. yep like you guessed:"Dogbones". I also added a plugin called NESTER to help nest the parts automatically but It didn't work.
To test everything, I made a mock-up with the laser cutter by scaling the design to quarter of its size. I used 3mm plywood and it was a success.
To start here we'll be using 6mm bit and 12mm plywood. We continud using artcam and Ahmed recommended using some parameters that will both make our design look good and make the machine work smoothly. One of the things that's really important is the plywood's fiber direction how each piece will hold itself against the other, this will help in making the part strong when assembled.
In addition to adding the endmill diameter and recommended Feedrate "2000" for plywood & spindle RPM of "1500". Along side feedrate and spindle speed we addeded ramp movement which will help elongate the endmil's life and make the machine not plunge 90deg in the plywood.
And bridges which help secure the pieces to the bigger sheet to avoid any accidents of the piece detaching, we used the 3D bridges and readjusted their position to be in the top and bottom to each side of the piece. Also, we chose conventional over climb cutting.
We used Mach3 to run the G-code and nail gun to secure the wood.After homing and setting the zero of the z axis correct, I clicked run and I was ready to go.
I used the sander to sand the pieces for-what-felt-and-actually-was HOURS. removed all the unnesseracy bits caused by the bridges.
Then it was time for sealer and sanding and finally staining.