Design rules, material identification, theory and practice with milling machinery.
First designs, testing of speed, power, depth of cut and milling, pre-visualization of results, depths.s
First soldering tests, multimeter verification, applications and improvements.
Before starting the tasks, together with my partner Hans, we made a complete inventory of all the electronic components and tools we needed for this assignment, as well as an inventory of the things we were missing.
We were able to verify that we have 1/64 and 1/32 milling cutters!
Here we have all the parts to use and assemble! Let's get to work!
The milling machine that we have at the Universidad Cientifica del Sur is the MONOFAB SRM-20 that we will use for this week's assignment. Here are some specifications of the machine:
Read more about the SRM-20| WORK SURFACE | 232.2 x 156.6 mmm |
|---|---|
| OPERATING SPEED | 6 mm/min to 1.800 mm/min |
| POWER CONSUMPTION | 50 W |
| SPINDLE ROTATION SPEED | 3.000 RPM to 7.000 RPM |
TRACE WIDTH TEST
We start with the preparation of the cutting area, we place the double contact tape on a small ABS base (we chose it for the height and density) in order to avoid damaging the base of the milling machine.
Then we put the copper plate secured with the same tape, so that it does not move, preventing the milling cutter from breaking.
CALIBRATION
After having the circuit board correctly glued. We configure the X, Y and Z axes of the milling machine. We start with X and Y, aligning where we want to start the work, with the help of a bond sheet we calibrate the Z axis. We will be careful and work with the movement in x10 or x100 depending on the case.
After obtaining the correct location of the X, Y and Z axes, we set the origin from the program. This is where all the values will change to 0.00 mm and the machine will be ready to start working.
LINE TEST
We start with the line test, where we will perform the milling of this image, remember that first we will perform the milling and then the cutting. IN TWO PARTS!
With the help of the SRM-20 program, "iModela Creator", we configure lines and thicknesses:
- First we import the traces to the program to start milling and set up the machine, we will use the 1/64 bit for this occasion.
- Second, the iModela program through its simulator "Virtual Modela" does not show how the work will look like. We thought it was correct, so we sent it to milling, the result was not as expected.
RESULTS
After the import, we proceed to the cutting with the machine. In the first test we failed because the cut came out backwards, that is, instead of cutting the part we did not need (black area), it started to cut the lines and numbers (white area) and this is the result. But the cut was accurate and looked very good.
A FEW ERORRS
After 5 more failures, we couldn't understand what the error was. We coordinated to verify each step, we began to discuss the failures and analyze each step, in our meeting we understood through organizing our ideas on the board, what we were doing wrong. After discussing it, we realized that there was a cutting configuration "inside, outside or in the center", we cut again and it came out much better. We discovered the difference between POCKET, ENGRAVING, HOLE AND CUTTING, it helped us make the test look similar to the expected result. Finally we see test 7 and 8, in the last one we achieved the objective. We understood the processes, configurations and were able to get our board tested.
Many tests and great lessons learned
Re-configuration of machinery and parameters.
More configurations to ensure results, verification and pre-milling simulation.
First cutting and milling results, channel verification
Through the PNG of the plate in 3 layers: DRILLS, INTERIOR and TRACES, we import to the iModela program, we consider:
- After importing we can VECTORIZE the PNG to find the strokes to make, we must select "EXTRACT CONTOUR LINES", in preview we verify it, click on "OK".
- It is important to set the thickness of the plate and the thickness of what we are going to mill, to avoid the milling being too deep
- We will configure the cutting speed, thickness and passes, it is determined in the following image.
Link of the PNG's files
- The diameter of the milling must be changed according to the 1/64" - 0.39 mm milling cutter in order to obtain good detail on the plate.
- In the “MILLING PARAMETERS” button I configure the cutting speed, the number of passes and save for safety.
- Then we simulate the milling with the "3D Preview" button, checking that the traces are correct.
- We activate "OUTPUT TO FILE" to create a .pcm file, save and open the Monofab Panel to load from "Cut" using the Add button, the .pcm file, this is the final step to send to milling.
Queentorres website to understand
This is the result of the milling and cutting of the plate, everything is fine except for the OFFSET of the FOOTPRINTS, which should be wider, however in our meeting on Saturday 02/17/2024 we did not resolve it.
I couldn't find a way to enlarge the milling with the 1/64" milling cutter, so we used the 1/32" milling cutter, however, on the very close TRACES they were tight.
Download my files
I was thinking that maybe the error came from the iModela program, so I had to change to MODS, from here I show you the steps to download the file, I leave it in the link.
The first test with this MODS was a total success!
MODS WEB SITE Download my files
I was able to perform two tests with different depths, I verified that some of the circuits were very thin, so I performed the second test, highlighting the paths with greater depth.
The first test was milled in 25 minutes, the cut in 5 minutes.
The second test was milled in 35 minutes, the cut in 5 minutes.
After determining the board to be used, test 2 is chosen, because the channels are shallower and contain more continuity, which serves as a basis for placing our circuits.
Continuing with the selection, we proceed to locate the components in the list:
-SEEED STUDIO XIAO RP2040
-CONN HEADER SMD 10POS 1.27MM
-CONN HEADER SMD R/A 6POS 2.54MM
-Tactile Switch SPST-NO Top Actuated -Surface Mount
-LED BLUE CLEAR 1206 SMD
-RES 1K OHM 1% 1/4W 1206
-RES 499 OHM 1% 1/4W 1206
-CONN HDR 7POS 0.1 TIN SMD* -CONN HDR 7POS 0.1 TIN SMD* -CONN HDR 7POS 0.1 TIN SMD
We performed some welding tests on poorly milled plates, considering the following materials in our space:
- Flux
- Soldering iron
- Tweezers
- Soldering mat
- Magnifying glass
- Base to hold plate
- Tin
We start by placing a little flux, followed by the electronic part, we pass the tin through the tip of the soldering iron until it is tinned, we clean it and take two balls of tin to position directly on the board.
I could notice, together with the plate of my partner Silvana, that the routes of my plate are more detailed, this is because the first time we did the test, it was not so good, the routes were very thin so the soldering was even more complex.
You can also see in the images and video that the soldering on the test board 2 is more detailed, allowing the components to adhere more quickly.
After soldering, the next step is to connect the board with the Xiao to the pc, so that it can be turned on, of course I previously verified that there is no contact between the soldering and the boards, this is how it was finally.