diff --git a/UrumbotXY-Fall2022/README.md b/UrumbotXY-Fall2022/README.md index 617305c4a1bae7e8e3b927b5997530196b9a32eb..aa5d00ded8d3a550c53ffffa518e4510e5afd083 100644 --- a/UrumbotXY-Fall2022/README.md +++ b/UrumbotXY-Fall2022/README.md @@ -49,57 +49,6 @@ Drawing: <img src=video/corexy_spiral.mp4 width=100%><br> -## Circuitboard Milling - -Dec. 17-19, 2021. Set up CoreXY for milling, using a linear axis for z-travel and a spare Roland MDX-20 spindle. Keep the original python code, removing the homing step and changing speed to 5 mm/s. - -Run a text file for xy motion. Start, -10.0,-10.0:-10.8,-10.0: -0.8,0.0: 0.0,0.0. - -Axis setup: - -<img src=img/milling_axes_setup.jpg width=50%><br> - -As constructed, end effector responded to sideways force with ~20N/mm. This led to about 0.5 mm oscillation while milling - not stiff enough. Added a clamp to stiffen, which allowed milling of traces. Adjustment of z-axis for milling was accomplished by manual adjustment of bit in collet. Z-axis motor was energized in order to constrain z-motion. Good enough to demonstrate. - -<img src=img/milling_axes_clamp.jpg width=50%><br> - -Movie: - -<img src=video/milling_movie.mp4 width=100%><br> - -Closeup of traces: Using 1/64" bit and 0.8 mm horizontal separation of paths, at a 45 degree angle, the calculated trace width is 0.3 mm. Looks pretty close to this. - -<img src=img/traces.jpg width=50%><br> - -This machine is close to being able to mill circuitboards. For the first try, the stiffness of the end effector wrt sideways force seems to be the limiting factor, rather than the xy stiffness. Next step: a better arrangement of z-stage and full incorporation of the z-motion into the software. - -### Small-excursion z-axis design: - -A cam translates the spindle by flexing the beam a few mm. Total excursion at the spindle is about +/- 2 mm. - -<img src=img/fixed_z.jpg width=50%><br> -<img src=img/z-cam.jpg width=50%><br> - - -#### Metrology - components and assembled parts. - -Initial results and setups are <a href="https://gitlab.cba.mit.edu/classes/865.21/projects/machinemetrology">here, temporarily.</a> - -Fishing line: 3.3 kN - -Seven-strand stainless: 11 kN - -#### Jan 14, 2022 - -Using the limited z-excursion setup above, tested g-code parsing python code and ran PCB milling linetest. Results below are comparable to Roland SRM20 using the same endmill. Cutting was interrupted by a python write timeout error: "serial.serialutil.SerialTimooutException: write timeout" Code used is urumbu_gcode_1.14.22.py . Spindle speed in these tests is 16kRPM. - -<img src=img/linetest.jpg width=50%><br> - -#### Jan 15, 2022 - -Added an ESC to control the BLDC motor. We can use the same board used for servo control. Like the servo, the ESC accepts positive pulses 1-2 ms wide, 20 ms period. To arm, apply 1ms pulses for one second, and then apply pulse length for desired speed. With 12V supply, no load speed is 17kRPM at 1.40 ms pulse length. These pulses need to be applied continuously to run the motor. (this is typical ESC behavior, I think.) Details in Rob's documentation. - -<img src=img/bldc_resize.jpg width=50%><br> ## Linear axis