Topic: [HOWTO] Convert da Vinci Mini to RAMPS 1.4
Hi guys,
First of all I would like to thank Anthem for his great guide on converting the da Vinci Jr to RAMPS, which I based my conversion on. Since I'm only explaining differences between his guide and the da Vinci Mini, please read his guide too, it's totally worth it: http://www.soliforum.com/topic/15273/ho … -ramps-14/
I performed the conversion on my da Vinci Mini w and like his conversion it's a total success. The printer may be printing even better now and since I don't need any NFC chips anymore, I can use filament bought for about one thired of the XYZPrinting price.
I would like to share a few experiences I made with other da Vinci Mini owners, cause there are a few differences between the Jr and the Mini printers. Sorry in advance for my bad english, I'm actually from germany.
My printer now looks like this:
Power supply
One of the major differences is that the Mini is not powerd by 12 Volts like the Jr, but by 24 Volts.
The upside of that is that the currents flowing in the da Vinci Mini are only half as high as the ones in the Jr, so you can use thin cabels. Nevertheless I still used four wires for the extruder, cause there are still about 1.3 Amps flowing.
The downside is that since the RAMPS board has to be powered with 24 Volts too, you can't use it to power the Arduino directly, cause accoring to the manufacturer it can only take Voltages up to 20 Volts. Therefore you have to remove the diode D2 thats connecting the RAMPS power supply to the Arduino. It's placed directly under the place where the driver for the X motor is located. Because I did'nt want to power the Arduino over a second power supply, I replaced the diode with a AN7806 voltage regulator that decreses the 24 Volts to 6 Volts with which the Arduino can work. Even though the voltage regulator can take up to 1 Amp and there are usally only 0.1 Amps flowing through it, it gets pretty hot (I messured up to 70 °C) which is why I attached it to an extra heatsink.
I had no problems with that system at all, it's running flawlessly.
For the actual power supply I'm using a 24 Volts, 5 Amps switching power supply which is more than sufficient to power both the printer and my heated bed.
My electronics look this:
Z motor
Surprisingly the Z motor does'nt have 200 major steps like the X, Y or Extruder motor, but only 48. Combined with the used M5 spiral, you have to set the steps per mm value in the firmware to 960 assuming your stepper driver is set to 1/16th steps. Otherwise you risk crashing the extruder bridge into the top of that printer. If that happens, press the Reset button on your RAMPS board FAST to prevent damage.
Accessability
I noticed that unlike Anthem wrote in his guide I had to remove nearly no parts from the printer to gain access to the needed parts. The only thing I had to remove is the plate that covers the mainboard of the printer. I left all cables in it, cause they are not in the way and I might build the printer back to stock version in case I need to use warranty.
Extruder
There are nearly no differences between the extruder of the Jr and the Mini. The heat detecting resistor should work fine with the settings of Anthem (Type 1). The only differences I noticed are that the parts of the extruder of the Mini are designed for 24 Volts instead of 12 Volts and that the flat stock cable is attached to the extruder not at the side but on the top. I removed the board in the extruder and routed the cabels I made for the extruder through the top and along the filament tube, so that they are out of the way.
Endstops
I guess the endstops of the Mini are the same like the ones in the Jr. I noticed that the middle cable of the 3 cables going to the endstops is used as ground. The cable with the Xs on it for the + power supply of the LED and the cable with the text on it is the signal cable. Like Anthem I had to add 220 Ohm resistors to power the LEDs without damaging them. The pullup resistors between +5V and the signal cables are not nessesary since they can be included by the RAMPS board if you define that in the firmware. Nevertheless I added 10 kOhm pullup resistors to be on the safe side.
Calibration
Except the Z calibration, the steps per mm settings should be the same as for the Jr. I calculated 80 steps per mm for the Y and X axis as well as [s]88[/s] (88 seems to be too much, I'm testing 86 at the moment) steps per mm for the extruder and the results are only divercing about 1/10th of a mm from the anticipated value. The maximum ranges of the axes I got are 0 - 170 for the X-axis, 0 - 185 for the Y-axis and 0 - 145 for the Z-axis.
Mind that I installed a heated bed which takes about 1 cm away from the Z-axis, so the actual range might be 0 - 155.
I am only giving these values to you as a guideline and am not responsible for any damages to your printers while using these values. I advice you all to test out your individual values very carefully and AFTER calibrating the steps per mm values. Also keep in mind that all these values only apply to the printer after it has been homed by the endstops, cause otherwise the printer does'nt know the 0 position!
The (0, 0) position of the bed (the left edge in front of the bed) is positioned at about (13, 20) relatively to the endstop positions. You have to define these values in your printer software, so it knows where the bed starts. The size of the bed is about 150x150.
Furthermore I about halfed the acceleration and maximum velocity values from the default firmware, cause it's much better for the print quality and protects the parts of the printer against damages.
Heated bed
As I already mentioned, I build myself a heated bed for the printer. Therefore I replaced the stock bed with a thin wooden plate which I can easiely drill through and which is much lighter than the original alu plate. I build the bed itself from an about 4mm thick alu plate which I attached a kapton foil on the top and two 15 Watts, 12 Volts car mirror heaters to. I connected them in line so that they an be powered by the 24 Volts of my RAMPS board. I attached the heat detecting resistor to the middle of the alu plate with a tiny screw.
Since the power of my heated bes is'nt too high, it can only reach temperatures of about 80 °C which is insufficient for printing ABS, but perfect for PLA.
Because the surface of the bed is now about 1 cm higher than the surface of the stock bed, the extruder bridge would crash into the bed while calibrating. Because of that, I raised the Z endstop with longer screws by about 1 cm which is the reason for my upper maximum of the Z axis being only 145 mm.
All in all I hope I could help everyone owning a da Vinci Mini and is considering converting it to RAMPS.
If you got any further questions, feel free to write me a PN or comment the thread.
Happy printing!