- February 24, 2017 at 8:30 pm #28391
So, I did my first test plotting with my recently completed MPCNC. I am using the drivers and wiring kit I purchased from the website.
So, originally the drivers were set to .7 volts, and I noticed the movement was a choppy at times. When I kick the voltage up to 1.4 volts per driver. When I did this, the movement is a lot smother, but the drivers are running hot, and one will I believe do a thermal shutdown after being plugged in and running for 30 minutes.
What is the proper voltage that I should set the drivers to?February 24, 2017 at 9:33 pm #28392
.7 for the drv8825’s and my steppers.
If you answer the questions in the stick I might be able to help more. gcode, software, speeds, rapids, use, ect.February 26, 2017 at 8:52 am #28496
I have a 20″ by 20″ MPCNC setup with all purchased parts from MPCNC and all settings as per the instructions with the kit.
I have a 7″ by 8″ heated alum surface for 3d printing and want to be able to control where the head starts. I am trying to understand what controls the movement of the head, what is the “Home” logic? What functions do the min/max offsets provide? How can I define the center of my worksurface and have the head move to the center upon my command? I want to be able to place several sizes of work surfaces under the head and have the print start in the same spot . When I position the head to start printing and it reaches temperature it moves to an unknown position before it prints. Does anyone know what controls this?February 26, 2017 at 9:12 am #28497
There are 3 main ways to to do this. Let me walk you through the most common way on the MPCNC.
1-Setup-The way I do it is set the leftmost bottom corner and bed surface as my “home” in the software. This lets you position the part to be printed anywhere you want on the plate in the slicing software. Remember this is relative to where you start the nozzle. Make sure you follow my setup and remove any starting gcode commands to “home” no need for endstops.
2-running-Start the nozzle in the leftmost bottom corner the first time you power on. When it is there make sure your display reads all zeros or question marks. If it does not the easy thing to do is just hit the reset button on the arduino. If you put the nozzle there, you slicer will make the part print exactly where you want it. If you are too high or too low you can use your hand to force the z axis to move up or down while your part is printing the skirt.
3-repeating- Now for clarity sake, and the way I use mine. When your print is done the arduino still knows where your nozzle is provided you do not touch it or power off. You can just hit print again, or even a different part. The nozzle will move to the start position and start a new print. If you move it for any reason or power it off, you need to go back to step 2. I print with mine for weeks at a time without ever needing to set “home” again.
If you slice your part in the center of the bed, it will print in the center of the bed.(depending on your slicer, some auto center things and then it causes a mess)February 26, 2017 at 9:19 am #28500
To address you question a little more directly, home is where the screen reads 0,0,0 (or question marks depending on your firmware version).
Home is a position. Wherever the head is when the screen reads 0,0,0, meaning anywhere you want. If the screen reads 0,0,0 and you move it by hand (the way I do it) it is still home.
Homing is an operation. Homing tells the machine to “move each axis until you hit and endstop then set that position on the axis to = 0”.
Homing requires endstops and I argue for this type of machine is more complicated. For reasons covered in the FAQ’s. If you only plan on printing you can use endstops no problem, but really it is just as easy without them.February 26, 2017 at 9:37 am #28502
The drivers, wiring harness, and plavparts I got from your site. The stepper motors I repouposed a Trondheim ipusia I had purchased but had a crappy acrylic frame (I had purchased it before discovering your project) the stepper motors are 1.5 amp per phase and I was using the test crown drawing from your site.
What amps per phase are the steppers from your site? Should I still set them at .7 volts?February 26, 2017 at 9:53 am #28504
.7 will work but is close to there maximum if you are using the series harness, parallel no problem. keep an eye on them if they get too hot turn them down before they soften the plastic. Maybe start with .6 instead.
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