I finished building my Los Angeles MPCNC build and ran my first test of the crown with a pen. Overall, it was a great success, but clearly I need to get a better understanding of how to control the Z axes and understand its starting position. Any hints would be greatly appreciated. I ran the gcode from EstlCAM and used repetier-host to speak to the MPCNC. I was using the EstlCAM basic setup and in step 8 was going off the sentance “Start. Put the tip of the pen (or tool) a hair above where you want it to start and hit run. It should pick up, move, drop down and go.” Clearly I got something wrong.
My guess is that the steps per mm of the Z axis is too high. Could be due to a different lead screw than the firmware was built for (4 start vs 1 start), or missing jumpers on the control board (depending on what board you’re using) or microstepping settings for the drivers.
Have you measured whether a commanded 20mm move actually moves 20mm? You’ll want to do that on all the axes.
Thank you for the insight. The lead screw and Rambo board were both purchased from the V1Engineering store, so I am wondering if I am just misunderstanding the Z axis starting height being derived from EstlCAM. But I havnt tried measuring the steppers to see if the accuracy is correct per your suggested test. I will test that out and report back. Thank you again!
I uploaded a video of the building process for my MPCNC. I work as a project designer for an architecture firm and help out with the digital practice group. I wanted to start exploring how digital fabrication could change the industry, which lead me to this community and building my own CNC. You all rock. Thanks for everything!
Sorry, I didn’t watch the video the first time. I think you’ve made your own gcode, but those instructions are for running the premade gcode test crown. If you download that premade gcode file, you will see that near the top, there is a G92 X0 Y0 Z0. This tells the rambo “you are at the starting line”. If you made your own gcode file from the crown svg/dxf, then you probably don’t have that line in the starting gcode, and it assumed that wherever you turned on the machine, was the starting place.
There are many ways you can fix this:
Manually put the G92 in the top of your gcode files. But that’s no fun
Change the Estlcam Settings for starting gcode and add in that line. Then any gcode created by Estlcam will have that line in it.
Remember to set the zero before running any job. If you use RH, you can make a macro with this in it (isathome tells RH it is at home, it is special to RH):
G92 X0 Y0 Z0
@isathome
If you are using an LCD, there is a “Set home offsets” menu option (I think that’s what it says, it has been a while for me).
You can reset the firmware when you are where you want to start, and the Rambo will think that is the starting spot.
It is important that whatever spot you choose is the same as the origin in Estlcam. That is the lower left corner by default, but you may want it on a particular feature or in the center of a design depending on what you want lined up. It doesn’t mean anything, except it has to be the same spot in estlcam and on the workpiece.
I like to do 3) above. The reason for that is, I like to set the start, then raise the bit 5mm or so, then start the router, and then hit play. It won’t marr the wood at the origin that way. But do whatever works for you. We won’t judge.
I wrote most of this up in more detail in the docs (in the learning section, it isn’t required reading).
That timelapse is awesome. Thank you for doing that and sharing it. It is so easy to just get started, and instead you went through the work to think that through and set up the recording. Very fun video (for those of us who love this stuff).
Thank you so much for the help. You are correct, I did make my own gcode. I have now read through the document you linked which was really helpful. I hadnt run into it before, but I think I have a better sense of how to get things set up now. I am excited to get to some milling, but wanted to make sure I didnt plunge the tool deep into the project before it did anything else. I will definitely be starting with foam.
It was a lot of fun making the video. My plan is to try and keeping making more as I dive into milling and laser cutting. Hopefully they are fun and helpful for others.
Not sure if I should start a new thread, or keep going with this one. Here is a video I created to show the architecture firm I work for how we could begin to utilize digital fabrication in our designs. I huge thank you to this community. You have made exploring this topic so accessible and enjoyable. I am excited to keep milling. I will keep posting videos as I make them.
Thanks for the reply. Have you found any ways to bring digital fabrication into your work? I am trying to show my firm the possibilities, but I think it will be a slow process.
