Hi there, I just finished putting the Altmill 4x4 together. Iâm new to CNC and just have a few questions to get to know this machine better.
I was expecting physical limit switches on both ends of each axis to prevent crashes - am I right in assuming that the closed-loop stepper controllers act as a limit switch here? In other words - in case of an error the machine would âcrashâ in to the rubber bumpers and trigger a stepper controller error when it canât move any further? What about the Z axis (no rubber stops)? (I understand that homing on startup and correct max travel in firmware settings should usually prevent this)
In the video tutorials, G-Senderâs firmware tool has descriptive names for all the $ settings (at least the ones they show in the video). But when I tried to change my default spindle, my $395 setting, and all the $ settings after 133 are all just called âCustom EEPROM fieldâ. I did select Altmill 4x4 + Spindle as my profile. Could this be a bug? The spindle works but Iâd like to really get to know this software and how it works.
The altmill has physical limit switches but I can not recall having seen a CNC setup where these switches actually directly interact with the motors/power in order to prevent an actual crash. They talk to the controller and it is the controller that acts on that input.
There are many scenarios where the controller raises an error condition and shuts down the motors. Hitting an obstruction (such as a bumper or maybe a fixture clamp) is one reason.
The physical zero position is slightly off from the rubber bumper. If everything works as it should, the rubber bumper would never be bumped. Alas, crap happens and that is why you have a bumper.
The z axis has the limit switch but you are right, there are no bumpers. Guessing on the reason, I would say the axis has very little mass and is relatively slow speed so a bumper would likely not be needed.
Regarding the second question - yes, itâs annoying that a field is labelled âcustom eeprom fieldâ. I wouldnât call it a bug, it is done on purpose for some unknown reason. There might be documentation available for these entries but I am not aware of anything - ask Sienci tech support and maybe they can help or explain why there isnât a better field description.
I can only chime in on part of question 1 as I own a LongMill without the SuperLongBoard.
That is why only one switch per axis is needed. Once the machine is homed it knows where zero is and that it canât go beyond the max travel for that axis. Of course my machine does not have closed loop steppers so if something caused me to lose steps then my machine could still crash. That shouldnât be a problem for you with the closed loop steppers on the AltMill.
Be safe, the AltMill is a beast compared to the little 3018 that I made my beginner mistakes on. Now I only have to worry about non-beginner mistakes.
You need to connect using the grblHAL firmware, not grbl. I can see in your screenshot you are using the wrong controller. That is why you donât have proper descriptions. Itâs not a bug, just user error.
