Setting the home position on a new printer

Continuing the discussion from Best 3D printer or kit under $400:

I just finished assembling a Max Micron aluminum frame Prusa i3 from The Online 3D Printer Store. It appears to be a solid little unit, and the hardware is good. It has a Mk3 heated bed ,Mk8 extruder and autoleveling. All up it was only $340. But I do have an issue. The home position for the XY axis are off. When I go through the menu on the LCD screen, there is nothing to set for the axis home positions. They sent me the firmware and some seemingly unrelated files as well. It just confuses things because I have no way of knowing what applies and what doesn’t. It has Marlin firmware. When I hit auto home the X axis moves all the way left, ignores the stop switch and binds the motor until I stop it. Also the X axis runs the bed all the way forward, making the auto level sensor miss the bed completely. If I can get past this hurdle, I can at least start to print. My son was a member out there and got me interested in 3D printing. I was just hoping someone there would share some of their wisdom with an old man. I might be wrong, but I can’t help but think the firmware needs to be reflashed. Any thoughts?

There are settings in marlin configuration.h that set the extent of the bed, but not the offset from the home switches to the corner of the bed. You can use M206 to set the offset for printing, and if your controller is working correctly, M500 to store that setting. On mine, it won’t store, and I am going to have to add (in my case) M206 X-17 Y-7 to my slicer pre print commands.

Is there any way to view the data in configuration.h ?

M503 will display some of the settings that come from configuration.h, but can be overridden with certain commands and written with M500. But configuration.h is one of the files that gets compiled into marlin. Your printer probably has a version of marlin that they package for it. That would contain their configuration.h file, which is hopefully what is on your controller. I’ve compiled and uploaded marlin to my X3 probably a dozen times this week tweaking the configuration.

Well if you could look at mine and show me the process that would really help. Is this done within a program like Repetier?

If you use octoprint, there is a place you can send commands. Outside octoprint, I have used putty, and specified the serial port and speed and run commands there. Note that marlin does not echo what you type, and is case sensitive. I suspect most 3d printer drivers like pronterface probably have some terminal page where you can see the G code and send manual commands. Note that M503 will send you the G code commands for the values it shows. You then have to look up the G code commands to see what values they correlate to in configuration.h. I would love to help, but I’m not sure when I can. I’m already a bit over committed this weekend.

I understand. I don’t want to inconvenience anyone. Thank you.