I purchased a pre built mpcnc. Not sure which version but it has the Rambo mini board and no end stops.
A few things that are escaping me… how do I define the min and max for z height and x/y?
I’m not sure how to tell it so it doesn’t keep going way beyond the maximum for z and y. I can job the machine using whatever software is out there to connect to marlin machines. Also how do I define what is “home”.
Sorry if this has been asked but I can’t seem to find anything related to non end stop machines. With my 3d printers I just clic home. And it tell it to go too far one direction it will prompt me or just stop moving.
For CNCs, typically jobs are defined relative to the stock, not relative to the machine. You set up your toolpaths in your CAM (EstlCAM, Fusion 360, …), and pick some location on the stock to be your “home” for that job. Once your stock is mounted in your machine, you will position the tip of your router bit over the “home” relative to the stock you selected in CAM and then zero the machine to that position using a G92 g-code.
The most common “home” positions are the top of the stock at the left bottom corner of the stock, though for some jobs, other positions might make more sense.
Note that when your “home” is relative, and you’ve defined your toolpaths correctly in your CAM program, your machine will not exceed the machine maximums and maximums. If you happen to make a mistake with your setup or CAM and exceed the minimums or maximums, the steppers are not powerful enough to damage the machine. You just mess up your job.
When steppers hit the limit of their travel and try to keep going it sounds awful, like you’re stripping the teeth off meshed gears - but there’s no gears involved so nothing is being damaged.
I just have to keep telling myself that when it happens…
I had some success!, I followed the guide to setup estlcam, that worked fine. I used the crown DXF file. When I import the gcode file generated from estlcam into repetier host it seems to look fine. I 3d printed an attachment for a pen to affix to the tool head. When the job starts the tool head moves to the origin position but the z height is waay too high. When i import the gcode crown file in the guide the tool head has the correct z height and draws the crown image just time. My question is what am i doing wrong when i generate my own gcode?
I should also note that in repetier host before i start the job i jog the z height so its just a hair above the work surface and I did this for both crown gcodes.
Before you start the job, you need to use the Probe Command G38.2 Z (0) to bring the tip of the endmill to a known distance above the work surface (V1’s Tiny Touch Probe is about 0.5mm). You COULD set this position manually, but it won’t be nearly as accurate.
Then you need to tell the machine where it is in relation to the material, using a G92 Z (where = thickness of metal probe tool). So if using the Tiny Touch Probe, the command would be G92 Z0.5.
Now when you run the gcode for your CAM, the machine will use all of its Z commands in relation to the top of the work surface = 0.
You need to execute a G92 X0 Y0 Z0 at the start of your job. This establishes the current position of the pen as (0,0,0). There are ways to automatically insert this command EstlCAM as well as other tools like RepetierHost. Note that the G38.2 command mentioned by Bartman is a probing command that works with a touch probe and is also only enabled (by default) in the LowRider firmware.
If you have a display with your setup, there is a menu item in the custom menu for zeroing out the coordiantes.
That was the IT! thank you. I am running a rambo mini with no end stops and no z probe. Its quite an earlier edition of the mpcnc. Ive owned it for a few years and couldn’t figure it out then. I decided recently to delve into it again. I am way further ahead than before with the help of this forums and users. Thank you.
You can add a touch plate to the Mini Rambo like the one in the V1 store or something you make. It attaches to the Z min ‘S’ and ‘-’ pins, and you use the home Z command to run it.