Understanding Homing, and Display Readouts

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This topic contains 13 replies, has 6 voices, and was last updated by  Phil Kelly 1 month ago.

Viewing 14 posts - 1 through 14 (of 14 total)
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  • #96051

    Phil Kelly
    Participant

    Hello,

    I’m new to MPCNC and the forums, so forgive me if my quick search failed to find answers!

    I’ve been looking at buying an MPCNC kit for the last year, and as fate would have it, I recently acquired a FULLY BUILT MPCNC (thanks to MRRF2019 and a certain VERY active forum member 😉 😉 ).

    While it was great to get a unit ready to go, I kinda miss the learning that goes on when you build it yourself!  Both my 3D Printers were build-from-kit, real Prusa i3 (MK2S now MK2.5 and a MK3).

    The MPCNC is currently setup with an Ink pen plotter tool & a small Staples-brand whiteboard to allow for magnetically attaching paper for plots. It has the RAMBO 1.4 and the Full Graphic Smart Control Display.  I’ve been successful in getting plots off of it, including 2 MPCNC selfies, the ubiqutous crown, and 2 custom logos run through multiple conversion programs and ESTLCAM.

    Now for the questions & confusion:

    1. When I power up the unit, I typically use the Marlin commands to Auto Home X and Y, and then I move the Z until the pen is barely not marking a piece of paper laying on top of the paper that I intend to use for the plot.  I then go into the Custom Commands section and run Reset All Coordinates command.  The unit beeps, and when I return to the main screen, I expected all three coordinate readouts to say 0, but the Z coordinate shows alternating 0  and ?.

      Is this normal and why isn’t the Z=0?   Also, is this the correct procedure before starting a job?

    2. It appears that when you start a job, the firmware decides to call where-ever the tool is 0,0,0.  Even though the G-code generated from ESTLCAM is using ABSOLUTE coordinate moves (G90 and lots of G00, G01, and G02 commands).  Is that correct?
    3. Even AFTER doing the steps in #1 from above, if I hit Home Z, the unit HARD drives the z into the white board, well below what would even be Z=0 if the whiteboard weren’t there.  This seems wrong!  What do I need to do to actually get the Home Z set correctly so that if I autohome all 3 axis, the unit returns to where I had it after step 1?
    4. It would seem nice to have the gantry move out of the way at the end of the job, is there a way to have CAM S/W move it out of the way?  Using ESTLCam or Fusion 360–as that is where I intend to go with most of my work, as I’m already very familiar with designing in the Model workspace for my practical 3D-printed parts.  In a Slicer for 3D printing, there is a custom G-code section.

    Thanks in advance for your advice!

    Phil

    #96111

    Josh
    Participant

    0,0,0, is wherever the carriage is when the machine is powered on.  I dont mess with the home button.  I place my material, move the bit to wher ever I want it, set hard end stops, then set the bit on the material to set Z.  If I need more accuracy I use foil tape and a multimeter.  Once the bit is set I power on the controller which sets 0,0,0 select the gcode and turn on the spindle.  After the cut I power the machine down and move the gantry out of the way.

    This machine is capable of whatever you want and I’m sure the other guys will chime in on how to make that happen.

    For me the beauty is in the ability to manually manipulate the machine without having to wait for it to run through any cycles.

    1 user thanked author for this post.
    #96113

    Dakota Jim
    Participant

    Hi Phil, welcome to the wonderful world of MPCNCing.

    CNC is different from 3d printing in that it is starting at the top and works its way down and is removing material instead of adding it. So in regards to homing Z the “build” surface is always different (mostly) so there is not a “built in” end stop switch for Z like 3d printers have. You can add a Z home “switch” that will work with router bits but not plastic pens. It consists of a 2 conductor wire from the board that is connected to Z-min – and S and terminates with 2 alligator clips (using sufficient wire to reach the router wherever it is located at (typically home) with 1 alligator attaching to the router bit and the other connected to a bit of metal on the surface of your work piece (some use aluminum tape, others use spatulas (seems too thick to me) and I use a blade from a feeler gauge (.2mm – much thinner and it gets dented when the router bit hits it and it is difficult to keep thinner blades flat). This acts just like an endstop switch does by closing a circuit.

    My personal work flow is as follows starting with power off and unplugged to the MPCNC and router.

    1. mount workpiece square
    2. With power off position router to x-y home
    3. Insert SD card into LCD controller
    4. Plug in power, turn on power to the board
    5. connect alligator clip to the router bit, position the feeler gauge under the bit making sure the other alligator clip is still connected to it and holding it firmly down to the work surface.
    6. Home Z through the control board
    7. disconnect the clip on the router, slide the feeler gauge out and hang it out of the way off the work surface making sure the clips do not touch each other (I just clip the alligator clip that was on the bit to the insulation of the other wire)
    8. Plug in and turn on the router (never have your hands near the router bit with the router plugged in)
    9. Select the file you want to use and let it start creating for you. Pull up a chair and watch it run. Never, ever leave your CNC (any CNC) running without you being right there to be able to shut it off in case something fails. I have seen some youtube videos where people think double sided tape is good enough to hold their material (it’s not), walk away only to come back to a room or garage full of smoke and a destroyed cnc machine. I have not seen any with the building burned down but that may be because they destroyed their computer and camera and just can’t upload them (or they are afraid their insurance company may not pay the claim due to negligence)
    10. When file is done running, power off the router, power off the board, manually move the router out of the way, remove the work piece and admire it.

    I read through a lot of posts on here and decided that x-y endstops would just overly complicate and slow down my personal work flow (I’m about 5-6 months into CNCing and 4-5 months into 3d printing so I am not an expert by any means.) I do have a Maslow CNC that I think I will probably end up selling and then build a Lowrider if I decide I “need” a large format cnc but so far my MPCNC gets used probably 40-50 times as much as the Maslow.

    I am also very happy with Estlcam for my cam and am still trying to learn F360 without having to watch tutorials (I’m old, don’t judge me)

    Hope some of this helps, keep updating us on your progress.

    1 user thanked author for this post.
    #96124

    Kelly D
    Participant

    Did you score a MPCNC built by Ryan himself?! I hope he autographed it for you! Jealous.

    The Home Z moves the tool down in search of the closed circuit formed when the tool touches the metal touchplate on the material surface. I’ve measured mine and added to the start gcode the subtraction of this thickness so Z-0 should technically be right at the material surface. You can read about it here. I don’t know how I got along without it but then again almost all of the projects I’ve tackled with the MPCNC have involved tool changes which were very challenging for me prior to the endstop addition. Z height was always off by just enough that I was never perfectly happy.

    #96129

    Ryan
    Keymaster

    While it was great to get a unit ready to go, I kinda miss the learning that goes on when you build it yourself!

    Don’t worry, one is never enough…

    Let me know if anything is still unclear. You have the super deluxe complicated version so you did dive in to the deep end, but with a few printers under your belt I am confident once a few things are cleared up you will be comfortable and confident…until you throw a spinning tool of death on there.

    1-Yes, several ways to “home” that is one. Adding a Z home, when milling comes in handy if there is going to be a tool change otherwise, don’t bother.

    2-Yes and no. Typically wherever the head is is 0,0,0. Unfortunately not with The dual firmware firmware, you will not be able to move negative in the X and Y unless you home first (you can swap firmware to bypass the endstops).

    3-Do not use the home button. If you actually want to home all three axis you need to plan out your Z moves. I have my basic routine on the milling basics page.

    4-For sure. Stick with Estlcam, FusionCAM is a nightmare until you have a very deep understanding of CAM (I do not use it). You can use any ending routine you want, there is start, end, and tool change Gcode sections in estlcam (and Guffy’s fusion360 PP (post processor)), and even some basic ending settings built in.

    Keep that phone call banked…

    #96130

    Ryan
    Keymaster

    Did you score a MPCNC built by Ryan himself?! I hope he autographed it for you! Jealous.

    I thought I might find some dude wandering into MRRF with a dripping bag full of Ice Carvings, sadly you never showed… It even started to snow for a second and I ran outside and yelled “Kelly it is cold enough now, you can come in!”.

    I then ran back inside because in my neck of the woods if you see snow you made a wrong turn 4 hours ago.

    1 user thanked author for this post.
    #96142

    Barry
    Participant

    Did you score a MPCNC built by Ryan himself?! I hope he autographed it for you! Jealous.

    I thought I might find some dude wandering into MRRF with a dripping bag full of Ice Carvings, sadly you never showed… It even started to snow for a second and I ran outside and yelled “Kelly it is cold enough now, you can come in!”.

    I then ran back inside because in my neck of the woods if you see snow you made a wrong turn 4 hours ago.

    Dude!  On my drive home I couldn’t read half the damn signs!  Wind must have been blowing with the snow, almost every one was plastered white.  Once I got out of Goshen the yards were white, it snowed more than I thought it did.

    #96175

    Phil Kelly
    Participant

    Well, Ryan DID sell it to a Kelly, just not one with that as the FIRST name ;-).  I didn’t have him sign it–but I should have!  My first Prusa i3 MK2.5 is signed by it’s creator.  Seems only fair that my first MPCNC (first CNC actually) should be too!  I see the cover of the control box making a return trip to Goshen next year!!!

    Hmm, maybe I can even transport a couple example projects to sit on Ryan’s table. . . . . a challenge!!

    Yes, I’m definitely diving into the deep end.  My first 2 milling projects are already taking shape, so I need to go order those endmills!  One is wood, one is plexiglass.

    Ryan said you guys in the forum would be helpful and his faith is not misplaced!

    Phil

    #96177

    Phil Kelly
    Participant

    @Ryan,

    The spinning tool of death arrived on Saturday–Dewalt 660 as recommended.  The holder print finished this morning and the perpendicularity checker is on the printer now.

    Oh, I forgot to ask about the recommended clamp down system / wasteboard process.

    And HOW in the world did you attach that whiteboard to the wasteboard–it doesn’t want to easily peel off!!!

    #96185

    Barry
    Participant

    Cheap double sided tape!  We were surprised it was as level as it was.

    1 user thanked author for this post.
    #96190

    Phil Kelly
    Participant

    So Barry,

    Did I see you there?  Did you cut the mounting board for Ryan & print the endstops?

    Phil

    #96331

    Barry
    Participant

    No, that was Ron.  I was wearing the flannel shirt talking to everyone.  I was only there Friday and Saturday.

    #106387

    Ryan
    Keymaster

    How you treating my baby? Give up or still messing around with it?

    #106587

    Phil Kelly
    Participant

    Still with it, no chips yet, but soon!  Work just got really busy on me.  I have the first carving project in mind, but still debating on Fusion or Estl or Kirimoto for CAM. Speeds & feeds are also a bit terrifying!

     

    (Just realized I replied to this via an email reply to “no reply” a few days ago!).

    1 user thanked author for this post.
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