Can't get it to start where I want

New Home Forum Mostly Printed CNC – MPCNC Troubleshooting – MPCNC Can't get it to start where I want

This topic contains 17 replies, has 3 voices, and was last updated by Profile photo of John John 1 year ago.

Viewing 18 posts - 1 through 18 (of 18 total)
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  • #14311
    Profile photo of Matt saeger
    Matt saeger
    Participant

    I almost have this thing working!

    I have a pen attached and am trying to draw a square. I set the tool where I want it to start but it moves as if it is trying to go to a home position before starting.

    In estlcam I have cnc program start set to start at origin and in the marlin configuration.h I have uncommented //#define DISABLE_MAX_ENDSTOPS and //#define DISABLE_MIN_ENDSTOPS

    If anyone could let me know what else I need to change it would be great.

    #14312
    Profile photo of Matt saeger
    Matt saeger
    Participant

    Oh and the process I used was draw the square in onshape, export it as a dxf, open that file in estlcam. Then in estlcam I picked outside and in tool path properties I set tool path depth to 0 and start level to 0 and exported the NC file. Then I opened that in repetier and saved the gcode file to sd. I also tried sending it via usb.

    I am able to manually move all the axis’s.

    #14314
    Profile photo of Ryan
    Ryan
    Keymaster

    You need to give the path some depth, even with a pen.

    #14320
    Profile photo of Matt saeger
    Matt saeger
    Participant

    I tried some other files and it seems like it starts where I want on X and Y but Z lifts up a couple inches before it starts and doesn’t go back down. I did try putting in .5mm for the depth and I think it forces you to have something anyway.

    #14322
    Profile photo of John
    John
    Participant

    Are you using repetier to move the z axis to the start? If so you need to re-zero after you get in position… Perhaps hit emergency stop in repetier after you get positioned…

    #14323
    Profile photo of Matt saeger
    Matt saeger
    Participant

    It seems like there is something telling it the thickness of the work piece.

    #14324
    Profile photo of John
    John
    Participant

    What do you do in order to get the pen to start position?

    I’ve not seen that behavior unless I had used manual control in repetier to move the z unit around and then it does exactly what you describe…

    Perhaps also post the gcode you are using…

    #14325
    Profile photo of Ryan
    Ryan
    Keymaster

    Check your start position. It should be at z axis origin=worpiece top side, then start the machine touching the top of your material. Sounds like you have it at machine bed.

    #14327
    Profile photo of Matt saeger
    Matt saeger
    Participant
    What do you do in order to get the pen to start position?

    I’ve not seen that behavior unless I had used manual control in repetier to move the z unit around and then it does exactly what you describe…

    Perhaps also post the gcode you are using…

    That is exactly what I was doing…. I moved it to the start by hand and it worked as expected. I was trying to plot the vicious1 logo and I didn’t have grid on in estlcam so I didn’t realize the size and it printed about the size of a dime 🙂

    #14328
    Profile photo of John
    John
    Participant

    Welcome to the start of the learning process… 🙂

    #14337
    Profile photo of Matt saeger
    Matt saeger
    Participant

    Thanks for the help guys.

    It didn’t seem to be putting the plot on the page where I thought it should so I went back to the 200mmx200mm square. I figured out it plots the square exactly twice the size it should be so that was making it hard to figure out where it was going to put it. I must have missed a step somewhere in the software part.

    After the 4 year old goes to bed maybe I will be able to figure it out. I must just have the steps set wrong.

    #14338
    Profile photo of John
    John
    Participant

    Things which occur to me to check:
    Are the steppers set to the right amount of micro stepping?
    Correct steps-per-mm setting in the software?

    My laser engraver was initially wrong on both counts when I started working on it. The micro stepping being off by one setting could double the print size…

    #14340
    Profile photo of Matt saeger
    Matt saeger
    Participant

    I must be running in 1/16 micro stepping mode I have the jumpers installed on the ramps board under the drivers so I will have to figure out why it’s running in 1/16 or change my steps in marlin.

    #14341
    Profile photo of Matt saeger
    Matt saeger
    Participant

    I guess I have the A4988 drivers so I will be changing my steps in marlin. I didn’t realize they did 1/16 microstepping when I got them I was too excited when ordering I guess.

    I checked and my prusa just has thr A4988’s too so I think 1/16 will be ok.

    #14343
    Profile photo of Matt saeger
    Matt saeger
    Participant

    Changed my X,Y,Z steps to the values from the prusa calculator and now it is plotting the right size and I can figure out where it’s going to put the thing on the paper yay! Maybe one of you guys could tell me if I should do anything with the acceleration and feed rates? I have not had to mess with those in my 3D printing experience. I think I may need to change something one the Z it’s making funny noises now it didn’t with the wrong steps/mm.

    Now I need to get this thing in the garage and get it all leveled and stuff.

    #14345
    Profile photo of Ryan
    Ryan
    Keymaster

    What Numbers do you have in there, you just changed the steps in my firmware correct?

    Its odd, the accel and speeds should be pretty mellow for 16th stepping, if you are using mine. If you matched your printers settings that’s the issue.

    #14355
    Profile photo of Matt saeger
    Matt saeger
    Participant

    I changed the configuration.h

    I have 100,100,2267.72,100 for steps I left the acceleration and feed at what you had. I just used the numbers from the prusa calculator and it makes sense since they are half of what was in there for 1/32 micro stepping.

    The Z still ran fine it just sounds different but maybe I need to adjust the driver current or something is rubbing. X AND Y are better. With the wrong steps in there if I told it to move 50mm in one shot the motors would lock and now they run good.

    My 200×200 square was perfect size and even square.

    #14356
    Profile photo of John
    John
    Participant

    You might consider some lube on the Z threaded rod.. Mine quieted right down…

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