Circles not centered

This topic contains 63 replies, has 5 voices, and was last updated by  Jeffeb3 5 months, 1 week ago.

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  • #50592

    Damien
    Participant

    Hi,

     

    While trying to cut some washers the centre hole seems to be shifted to the right and maybe a bit up.  Hope the picture explains what I mean.

    I drilled some marker holes in my bed at 60cm from zero and measured with a measuring tape.  The Y axis seemed ok, but the X was 1mm less than 60cm.  Would this cause this misalignment of holes?

    Is there anything else that would cause this? Or is there a way of calibrating the machine?

     

    Its strange that the centre holes are offset for all the washers considering they were cut one after the other.

     

    Hope someone can help.

    Cheers.

    Attachments:
    #50596

    Jeffeb3
    Participant

    Would this cause this misalignment of holes?

    I doubt it. But that’s odd. Try it at 30mm. If it’s down to 0.5mm error from 1mm then it’s linear, and wouldn’t have that big of an effect on the washers.

    But the machine should move 60mm with less than 0.1mm error. See if you can measure the movements without cutting anything. If it’s not right on by the tape measure, then something is wrong (installed wrong, or loose or wrong parts somewhere).

    W.r.t. the washers. If you’ve eliminated the obvious things, like making sure your CAD and CAM are actually in the right place, I would guess things are flexing a bit under the pressure of the cutting. You could try:
    – Cutting the middle with a helical drill instead of a hole operation. Those are EstlCAM terms.
    – Test in high density foam because the resistance goes away.
    – Go slower. That might help.

    #50597

    Jeffeb3
    Participant

    For testing movements. Be sure you mark where you start, make a movement. Measure, then go back to the start and see if it returned to the right spot.

    #50605

    Ryan
    Keymaster

    I can not think of a way it could do that other than CAM. If you cut the outside of one then the inside, then moved to the next it doesn’t make sense to be a machine issue. The outsides seem to be aligned correctly.

     

    How fast and deep were you cutting with what diameter, and how long is your Z axis?

    #50617

    Damien
    Participant

    I can not think of a way it could do that other than CAM. If you cut the outside of one then the inside, then moved to the next it doesn’t make sense to be a machine issue. The outsides seem to be aligned correctly.

    That’s what I was thinking was strange.

    How fast and deep were you cutting with what diameter, and how long is your Z axis?

    1/8 single flute, 12mm/s, 1.5mm depth of cut, with 12k spindle

     

    Thanks.

     

    #50618

    Ryan
    Keymaster

    Could you drop your gcode here and I will see if the circles are concentric.

    #50696

    Damien
    Participant

    Ryan, I have attached gcode.

     

    Thanks.

    Attachments:
    1. washer_Array.gcode
    #50699

    Ryan
    Keymaster

    I see what happened there is no way to diagnose this. You missed a single step somewhere.

    Next time do each full part at once. Inside, outside, then next one, the last thing is cut out the whole thing. You cut out all the outsides somewhere in the middle you cut out the entire piece, them some more outsides, then the insides. This results in all the pieces not working.

    If you do the sequentially, you will see where it went wrong, and always do the outer biggest cut last in case it breaks free or the comes loose.

    #50771

    Damien
    Participant

    Ok, I’ll do that and report back.

    #50930

    Damien
    Participant

    Ryan, ok that went better. Cutting the whole part at a time seems to have made a difference. Although on the first pass of the large outside cut it paused for a split second which made it cut the box wrong. You should be able to see from the picture.

     

    So so does that mean I’m still going too fast, or too deep?

     

    thanks

     

    Damien

    #50938

    Ryan
    Keymaster

    Is that aluminum? Do a test in something softer to make sure the Gcode is good. Check your pulleys, almost looks like one might be loose.  (that would explain a momentary pause)

    It should never pause, you can look at the gcode to see if there is any weird happening right at that point.

    In aluminum fine tuning comes down to you ear for the most part. Too fast or too slow and the bit breaks, anything in between should sound good, as it cuts you should be able to hear parts where it obviously is under more load (90 degree corners). Skipped steps are usually a sign of other issues. The CNC is strong enough now to never skips steps it should always break a bit before it skips now. I originally designed it with weaker steppers and it would skips steps if your gcode was too far off. Now it is just a monster.

     

    #50946

    Damien
    Participant

    No, its HDPE 10mm thick.
    When I say pause it was as if it struggled to cut and skipped steps.
    Interesting that you say it shouldn’t do this. My steppers are 82gcm2, are they strong enough?
    How can I make it a monster 🙂

    Cheers,

    Damien.

    #50947

    Ryan
    Keymaster

    What are your cutting specs, speed depth spindle bit and just your gcode.

    #50979

    Damien
    Participant

    I am cutting through 10mm HDPE

    Feed: 12mm/s
    plunge: 1.8mm/s
    Depth of cut: 1.5mm
    Spindle rpm: 12000
    Bit: 1/8″ Carbide Single Flute Long (the one in your shop).

    Gcode is attached.

    Thanks.

    #50982

    Ryan
    Keymaster

    Everything looks good, the gcode you sent was not from the previous pic?

    There is a ton of moves in that file, try turning on arcs that is going to cut that code down significantly. Another option is slow down to 8mm/s and if that works make deeper cuts instead of faster.

    You don’t have a 660 on there, so I can’t give specific suggestions, and I have no idea how long your z axis is. no matter what arcs should be on for circles larger than 6mm or so and go slower since you don’t have the power of the 660. If it is really tall you might need to go even slower.

    #51833

    Damien
    Participant

    I turned on arcs and reduced speed to 8mm/s. All went well until the last circle that totally went wrong. Its as if the bit hits denser material that’s harder to get through, which then throws off the rest of the cut.

    I will try cutting shallower.

    I was also playing around with tool change code. For some reason this code restarts the ramps board. Can you tel;l me why?
    G0 X0 Y0 F2100 ; move head to safe area
    G0 Z45 ; Raise spindle for tool change
    M84 S999 ; keep motors on forever
    M18 Z ; release Z
    M05
    M107
    M000 ; pause for user
    ;Change tool: <n>
    G28 Z ; Home Z axis to touch plate
    G1 Z2 F150 ; Raise Z axis 2mm
    M000 ; pause for user
    G0 X0 Y0 Z0 F2100 ; move head to safe area
    G0 Z45
    M03
    M106

    Thanks.

    #51835

    BT
    Participant

    Have you tried using Repetier to enter the sequence manually to see which line causes it to reset?  Did it occur before or after the pause (M000)?  If it was after, then it could be either of the first two lines following M000 because one of them has a speed greater than 8 mm/s (F2100) and the other has no speed.  Note, I’m making the assumption that you are using the threaded rod and not the leadscrew, because the same issue happened to me until I limited the Z speed to below 480 mm/min.

    #51836

    Jeffeb3
    Participant

    G0 X0 Y0 Z0 F2100

    Which line does it fail on? This one has a large speed for Z.

    You could send each line one at a time, through the terminal. I’m not sure what some of them do.

    #51841

    Ryan
    Keymaster

    Small holes don’t do well with arcs. Depends on what size they are and how fast you tried to cut them, did you do a finishing pass?

    #51848

    Damien
    Participant

    It moved spindle to safe area, and raised spindle to 45mm before resetting. I didn’t get a pause indication on lcd.

    I will try each line in repetier and see what happens.

    #51850

    Damien
    Participant

    Small holes don’t do well with arcs. Depends on what size they are and how fast you tried to cut them, did you do a finishing pass?

    The centre hole is about 20mm. I was cutting at 8mm/s at 1.5mm depth, and yes i did a finishing pass at 5%

    #51858

    Ryan
    Keymaster

    Those look pretty good as long as you have a good bit in there. I guess the best thing to do is try a test with arcs off, 20 is small-ish. We found a good gcode visualizer so now maybe I will be able to finally tune the arc settings in the firmware better.

    #51859

    Damien
    Participant

    Ok its M000 that’s causing the restart for some reason. If I enter it manually it comes up on lcd “waiting for user” and goes away when I click the thumb wheel.

    But if I enter it in the gcode editor like this, it restarts:

    G0 X0 Y0 F2100 ; move head to safe area
    G0 Z45 ; Raise spindle for tool change
    M84 S999 ; keep motors on forever
    M18 Z ; release Z
    M05
    M107
    M000 ; pause for user

    If I remove M000, it continues running.

    Anyone have any ideas?

    Cheers.

    #51860

    Damien
    Participant

    Those look pretty good as long as you have a good bit in there. I guess the best thing to do is try a test with arcs off, 20 is small-ish. We found a good gcode visualizer so now maybe I will be able to finally tune the arc settings in the firmware better.

    same thing happened with arcs on and off, Maybe it is the bit. I will test more

    Thanks.

    #51863

    Jeffeb3
    Participant

    If I remove M000, it continues running.

    Anyone have any ideas?

    You can split the guide into different files, and don’t use the pause.

    You can try it with fewer zeroes, M0 instead.

    I can think about it some more, but those are my first ideas.

    #51869

    Damien
    Participant

    Cool, Cheers

    #51883

    Ryan
    Keymaster

    You saw the “Some old guy coding” video? It covers a few ways you can do this. Your code is a little out of order and incomplete. Try this way to see what you might want to tweak.

    Some Old Guy Coding Teaches How To Do A Tool Change.

    #52530

    Damien
    Participant

    Ok, got a chance to do a bit more testing and realised there is something more wrong. the firmware keeps resetting in middle of a job. I have attached some gcode. I am not sure exactly when it resets, but its around the 30mm depth of cut mark.

    I thought it was the tool change code that was causing the reset, but this shows that there is something else going on.

    Any ideas what would be causing this?

    Cheers

    #52549

    Ryan
    Keymaster

    Gcode looks okay from what I can tell. Check all your connections including the lcd. Not sure how to check from here. Run the code again in the air and see if it stops again.

    #52550

    Ryan
    Keymaster

    30mm? How do you plan on milling that deep?

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