Autolevelling doesn't act properly

[mdsultan11]

Hi Martin,

I'm facing issue while uploading the code to OpenCNCpilot. I have gernerated my PCB gcode using Flatcam. yo can see the error issue in picture. And one more issue is that my CNC is not making a track in the place of red marked area in height map. please solve my problem as soon as possible.

Thanks and Regards Md. Sultan

[martin2250]

Hi,

from what I can tell you can ignore these warnings, no worries there. I should probably get rid of the 'zero-length' warning.

As for your other problem: this sounds a lot like the PCB is not glued down properly, so it can bend under the pressure of milling (but not during probing, which is why it still shows up as red). If you aren't doing so already: use a stable wasteboard (I'd recommend plywood at least 9mm thick) and use double sided tape to glue the PCB down over the entire surface.

Best Martin

[mdsultan11]

Hello Martin,

Thanks for the Clue you have shared with me. I will come back once i check with the PCB cutting using double sided tape.

Thanks and Regards Md. Sultan

[mdsultan11]

Hello Martin,

As you said i ignored the error i will get in the beginning while dumping the code to OpenCNCpilot and also i glued it my PCB plate using double sided tape to the plywood waste-board, but then also you can see the Red area occurred on height map done by probing and also you can see the actual PCB cut has not occurred in the same place(Red area) in another pic. Can you please tell me the reason for this and solve my problem as soon as possible.

Thanks and Regards Md. Sultan

[deHarro]

Hello mdsultan, from the picture it seems that only one single point is probed wrong. Questions to your findings:

• does this error occur every time you do a probing session?
• is it always at the same position related to your waste-board, or does the error positon move around from run to run?
• is there the chance that your probing contact gets shorted to ground of your router at any other point (cable sqeezed or similar fault)?
• do you encounter other problems created by means of electrical influences (e.g. do your limit switches sporadically trigger without obvious reason)?

To get a quick remedy for you, you may safe the height map after probing, open the map file in an editor and find the one probe point which is significantly out of sequence and edit this point to the middle value between the two adjacent points. This should "heal" this deviation for the given probing run and you will be able to mill your board without the error.

[edit] Explanation for my questions: From my point of view this problem is not related to Martins program but has something to do with your environment. [/edit]

Harald

[luizabbadia]

Hi, all.

I had the same problem some time ago, and I can remember because your problem has the same symptom as mine. If you observe, the round tracks that represent the area where the IC is fit, they are not perfectly round. I found this problem after rechecking all the motors connections, ( they were not good, poor contatcs, bad connections etc...). Those "not-round" elements were the consequence of poorly connected XY motors and, off course, depth variances were caused by bad connections to Z motor. Weel I hope this is helpful

On Thu, May 2, 2019 at 9:22 AM deHarro notifications@github.com wrote:

Hello mdsultan, from the picture it seems that only one single point is probed wrong. Questions to your findings:

• does this error occur every time you do a probing session?
• is it always at the same position related to your waste-board, or does the error positon move around from run to run?
• is there the chance that your probing contact gets shorted to ground of your router at any other point (cable sqeezed or similar fault)?

To get a quick remedy for you, you may safe the height map after probing, open the map file in an editor and find the one probe point which is significantly out of sequence and edit this point to the middle value between the two adjacent points. This should "heal" this deviation for the given probing run and you will be able to mill your board without the error.

Harald

— You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub https://github.com/martin2250/OpenCNCPilot/issues/105#issuecomment-488651598, or mute the thread https://github.com/notifications/unsubscribe-auth/ABJIM3QXBKXDOIHEJ4CEA53PTLMI5ANCNFSM4HISWPIA .

-- Sds L.Abbadia

[deHarro]

Hi Luiz, I think, that is not the problem of mdsultan.

But to emphasize on the not round tracks, another reason for such results is mechanical backlash at one or both axis (X and Y). Since all of the (not) round traces in mdsultans picture are shaped very equally, I think this is more likely the reason for this sort of problem.

But again, backlash on the Z axis (as I understood what you wrote) wouldn't result in one sharp jump at one point. The reason for his problem must lie elsewhere IMHO

Harald

[mdsultan11]

Hi

Hello mdsultan, from the picture it seems that only one single point is probed wrong. Questions to your findings:

• does this error occur every time you do a probing session?
• is it always at the same position related to your waste-board, or does the error positon move around from run to run?
• is there the chance that your probing contact gets shorted to ground of your router at any other point (cable sqeezed or similar fault)?
• do you encounter other problems created by means of electrical influences (e.g. do your limit switches sporadically trigger without obvious reason)?

To get a quick remedy for you, you may safe the height map after probing, open the map file in an editor and find the one probe point which is significantly out of sequence and edit this point to the middle value between the two adjacent points. This should "heal" this deviation for the given probing run and you will be able to mill your board without the error.

[edit] Explanation for my questions: From my point of view this problem is not related to Martins program but has something to do with your environment. [/edit]

Harald

Hi Harald

Thanks for the response , I was able to corner the problem of the "missing" a particular probing point while probing and marking it as "red". As you have suggested it looks to be random electrical noise going to Arduino UNO's A5 pin had caused the problem. The Probe pin (connected to the spindle's v bit) is at Arduino's A5 pin and the the ground was connected to the PCB copper. And I measure voltage at the Probe pin when it was not touching to the PCB and found to be around +4.8Volts and when it touches the PCB the pin A5 becomes zero volts. I added a 0.1 uF ceramic capacitor between the pin A5 and the +Ve 5V of Arduino assuming that some random ground noise is entering the pin A5 and randomly makes it low (without the probe actually touching the PCB ) . It looks like this (i.e adding a 0.1uf capacitor between A5 and +5V) has worked and I repeated the probing for 3 to 4 times and did not find any missing probing point any more.

You can find the repeated probing after the capacitor addition photos below - No missing probe

Thanks once again for pointing the right direction to go !.

[deHarro]

Hi mdsultan, glad I could help :-) Harald

[mdsultan11]

Hi mdsultan, glad I could help :-) Harald

Hello Harald,

I have small Openbuild CNC machine which 'm using for PCB cutting, as you have mentioned the round tracks in PCB are not coming properly because of mechanical backlash, can you please give a solution how can i get a reduce the backlash in my CNC machine.

Thanks and Regards Md. Sultan

[deHarro]

Hi mdsultan, my machine has threaded rods and plastic nuts. What is your type of transmissioin? lead screw and nuts or pulleys and belts?

If you have lead screw and nuts you probably have the option of two nuts which are to be countered / locked against each other or against the base from one side and the other to minimize the backlash.

The force of this counter against each other has to be high enough to minimize the backlash but not too strong. The screw must turn easily still. Normally there is a means of locking the two nuts with headless screws or something similar. [edit] This is expressed unclear, I'll try to explain deeper: The two nuts are adjusted to minimize the play as described above, then the two nuts have to be fixed in this position. This fixing is done with screws which lightly touch the thread of the nuts from the side to prevent them from turning anymore. [/edit]

If your machine is driven with belts, then the backlash depends solely from the tension of the belts, provided the stepper motors drive the blet pulley directly (without gearing). If there are gears, their mechanical play adds to the backlash.

[edit2] I just stumbeled over this: Backlash-Screw on OprnBuilds Have a look, perhaps you can see or derive what you need... [/edit2]

HTH Harald