Getting dual axis self square gantry working

ryan
Posts: 7
Joined: Thu Jul 23, 2020 6:04 pm

Re: Getting dual axis self square gantry working

Post by ryan » Sat Sep 05, 2020 11:52 pm

PropellerHat wrote:
Fri Sep 04, 2020 1:11 pm
The most valued info right here, thanks! Going to try this on 2 machines this weekend.

Just one question: The bridging of the clone drive thingies... the way it is done in the second pic of the theme in https://wiki.protoneer.co.nz/Raspberry_Pi_CNC
right? (4th socket cloning Y axis) There are a couple of different pics in the web how to connect these dots and frankly the system could be more intuitive.

Thanks again mate!
That doesn't sound correct, but I could be misunderstanding what you mean. Nevertheless, in this case with dual axis squaring you only make solder bridges only for the A3 & A4 labeled pins. You do not want to have any other solder bridges (X,Y,Z). It sounds like you have Dual Y setup, so make sure you change the config.h to `#define DUAL_AXIS_SELECT Y_AXIS` as the default is to clone the X axis with this firmware instead.

This probably goes without saying, but just in case -- make sure you test this without the steppers actually able to rack the machine around so that it doesn't end up tearing itself apart if things aren't quite right on the first go.

priority
Posts: 12
Joined: Sat Feb 22, 2020 8:01 pm

Re: Getting dual axis self square gantry working

Post by priority » Sun Sep 06, 2020 1:30 am

PropellerHat-thanks for asking for clarification. This should be the standard setup on all dual-axis CNC machines IMHO and hopefully we can remove any ambiguity for anyone reading this thread in the future. Good look on your setup and post back here your results or challenges!
PropellerHat wrote:
Fri Sep 04, 2020 1:11 pm
The most valued info right here, thanks! Going to try this on 2 machines this weekend.

Just one question: The bridging of the clone drive thingies... the way it is done in the second pic of the theme in https://wiki.protoneer.co.nz/Raspberry_Pi_CNC
right? (4th socket cloning Y axis) There are a couple of different pics in the web how to connect these dots and frankly the system could be more intuitive.

Thanks again mate!
This IS NOT correct and WILL NOT work for self-squaring. DO NOT clone the Y axis. The proper solder configuration for self-squaring is NOT shown on the wiki.

Referring back to my original post in this thread:
....
Place solder bridges on the clone config A3/A4 clone config and make sure no other solder bridges are present.
...
Here's a picture to hopefully remove any ambiguity. (Note for Bertus: I tried to attach this message so it would be more permanent, but your forum software is not allowing me to add attachments. "ERROR Sorry, the board attachment quota has been reached.")
Image

In order for self-squaring to work, the Y and A steppers must be driven independently by the grbl firmware. So, in the self-square case, there is no "cloning" of an axis with the solder jumpers. Rather, we are simply connecting pins A3 & A4 to the dir/step pins for the A driver and the "cloning" is done by the grbl firmware compiled with the edits shown in the original post in this thread.

ShaneNZ
Posts: 3
Joined: Sat Jun 27, 2020 1:36 am

Re: Getting dual axis self square gantry working

Post by ShaneNZ » Tue Sep 15, 2020 8:29 am

Perfect timing as I've finished the new build and was wondering how to tackle the sync/squaring up of the dual y axis. Now, if only I can get hold of Bertus to get a Pi CNC shield. As much as I would like to support the Canadian/US/DE economy..seeing as how I live just on the other side of the hill to him, would prefer to support local. Might still be in Lvl4 over that side? :P

ryan
Posts: 7
Joined: Thu Jul 23, 2020 6:04 pm

Re: Getting dual axis self square gantry working

Post by ryan » Tue Sep 22, 2020 3:11 am

Is it possible to use normally-open switches instead of normally-closed switches with self-squaring config?

I would prefer to use normally-closed, but I bought a bunch of the OpenBuilds "Xtension Limit Switch Kit" switches only to discover during installation that the PCB is hard-wired to operate as normally-open. I *can* solder wires directly to the switches, but it would be nice to be able to use the onboard low-pass filter. If I can't use NO switches... I probably will just solder the wires.

priority
Posts: 12
Joined: Sat Feb 22, 2020 8:01 pm

Re: Getting dual axis self square gantry working

Post by priority » Tue Sep 22, 2020 10:59 am

ryan wrote:
Tue Sep 22, 2020 3:11 am
Is it possible to use normally-open switches instead of normally-closed switches with self-squaring config?

I would prefer to use normally-closed, but I bought a bunch of the OpenBuilds "Xtension Limit Switch Kit" switches only to discover during installation that the PCB is hard-wired to operate as normally-open. I *can* solder wires directly to the switches, but it would be nice to be able to use the onboard low-pass filter. If I can't use NO switches... I probably will just solder the wires.
Caveat Emptor!

I recommend against using NO switches for homing switches. There is no difference electrically between a broken/disconnected wire and a NO switch. Additionally, switches usually fail open in low voltage usage. Any of these failure scenarios will NOT be noticed until after a homing cycle rams your machine into the end of an axis; however, a NC setup will not even start a homing cycle if one of the above faults is present. Or, for that matter, GRBL won't even let you move your gantry unless you correct the fault or knowingly disable the limit switches in a NC setup. Additionally, NO circuits are generally more susceptible to noise.

Even with this gloom and doom, can you make your Openbuilds switches support auto squaring without soldering? Likely. Wire the Z and A limit switches in Parallel instead of Series as described in my original post and set the grbl settings for NO operation. I have not tested it. I do not recommend it. But it may work.

PropellerHat
Posts: 6
Joined: Fri Jun 19, 2020 11:09 am

Re: Getting dual axis self square gantry working

Post by PropellerHat » Fri Sep 25, 2020 1:06 pm

Hi again. Finally I have gotten the machine in the state of getting this self squaring to work but no, I can not manage. If I have the Y clone bridging applied, the machine homes otherwise perfectly but there is no squaring what so ever. If I remove the Y cloning bridges and replave them with A3 A4 bridges as guided in this thread, the "A" axis doesn't move at all.

I have uncommented the lines in config.h mentioned and flashed the GRBL again on my cnc board (2.60 as supposed).

I also tried swapping the Step and Dir wires that go to my "A" axis (external) drive, no movement on A axis.

What does it mean, the A3 A4? When I solder the Y bridges, I can measure that the Step and Dir pins of A and Y are connected. This makes all the sense (cloning an axis, whether it is X, Y or Z, to become a duplicate of the chosen axis) . But what am I connecting when soldering the bridges on A3 and A4? Does the letter stand for A axis or is the letter just a pin name that don't necessarily have to be for A axis? I see one of them goes to the coolant connector.

I have been dismantling my electronics several times now to get to swap them cursed bridges and now I soldered pins on the holes next to the internal driver sockets to be able to clone stuff with jumper wires instead.

Still confused, soon not going to fight more with the auto square but just do it by hand against some reference points before startup.

thanks!

priority
Posts: 12
Joined: Sat Feb 22, 2020 8:01 pm

Re: Getting dual axis self square gantry working

Post by priority » Sat Sep 26, 2020 1:03 pm

PropellerHat wrote:
Fri Sep 25, 2020 1:06 pm
....
I have uncommented the lines in config.h mentioned and flashed the GRBL again on my cnc board (2.60 as supposed).
....
What does it mean, the A3 A4?
....
A3 and A4 refer to the Pin Names on the Arduino that is on the Protoneer shield. In order to have self-squaring work properly, the Arduino must have 2 pins for Step and Dir controlling the Y motor and 2 completely different pins for Step and Dir for the A motor. When this is setup correctly for self-squaring, the Y and A motor signals are cloned in the Arduino firmware. When the Protoneer shield homes and is correctly setup for self squaring, it can independently move Y and A (within firmware defined limits) to align the gantry.

Based on your post, my initial guess is that you are are not successfully modifying, compiling and uploading the modified firmware to the Arduino on the Protoneer shield. Did you verify the version of GRBL changed after modifying, compiling and uploading the modified firmware? An easy way to check the grbl version:
  • Connect to Grbl using the serial terminal of your choice.
  • Set the baud rate to 115200 as 8-N-1 (8-bits, no parity, and 1-stop bit.)
  • Once connected you should get the Grbl-prompt, which looks like this:

    Grbl 1.1h ['$' for help]

PropellerHat
Posts: 6
Joined: Fri Jun 19, 2020 11:09 am

Re: Getting dual axis self square gantry working

Post by PropellerHat » Sun Sep 27, 2020 10:30 am

Hi

The version was 1.1h already before flashing again, so I can't say if it actually went right. I am not very experienced in using Arduino IDE but it said "Upload complete" or something similar after everything LOOKED like it went as supposed.

Guess I'll try to upload it again some day, starting from 0.

Thanks

priority
Posts: 12
Joined: Sat Feb 22, 2020 8:01 pm

Re: Getting dual axis self square gantry working

Post by priority » Sun Sep 27, 2020 2:07 pm

PropellerHat wrote:
Sun Sep 27, 2020 10:30 am
...
The version was 1.1h already before flashing again, so I can't say if it actually went right.
...
You can change the version string to a unique value--say "1.1i" so that you know the upload worked. It is located in grbl.h IIRC.

Also, double check your edits in the grbl code to make sure they are still present. The Arduino IDE sometimes exhibits bad behavior.

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