Getting dual axis self square gantry working

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

Re: Getting dual axis self square gantry working

Post by PropellerHat » Thu Oct 01, 2020 1:42 pm

Hi again

Ok... I got the GRBL flashed (IDE says "Done uploading") BUT only when the #define ENABLE_DUAL_AXIS is commented out. If I take away the "// " from that line, it won't compile. Whaaaat the.....??

Renaming the version worked ( $I tells me "ver:1.1x.20190825:" )

But What am I missing in the config.h? I only changed the mentioned line and DUAL_AXIS_SELECT_X into "Y".

DebbySherr
Posts: 1
Joined: Fri Oct 16, 2020 12:42 pm

Re: Getting dual axis self square gantry working

Post by DebbySherr » Fri Oct 16, 2020 12:55 pm

Hello...Homing the machine won't tackle the difficult he is depicting. He's discussing 1 side of the Y pivot being out of square with the opposite side of the Y hub. (for example the separation between the Y end plates is diverse on each side of the X pivot.
A few people have indistinguishable squares they put between the X hub and Y end plates and utilize those to square the X hub before controlling on/homing.
That is most likely the best answer for fix the issue.

pcb quote
Last edited by DebbySherr on Wed Nov 04, 2020 9:54 pm, edited 1 time in total.

priority
Posts: 19
Joined: Sat Feb 22, 2020 8:01 pm

Re: Getting dual axis self square gantry working

Post by priority » Tue Oct 20, 2020 5:46 pm

PropellerHat wrote:
Thu Oct 01, 2020 1:42 pm
Hi again

Ok... I got the GRBL flashed (IDE says "Done uploading") BUT only when the #define ENABLE_DUAL_AXIS is commented out. If I take away the "// " from that line, it won't compile. Whaaaat the.....??

Renaming the version worked ( $I tells me "ver:1.1x.20190825:" )

But What am I missing in the config.h? I only changed the mentioned line and DUAL_AXIS_SELECT_X into "Y".
Sorry about the slow reply. Did not get a notification of your post.

What is the error message from the Arduino IDE?

Other items to check--make sure you are making the modifications to an unmodified version of GRBL v1.1h. Also check that your code modifications are correct--there is no DUAL_AXIS_SELECT_X in config.h.

vitalibr
Posts: 5
Joined: Wed Feb 05, 2020 6:24 pm

Re: Getting dual axis self square gantry working

Post by vitalibr » Fri Oct 23, 2020 5:56 pm

priority wrote:
Tue Apr 28, 2020 4:08 pm

Since there are only 3 axis limit switch circuits, in order to auto-square, connect the Z-axis limit switch in series with the A-axis (second Y-axis) limit switch. This will allow grbl to sense the Y and A limit switch engagements separately when homing since the Z-axis is homed separately from X & Y.
Thanks a lot for that!
I will try to do this next week!


I didn't understand this part of the switches very well.

Our CNC hat has 3 pins for switches, X/Y/Z right?!

My switches for A-axis (second Y-axis) will be connected with the Z-axis switch in the Z-axis pin?!
also, Do I need 2 switches for A-axis to do the self square? because I have 2 switches on each axis (one at each end of the axis)


Best Regards,

priority
Posts: 19
Joined: Sat Feb 22, 2020 8:01 pm

Re: Getting dual axis self square gantry working

Post by priority » Sat Oct 24, 2020 2:59 am

vitalibr wrote:
Fri Oct 23, 2020 5:56 pm
....
I didn't understand this part of the switches very well.

Our CNC hat has 3 pins for switches, X/Y/Z right?!

My switches for A-axis (second Y-axis) will be connected with the Z-axis switch in the Z-axis pin?!
also, Do I need 2 switches for A-axis to do the self square? because I have 2 switches on each axis (one at each end of the axis)
For what its worth, I found this very confusing as well when I was initially trying to get it working!

You need a total 4 switches for self-squaring to work. One switch on each axis (X, Y, Z, A) should be located at the machine home position. I prefer home to be in the front, left corner. So, my X homing switch is on the left end of the gantry, the Y & A homing switches are near the front of the aluminum beams that form my Y and A axis, and the Z homing switch is activated when the spindle is elevated as high as possible.

Since the Protoneer hat only has 3 homing/limit switch inputs, you need to "share" one pin between 2 homing switches. Perhaps an understanding of what happens during the auto-square process will help explain how this works. GRBL's self-square routine first finds Z max to reduce the chance of inadvertently moving the gantry while a bit is engaged in a workpiece. After successfully finding Z max, GRBL moves the Z position down slightly so that the Z max switch is no longer engaged. GRBL then searches for the X & Y home switches by moving the X, Y & A axes. In my case, that is X min and Y min and A min. Since the Y and A stepper motors are controlled independently by the GRBL firmware in this configuration, GRBL can move the Y and A side of the gantry so that the Y and A homing switches are both engaged. Assuming you have properly positioned the Y and A homing switches, then GRBL's homing routine will have located X, Y, Z home and the X axis and Y axis will be orthogonal when the homing procedure completes.

You can add additional switches if you wish, but they will not affect self-squaring during homing. One of my CNC's has a total of 6 switches: X min, X max, Y min, Y max, A min, and Z max. This CNC uses 4 switches to home & self square: X min, Y min, Z max for locating home and the Y min and A min are used to self square the gantry. The X max and Y max are used as limit switches to raise an alarm and disable signals driving the stepper motors should I run some errant g-code. Assuming you are using the NC switch configuration with a Protoneer hat with home at X min and Y min, the X max limit switch should be wired in series with the X min switch and the Y max switch should be wired in series with the Y min switch. You could also have an A max limit switch wired in series with Z & A homing switches if you wanted, but I personally don't do this.

TheTechRunner
Posts: 3
Joined: Thu Feb 04, 2021 3:41 am

Re: Getting dual axis self square gantry working

Post by TheTechRunner » Thu Feb 04, 2021 4:10 am

Hey Priority - hopefully you'll get this and respond. I'm trying to get this setup going - just using X axis instead of Y. My problem now is the normally closed switches. How do you have that wired up and were there any other modifications you had to make? I'm using LJC18A3-H-Z/AX NC NPN switches. They have a positive, negative, and positive when activated.

I feel like the 2.60 has external pull-up resistors that are causing me grief with the normally closed switches. Even if I set DISABLE_LIMIT_PIN_PULL_UP in config.h I am getting 5V measured between the X/Y/Z and ground.

Any insight you can provide would be fantastic. Thanks!

TheTechRunner
Posts: 3
Joined: Thu Feb 04, 2021 3:41 am

Re: Getting dual axis self square gantry working

Post by TheTechRunner » Fri Feb 05, 2021 1:41 am

Hey priority - how do you have this physically wired? I have a NC NPN sensor I'm trying to use and can't for the life of me figure out how to do it. No matter what I do I'm always getting 5V measured between the X-Axis limit and ground. Any input on the physical wiring of the NC switch would be greatly appreciated. Thanks!
Last edited by TheTechRunner on Wed Feb 10, 2021 12:10 am, edited 1 time in total.

Bertus Kruger
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Re: Getting dual axis self square gantry working

Post by Bertus Kruger » Mon Feb 08, 2021 6:40 pm

TheTechRunner wrote:
Thu Feb 04, 2021 4:10 am
Hey Priority - hopefully you'll get this and respond. I'm trying to get this setup going - just using X axis instead of Y. My problem now is the normally closed switches. How do you have that wired up and were there any other modifications you had to make? I'm using LJC18A3-H-Z/AX NC NPN switches. They have a positive, negative, and positive when activated.

I feel like the 2.60 has external pull-up resistors that are causing me grief with the normally closed switches. Even if I set DISABLE_LIMIT_PIN_PULL_UP in config.h I am getting 5V measured between the X/Y/Z and ground.

Any insight you can provide would be fantastic. Thanks!
Yes, it has a Resistor/Capacitor filter that will pull the line up. There is a 4 pack resistor close to the green connectors that does the pull up. Removing that might help but that will also remove the filter bit.

TheTechRunner
Posts: 3
Joined: Thu Feb 04, 2021 3:41 am

Re: Getting dual axis self square gantry working

Post by TheTechRunner » Wed Feb 10, 2021 12:24 am

Alright, I gave up on the NC sensor (which is disappointing but obviously way over my head) and got some NO ones. I'm still unable to get it to work correctly. I have a 5V NO NPN sensor with brown (+), black (signal/load), blue (-). How should I be wiring that up? I've tried brown to x-limit + black to nothing + blue to gnd, x-limit + black to gnd + blue to gnd... neither of these seem to trigger a sensor in grbl (using ? to try to see them).

Edit: OK, I got it working! For anyone needing this information. For a 5V NO NPN switch I wired brown (+) to a 5V power source, black to the z-limit on the hat, and blue (-) to a gnd on the hat. I also wired a gnd from the power source to the gnd on the hat.

priority
Posts: 19
Joined: Sat Feb 22, 2020 8:01 pm

Re: Getting dual axis self square gantry working

Post by priority » Wed Feb 24, 2021 3:35 pm

TheTechRunner wrote:
Wed Feb 10, 2021 12:24 am
Edit: OK, I got it working! For anyone needing this information. For a 5V NO NPN switch I wired brown (+) to a 5V power source, black to the z-limit on the hat, and blue (-) to a gnd on the hat. I also wired a gnd from the power source to the gnd on the hat.
TheTechRunner--That is great to hear and thanks for posting info on how others to do this.

Sorry for being slow to respond. Between a family issue and surviving the winter storm of the century, my CNC time for the month of February was obliterated until today!

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