Tandem Y never runs two steppers

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08 Jul 2021 03:49 - 08 Jul 2021 03:51 #214006 by PCW
I think one issue is that there is no provision in the config utilities to setup
A gantry without gantry homing (squaring) ability. If you are comfortable with
hal you can add this to the hal file with some relatively simple copy-paste mods.

You could also do this rather simply in hardware if you don't need to jog the joints
separately, ether by simply tying the Y,Y2 drives STEP/DIR pins together, or if
the 7I96 doesn't provide enough electrical drive to run both drives, you could wire
the STEP+,DIR+,GND pins to step drive Y and STEP-,DIR-,+5V pins to step drive Y2
with the STEP- and DIR- pins of the Y step drive connected to GND and the STEP+
and DIR+ pins of the Y2 step drive connected to +5.
Last edit: 08 Jul 2021 03:51 by PCW.

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08 Jul 2021 07:01 #214009 by Clive S

... it should not be this difficult to setup a simple 3 axis with two Y motors...

It's difficult because the crystal ball has broke  . You need to give more info. for a start post your ini and hal files and answer the questions.

As have been said you need 2 inputs for the Y axis.  Start by having  just 1 home/limit  switch for each side of the Y gantry (Y1 and Y2)

It is better to edit the hal and ini files directly.  Show how you have actually wired the switches physically to the card.
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08 Jul 2021 09:43 #214017 by hairyMug
Thank you; I'll give one last shot through editing the HAL... and then try the hardware solution...

>> I just retired after 30+ years as IT guy and was hoping to get away from programming ;-) but it looks like I may have to dive into the HAL manual...

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08 Jul 2021 15:33 #214032 by hairyMug
took the hardware approach and things are progressing...
next challenge; getting the right signals to the "spinx" board...
thanks for your help...
>> YOUR crystal ball must be working! :LOL

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17 Jul 2021 12:37 - 17 Jul 2021 12:39 #215134 by fernandosf

Do you have limit switches on both sides?
If not, do not set a tandem axis, it will not work as it is intended to.
Again if not, set a 3 axis/3 joints machine just select the same axis outputs for two drives.


Hey TommyLight, 
    I have a gantry with 4 joints (XYYZ) and have set it up in the hope of been able to correct Y alignment by jogging both Y separately (although I still could not figure it out how). Is it possible?

   Since I have just 1 input pin of parport to handle Limits+Homing I guess it is not possible to align Y by using 2 switches (one for Y1 and other for Y2). Is that correct?

Thanks,
Last edit: 17 Jul 2021 12:39 by fernandosf. Reason: quoting for clarity

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17 Jul 2021 12:46 #215135 by rodw

   Since I have just 1 input pin of parport to handle Limits+Homing I guess it is not possible to align Y by using 2 switches (one for Y1 and other for Y2). Is that correct?

Thanks,

Yes, thats how you do it but they must be separate inputs on your parport. Set the home_offset of both to = -1 and you should be good. 
To align the gantry, yu just need to adjust the home_offset on each side.
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