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marlin corexy replicate step and dir signal only x axis or y axis..

Posted by smeric 
marlin corexy replicate step and dir signal only x axis or y axis..
July 24, 2018 04:38AM
Hi all
I need help about new marlin 1.1.08. I have a corexy build printer. x motor stepper and y motor stepper are using for corexy , z motor driver for z axis, E0 and E1 are not using.
I wanna build a special extruder so for my electronic card I need a X movement step and dir signal to other empty pin. I mean when corexy is moving I need only X axis step and dir signal .. how its possiable ?
Re: marlin corexy replicate step and dir signal only x axis or y axis..
July 24, 2018 04:42AM
You can edit pins.h in Marlin and copy the X-driver signals to one of the empty Extruder ports.
Re: marlin corexy replicate step and dir signal only x axis or y axis..
July 25, 2018 05:13AM
ok but corexy has different algoritm so it can not be correct when I change only pins , am I wrong ?

I wanna only algoritm which is is working normally corexy but external output like cartesian.
Re: marlin corexy replicate step and dir signal only x axis or y axis..
July 25, 2018 08:21AM
Hi I am trying to new extruder mod├╝le and I need only X and Y step signal and direction signal for cartesian systems. but my printer build corexy..

so I need to change some code for this.
my marlin firmware must work corexy .. as same time I need x axis step, direction signal from E1 step and direction pins..
what I must to do ..
who can help me about it.. but I know its not enought to take directly take from X or Y motor step output ..
Re: marlin corexy replicate step and dir signal only x axis or y axis..
July 25, 2018 01:21PM
Your X/Y axis are reserved for CoreXY, so you have to define other axis, like A, B, C or U, V, W that work cartesian-style.
I don't know if Marlin can do that, but RepRapFirmware can. ( Others like Smoothiware too ? )
But these firmwares run on different controllers.
Re: marlin corexy replicate step and dir signal only x axis or y axis..
July 26, 2018 05:13AM
ok.. as you said x/y axis ( and motors ) will reserved for corexy .. and I need E1 ( on ramps ) only cartesien x axis movement information ( step and dir ) so its replication of X axis .. if corexy try to move x axis as same time I need x direction output and x direction step ..
I think I need some change
stepper.cpp
stepper_indirection.h
at that files..
Re: marlin corexy replicate step and dir signal only x axis or y axis..
July 26, 2018 11:44AM
What are you trying to accomplish? To have the extruder separate from the hotend carriage, yet still move it along the x direction as the carriage moves?

Edit: Deckingman does this by having a whole other gantry above which the hotend carriage drags along with it when it moves.

https://somei3deas.wordpress.com/my-corexy-printer-build/5-colour-upgrade/

Edit: He used to have it physically dragging it along, now looks like he has it completely run by motors by duplicating the signals to other motors. Still CoreXY though, not a hybrid like what you're looking for.

Edited 3 time(s). Last edit at 07/26/2018 11:54AM by FA-MAS.
Re: marlin corexy replicate step and dir signal only x axis or y axis..
July 27, 2018 12:06AM
The X-motion of a CoreXY isn't done by one motor, but both motors. You either rebuild it to work like a H-Bot or take a different controller, which is able to deal with more axis┬┤.
Re: marlin corexy replicate step and dir signal only x axis or y axis..
July 27, 2018 11:00AM
I was working this out as a thought exercise, and it's a bitch.

It would be one thing if every step was either an X motion or a Y motion. if the DIR pulses are the same, then the STEP pulse counts as X motion. If they're different then it counts as Y motion.

The problem is that if the firmware can/will move the print head in a diagonal direction. In the simplest case, a 45 degree diagonal will pulse either the A motor, or the B motor, but it need not trigger both. On its fundamental level, the firmware can move the print head on the X/Y plane in 8 directions. In this case, you can still track this as an X motion, but it does not move the carriage in either plane the distance of a full step, but instead it moves it as a half of a step in both directions. This actually might be more to the point, to count each STEP pulse of the A motor as half of a step in the direction of the DIR pulse, and each STEP pulse of the B motor as a half a step in the opposite direction of the DIR pulse.

Probably something could be done as an Arduino sketch to track these, and output them to another stepper driver. probably easy enough to use a cheap Arduino, it would need 4 inputs, 2 as interrupts, and 2 outputs. This could do the job to make another motor follow the axis, but it wouldn't "know" the current position, only relative movement. If things got moved manually, or while the machine was turned off, it couldn't tell. It might require a second set of homing switches to keep it from going off the rails, of course with associated inputs.

Probably more complicated than it's worth.

To track it from within the Marlin firmware, I'm pretty certain that it would take a knowledge of the code and programming in general that would probably mean someone who wouldn't be asking here.


MBot3D Printer
MakerBot clone Kit from Amazon
Added heated bed.

Leadscrew self-built printer (in progress)
Duet Wifi, Precision Piezo parts
Re: marlin corexy replicate step and dir signal only x axis or y axis..
July 27, 2018 01:48PM
I assume that what you want to do is to have the extruder drive on a separate axis that tracks the X-position of the print head. I guess this is so you can use a shorter Bowden tube, or something like that.

You have two problems to solve:

1. Driving your additional axis in sync with the X position.

2. Homing the new axis synchronously with homing the print head in the X direction - unless you set the initial position of the new axis by hand and hope that it stays in sync.

I can't help you with how to do this using Marlin. What I can say is that unless I am missing something, the standard RepRapFirmware distribution binaries already support this. In the config.g file on the SD card you would need to:

- Create a new axis (let's call it U) using the M584 command;
- Modify the homex.g and homeall.g files on the SD card to home the U axis at the same time as homing X (assuming U has its own endstop switch);
- In your tool definition command (M563) map X to both X and U.

RepRapFirmware runs on compatible 32-bit controller electronics.



Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: marlin corexy replicate step and dir signal only x axis or y axis..
August 01, 2018 07:15AM
ok.. I fixed it, with 4 byte variable and a minimacro code, add it in "stepper_indirection.h" file so I fixed .. body is using corexy system and same time its sending cartesien pulse..
Re: marlin corexy replicate step and dir signal only x axis or y axis..
January 05, 2021 08:18AM
Hi smeric, are you able to post or pm me the changes you made to "stepper_indirection.h"?
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