2 y axis steppers and linuxcnc

Need some help, I am trying to configure linuxcnc to run my machine, I use two nema 23 steppers to move the y axis, but i can not figure out how to configure this in linux, i am not programmer, so any files, videos or detailed help would work.


please


Jeff

I am in the same boat...

Depending on the version of Linuxcnc your using, there is a new hal component called gantry.comp. It was just added to the 2.7.4 release. I don't think there is any documentation for it yet.
Here is a link to a configuration example(s) made by the author using it.
There are some other ways, to set up a gantry as well, none of which I would consider really simple to set up for a novice user. There are varying degrees of complexity you can add that may give better results to the end product.

The simplest way to start with:
Simply send the same step/dir output signal to 2 drives, This is the simplest solution to a gantry machine but has the draw back of not offering any way of squaring the gantry, other than running the machine against hard stops. Not the most elegant solution but can be effective.

The next step in complexity would be the above gantry comp.

Third way is to add a means to square the a simple slaved set up (simular to the above). This is my personal preference. I would set up each side of the gantry with seperate step generators (like the gantry.comp example), both driven by the same axis position command, except one would also pass through an offset.comp. Home both sides of the gantry together using a home switch on one side (call that the master side). Then use a probe routine to locate a second home switch on the "slave side". Then calculate the offset for the slave side from that probed position to adjust the square of the gantry. (The advantage to this is that the home switches don't need to be perfectly square to each other.)

A 4th way would be to use a Gantrykins set up. There is an example simulation configuration included with Linuxcnc. This way has advantages and disadvantages.

A 5th way would be to install an experimental branch version of Linuxcnc called Joints-Axis, and use another kins called Gentrivkins. This has most of the advantages of Gantrykins, without many of the disadvantages.

It is very unfortunate that there isn't a clear well documented path for configuring a machine like this. Nor even a consensus as to the best way. (let alone a simple way.)

I am just setting up LinuxCNC and have been using Mach3 with two motors on the Y-Axis. For my initial setup of LinuxCNC I set both motors to use the Y-Dir and Step so they run together, however I want to start using the Gantry Component mentioned in this thread so I can have it auto-square the gantry when homing like Mach3 did, I looked at the manual but am not sure how to implement it, can someone explain how to add that component into my HAL configuration?

Thanks,
Matt

Todd wrote:

Depending on the version of Linuxcnc your using, there is a new hal component called gantry.comp. It was just added to the 2.7.4 release. I don't think there is any documentation for it yet.
Here is a link to a configuration example(s) made by the author using it.
There are some other ways, to set up a gantry as well, none of which I would consider really simple to set up for a novice user. There are varying degrees of complexity you can add that may give better results to the end product.

The simplest way to start with:
Simply send the same step/dir output signal to 2 drives, This is the simplest solution to a gantry machine but has the draw back of not offering any way of squaring the gantry, other than running the machine against hard stops. Not the most elegant solution but can be effective.

The next step in complexity would be the above gantry comp.

Third way is to add a means to square the a simple slaved set up (simular to the above). This is my personal preference. I would set up each side of the gantry with seperate step generators (like the gantry.comp example), both driven by the same axis position command, except one would also pass through an offset.comp. Home both sides of the gantry together using a home switch on one side (call that the master side). Then use a probe routine to locate a second home switch on the "slave side". Then calculate the offset for the slave side from that probed position to adjust the square of the gantry. (The advantage to this is that the home switches don't need to be perfectly square to each other.)

A 4th way would be to use a Gantrykins set up. There is an example simulation configuration included with Linuxcnc. This way has advantages and disadvantages.

A 5th way would be to install an experimental branch version of Linuxcnc called Joints-Axis, and use another kins called Gentrivkins. This has most of the advantages of Gantrykins, without many of the disadvantages.

It is very unfortunate that there isn't a clear well documented path for configuring a machine like this. Nor even a consensus as to the best way. (let alone a simple way.)

How do I get the Joints-Axis branch? Looking at the install document for Ubuntu (www.linuxcnc.org/docs/ja/html/getting-st...ng_on_ubuntu_precise) it is the same apt-get command as you use for the standard linuxcnc, shouldn't that be different for Joints-Axis?

- Matt

andypugh wrote:

Todd wrote:

A 5th way would be to install an experimental branch version of Linuxcnc called Joints-Axis, and use another kins called Gentrivkins. This has most of the advantages of Gantrykins, without many of the disadvantages.

Just as a point of information, Joints_Axes no longer includes gentrivkins or gantrykins, all the functionality of those kinematics is included in a modified trivkins.

The documentation for the Joints_Axes branch is now available at www.linuxcnc.org/docs/ja

The specific change relating to kinematics is described here:
www.linuxcnc.org/docs/ja/html/getting-st...#_kinematics_modules

There is also the "Gantry" component for that use. ( linuxcnc.org/docs/2.7/html/man/man9/gantry.9.html )
I have it working with two Y steppers quite nicely. There's a sample HAL file here:
forum.linuxcnc.org/forum/47-hal-examples...8-gantry-hal-example

It was (for me) a good way to get in to how HAL syntax works. Give it a shot =)

/Peter