Rotary Axis Locking

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07 Jun 2021 20:06 #211440 by jochen91
Rotary Axis Locking was created by jochen91
Hi Folks,

as we know it's possible to lock a rotary axis with the "Locking Indexer" function which works fine.

But a pure indexer function is not always wanted. A programm for a rotary axis may include G0 and G1 which brings up the problem, that the Locking Indexer function only works with G0.

So my question is: How can a locking/unlock function with G1 feed moves be implemented?

I know that LinuxCNC does lock ahead in the G code. So it should be possible to determine when to lock/unlock (wait till unlock/lock) and than continue the processing of G code. Or to determine if its worth locking if i.e one line of g1 ends but in the second next line a G1 comes again.

Greetings,
Jochen

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08 Jun 2021 21:34 #211549 by andypugh
Replied by andypugh on topic Rotary Axis Locking

jochen91 wrote: So my question is: How can a locking/unlock function with G1 feed moves be implemented?


The way that I would like to do it is to remove the restriction to G0 moves. And I would also quite like to remove the restriction to only working on rotary axes. The lock/unlock pins would be a really good way to handle the old-style CNCs with one motor that is clutched on to each axis on-demand.

As a workaround I came up with a HAL component that sets feed-override to 0.0001% (it needs to be tiny but non-zero, so that it can see if an axis is moving). If it sees no rotary move then it locks the axis, otherwise it unlocks, waits for an "is-unlocked" and then allows normal motion.

I thought that I had written such a HAL component, but I can't find it now.

A possibly more reliable approach would be to run the G-code through a filter file (this can be configured to happen automatically) that inserts command unlock - wait for is-unlocked ..... command lock - wait for is-locked G-code as required in the input file.
The following user(s) said Thank You: jochen91

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09 Jun 2021 19:01 #211633 by jochen91
Replied by jochen91 on topic Rotary Axis Locking
Hi Andy,

yes thats a great idea to make the locking more universal.

For the old style mills and for the trend building 4 or even 5th axis machines with Linux. Linux is such an extrem capable piece of software it's nearly a shame that such a basic feature is not nativly supported yet.

By any chance, could you post your HAL Component here if you find it? I would be realy happy, cause i dont wanna miss this feature on my rotary axis.

Kind regards,
Jochen

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