I concede a fix is needed - I still would like to see a clean solution 
eventually, at least conceptually.

LinuxCNC is not to first control where the requirement for more flexible 
arrangements than just coord mode (all joints) or joint mode (per joint) moves 
pops up, so let's see how other people deal with the issue.

Can I suggest to:

- read pages 271 ff 'Setting up a coordinate system' in the 'Turbo PMAC User 
Manual' : 
http://www.deltatau.com/manuals/pdfs/TURBO%20PMAC%20USER%20MANUAL.pdf?id=635013658588771523
- consider whether 'configurable coordinate systems' as outlined there are a 
solution to the issue at hand

- Michael

ps: 'LinuxCNC "joint"' == deltatau "motor"


> Right now we have coordinated (all joints driven through kinematics 
> transform) and non-coordinated modes; however, the coord mode joint/axis 
> binding is fixed at configure time; and I think (stand to be corrected) it 
> isnt currently possible to mix coordinated and joint moves.
> 
> PMAC deals with this by defining what they call 'coordinate system' - I 
> understand it to be a instance of a kinematics and joints binding; so you 
> could have a 'coordinate system' which has some joints not be coordinated but 
> still be subject to interpreter control.
> 
> This abstraction looks like a rather interesting idea to me, in particular as 
> it seems runtime-selectable at the motion script level.
> 
> A related theme recently has come up in a thread about 3D printers where the 
> extruder seems to not be part of coord motion (or so I understood).
> 



Am 16.08.2013 um 20:28 schrieb Charles Steinkuehler <char...@steinkuehler.net>:

> On 8/16/2013 11:28 AM, Chris Radek wrote:
>> On Fri, Aug 16, 2013 at 09:22:09AM -0500, Charles Steinkuehler wrote:
>>> 
>>> I _think_ this is "spindle hold" in "conventional" LinuxCNC usage, 
>> 
>> motion.spindle-at-speed
>> 
>>> where you don't want to start moving until the spindle is up to
>>> cutting speed.
>> 
>> Don't want to start *cutting*.  You do want to be able to rapid into
>> position while the spindle is spinning up.
> 
> Yep.
> 
>>> Can anyone point to an overview of how to use the spindle signals in
>>> HAL, and/or comments on if this would be applicable to use to prevent
>>> motion on *SOME* axis (ie: the extruder) but not others (ie: X, Y, Z)?
>> 
>> I think by axis is probably the wrong way to think about it, and you
>> should consider rapid vs feed instead, as linuxcnc already does?
>> 
>> http://www.linuxcnc.org/docs/html/man/man9/motion.9.html
>> 
>> motion.spindle-at-speed IN BIT:
>>      Motion will pause until this pin is TRUE, under the following
>>      conditions: before the first feed move after each spindle
>>      start or speed change; before the start of every chain of
>>      spindle-synchronized moves; and if in CSS mode, at every
>>      rapid->feed transition.
> 
> It sounds like this would work pretty well as a start, but unless I'm
> missing something it would still allow rapid moves on the extruder axis
> when the extruder wasn't at temperature.  Ideally all extruder movement
> should be gated by the extruder-at-temperature signal.
> 
> Is there a way to disable motion on an axis via HAL without causing
> joint following errors (or is that perhaps the best way to do it...just
> mask the motion, let a joint following error happen, and deal with the
> fallout)?
> 
> -- 
> Charles Steinkuehler
> char...@steinkuehler.net
> 
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