For spindles that don't have control all you need is M3/4 S1.

JT


On 1/23/2017 11:18 AM, Robert Ellenberg wrote:
> John, you raise a good point here. The general assumption is that the S
> word is a reasonable prediction of spindle speed. What do you think of
> having a check at both interp time and runtime? That would cover all cases.
> For machines like yours, we could suppress the interp-time error. Is there
> an INI or HAL setting to tell LinuxCNC that the spindle is manually
> controlled?
>
> On Mon, Jan 23, 2017, 9:46 AM John Kasunich <[email protected]> wrote:
>
>>
>> On Sat, Jan 21, 2017, at 04:28 AM, John Morris wrote:
>>
>>
>>> I also thought of these three possible intended scenarios pointed out in
>>> this thread, and can think of valid arguments for each, briefly:
>>>
>>> 1. The manual says it's an error, and it's up to the user to avoid it
>>> (status quo)
>>> 2. The controller detects the condition, and informs the user
>>> 3. The controller detects the condition, and compensates by adjusting
>>> spindle speed
>> #3 is impossible for machines where spindle speed is not controlled by
>> LCNC.
>> For example my lathe has only M3/M5.  Single phase motor controlled by
>> contactor, with manually changed belts to the spindle.
>>
>> #2 is possible during actual program execution - can't do G33 without a
>> spindle encoder, and if you have an encoder, you have spindle speed
>> feedback and can decide if the speed is OK.
>>
>> But #2 may not be possible during generation of the preview.  During
>> preview the spindle is not running.  The only thing LCNC can do is assume
>> that the spindle speed will be whatever the most recent S-word specified.
>> But on a machine like mine, the S-word doesn't actually control anything.
>> IF the programmer is disciplined enough, he can use the S-word to tell
>> LCNC how fast he intends to run the spindle.  But LCNC can't rely on that
>> being the actual spindle speed.
>>
>>
>> --
>>    John Kasunich
>>    [email protected]
>>
>>
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