Rapid over ride percentages

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25 Oct 2013 12:00 #40275 by JR1050
Replied by JR1050 on topic Rapid over ride percentages
Ok,that makes sense. Im trying to get an operator interface as close to what most machinists are used to. I have not seen any one else attempt a rapid over ride(not in my searches) and the only thing that halui seemed to offer was max velocity, which seems like rapid if you have a separate fro available,as halui does. It almost doesnt make sense, but,Im figuring it out as I go....

Anyway, Im using a 7i84 sserial board for panel inputs and the first 3 inputs will accept an analog signal , pots seemed easier.

Yes the FRO is annoying, the original control only had FRO, so rapids were controlled by cranking the knob, which made for a tired elbow....

It seems like setting a scale based on the input voltage of a pot x feed rate would work with a pot, I just have to figure out how to make that happen. If i have a 0-12v signal ,
every. 12 v is 1%. If i set each percent to .06v, I can have 200% feed or spindle increase. so it seams like if 6v is 100% ,every .06v either way will increase or decrease the speed. Sound right? Its late in Fl.....

JR

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25 Oct 2013 12:30 #40276 by cmorley
Replied by cmorley on topic Rapid over ride percentages
Yes max_velocity is the only thing available.
IIRC max velocity was added later as a request - doing it the way they did was easy programmically not sure if there is another reason.


I did a little experimenting once with analog override.
IIRC I needed to add some hysteria, as the voltage fluctuated slightly all the time.
I never finished the component.

Chris M

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25 Oct 2013 15:51 #40284 by andypugh

Anyway, Im using a 7i84 sserial board for panel inputs and the first 3 inputs will accept an analog signal , pots seemed easier.
...
It seems like setting a scale based on the input voltage of a pot x feed rate would work with a pot, I just have to figure out how to make that happen.


You might want to read this thread:
www.linuxcnc.org/index.php/english/forum...d?limitstart=0#39900

There is a solution at the end, one that you would probably need to implement too.

Personally, I prefer little panel encoders, they cooperate better with other inputs. (Which is why they are used on car radios which have both automatic and manual tuning, for example).

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26 Oct 2013 01:09 #40291 by JR1050
Replied by JR1050 on topic Rapid over ride percentages
Thanks Andy, that post was helpful. I hooked up a 20k pot on 7i83.0.analog0 and got a swing of 10.9 to 12.1 volts, it seems if I set the scale to 1 and divide whatever the present voltage by 11.5(the average mean of what the pot swings) I should end up with immediate percentages that can be fed directly into halui.feed-override.counts, sound right? Upward and onward...

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26 Oct 2013 01:25 - 26 Oct 2013 10:04 #40292 by PCW
Replied by PCW on topic Rapid over ride percentages
To use a potentiometer for analog input you will want to tie the top leg of the potentiometer to VField (higher is better since the full scale is 36.3V), the bottom leg to field voltage ground and the wiper to the analog input.

Note that the 7I84 inputs have a 22K impedance so a lower value pot (say 5K ) is a better choice for linearity (a 20 K pot will be still adjust from 0 to full voltage but will be non-linear, about 10% low in the center of the range)
Last edit: 26 Oct 2013 10:04 by PCW. Reason: sp

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26 Oct 2013 02:44 #40293 by JR1050
Replied by JR1050 on topic Rapid over ride percentages
Thanks for the suggestion, I set up a 2k pot,which was pulled from an old 550t panel and it reads from 0 to 12v (the actual supplied power). Thanks again to all.

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