Time to setup my lathe with 7i76e

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8 years 10 months ago #103705 by tecno
Replied by tecno on topic Time to setup my lathe with 7i76e
Yes I do have some laying around, always good to practice on.

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8 years 10 months ago #103706 by RotarySMP
Replied by RotarySMP on topic Time to setup my lathe with 7i76e
What type of lathe is that?
Mark

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8 years 10 months ago #103708 by tecno
Replied by tecno on topic Time to setup my lathe with 7i76e
Mark, this an old Swedish CNC school lathe from late 90's

www.93x57r.se/tecno-cnc/images/CNC3000/O...NC3000%20images.html


Here the new gear to be installed when I am fit enough to do it.
www.93x57r.se/tecno-cnc/CNC3000.html

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8 years 10 months ago #103710 by RotarySMP
Replied by RotarySMP on topic Time to setup my lathe with 7i76e
Lovely lathe. You are doing a great retrofit on it.
Mark

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8 years 10 months ago #103711 by tecno
Replied by tecno on topic Time to setup my lathe with 7i76e
Thanks

Happy Holidays

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8 years 10 months ago #103750 by tecno
Replied by tecno on topic Time to setup my lathe with 7i76e
Got some mail today from China, 2x 100ppr encoders.

Directly to 7i76e
Want to use 1 analog input for selection of steps/detent so is following resitor values OK 1K 10K 100K?

What if using a 100K potentiometer = usable or not?

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8 years 10 months ago #103753 by PCW
Replied by PCW on topic Time to setup my lathe with 7i76e
if you want to use a potentiometer for 7I76E analog inputs, 5K is a good choice

100K will work but will be quite non-linear. it will be correct at 0 and 100% but droop
significantly in the middle, that is at a 50% pot setting the analog reading will be around 15%.
This is because of the 22K load resistance of the 7I76E inputs

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8 years 10 months ago #103755 by tecno
Replied by tecno on topic Time to setup my lathe with 7i76e
OK then 5K it is.

What is the pros and cons using pot versus selector switch?

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8 years 10 months ago #103764 by rodw
Replied by rodw on topic Time to setup my lathe with 7i76e
I think that the selector switch is a better option as thats what LinuxCNC expects. If you use a 4 position binary coded switch, you can do it with just 2 inputs. That gives you 3 scales plus an off position
Code:
# Metric units used loadrt hm2_eth board_ip="10.10.10.10" config="firmware=hm2/7i76/7i76e.BIT num_encoders=1 num_pwmgens=0 num_stepgens=5 sserial_port_0=2xxxx" loadrt mux4 count=1 addf mux4.0 servo-thread loadrt or2 count=4 addf or2.3 servo-thread setp axis.x.jog-vel-mode 0 net x-jog-counter <= hm2_7i76e.0.7i76.0.0.enc0.count net x-jog-counter => axis.x.jog-counts net mux-in1 or2.3.in0 <= hm2_7i76e.0.7i76.0.0.input-22 => mux4.0.sel0 net mux-in2 or2.3.in1 <= hm2_7i76e.0.7i76.0.0.input-21 => mux4.0.sel1 net x-jog-enable <= or2.3.out net x-jog-enable => axis.x.jog-enable setp mux4.0.in0 0.0 setp mux4.0.in1 1.0 setp mux4.0.in2 0.1 setp mux4.0.in3 0.01 net x-jog-scale mux4.0.out => axis.x.jog-scale

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8 years 10 months ago #103765 by andypugh
Replied by andypugh on topic Time to setup my lathe with 7i76e

rodw wrote: I think that the selector switch is a better option as thats what LinuxCNC expects.


I think using a wafer switch and fixed resistors into an analogue input is fairly cunning. You can have several positions into a single IO pin.
The HAL side can be a set of wcomp components or a lincurve component with the output converted to integer.

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