Time to setup my lathe with 7i76e

tecno
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26 Dec 2017 19:19 #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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RotarySMP
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26 Dec 2017 19:20 #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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tecno
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26 Dec 2017 19:25 #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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RotarySMP
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26 Dec 2017 20:15 #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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tecno
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26 Dec 2017 20:16 #103711 by tecno

Replied by tecno on topic Time to setup my lathe with 7i76e

Thanks

Happy Holidays

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tecno
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27 Dec 2017 14:49 #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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PCW
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27 Dec 2017 15:47 #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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tecno
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27 Dec 2017 16:10 - 27 Dec 2017 16:10 #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?

Last edit: 27 Dec 2017 16:10 by tecno.

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rodw
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27 Dec 2017 21:13 - 27 Dec 2017 21:13 #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

# 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

Last edit: 27 Dec 2017 21:13 by rodw.

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andypugh
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27 Dec 2017 21:57 #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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