My 7i76e Connection Sheet

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11 Feb 2021 15:14 #198407 by fons
Replied by fons on topic My 7i76e Connection Sheet
i'm working on a mill (cincinnati cim-x) there is no encoder on the mill-axis and mechanical nearly inposible to place it there
can it also work when i place the encoder on the motor and add some lines in the hal (an idea of what lines)
i like to use rigide tapping
how many puls do in need maybe 2 or 3 magnetic sensor placed on a gear in the gearbox can also work ?

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11 Feb 2021 19:23 #198430 by andypugh
Replied by andypugh on topic My 7i76e Connection Sheet

fons wrote: i'm working on a mill (cincinnati cim-x) there is no encoder on the mill-axis and mechanical nearly inposible to place it there
can it also work when i place the encoder on the motor


I think that there are probably more CNC machines with the encoder on the motor than on tha axis.

Encoders on the motor works fine, and needs no special config.

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11 Feb 2021 21:39 #198449 by fons
Replied by fons on topic My 7i76e Connection Sheet
when you use rigid taping the system need to know the puls/ revolution
there is a gearbox with 16 speeds
when the encoder is placed on the spindel its always the same value of pulses
not with a gearbox place in different gears
or does it mathers ? what i don't believe

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11 Feb 2021 22:02 #198452 by andypugh
Replied by andypugh on topic My 7i76e Connection Sheet

fons wrote: when you use rigid taping the system need to know the puls/ revolution
there is a gearbox with 16 speeds
when the encoder is placed on the spindel its always the same value of pulses
not with a gearbox place in different gears
or does it mathers ? what i don't believe


The spindle encoder needs to be on the spindle, yes.

But there was nothing in your previous post to suggest that you were talking about a spindle.

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12 Feb 2021 09:18 #198505 by fons
Replied by fons on topic My 7i76e Connection Sheet
what is the min of puls to work propper i have to make one by meselve at the outside of the gearboc
can 180puls/rev be enough ?

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12 Feb 2021 13:19 #198529 by andypugh
Replied by andypugh on topic My 7i76e Connection Sheet

fons wrote: what is the min of puls to work propper i have to make one by meselve at the outside of the gearboc
can 180puls/rev be enough ?


50 is enough for lathe threading or for gar hobbing, as at a constant speed LinuxCNC can interpolate the output from a low-count encoder.
For rigid-tapping you need to know exactly when the spindle reverses.
With 180 counts you can have (about) 2 degrees of uncertainly in the reversal position.
Does this matter? Quite possibly not. The effect is to give a slightly sloppy thread (assuming perfect Z-axis tracking) but 2 degrees with a 1mm pitch tap is only 5 microns error.

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12 Feb 2021 23:08 #198607 by fons
Replied by fons on topic My 7i76e Connection Sheet
thx for the quick reaction i can go work on mine project in thise way prepairing a 180puls enconder is ABZ enough or do i need also the inverve pulse-A-B-Z
an other problem why an unloaded steppermotor stall at higher speed ?
i make several test and always the same result the stepper motor will not run
i use a mesa 7i76e
i try a nema 17 motor with a lowcost stepper driver 6600 from alliexpressalso
i try it with a leadshine dm556 driver
from xinlichuan the mc425e and mc442e driver with all the same result
i use a small, the adjusted and a high a curent
what more can i try ?

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12 Feb 2021 23:23 #198609 by andypugh
Replied by andypugh on topic My 7i76e Connection Sheet

fons wrote: thx for the quick reaction i can go work on mine project in thise way prepairing a 180puls enconder is ABZ enough or do i need also the inverve pulse-A-B-Z

The inverse pulses would be generated by a line-driver, not by the encoder itself.
Single-ended works fine.

why an unloaded steppermotor stall at higher speed ?


Steppers have a lot of poles, so the back-emf becomes a problem at lower speed than with a lower pole-count motor.

To run faster, use a higher voltage. What voltage are you using? what is the max that your drives can handle?

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10 Mar 2021 14:04 #201647 by Robert T.
Replied by Robert T. on topic My 7i76e Connection Sheet
Hello Norbert,

I´m working to retrofit an EMCO VMC100 Mill, your connection sheet helped a lot for wiring.
Thank you for the great job you´ve done. MESA´s documentation to their 7i76e delivered more questions than answers to me ...

Robert

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16 Mar 2021 20:41 - 17 Mar 2021 08:11 #202512 by Creative25
This sheet helps me a lot.
Just a question. I connected my 7i76e b board with a 5v isolated Power supply at P3 First just left it like that to test Stepper Motors etc. Then I added field power to Tb1 as on your sheet however I did not connect it to Tb3 since I assume that is powered by the 5 volt power supply. When starting linuxcnc I get an error. It warns me about undervoltage.

Also if I measure on pin 5 I get 24 volt.
But there is no power on pin 1-4

I see the manual says both power supplies should have common ground. In my case both are isolated power supplies. Does that mean I should connect the negative poles of the two power supplies together?
Last edit: 17 Mar 2021 08:11 by Creative25.

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