Retrofiting an old big milling machine

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20 Jul 2018 23:23 - 20 Jul 2018 23:28 #114619 by vre
Here is the machines motor that moves XYZ / controller / electric cabinet
What motor is that?
Also what are the components in the cabinet (except relays/transformers)?
Last edit: 20 Jul 2018 23:28 by vre.

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27 Jul 2018 15:04 #114952 by andypugh

vre wrote: What motor is that?


A Russian one? :)

It looks like probably a DC servo. How many power cables go to it?

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29 Jul 2018 07:15 - 29 Jul 2018 17:15 #115044 by vre
Motor is
ЕЛПРОМ ТРОЯН
2МТА
here is the datasheet but i don't know russian
elektro-dvigateli.ru/postoyannogo-toka/d...odstva-bolgarii.html

I think is a simple brushed DC motor so i can drive it with pwm from linuxcnc
and take position feedback from linear scales(sin cos 1Vpp) that each axis has.

This motor moves all axis 1 axis each time
each time the axis will be moved engaged with the mechanism shown in the attachment photo.

So what you think can this converted to linuxcnc as is without mechanical modifications ?
Each time 1 axis will be moved so no arcs only linear moves.
Is that possible with linuxcnc ?
Or must attach 1 motor per axis and make a full cnc ?

Or make a pseudocontroler with arduino with 3 buttons XYZ for each axis engagement 6 buttons for movement direction
pwm with a potensiometer for the feed speed
and 3 x 7 segment LED displays that will show the position of each axis reading the scales ?
Also i got a vfd to control the spindle.
Attachments:
Last edit: 29 Jul 2018 17:15 by vre.

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30 Jul 2018 12:43 #115131 by andypugh
I think that LinuxCNC probably can control this type of machine, see the parallel discussion here:
forum.linuxcnc.org/12-milling/34239-serv...?limitstart=0#107767
(I see you have already posted there).

I am pretty sure that this can be done. I am just not sure how yet :-)

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30 Jul 2018 15:46 - 30 Jul 2018 15:46 #115149 by vre
I have a plan to use the machine as is without mechanical modification with linuxcnc.
After that and if it works i will add 2 more servos to X & Y and keep the existing motor for Z to make it full cnc.
I have already 2 1.8kw ac servos.
Last edit: 30 Jul 2018 15:46 by vre.

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11 Sep 2018 22:41 - 11 Sep 2018 22:45 #117367 by vre
Hello again.
I have removed a scale from machine and it has 6 wires+1 chasis ground
It says on the label 15V and 40um.
It is made in Bulgaria 1992.
Inside has an IC TL084CN with 5 multiturn trimmers and 2 small electrolytic caps.
The small pcb in scale has no solder mask is only tinned.
How i can identify that the wires are?
Last edit: 11 Sep 2018 22:45 by vre.

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11 Sep 2018 23:38 #117370 by andypugh
That's a quad op-amp, so the trimmers are probably gain adjustment.
Given that it's all analogue on the board, I would expect that the 6 wires are two differential outputs and 2 power inputs. From the op-amp data sheet you can probably work out which wires are power supply with a multimeter just by checking continuity.

www.ti.com/lit/ds/symlink/tl084.pdf
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12 Sep 2018 13:18 - 12 Sep 2018 13:23 #117395 by vre
Ok i got it how to find VCC & GND wires.
I also have this schematic if helps for the signals..

What is the 7.5V & U3 rep shown in schematic?
Is this scale 1Vpp ?
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Last edit: 12 Sep 2018 13:23 by vre.

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12 Sep 2018 13:46 - 12 Sep 2018 13:47 #117398 by andypugh
It looks like sin/cos voltage on U1 and U2 and possibly an index on U3.

It also seems that you might need to supply both 15V and 7.5V.

That said, Uref Usin and Ucos looks a lot like a resolver. Does the scale appear to be optical, or is is like the Accupin system?
Last edit: 12 Sep 2018 13:47 by andypugh.

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12 Sep 2018 16:19 #117410 by vre
I will give VCC & GND 15VDC and i will see the output on oscilloscope

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