Hobby lathe with AC servos

Post your completed retrofits for the world to see.

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suntravel
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Re: Hobby lathe with AC servos

Post by suntravel »

Philtrueman wrote: Sat Apr 30, 2022 7:48 am When you say that you have servo motors. Do you mean stepper motors with encoders "hybrid steppers"? I have a milling machine with servo motors but they are DC and i don't think that they will work with the Acorn control board.
nope I use AC servos with 220V, but IMHO most servos or CL-steppers work well with Acorn if set up right. Normal steppers are just outdated, I dont want to use them for saving 10 bucks ;-)

Uwe
suntravel
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Re: Hobby lathe with AC servos

Post by suntravel »

Something I had to make today using my Acorn CNC stuff.

I love the fast workflow possible with Acorn CNC :)



Uwe
suntravel
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Re: Hobby lathe with AC servos

Post by suntravel »

lavrgs wrote: Sat Apr 30, 2022 9:33 am Prior to my conversion I bench tested Acorn using the original DC motors and Gecko G320 drivers. The problem with the Geckos is they are limited to 80 VDC.. among other limitations.
On my job I had AMK DC servos on old Index CNC...

... glad I could scrap them all :D

Uwe
Philtrueman
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Re: Hobby lathe with AC servos

Post by Philtrueman »

Can you describe how you got your AC servo motors working with an Acorn board. How did you wire the motor and driver to the Acorn. I thought that the Acorn board would only accept step and direction drivers/motors.
Spartan117
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Re: Hobby lathe with AC servos

Post by Spartan117 »

Philtrueman wrote: Tue May 03, 2022 3:26 am I thought that the Acorn board would only accept step and direction drivers/motors.
And this is why the servo has got a step/dir-port ;)
Philtrueman
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Re: Hobby lathe with AC servos

Post by Philtrueman »

Spartan117 wrote: Tue May 03, 2022 5:01 am
Philtrueman wrote: Tue May 03, 2022 3:26 am I thought that the Acorn board would only accept step and direction drivers/motors.
And this is why the servo has got a step/dir-port ;)
Why do Centroid make a allin1DC if the the Acorn will run servo motors? I have large servo motors on my milling machine which have tachometers. In one of Marty's videos he said that you have to remove the Tachometers and fit encoders to the DC servo motors.
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Re: Hobby lathe with AC servos

Post by Spartan117 »

I am not (yet, i hope^^) a centroid-expert.
But not every servo-drive is equipped with step-dir-inputs.
To be honest, today they are mostly found at old or cheap (often chinese) servo-drives. My newest Bosch-Drive with pulse-dir is about 25years old^^

I would guess the Allin1DC is made for easy retrofitting of machines with matching drives that can be driven by the Allin1DC directly.
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Re: Hobby lathe with AC servos

Post by tblough »

The AllIn1DC and the Oak are TRUE closed-loop servo systems with position feedback to the control. With the Oak and AllIn1DC, you can remove power to the motors, manually move the machine, and re-power the motors without loosing position. The control always knows where the machine position is.

With the Acorn, it is an open-loop control. You can use hybrid closed-loop drives that will let the motor drives know it the motor is not at the commanded position, and they can then signal an error to the Acorn, but the Acorn will not know the machine position. You cannot manually move an Acorn axis without loosing the machine position.

If you don't hook up the drive alarm output to the Acorn, then the Acorn will happily keep outputting pulses to the drive even if the drive/motor has an error and is not moving. The DRO's will update and Acorn will continue running but the machine will not be moving.
Cheers,

Tom
Confidence is the feeling you have before you fully understand the situation.
I have CDO. It's like OCD, but the letters are where they should be.
suntravel
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Re: Hobby lathe with AC servos

Post by suntravel »

Philtrueman wrote: Tue May 03, 2022 3:26 am Can you describe how you got your AC servo motors working with an Acorn board. How did you wire the motor and driver to the Acorn. I thought that the Acorn board would only accept step and direction drivers/motors.
JMC Servos with Acorn:

https://centroidcncforum.com/viewtopic.php?f=60&t=7119

Uwe
Stephan
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Re: Hobby lathe with AC servos

Post by Stephan »

Hallo Uwe,
Ich habe dir auf Youtube bereits geschrieben.
Ich habe mittlerweile mein Acorn bekommen und auch angeschlossen. Beim anschliessen sind mir so ein paar komische Sachen aufgefallen. Vielleicht weisst du was zu tun ist???
Aber eins nach dem anderen:
Ich habe eine Maximat Standard BJ schätze Anfang der 60ger.
Für die Achsen habe Ich JMC Closed Loop 3 Nm 1:1 .
Also das Grösste Problem was Ich habe ist das Ich meinen Encoder von der Maschine entkoppeln musste.
Aus einem von mir unbegreiflichen Grund ist es so wenn Ich den Encoder direkt an die Maschine schraube bekommt er falsche Signale. Das das Entkoppeln musste Ich mit Folienklebeband (sehr dick) was zum Pulverbeschichten benutzt wird machen. Das heisst Klebeband an den Encoder,Anbausatz und an die Verbindung dazwischen....Das hält eine Weile aber Mhhh.... sobald wieder die Verbindung zwischen Maschine und Anbausatz in Kontakt komme zack kommen falsche Signale an.
Jetzt zur Frage:
Ich habe gesehen du hast ein Plastik Rad am Encoder.Hilft das ? oder hast du den Encoder auch entkoppelt.
Natürlich habe Ich geschirmte Kabel verwendet ist klar.

Danke dir für deine Hilfe
Gruss Stephan
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