Rebuilding Plasma CNC

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25 Mar 2020 21:12 - 25 Mar 2020 21:13 #161508 by tommylight
Replied by tommylight on topic Rebuilding Plasma CNC
Could be but we are just shooting in the dark here.
And his motors do not have brushes. And yours have encoders on the back. And there are no shielded cables on that big ATX connector.
Still could be that the brushes and encoder are inside that silver cap, but i doubt it, encoders would go to hell in a hand basket rather quickly from the dust produced by those brushes.
Anyway, if they are DC servos, there are some rather cheap drives that can be used, and i think Mesa has something suitable and a single board for both motors if i am not mistaken.
Last edit: 25 Mar 2020 21:13 by tommylight. Reason: added more info

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25 Mar 2020 21:20 - 25 Mar 2020 21:22 #161509 by thefabricator03
I agree he should test them first by hand to determine the type of motor,

But just thinking out loud based on this AC servo I have on my desk, the encoder is mounted behind the motor frame with a cap cover.

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Last edit: 25 Mar 2020 21:22 by thefabricator03.
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25 Mar 2020 21:30 #161511 by tommylight
Replied by tommylight on topic Rebuilding Plasma CNC
Yummy AC servo ! :)
Well those do not have brushes, and what are the chances of getting AC servo motors and drives on a machine with skate bearings ??? :)

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25 Mar 2020 22:28 - 25 Mar 2020 22:52 #161514 by thefabricator03

tommylight wrote: Yummy AC servo ! :)
Well those do not have brushes, and what are the chances of getting AC servo motors and drives on a machine with skate bearings ??? :)


Slim to none I would say,

In around 2013 I inquired to a welding supply shop about buying a Hypertherm plasma unit. I then had a sales rep call me every other month trying to get my to buy one of these toys,

www.cncplasmacutters.com.au/cnc-plasma-c...c2-cnc-plasma-table/

I am sure it is a very similar machine to the OP. It advertised servo motors. Maybe though they are a form of closed loop steppers, or a brushless DC servo?

I am by far no expert on servo motors. But I have never seen online or in person a round frame stepper motor. Do they exist? Most steppers I have seen are a square frame. The only round frame servos I have seen are DC servos. But I am sure there is a whole world of servos I have never come across :). Thats the best thing I think about the world of CNC, I am always learning something new.
Last edit: 25 Mar 2020 22:52 by thefabricator03.
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25 Mar 2020 23:20 #161518 by tommylight
Replied by tommylight on topic Rebuilding Plasma CNC

thefabricator03 wrote: I am sure it is a very similar machine to the OP.

That is the same machine, same manufacturer, as it seems.

thefabricator03 wrote: But I have never seen online or in person a round frame stepper motor. Do they exist?

Proof coming soon ! :)
I have plenty of them, 2 and 5 phase, not sure if i have 3 phase round ones.
It is to damn cold to go to the shop now to take pictures, so hold on till tomorrow, i have quite an assortment, or what is left of it !
Back on topic, can you please remove the cover from one of the motors and take some pictures.
Thank you.
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26 Mar 2020 03:24 #161535 by islander261
Replied by islander261 on topic Rebuilding Plasma CNC
Probably old news by now, that is a PlasmaCam machine. I would need to see a photo of the original controller to guess what model. The original drives are brushed servos with an encoder on the back. Proprietary electronics. It escapes me now but the servos are from an established motor manufacture just not one typically associated with CNC machines.

John
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26 Mar 2020 04:54 #161541 by tommylight
Replied by tommylight on topic Rebuilding Plasma CNC
All this reminded me, ClearPath servos are not servos, but no one seems to look at the torque curve.
Even the Chinese have the decency of writing "Hybrid Servo" for steppers with encoder feedback.
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26 Mar 2020 08:24 #161544 by machinedude
Replied by machinedude on topic Rebuilding Plasma CNC

tommylight wrote: All this reminded me, ClearPath servos are not servos, but no one seems to look at the torque curve.
Even the Chinese have the decency of writing "Hybrid Servo" for steppers with encoder feedback.


i had to laugh a little when i seen this. i posted on cnczone to someone who asking for an opinion between clearpath and DMM . i told them i would go with the DMM with a DYN4 drive and have a real servo system in stead of something i would consider a closed loop hybrid stepper system in the clearpath as a choice. some random guy chimes in and wants me to provide documentation to my opinion. i then told that guy to look at the torque speed charts from clearpath and take note of the speeds. i then told the guy that that was something i would expect to see in a stepper system and that was enough for me to make my choice. turned out the butt hurt guy was a builder who used clearpath on his machines :) go figure :). then a day or so later some guy from clearpath chimes in to defend their good name as a servo manufacture :) i just let it go at that point and walked away :)
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26 Mar 2020 09:33 #161547 by bbsr_5a
Replied by bbsr_5a on topic Rebuilding Plasma CNC
a full refit with cheep NEMA34 kit will cost less then a single AC servo
and as it is a plasma it will fit the need

cheep and workable fast transicion

BUT if this mashinegoes in full 8hr production it is best to stay on but cost will rise
7i92/7i77

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26 Mar 2020 09:45 - 26 Mar 2020 09:48 #161549 by thefabricator03

machinedude wrote:
i had to laugh a little when i seen this. i posted on cnczone to someone who asking for an opinion between clearpath and DMM . i told them i would go with the DMM with a DYN4 drive and have a real servo system in stead of something i would consider a closed loop hybrid stepper system in the clearpath as a choice.


Not to hi-jack OP''s thread (although I am good at doing that) but its funny you mentioned DMM.

I have this drive on my desk that I am about to use to retrofit some old Yaskawa AC servos. If this works out like I hope it will be a viable work around for my old AC servo motors. Although I need to fit the DMM absolute encoders, the encoder is not very expensive. The guys at DMM have been very helpful and have explained how they use the DYN4 drives with other makes of motor.

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Last edit: 26 Mar 2020 09:48 by thefabricator03.

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