Rebuilding Plasma CNC

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.

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.

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

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

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

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.