[klm123]

How can a vfd be used to index a spindle for a tool change , is there a special type needed , encoder needed , brake needed.
How does this all work together ?

[Jim Dawson]

Maybe. I would use a sensorless vector VFD. Yes, an encoder would be required. Brake, maybe. What kind of a machine is this?

A VFD is not a servo drive, thus will not have the positioning accuracy of a servo spindle. But it might be close enough. Modern sensorless vector VFDs have a lot of features that make them almost like a servo drive and the line between the two is blurring. A normal 3 phase motor is not designed like a servo motor, but can be pretty accurately controlled.

[klm123]

I am retrofitting a maho 700 mill , my idea is to use it as a 5 axis horizontial mill and a gang tool chucker lathe with y axis milling .
I would like to be able to index for tool change and to index for y axis milling.
I allready stripped the old motors drives and controll and will build up a new system that I can run on 220v single phase

[Jim Dawson]

That is going to be quite a machine. I'm trying to wrap my head around exactly what you are wanting to do with the spindle and indexing. Is this motor going to be used for the mill spindle as well as a tool changer/holder for the lathe tooling? If that's the case you will need a mechanical wedge lock system for the tool turret for accurate positioning and stability. In that case, the VFD should position close enough to engage a mechanical lock/positioner for the final location.

[klm123]

I am looking to index the spindle , so the key alings with the tool changer .

[Jim Dawson]

If you have the encoder on the spindle or a timing belt drive and the encoder on the motor it will probably work. I have never tried to use a VFD and standard 3 phase motor for positioning. In either case, a sensorless vector VFD with encoder feedback capability will be required. Controlling the spindle with a motion controller would be the best, just make it another axis on the system.

My personal preference for VFDs is the Automation Direct GS series and for this application a GS3-xxxx would be the correct choice.

[klm123]

Thank You for the information , I will let you know how it works .