Rivett 1020s VFD Conversion Motor Size

[alcro1998]

So I kinda forgot but the Baldor motor I have is setup with an encoder for a closed loop vector system. Is it worth getting the closed loop vector working? Not sure how easy it is to hook into the VFD. I have never done it before.

Thanks

 

[tailstock4]

So I kinda forgot but the Baldor motor I have is setup with an encoder for a closed loop vector system. Is it worth getting the closed loop vector working? Not sure how easy it is to hook into the VFD. I have never done it before.

Thanks

You not only have to have a motor that is encoder capable but also a drive that is capable of running closed loop. And you need to make sure that it is all compatible. The design of a closed loop system is more complicated to set up and tune. The final tuning of mine was done on an oscilloscope. There are also choices such as remote power for the encoder versus the drive’s internal power and many more parameters to set. This is one of the reasons I used D.P. Brown for consultation and component selection.

What I find with the closed loop on my 10EE is a little more torque in the lower ranges but perhaps more important is the smoothness and quickness in which it applies that torque. It has a little more of a DC feel to the drive, and it is my favorite drive to use. However, it is quite a bit of work and money for a little more gain. But then again that could be said of a 10EE or a Rivett, too.

 

[alcro1998]

The motor already has the encoder on it and it is an encoder capable motor. Blador Inverter Drive motor. Encoder is dated 1999 so might be tricky finding the right drive. I also have an extra encoder which I believe is newer so that one may work as well assuming the mounting is similar. Smoothness and responsiveness are two things that I want to prioritize in this build though.

I'll start reading more and see if I can learn more about close loop drive. I have looked into them a bit in the past but have no hands on experience with them. Thanks for the help!

 

[Halcohead]

Okay, drive details. The full lathe with its ugly headstock tray:


The two motors. I’ll add an open belt spindle brake someday, but it’s a low priority. The bike brake has plenty of strength to lock the spindle when changing chucks. The waterjet aluminum plates below the brake are just to shim it into alignment because the mount wasn’t quite right the first time:


The VFD visible thru the front door. The plugs go to the motors. In the back behind those plugs is the box to convert the VFD analog output from 0-10V to 0-28V. Braking resistors below the VFD, very carefully mounted:

Under the cover at the back of the headstock. Note my open belt shifter dog is something I made from scrap cast iron to replace the original, worn out unit (the lathe had been run in some stupid ways before I got it and had drive problems). The microswitch to sense gearbox state is behind this custom dog. Also if you ever want to make custom end gears for the rivett, they’re 16dp 20deg PA, noted in this photo: the splines are a pain:


Showing more detail on the microswitch. The aluminum block between the headstock casting and shifter dog is something I added to carry the microswitch. The microswitch is actuated by an adjustable setscrew in the shifter dog. (Second photo is looking forward from the back of the lathe, headstock is at left).


Anyways I hope this is interesting to some. Maybe I should’ve just made my own thread, but this project was like 5yrs ago so I kindof stopped thinking about it since the lathe just works.

On edit: I forgot to snap a photo of the controls but you can see them in the first photo. The top switch is FWD/REV, the second down is the speed potentiometer, 3 is E-stop (triggers e-stop on VFD), 4 is an intermittent jog FWD/REV switch (useful for threading and power tapping), and 5 is unused, but used to be the open belt/back gear selector switch before I wired in the microswitch for automating this shifting. It’s kindof satisfying to hear the clunk of the contractor shift every time you shift the gearbox.

I didn’t snap a photo of the controls cabinet because if memory serves it’s a little uglier than I would like it to be, and there’s nothing special going on other than some changes to the wiring. I reused as much of the original control relays as possible, which was surprisingly easy. The ELSR function works like normal, and has been a pleasure to use on this.