Thread: VFD conversion started

I now needed to finish boring out the hole for my motor shaft and bore the seat for the oil seal. Since the original precision fit of the hole on the shaft was the reference point for all the alignment issues of this project, I didn't want to loose that when finishing out the hole. To make sure I could always go back to this original alignment, I drilled two holes thru my adaptor plate and into two unused bosses on the C face of my motor. These two holes were then reamed and fit with taper pins. Now I was able to finish my adaptor plate. The seal was placed and the plate was attached to the motor. At this time I was able to tap the key into the shaft with some red loctite and place the two retaining screws. The shaft was checked again for proper overall length and proper sliding fit of the gear. I can't believe that I haven't screwed anything up yet, but I have had some pretty good help. I'll have just a little bit more on the mechanical end of this conversion before proceeding to the electrical part.

After some minor hand fitting, the transmission was bolted down to the adaptor plate and checked for proper shifting . At first it didn't want to shift into high gear, but I discovered that the high speed internal gear teeth were burred and after removing these burrs everything checked out. Since my center height on the new motor was .750 lower than the original, I made a couple of mounting bars from 3/4 hot rolled. My motor adaptation is now done and I hope I haven't bored you guys that do this for a living with too many pictures and too much explanation. I'm sure there are some other hobby machinists out there, like myself, that appreciate the extra dialogue and pictures. I find it very helpful when I am trying to understand and follow some of the other posts. Thanks for the patience!

Doc
That was definitely not too much detail. I will be going the same route some day with my '67 modular. It only takes the purchase of a C16J or two or a Monarch custom relay to demonstrate the cost effectiveness of a VFD conversion. I can also live without the heat output of the tubes in warm weather. I find the 10EE is an even more effective space heater than my RPC/Deckel FP2NC mill setup.
RKlopp

"It only takes the purchase of a C16J or two or a Monarch custom relay to demonstrate the cost effectiveness of a VFD conversion."

A-men.

Definitely not too much detail.

I am in the process of doing the same coversion on my "56 10EE and I am very happy to see this here. I am going the flux vector rout but pretty much the same process. This info you are posting couldn't be more valuable. Thanks for all the detail. I'm right behind you on the conversion. I'll probably be needing some help with the electrical eventually so I can still use the stock controls. Thanks again!

What is the potential downside regarding harmonics by switching to AC from DC?
Is finish comprimized?

Originally Posted by ditto_95

What is the potential downside regarding harmonics by switching to AC from DC?

Harmonics???

- Leigh

Harmonics from the AC current. Each phase is 120 degrees out from each of the other phases.
DC current is flat and smooth.
I was just wondering if there was any potential loss of finish due to the Frequency of the AC current.

I'm not electrically inclined, but I haven't noticed any finish problems with my VFD conversion.
There have been quite a few of these conversions done, and this problem has never been presented.
Harry

Possibly in Optics? Dave

I was just wondering if there was a DC conversion instead of the VFD change. I have an older machine and I am sure with my luck the old system will not last.

If there were any harmonic resonanace it would probably be in the lower RPM range.

which can be resonated through cast Iron? Dave

Yes, I have seen it in printing presses.

At lower frequencies, that'd be referred to as 'cogging'... yes, that occurs, but running a lower-yet drive ratio helps reduce that.

There's plenty of other avenues where mechanical oscillation originates... the gear teeth, belt variation, and even transmission through the framework from the shop floor... enough so that which an AC drive would generate is apparently not great enough to cause concern in the 10EE's apron.

Monarch thought it unsubstantial, as moved to AC drives in both the 5hp backgear arrangement, and larger in direct-drive.

I frequently get mirror-finish results from my well-worn, sloppy old round-dial and homemade tooling in an imported piston BXA holder... and I'll attribute it to more luck than skill, but it's also testament to a very well-thought-out and solid machine.

Nice job, Doc, and thank you!!!!

I have a question:

I have a 1946 10ee all in working condition with the original MG and DC motor set up, but I don't have three phase in my garage. Can I just buy a VFD that can handle 5 HP and generate the three phase power using the single phase 220 Volts?
This way I can keep the lathe all original.

Pier

No.
Vfd needs to be connected directly to motor with no controls in-between.
It can be done by an electrician experienced with frequency drive conversions maintaining the original controls.
Will be expensive though. The conversion for my Rivett 1020S with parts including motor and 5hp vfd
and labor was $2600. Greg.

What about if you use a three phase inverter (i.e. Single phase 220Volts input, three phase 220V output). For a 5HP they sell for about $495.

YES you can. you get a 5HP motor and a 10HP VFD 220 volt single phase in 3 phase out. make the spacer plate for the c-face motor to your gear box and make the in put gear fit your motor shaft. about $1000. cost for the motor and VFD

Originally Posted by pier

I have a question:

I have a 1946 10ee all in working condition with the original MG and DC motor set up, but I don't have three phase in my garage. Can I just buy a VFD that can handle 5 HP and generate the three phase power using the single phase 220 Volts?
This way I can keep the lathe all original.

Pier

You can use a phase converter or VFD to power your motor/generator, you'll need about 7 HP IIRC to run the motor end. A 10 HP VFD with a soft start on single phase MAY work.

Steve

I have a 1967 10ee and am thinking of VSD conversion. My DC drive is only putting out 1500 RPM. so something is wrong.
I've been told that a Hitachi VSD is the way to go. Can anyone confirm this? I have an Anderson 3hp. rotary phase converter, so I would probably use a 3hp. motor which is adequate for what I do. I take it 3 phase power is required for this set up.