Single to 3 phase conversion problem

The reason I’m eating to do this is bc of the finish I’m getting using the lathe. The 1 phase 220 motor is causing hormonics that are showing up in my turnings no matter what metal I’m turning down.

I’ve isolated the motor and lathe with thick rubber.1/4 thick Red rubber used like on pipe work flanges. It’s very secure to the concrete floor and I’ve even went and spent 70 dollars on two link belts which helped but not cured the problem. The vibrations come and go with the harmonics the motor is making so I figured 3 phase would cure it. As far as buying motors I have two Baldor ,one 1.5 hp and one 2 hp, motors that are in great shape. Both are explosion proof motors even though I don’t need it. One was used for a tube axial fan for a paint booth and the other I can’t actually remember what I took it off of M.B. but I do know they were working when I removed them. So all I would have to do is buy the vfd and I’ve seen new 2hp vfd for about 100 bucks. That’s not an American made but I can’t afford that anyways.
 
The reason I’m eating to do this is bc of the finish I’m getting using the lathe. The 1 phase 220 motor is causing hormonics that are showing up in my turnings no matter what metal I’m turning down.

I’ve isolated the motor and lathe with thick rubber.1/4 thick Red rubber used like on pipe work flanges. It’s very secure to the concrete floor and I’ve even went and spent 70 dollars on two link belts which helped but not cured the problem. The vibrations come and go with the harmonics the motor is making so I figured 3 phase would cure it. As far as buying motors I have two Baldor ,one 1.5 hp and one 2 hp, motors that are in great shape. Both are explosion proof motors even though I don’t need it. One was used for a tube axial fan for a paint booth and the other I can’t actually remember what I took it off of M.B. but I do know they were working when I removed them. So all I would have to do is buy the vfd and I’ve seen new 2hp vfd for about 100 bucks. That’s not an American made but I can’t afford that anyways.

I have a variety of VFD's including Hitachi's, Allen Bradley's, Teco's and generics. The pricey ones generaly have more features but as far as actually running the motors I can't tell a difference between any of them. There are a couple of specific function integrated VFD control chips that I believe most manufactures and all the generic VFD's use... which is what has made VFD's so affordable.

https://www.google.com/url?sa=t&sou...FjABegQIBBAB&usg=AOvVaw1osb3GeNB-aqEUBWxP0w-0

At first I questioned whether a 3ph motor would make much difference in the finish of your parts... I doubt just changing to a 3ph motor will make any difference but being able to tweak the speed a bit with a VFD should definitely change any harmonics issues you are having.

If you are set on trying a VFD and 3ph motor I would reccomend isolating the lathe spindle motor control from the rest of the machine controls and ONLY running the 3ph lathe spindle motor on the VFD with no switches or relays between the VFD and the motor. If it works well and you love it so much that you want to change the mill spindle to 3ph and a VFD I would HIGHLY reccomend you purchase a second VFD and dedicate it to the mill spindle without any switches or relays between the VFD and the mill 3ph motor.

If it were me I would try to leave the original single phase control wiring intact to allow you or a future owner to easily convert the machine back to 1 ph if it is ever desired.
 
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Was just taking a quick overview of the schematic for your combo. Gotta love that Grizzly makes their manuals so readily available! Separating out the lathe & mill power is indeed beneficial in just the way you mentioned. Power feed on milling operations! It was easy on my G0773 (discontinued). Just plug the mill into a separate outlet on a separate circuit breaker - all 120V. Yours is much more complicated with many nice features. Since the guys with VFD experience are saying direct drive between VFD & motor, it appears that you would be abandoning those features - if they are not available functions of the VFD itself. If I recall, your reasoning for wanting a 3ph VFD on the lathe portion is your disappointment in surface finishes? I struggle with that as well - but, in my case, it is a lack of experience that I struggle with. Best wishes.
 
I have been out of town working a shutdown since July and have been so tired when getting off work I just wanted to sleep when I got off so that’s why it’s taken me so long to reply to all of you guys’ very helpful comments. I’ve actually learned quite a bit since then and have decided like suggested above to wire both motors separately and leave the original wiring for future if need to revert. I bought two Vfds for 110 a piece and have every bit the benefits of a unit 3 tines the price. Braking without an external resister is the feature that made my mind up. The only thing I can’t use is a wireless control pad but that obviously wasn’t a kill all bc I bought 2. They work flawlessly and the instruction manual was surprised easy to ready like the Chinese company paid a fluent English speaking person to write it which I didn’t think was going to be the case by reading the description on Amazon. And both are overrated at 3 hp so I shouldn’t see any overheating of the vfd. I have decided to find a lower hp motor than the 1.5 I originally was going to use. I think 1hp will be perfect. And I didn’t really explain what the main reason for the mill motor. The gears in the head have so much slop it’s ridiculous and they are extremely loud so I decided to make a single speed pulley and belt system and with the 3 phase motor controlled by the vfd I will then have control of the rpms and be able to have much faster rotator for small end mills. I just don’t see the benefit of small end mills and 2200 rpms, it just doesn’t work so well as y’all know and my machine isn’t rigid enough,even though I’ve fixed a lot of that too, to mill will larger end mills. Thank y’all for the help
 
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