Phase converter

So I am trying to figure out the best phase converter for my equipment. I have a variable speed lathe with 7.5 hp and a 1 hp Bridgeport mill. I've thought about running a 20hp rotary. Then thought about a static for the mill and wondered about a static for the lathe. I like that the idler won't have to run all the time. Any suggestions are experiences would be great to hear

Been using a Phase Perfect 20HP unit purchased from a fellow member and it has been great. Haven't thought about it once since it was installed. Would buy again in a heartbeat.

I have several machines running on static phase converters and all run well. The first one I did was a 1 1/2 hp Bridgeport Series I mill on a heavy Duty 1-3 hp Phase-o-Matic converter. It's been running on this converter going on 20 years without problems. The other machines running on static converters are a 1 hp Racine power hacksaw and a 2 hp Sheldon lathe. Both these machines are running on American Rotary 1-3 hp static converters. The saw has been in use for a couple years and the lathe for about 6 months. Both machines run trouble free.

I chose static converters over vfd's mainly because the installation was extremely simple, no wiring on the machines had to be changed, and all machines are capable of running through their entire speed ranges by using the original controls.

The long term plan was to run all the machines off a 15 hp American Rotary phase converter. I have the panel and the idler, but haven't installed the system yet. In my case I'll need to add another sub panel to power the converter, and all new circuitry to the machines. I estimate the cost of conversion to be in the neighborhood of $1,000.00. Right now the conversion is on the back burner, mainly because of lack of time and the fact that all the static converters are working fine.

The big thing with static converters is the fact that the machines run at approximately 2/3 the rated hp. The 3rd phase is only generated momentarily on startup. Having said that I've never had a situation where the lower available hp has been an issue. Given the fact that all the machines are currently running fine, and the cost of installing the new system it may be on the back burner for some time.

I have had a static phase converter for 20 years and it works just fine for my lathe, Bridgeport and grinder.
But be careful!!! A static phase converter creates a third phase for only a few seconds!! If you want to do a quick reverse on a lathe or Bridgeport it will not work. The momentum of the turning spindle will override the few second timespan of the third phase and your machine will keep running in the same direction as before. This can be tragic if you are tapping in a lathe or Bridgeport and want to do a quick reverse or if you are cutting a thread in a lathe.

I am digging the static phase converter. My lathe has a variable speed addition to it. Ive heard that the statics may have an issue with variable speeds. Is this correct?

If your 7.5 HP lathe does NOT have a clutch forget about using a static converter. Learned the hard way on larger HP lathes without clutches you need twice motor HP in your rotary converter.

I am used to an old southbend lathe. I just picked up a 67 lodge and shipley avs 1408 lathe. Ive read on this lathe and it seems like it might have a clutch. But not 100% sure. I am super excited to start using it and want to make sure i am making the correct phase converter choice.

Stharp said:

I am digging the static phase converter. My lathe has a variable speed addition to it. Ive heard that the statics may have an issue with variable speeds. Is this correct?

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It all depends on how the variable speeds are attained. My Sheldon uses a gear motor controlling a Worthington All Speed Drive. Essentially it's an infinitely variable speed machine. Speed is changed by 2 buttons on the control panel that control the gear motor. The gear motor opens and closes the variable sheaves in the Worthington drive. It's is powered by a transformer off the main power input. All the controls, Start, Stop, Fast, Slow, Forward, and Reverse are original to the machine. The static converter only creates the 3rd phase to start the main drive motor. All the controls run off either the 220 single phase or the 110 from the step down transformer.

As for the Bridgeport the variable speeds (J2J variable speed head) are attained by a variable sheave that is powered by a hand crank on the front of the machine. So there is no interaction with the electrical controls. The saw has multiple speeds that are attained trough the use of a transmission.

In all cases the use of a static converter has had no effect on the variable speed features of these machines.

Still for sale if you are interested in a RPC. http://www.practicalmachinist.com/v...ies-for-sale-or-wanted/sale-20-hp-rpc-338704/

projectnut said:

It all depends on how the variable speeds are attained. My Sheldon uses a gear motor controlling a Worthington All Speed Drive. Essentially it's an infinitely variable speed machine. Speed is changed by 2 buttons on the control panel that control the gear motor. The gear motor opens and closes the variable sheaves in the Worthington drive. It's is powered by a transformer off the main power input. All the controls, Start, Stop, Fast, Slow, Forward, and Reverse are original to the machine. The static converter only creates the 3rd phase to start the main drive motor. All the controls run off either the 220 single phase or the 110 from the step down transformer.

As for the Bridgeport the variable speeds (J2J variable speed head) are attained by a variable sheave that is powered by a hand crank on the front of the machine. So there is no interaction with the electrical controls. The saw has multiple speeds that are attained trough the use of a transmission.

In all cases the use of a static converter has had no effect on the variable speed features of these machines.

Click to expand...

It looks as though it's an add on by electronics. But reads it has a 8:1 variable speed drive rated for 7.5 hp capacity special let her duty and 5hp continuous operation. That's out of the manual

To OP: do you not know about the VFD/RPC forum here on PM?

metalmagpie

IIRC the L&S AVS is a pretty electronic heavy D.C. drive system.

No static box will work on it.

Just found this site. I havent had much time to browse around yet

Stharp said:

Just found this site. I havent had much time to browse around yet

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I would suggest that you take the time to READ the RPC subsection.
It will answer ALL your questions, and answer some you didn't even
know to ask yet.

Would it be beneficial to swap to a single phase 7.5 motor?

Stharp said:

Would it be beneficial to swap to a single phase 7.5 motor?

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PLEASE !

Read the archives, this has all been covered many times before.

The static box, the RPC, the Phase perfect, swapping single phase
motors, etc.

digger doug said:

IIRC the L&S AVS is a pretty electronic heavy D.C. drive system.

No static box will work on it.

Click to expand...

+1 Nor, very well, a Rotary, either.

AFAIK, the early ones were DC motor, DC Drive. Then they changed to AC motor + VFD.
"Built-in", either way. That is where the "VS" (Variable Speed) comes from.

AVS have only a few geared ratios - three is it? "Sibling" L&S, same/similar bed & all - had "many" geared selections.

Downsides?

Either way, DC Drive or VFD, the L&S AVS wanted true 3-Phase power, where the smaller Monarch was happy with single-phase.

Conversion of the later AC motored models, AFAIK, just wants a new(er) VFD that can take the place of the factory one.. AND, operate from single-phase power, in this case. Such VFD are no longer uncommon.

DC Drive, originally? I'd use a Parker-SSD 514C-32 for Armature, SSD 507 or 508 for field.

The 514C Armature supply would need a stout boost transformer and a SERIOUS ripple-filter (choke), the 50X Field supply, neither - just operated off 240 VAC, and limit-set for the motor's Field needs.

2CW. I don't HAVE an AVS, and have ceased scouting, what with the Cazeneuve HBX-360-BC under-roof.

Having run a couple of the AVS lathes, they all were the same.

Large handwheel to vary speed, with 3 gear (only speeds) gear selector
concentric to handwheel. Spindle speed readout was large electric meter
in the center.

"Clutching" was handled thru the drive, engaging handle to right (rides
along with the carriage) simply engaged switches, commanding drive
to go thru start sequence (a soft start).

They all ran D.C. drives with an M-G set.

digger doug said:

Having run a couple of the AVS lathes, they all were the same.

Large handwheel to vary speed, with 3 gear (only speeds) gear selector
concentric to handwheel. Spindle speed readout was large electric meter
in the center.

"Clutching" was handled thru the drive, engaging handle to right (rides
along with the carriage) simply engaged switches, commanding drive
to go thru start sequence (a soft start).

They all ran D.C. drives with an M-G set.

Click to expand...

Solid-state DC Drives and AC motor + VFD surely existed.

I don't THINK either of those were third-party conversions - though that, too must have been done to some, US DoD and their contractors, especially.

First & second generation, OEM, rather. Three if one counts MG to solid-state, still Dee Cee final-drive motor.

Someone on PM will have had sight of more examples than we have and can confirm.

Monarchist said:

Solid-state DC Drives and AC motor + VFD surely existed.

Click to expand...

As I remember they sort-of did but cost a gazillion dollars. I had a DC drive on a Heald id grinder about the time the AVS was new, looked into getting rid of the motor-generator thingy ... up to 2 hp or so Cleveland Machine Controls had them for okay prices but much over that, kazowie.

I think he's gonna have beega beega trouble trying to run an Answer lathe off a phase converter. Maybe a rotary but pretty sure not a solid state one. Not unless he's got an electronics engineer skilled with analog circuitry on board ... this is not your average three-phase lathe. And it's too nice to butcher.