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mich_88_13
08-21-2011, 03:24 AM
I bought a Bridgeport series 1 with the 1 horse 3ph "J" head. After looking at phase converters, the cost & the room they take up I started wondering if there might be a 1 horse 220 single phase motor that will bolt up to it & work??? Any help on the problem would be appreciated.

1-800miner
08-21-2011, 03:50 AM
The bridgeport motor has an oddball mounting flange,not like common motors.
I just went through the same problem.
I made an adapter plate from 1/8 plate steel.
It took some accurate measuring,but not a major project.
When it was done I had to slide the drive pulley down the shaft 1/8 inch to line up the belt.

macona
08-21-2011, 03:51 AM
Install a VFD.

davidwdyer
08-21-2011, 06:49 AM
If you change to 220V you lose your instant reverse capability.

I use this for tapping all the time and can't imagine being without it.

I just run an idler motor. (A three phase motor which has an momentary button and a capacitor on the third leg to start it. This then runs on 220 while generating the third leg of three phase.) The "generated" third leg only runs at about 80% power, but never has been a problem.

I'm sure the VFD solution others will talk about is more versatile and better, but often old 220 motors are easy to find if not free, if cost is an issue.

PS. You have to use an idler motor larger than the largest one you are running.

kennyd4110
08-21-2011, 09:28 AM
Install a VFD.
That is the best route for sure, and it gives variable speed as well without messing with the belts.

Scottike
08-21-2011, 11:12 AM
The adapter plate is entirely doable, and while you may not have "instant" reversing with a 1ph. 220 motor you will still have reverse - you just have to let things come to a full stop before starting up in reverse.

edit: For the cost of a new 1ph motor you might think about just getting a static ph converter, not the best solution, but it'll get you by for a while (several yrs) for much less money and won't take up the space a rotary will, you will lose some hp on the mill motor though.

mich_88_13
08-21-2011, 11:18 AM
but you loose instant reverse capability with a vfd also it says "You must be able to connect directly to the motor bypassing any existing switches and contactors." there is a little switch on the top of my mill that reverses it & I would loose my E-stop to.

MaxHeadRoom
08-21-2011, 11:25 AM
" there is a little switch on the top of my mill that reverses it & I would loose my E-stop to.

This would go into the FWD/REV input on the VFD, and the contactor would be moved to the VFD supply input for E-Stop function.
Max.

mich_88_13
08-21-2011, 11:33 AM
So what you are saying is that IF I get a vfd I need to make sure that IT has instant reverse???

Forrest Addy
08-21-2011, 11:54 AM
ANY VFD will give you instant reverse having regard for motor accel and decel times. I tap with mine and I'd almost swear the time from FWD to REV is about 1/10 second running the motor at about 15 Hz (1/4 rated RPM) in low belt direct.

My BP clone turret mill coasts to zero from 2750 RPM in about eight seconds. Under VFD brake it takes two. Don't use the E-stop for general motor stop on a FVD because you lose the electronic braking. Just hit the regular motor stop and the electronic brake will stop the motor in its programmed decel time.

Anyway, take a little time and study up on VFD's; there's a lot to them. Learn what they can and can't do.

A 1 HP VFD is about the size of Machinery's Handbook and has:

-variable speed,
-programmed accel and decel,
-hook up for the mechine's existing control station pushbuttons,
-jog and other control options if you monkey a litte with the programming.
-quieter and electrically more efficient
-adding Fwd/Rev tapping via a foot switch is an easy mod.
-develops full rated HP whereas your motor will run about 85% on an RPC.

All are all either difficult or impossible to do running from an RPC.

VFD's do not lay golden eggs or improve the weather.

A VFD's single disadvantage is it will run only one motor at a time.

Here's a link to only one of a dozen on-line VFD sellers

http://www.dealerselectric.com/mfg-subcat-item.asp?cID=28&scID=164&mID=-1

Scroll down about half way to get to the 1 HP units. These run a 1 HP 230 V 3 phase motor from a 115 volt wall outlet. No de-rating. A 1 HP unit will run a 1 HP motor to full ratings. No re-wiring your shop for 230 V if you don't have it. They also have 230 single phase models.

If your budget will stretch to $99 to $140 a VFD might be a good choice for you. Trust me. I have 4 machines equipped with VFD's: my mill, lathe, drill press, and table saw. If you can avoid an RPC by installing a VFD on your three phase equipment you will be glad you did.

PixMan
08-21-2011, 12:10 PM
My understanding is that the better VFD's have both a built-in reverse and E-Stop. And they're still under $350, which is cheaper than a rotary phase converter setup. It's also quieter, and delivers more power than a Phase-O-Matic static phase converter.

I ran a 1HP 3-phase Bridgeport off of a Phase-O-Matic static for about 2 years before I got a RPC setup. It was like half-power. I couldn't use any decent-sized face mills, bigger drills needed multiple pilot drills, and forget about power tapping.

My dad had got a 15HP 3-phase motor to use as an idler, free. The place he worked had 10 and 20 ton rooftop A/C units and the power company offered replacement "energy efficient" motors to them as part of a conservation program. He asked if he could have one of the old motors, they told him to "take 'em all". He didn't, but did take the nearly-new one he had recently replaced. I went to American Rotary Power for the "box only" deal on a RPC drive, and for about the price of one VFD, we got enough power to run all three 3-phase machines at once if we want.

The downsides are the noise and that it stays running even when spindles aren't making chips. I'm probably going to move it over to an outside shed, and just have an indicator light to remind me it's on.

If you only have the one machine, a VFD is the way to go. If you have multiple 3-phase machines, don't need variable speeds, and can find a decent idler motor for cheap, go RPC. I don't want a VFD on the surface grinder, and worry about affected lifespan of the Taiwanese 5HP motor on the lathe or OE 1961 motor on the BP if I were to use 3 VFD's. What you don't want is single-phase on a machine tool if you can have 3-phase.

MichaelP
08-21-2011, 12:12 PM
Since I'm using an RPC for all my machines, I always wondered how people manage belts/pulleys or speed gears on their VFD-driven machines. Do you still switch the speeds using the belts/gears and allow the VFD to regulate speed within each range?

lakeside53
08-21-2011, 12:27 PM
On my step belt, 99.9% of the I just leave the belt in the second to top position, and vary with the VFD. If I need torque at low speed, I use the back gear.


I put a 2hp motor on my step head - helps with low speed power. I turned down the shaft from a Varispeed head, and had the motor dynamically balanced. Lots of messed up varispeed motors out there -the shafts get worn beyond repair.

I've found on numerous BP's, particularly on the 2hp motors that you really need a VFD with more than the motor rated power. The 2 hp motor on later models was rerated to 3hp for max 30 minutes. On acceleration the 2hp motor easily exceeds the current of a 2hp vfd, and does so for more than the allowed overload period. Yes, you can use a 2hp vfd on the 2hp motor (and I currently do), but if you want rapid acceleration / deceleration, it's a delicate balance of parameters to stop vfd trips.

PixMan
08-21-2011, 12:28 PM
I wonder about that too.

Do you set the gearing of a lathe to maximum speed and run the motor very slow, or set the gearing at low and overspeed the motor? What about the torque curves? I know that with a fixed rpm motor I always have the same Kw rating available, and depend upon gearing to make the best use if it. How does this change with an VFD?

It seems to me that both situations are something the motors weren't designed to do, hence my fears of affecting the life of the motors.

bmw625
08-21-2011, 12:36 PM
listen to Forrest ! I read his posts a few years back, and now have 3 vfd machines ; drill press,lathe,and mill. super neat way to control the machines !!
bmw :)

PixMan
08-21-2011, 12:59 PM
How does a VFD work with the step-on-it brake of our lathe or the little brake lever on the Bridgeport that I've instinctively reached for over the last 35 years? Does one need an EE to wire the VFD into the circuits of the lathe's Forward-Neutral-Reverse lever, brake and jog buttons?

If my American Rotary Power brand RPC unit is delivering only 85% power, I'd be shocked. The cuts I take with the lathe and 1HP BP using 2-1/2", 3" and 4" insert face mills belie the 85% factor. If the old static converter was good for only 2/3rds (at best) of rated power, I tend to believe our RPC unit is pushing out far better than 85%.

I've seen how nice the VFD's can work. My neighbor Rollie G. has one on his newer Clausing 15x50 lathe, and it speeds up, slows down and reverses perfect. For me, the sub-$400 I spent for the RPC motor, starter/capacitor unit, and wiring made economic sense at the time. Being instant plug-n-play and not having to delve into any machine circuits made it completely painless.

I could be convinced to go VFD in the future, but I'm more inclined to look at a Phase Perfect as I intend to someday install CNC milling and turning machines.

lakeside53
08-21-2011, 01:01 PM
I wonder about that too.

Do you set the gearing of a lathe to maximum speed and run the motor very slow, or set the gearing at low and overspeed the motor? What about the torque curves? I know that with a fixed rpm motor I always have the same Kw rating available, and depend upon gearing to make the best use if it. How does this change with an VFD?

It seems to me that both situations are something the motors weren't designed to do, hence my fears of affecting the life of the motors.

On a lathe I change gears often, vfd or not, and use the ranges as required. VFD then gives me 20% to 150%. On a mill - I change rarely.

Just assume that at the "native speed", i.e, 60hz, it develops its rated hp. At 30hz, it's about half, at 90hz, maybe 60%. Above that, it's non-linear and you run out of torque really quickly. With older motors, I stay below 90hz. Sensorless vector vfd can help at the very low end but who want to 'work" down there anyhow?

As for motor life - VFD will help. Soft starting is great for everything in lathe; I hate hearing my headstock gears thud when the 3-phase is switched directly

vpt
08-21-2011, 01:05 PM
I am still leaning towards RPC as well. Plug and play, more than one motor, all the switches on the machines work like intended.

My plan is to wire the RPC in the corner of the shop and run the 3ph wire to outlets at what 3ph machines I have. Plug the machine in and away I go.

MichaelP
08-21-2011, 01:06 PM
whereas your motor will run about 85% on an RPC.
Where did you get the number, Forrest? It looks like it belongs to a good static converter rather than to a reasonably well balanced RPC.

All sources I ever seen quote full power when a motor is run out off a well balanced RPC. Granted that the output of an RPC is not as ideal as a 3-phase utility power, I doubt that you'll ever notice the difference in terms of your machine power. Whereas with a VFD you will for sure (mostly, closer to the extreme speed settings).

lakeside53
08-21-2011, 01:08 PM
How does a VFD work with the step-on-it brake of our lathe or the little brake lever on the Bridgeport that I've instinctively reached for over the last 35 years? Does one need an EE to wire the VFD into the circuits of the lathe's Forward-Neutral-Reverse lever, brake and jog buttons?
......

I could be convinced to go VFD in the future, but I'm more inclined to look at a Phase Perfect as I intend to someday install CNC milling and turning machines.


You can't use the brake on the vfd if you have programmed deceleration; simply set the vfd to freewheel on deceleration (i.e., it just cuts the power). On your mill, just take the handle off the brake :) On some VFD you can feed the the lathe brake switch to the vfd and have it freewheel only when you stomp on it.

Phase Perfect? ha, I just put one of those it, so now I'll run three phase vfds as well.

lakeside53
08-21-2011, 01:16 PM
Where did you get the number, Forrest? It looks like it belongs to a good static converter rather than to a reasonably well balanced RPC.

All sources I ever seen quote full power when a motor is run out off a well balanced RPC. Granted that the output of an RPC is not as ideal as a 3-phase utility power, I doubt that you'll ever notice the difference in terms of your machine power.


Balance? at what load? How many RPC are realy balanced within 5% at max load? How can the average guy at home even do this?

Still, you may be able to get 100% out, but at the expense of your motor. Motor are supposed to be derated if the voltages are unbalanced. A 5% unbalance requires derating to 75% or so... here a useful link to explain:
http://www.pge.com/includes/docs/pdfs/mybusiness/customerservice/energystatus/powerquality/voltage_unbalance_rev2.pdf


Static converters? I will never use one on any motor I care about. Maybe you get 50% power before you are overloading the motor, and how do you know? If you 'hear" it slow down, it's already way into overload.

PixMan
08-21-2011, 01:34 PM
Phase Perfect? ha, I just put one of those it, so now I'll run three phase vfds as well.

What do you mean by this?

A Phase Perfect Digital Phase Converter is no laughing matter in price or performance. Full power, perfectly balanced phase and voltage, and dead quiet. They are anything but cheap but if you're trying to power-up a 1990's vintage CNC mill or lathe such as I anticipate doing, a Phase Perfect DPC is the closest thing to incoming 3-phase, and probably cleaner.

http://www.phaseperfect.com/

Do you mean you have purchased and installed one of their products? If you have one of these, why spend even more money on 3-phase VFD's? I can see where some speed control on some machines would be nice, but it sounds like you'll be spending beaucoup bucks on power supply stuff. I try to spend it on tooling and machines.

JoeLee
08-21-2011, 01:37 PM
Install a VFD.

Agreed, this is your best bet. Yaskawa makes some real nice VFD that will run that mill without a problem.

JL.................

jcon
08-21-2011, 02:23 PM
mich 88 13

Sometime in the 70ís I bought a G.E. single phase ĺ Hp 115/ 230 motor from the local Bridgeport Dealer. It bolted on to my Bridgeport with no changes needed. It reversed instantly just as will as a three phase motor.

I do not understand what davidwdyer means by an idler motor. I ran my old 3 phase motor by hooking a capacitor to the third lag of the motor with a button hooked to one wire of the singer single phase. Turn the switch on while holding the button for a few seconds, the motor will run fine, but with some loss of power. Do not hold the button after the motor starts.

The ĺ Hp motor or the loss of power with the 3 phase motor has never been a problem .

Jcon (Jim Connell)

You havenít began to learn till you learn how little you know

davidwdyer
08-21-2011, 02:41 PM
mich 88 13

I do not understand what davidwdyer means by an idler motor. I ran my old 3 phase motor by hooking a capacitor to the third lag of the motor with a button hooked to one wire of the singer single phase. Turn the switch on while holding the button for a few seconds, the motor will run fine, but with some loss of power. Do not hold the button after the motor starts.

Jcon (Jim Connell)

You havenít began to learn till you learn how little you know

The idler motor is used as you are using the normal motor with a capacitor to start it. Except that the idler motor, while idling, generates your third leg of three phase although it does not generate 100%. This is a cheap way two produce "3 phase" with only slight reduction of power. I've never noticed any lack of power. However, using an "air over" motor is slightly noisy.

Your motor, when running was only running on two legs, which must have noticeably reduced power. Perhaps unbeknownst to you, it was also generating a third phase of power which went unused.

Forrest Addy
08-21-2011, 02:47 PM
I'm often challenged when I assert the 85% figure on HP attainable on motors run from an RPC. It's more a figure of merit than quantifiable expectation. 85% is pretty close to 100%. Without instrumentaton I doubt if I could tell if a machine motor was giving 100% or 85%. Most induction motors will 15% overload for the two or five minute duration of a cut. The motor will hum a little louder and the induction motor slip might be noticable in the note from the gear meshes. Otherwise I'd think the motor under 15% overload would do little other than warm a trifle more than normal. Keep it up for an hour and you may fry the motor. Depends on ambient temperature..

It stands to reason that an RPC balanced to run equal voltages at idle current will still have a weak leg at full current demand from the load motor. Whether the difference is 90% or 80% much depends on the relative rating of the idler motor, the load motor, and the circuit elements that "balance" the weak leg.

You really can't make these distinctions without instrumenting each individual case. Once upon a time I had time and resources to do just this. Results varied so I picked 85% as a fair approximation and went with it. YMMV

A VFD is not a universal solution. A little experience and strategy is needed to take full advantage of its benefits and features. A plain one motor manual machine benefits out of proportion to the investment from a VFD.

If you have single phase power and a complex machine combining motors, digital controls, and other wierdness, a Phase Perfect is the way to go. The output of a Phase Perfect can be treated just like three phase from the utilty company. Your machine won't know the difference except the power is a little cleaner on the synthetic leg.

Rant mode: The witless will install a VFD on a mill, set the step pully at 1700 RPM, dial the spindle speed down to 450, stall the mill with a 4" carbide shell mill, and forever after condemn a VFD as "having no torque". Idiot assertion.

People shouldn't use big words like "torque" if they don't understand what they mean. Torque is twisting force not power. You wouldn't lever up a rock by placing the fulcrum near your hands because of the mechanical disadvange. Similarly, you don't belt or gear a machine for high RPM, dial it down and expect it to develop full rated motor power at low RPM. An induction motor is a constant torque device. Dial it down in RPM and the developed mechanical power drops in proportion.

In these situations it's the operator setting conditions that's at fault not the VFD "reducing torque".

When ignorance of physics doesn't kill, it humiliates you or costs you money.

OK, rant off. The topic was a Bridgeport with a three phase motor. Yes, a VFD will do the job of running its three phase motor from single phase power and the features incorporated in a VFD will greatly enhance the operabiliy and performance of the machine. Thousands have made the conversion on similar amachines but very few were dissatisfied.

davidwdyer
08-21-2011, 05:49 PM
As you can see, I don't have a VFD, but it sounds like someone would need a different one for every machine. Is this the case or can I use one for the whole shop but only use one machine at a time?

Sorry if this is a dumb question, but I never have worked with VDF before.

MichaelP
08-21-2011, 06:06 PM
You'll need a separate one for each machine. Sorry! :)

Lakeside53,

Thank you for the very interesting link.

Now, some measurements and calculations demonstrate that my 3-phase RPC-based line, when fully unloaded, is 3.4% unbalanced. This is only slightly above the recommended 3% max. for the utility lines, but well below the 5% max. permitted by Nema MG-1 for motors.

As soon as I turn on one of my machines, the unbalance drops to 1.8-2%. Based on the table presented in the article, I can derate my motor to about 95-97% of its full capacity to be very safe. And it's not because the motor loses power, but in order to keep it at specs at full power (in terms of heat). Anything to avoid an extra 10% of temperature rise if I decide to take the motor to its limit.

How often, if ever, we operate our motors at their full capacity is, really, a rhetorical question.

davidwdyer
08-21-2011, 06:16 PM
You'll need a separate one for each machine. Sorry! :)

Well, that settles that question for me anyway. Everything is already working great without one.

Forrest Addy
08-21-2011, 06:52 PM
Well, IDEALLY you need a VFD for each three phase motor (single phase motors cannot be made to work from a VFD).

BUT - I went for years swapping plugs on my lathe and mill on a single VFD. I set the VFD in a central location, added a drag around control station with a magnet mounted on the bottom, made a long cord from control station to the VFD, and used good three phase rated plugs on the power connectios. I used this set-up from 1993 to 1998 when I lucked on to more VFD's.

A lot of home shop owners mounted their VFD's on a little stand they took from machine to machine. A VFD may run only one motor but it will run any three phase motor in a range from a little larger to 1/3 its rating - depending on the motor and how the VFD responds to it. You may have to jigger the parameters if the motor range is too extreme but that takes seconds once you're practice. Post a how-to cheat sheet on the VFD.

In the mid '90's, my VFD was a MagneTek GPD333. My mill motor is still 2 HP and Chinese. The lathe motor at the time was 5 HP and German. No parameter changes required. YMMV

flylo
08-21-2011, 10:00 PM
If you change motors I'd like to buy your 3 phase. Please let me know as soon as you decide. Thanks! Eric

lakeside53
08-21-2011, 11:12 PM
What do you mean by this?

A Phase Perfect Digital Phase Converter is no laughing matter in price or performance. Full power, perfectly balanced phase and voltage, and dead quiet. They are anything but cheap but if you're trying to power-up a 1990's vintage CNC mill or lathe such as I anticipate doing, a Phase Perfect DPC is the closest thing to incoming 3-phase, and probably cleaner.

http://www.phaseperfect.com/

Do you mean you have purchased and installed one of their products? If you have one of these, why spend even more money on 3-phase VFD's? I can see where some speed control on some machines would be nice, but it sounds like you'll be spending beaucoup bucks on power supply stuff. I try to spend it on tooling and machines.



yes, I just purchased and installed one (blue box to the left). 10hp unit for $1500 from CL - about half price. It currently runs my lathe and compressor, and a few extra outlets for whatever.


http://i238.photobucket.com/albums/ff150/lakeside53/Phase%20Perfect/DSCN2011Medium.jpg



VFD's offer much more than three phase conversion. Soft start, rated motor starter (over current protection) etc etc. and... single phase vfds over 3 hp get expensive. 3 phase means I can buy cheap surplus vfds. Industry seldom buys used vfds; homeshops rarely have 3 phase ;)


I'm about to intall a 240->480- transformer to take advantage of even cheaper vfd's :)

lakeside53
08-21-2011, 11:19 PM
You'll need a separate one for each machine. Sorry! :)

Lakeside53,

Thank you for the very interesting link.

Now, some measurements and calculations demonstrate that my 3-phase RPC-based line, when fully unloaded, is 3.4% unbalanced. This is only slightly above the recommended 3% max. for the utility lines, but well below the 5% max. permitted by Nema MG-1 for motors.

As soon as I turn on one of my machines, the unbalance drops to 1.8-2%. Based on the table presented in the article, I can derate my motor to about 95-97% of its full capacity to be very safe. And it's not because the motor loses power, but in order to keep it at specs at full power (in terms of heat). Anything to avoid an extra 10% of temperature rise if I decide to take the motor to its limit.

How often, if ever, we operate our motors at their full capacity is, really, a rhetorical question.


You are one of the lucky owners then; good, you can sleep at night :) You can even run cnc from that. Most rpcs I measure are far from balanced, and the owners are safely oblivious. In addition, most equipment I see in the home ship doesn't have over current protection for the motors, so I guess that they don't know won't hurt them:D Must be true, because few homeshops actually burn out motors.

uncle pete
08-22-2011, 02:40 AM
My electrical skills and understanding could fit on the head of a very small pin, But after seeing what a 3 phase motor VFD combination can do on my mill I'd never go back to single phase. Smoothness of opereration, Soft start, Programable ramp up/down, Variable speeds ect. In fact I plan to change my single phase lathe motor over to a 3 phase VFD set up. Forrest's point about not getting too far away from the motors normal operating range is of course 100% correct. Everyones needs and wants are different, But for 99% of us here I think that a VFD is the way to go.

Pete