Okay folks, I'm trying to figure out a way to wire up a Bridgeport mill in my garage. I don't have one yet, and figuring this out is one thing I must do. I'm looking to get a 1.5-2 hp variable speed unit... I've read of some of the different types of converters out there but I'd really like to know what the best would be. I'd really like to just be able to wire up a box to make it work, can anyone break down what these types are and which would be best? Thsnks
Phase Converters... Help
- Thread starter Crank1
- Start date
KF5LCH
Well-known member
I'll let the electricians fill you in on the rest, but a friend of mine made one out of an old 220v 3 phase motor. It uses a small 110v pony motor to start it up, then throw 220v single phase to the big motor & the output is 220v 3 phase. He runs a Piranha Ironworker with it. Works like a charm.
Your going to need a single phase 220 going into a three phase motor once the motor is spinning you will be able to grab the third leg for your three phase machine. If you run it on a 15amps breaker that's what the third leg will be rated for. What ever amperage your single phase 220 volts (input) is will be what your third leg on your three phase roto phase will be.
Josh
Josh
RCStocker
Well-known member
You will loose about a third of your power with a converter. You can make your own out of a large morter. You might need a smaller moter to start the larger one to run your machine motor.
You can look up what you need. It is all on charts on the web. Go larger than you need to get the power you need.
You can look up what you need. It is all on charts on the web. Go larger than you need to get the power you need.
You are absolutely wrong! A static will loose 1/3 but a rotary will not.
http://www.metalwebnews.com/howto/ph-conv/ph-conv.html
Be aware that on the linked document you have to click on the blue "figure" words to get the picture or schematic to come up. I built the 5hp one 10+ years ago and it is still humming along. I used the caps recommended and the balance was good. I changed the control circuit to 24vdc as I had all the relays in 24vdc.
lg
no neat sig line
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Just get a phase o matic...runs a few hundred dollars..and you can wire it up next to the mill (very small unit) it runs a bridgeport fine...it is Static..not Rotory...but I have never had a problem..and no my motor does not burn up...run slower etc. I talked to the guys at phase o matic before I bought..and for that low of a HP it works great..a Rotory unit is a few thousand dollars..
A VFD is another option to power the BP mill.
I think a VFD is Line in an out...same power on both but makes your motor adj, RPM's....put a few in...he needs a single phase to three phase unit...the converter adds a phase on start up and then drops it when the motor spins up...really had no issues with mine what so ever on the BPM
raskal
Well-known member
kinda on topic (I hope) but would a device like http://ab.rockwellautomation.com/drives/powerflex-4 work?
I was given one of these, and am trying to figure out exactly what it is (in very simple terms)
I was given one of these, and am trying to figure out exactly what it is (in very simple terms)
That's a variable freq drive (VFD). Yes if it's sized correctly it will work.
Givl Reggin
Banned
Call your electric utility company and find out how far you are from 3-phase power - if you have a business district nearby you might be able to get a 277/480v, 3ph, 4 wire service to your shop without messing around with converters.
onewaydave
Well-known member
I'm running several 3 phase machines with a rotary converter, but here are your options:
1. Replace the existing motor with a single phase motor. Probably not an option for the Bridgeport.
2. Static converter. Tricks the motor into starting and then runs on 2/3 of the 3 phases.
3. Rotary converter. This is the old standby. They can be made with a little scrounging. A 3 phase motor as large or larger than the largest machine you will run on it. Capacitors can be scrounged from dead window AC units or other scrapped electronics. You need a relay, I think I got mine from Grainger for 30-50 bucks. A magnetic motor starter (switch). A few conectors.
4. A VFD. Variable feed drive. It's a 1:1 unit for each machine, so if you have multiple machines needing 3 phase #3 would be a better option. These will cost about 150-200 bucks, I think. I haven't bought one but have taoked to many that have.
Either way, go over to the practical machinist dot com or other machinists sites as they have this down to a nit-pick in detail. When I did this, there were a ton of schematics and lectures on hows and whys. It was all very confusing, at first. I just chose one and plowed ahead and have been happy for about 10 years.
Dave.
1. Replace the existing motor with a single phase motor. Probably not an option for the Bridgeport.
2. Static converter. Tricks the motor into starting and then runs on 2/3 of the 3 phases.
3. Rotary converter. This is the old standby. They can be made with a little scrounging. A 3 phase motor as large or larger than the largest machine you will run on it. Capacitors can be scrounged from dead window AC units or other scrapped electronics. You need a relay, I think I got mine from Grainger for 30-50 bucks. A magnetic motor starter (switch). A few conectors.
4. A VFD. Variable feed drive. It's a 1:1 unit for each machine, so if you have multiple machines needing 3 phase #3 would be a better option. These will cost about 150-200 bucks, I think. I haven't bought one but have taoked to many that have.
Either way, go over to the practical machinist dot com or other machinists sites as they have this down to a nit-pick in detail. When I did this, there were a ton of schematics and lectures on hows and whys. It was all very confusing, at first. I just chose one and plowed ahead and have been happy for about 10 years.
Dave.
Jim Johnstone
Well-known member
I don't recommend using mortars in your shop, unless you like rebuilding it all the time
Says who? You can build rotary phase converters for very little money. The statics won't run the motor slower, they just lose 1/3 of the horsepower.
VFD's can be had in many different configurations, including ones that take single phase in and output 3 phase at full hp, and still allow you to adjust RPM.
Ultimately a rotary phase converter or a VFD is the best bet. VFDs typically can only be used on one machine, while a good size RPC can power several machines at once.
I don't want a small pony motor running and taking up space, more noise, etc. I think the phase o matic phase converter is what I'm after. I'm thinking if I get a 2 hp unit, and lose a little of the power it'll still be plenty. I ain't smart enough to make my own so probably just buy one... They do make 2 hp replacement motors for bridgeports in single phase but they cost a grand!
454ragtop
Well-known member
VFD for the win. Way too many benefits to do it any other way, especially for one machine. Soft start, variable speed, braking, adjustable ramp up and ramp down speeds, etc. Might even consider a simpler change pulley mill, rather than the more trouble prone variable speed. Have VFD's on 2 drill presses, and 2 lathes, biggest 1 has a 7.5HP motor, VFD's rock! I have a 5 HP rotary converter too, but much prefer the VFD's. Check out OWWM and Practical Machinest for more VFD info.
HTH, Jim
HTH, Jim
Packard V8
Well-known member
X2 on VFD. Spend a few bucks up front and you'll be glad you did every time you turn it on.
In fact, I've got a couple of static converters I'll sell, because I know I'll never use them again.
jack vines
In fact, I've got a couple of static converters I'll sell, because I know I'll never use them again.
jack vines
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If you don't want to build a rpc, my only other option would be a vfd.
A friend on mine works for Kaeser compressor. We though about installing one of his compressors in my shop, which is business zoned. We were worried the electric company would charge an arm and a leg to install the 3 phase then I would have to redo my whole service?
In his personal shop, he runs a rotary phase converter to power the 10HP kaeser compressor. I know he paid over $2000 for a scratch and dent rotary phase converter, I guess this was the only way to provide enough juice to the epack motor in the compressor, any one have any other ideas for doing this?
383 240z
Well-known member
I'm running an $80 e-bay static converter on my mill. It's a manual mill, I wouldn't use them for a CNC mill. However, mine is humming right along, I've never had it not run right up to speed and the loss of power, I have never noticed it, and I've pushed this mill pretty hard. I still don't know why they get such a bad rap. Keith
I've yet to hear anyone who could afford to add three phase utility power into a shop without it. As long as you have a large enough circuit, a rpc will work for a large compressor.
Yes I also heard it was extremely expensive, I was under the impression 3 phase was cost effective if you have it, but if you were to convert it was huge money as you have to get an entirely new electrical service, and I'm sure the elec company is not going to run it from the street for free.
He runs a rotary phase converter on his compressor as his regular phase converter blew up on first start up because of the compressor load.
does $2000 should reasonable for a RPC?
I started a 30 hp rpc on my current service. Motor was $85, I had the wire and a disconnect so $100 tops.
Start looking for a surplus 3 phase motor and 3 phase disconnects. The old 3 phase motors were built to last, bearing replacement is straight forward. I bought (3) 150ft rolls of 8ga wire off ebay a few years ago- cheap. Shop around on Craigslist if your serious about a converter.
I started a 30 hp rpc on my current service. Motor was $85, I had the wire and a disconnect so $100 tops.
I'm assuming the motor and disconnect power the 3rd leg, but how much did you pay for the RPC?
The RPC- consists of a 3 phase motor for and idler, a disconnect to start it and the proper ga wire, in it's simplest form.
The whole thing confuses me, I know he purchased the RPC from American rotary, but I remember it being the box the motor and disconnect switch. I don't think I have the knowledge to build one so I would probably have to purchase it.
The American Rotary has a control panel with start/run caps and an idler. With all the options available the cost can go up rather quickly.
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454ragtop
Well-known member
Before spending $2000. on a phase converter, consider just changing the motor to single phase. Compressors are tough duty, don't need variable speed or reverse, so I think the best is just convert to a single phase motor. That's what I did 25 years ago. Have a great industrial compressor, 120 gal tank, changing to single phase motor was the best and most reliable route.
Jim
Jim
if your smart enough to use a bridgeport milling machine you are most certainly smart enough to put a rotary phase converter together.
its a very simple setup, consists of double or tripple your rated hp. 3phase motor(these motors can be had anywhere from 5hp-30hp all for under $100) some good 8 guage or so wires(this you would have to determine for yourself, through some of the links that were posted) and a on off switch essentially.
i built mine using a 7hp 3phase motor i got for free, yes i have to use a pony motor to spin it up, but that is simply because i have not installed the start/run capacitors.
this is to illustrate how easy it is
<a href="http://photobucket.com" target="_blank"><img src="http://img.photobucket.com/albums/v603/malodin/IMAG0457.jpg" border="0" alt="Uploaded from the Photobucket Android App"></a>
the white/green/black wires on the left are coming from my 220v air compressor(i just tapped off them for temporary use) going down into the switch box, then out to the motor, then the 220 goes through the motor and feeds two of the legs on the lathe, then one comes out the middle leg of the motor and feeds the lathe. i started with a rope wrapped around it but couldnt get enough of a spin over and flip the switch to make it work. so i grabbed the little 110v 1/2hp motor down to the left and a fan belt, put them side by side and started the little motor, pulled the belt tight, let the motor do the work, then flipped the switch and the RPC stayed running. I was able to complete the work on the lathe i needed.
very very simple
please dont lay into me on the wiring or how unsafe it is, this was just a proof of concept, i needed to use the lathe for 1 quick thing so i slapped it together. i will build all the necessary safety features in when i actually use it again.
onewaydave
Well-known member
There a few ways to start a 3 phase rotary converter. There a lot of examples of pony motors being used as an "automatic" starter.
The pony motor does not have to function like this. It can be set up to not spin when the idler motor comes up to speed.
I have also seen a rope pull like the old lawn mowers (I couldn't find a pic, but imagine wraping a rope around the shaft of a motor and pulling the end forcefully causing the rope to unwind and spinning the shaft at light warp speed). All you have to do is spin the shaft of the 3 phase motor to about 1/3 speed, or so.
Or you can do it electronically. I mentioned in my previous post that there is a relay (fro Grainger, McMaster-Carr, others) that can be wired to do it for you. No noise and costs about30-50 bucks. If you can wire the space shuttle, you can do this. Just kidding. It is not much more difficult that installing a TV/DVD/satellite combo. No, no, no its really not that hard.
1. OK, I lucked out and found a free 35 HP 3 phase motor. But if you mosey out to the country (rural) you find them for very reasonable prices.
2. That relay (points up).
3. Some 12 g wire, lengths up to, hold on, 2-3 feet.
4. Some connectors, gasp try HF if your that cheap.
5. An enclosure can be found in most dumps. An old breaker box could be stripped and used.
6. Capacitors. A variety of sizes to experiment with to get the right balance can be found in a variety of electrical appliances. I find dead window air conditioners the best source.
I'm out of town until next week and can't get pictures until then, but if this thread is still active then, I will post some pics.
Until you get to see mine, take a look at this one. He went way overboard on the OCD neatness and organization of the layout but did a really good job. BTW, he calls a switch what I called a relay.
http://www.google.com/imgres?imgurl=http://www.cutterod.com/cutter_zone/3phase/start1%2520wired.jpg&imgrefurl=http://www.shopfloortalk.com/forums/showthread.php%3Ft%3D3035&usg=__b7H3PXJ2Gk_Ta7vWjXxXLNRoGPU=&h=459&w=536&sz=39&hl=en&start=19&zoom=1&tbnid=Bf2VHmOM87AB3M:&tbnh=113&tbnw=132&ei=dwK_UNGNLeXLyAHw54GgCw&prev=/search%3Fq%3Dpull%2Bstart%2Brotary%2Bconverter%26hl%3Den%26safe%3Dactive%26sa%3DN%26rls%3Dcom.microsoft:*%26tbm%3Disch&itbs=1
Dave.
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banditbigdog
Well-known member
I've used several of these
Single phase 230 volt input
Three phase 230 volt output
Up to 10.5 amps output max
3 hp max
http://www.factorymation.com/Products/FM50_230V/FM50-203-C.html
Single phase 230 volt input
Three phase 230 volt output
Up to 10.5 amps output max
3 hp max
http://www.factorymation.com/Products/FM50_230V/FM50-203-C.html
joe_padavano
Well-known member
What he said!
If the only three phase tool you have is the mill, and assuming we're talking somewhere in the 1.5-3 HP range, just buy a single phase motor. It will be cheaper by far. If you plan to buy several three phase tools, then it pays to get a converter to run them all. By the way, used rotary converters under 5 HP are pretty common on Craigslist for small dollars. I needed a 15 HP rotary converter for my industrial air compressor and that took a while to find, but I finally got one (20 HP start, 60 HP total!) for $800. It's not easy or cheap to find and power a 15 HP single phase motor, plus I have other three phase tools.
justanengineer
Well-known member
Single phase on a mill or lathe = TERRIBLE idea.
RPCs = noisy, wasteful of energy, expensive to run.
SPCs = not a terrible idea, but they do come with a significant derate.
VFD = great idea for safety reasons if nothing else. You can also program the VFD to make the tool very enjoyable to use. I use one on my Bport....cost = ~$75 shipped brandy new. For the price, they cant be beat.
I inquired with the municipal electric co a few years ago about having 3 phase installed back east, $3k IIRC for the farm.
RPCs = noisy, wasteful of energy, expensive to run.
SPCs = not a terrible idea, but they do come with a significant derate.
VFD = great idea for safety reasons if nothing else. You can also program the VFD to make the tool very enjoyable to use. I use one on my Bport....cost = ~$75 shipped brandy new. For the price, they cant be beat.
I inquired with the municipal electric co a few years ago about having 3 phase installed back east, $3k IIRC for the farm.
Short answer;
Inside the VFD you'll find a rectifier that converts the AC power input to DC. this DC voltage is switched on and off into the motor by 3 pairs of transistors, (one pair for each phase). The switching is very fast (over 8000Hz or 8000 times per second - you can often hear the motor 'singing' at the switching frequency) and timed in such a way to create a replicate low frequency AC current in the motor windings. By changing the timing of the switching, the frequency (0 to 400Hz typically) of the replica AC output and hence the speed of the motor can be changed.
justanengineer
Well-known member
930dreamer did a pretty good job on the science, but to add a tiny bit, a VFD gives you electronic control over the motor you wouldnt get otherwise. Other VFDs may have more/less functionality, but the functions I find useful and my current one has is:
1. "Soft" start and stop the motor - start/stop the motor at a slower acceleration than usual which is easier on the backgear and other parts.
2. Emergency stop the motor very quickly via single big red button.
3. Jog - preprogrammed ultra low spindle speed for tapping, drill spotting, etc.
4. Change speed via a single dial.
Irregardless of what type of converter you use, make sure #2 is available and working at all times.
So if I was using a rotary phase converter you can bypass using a single phase motor to spin the 3 phase one with capacitors and other stuff? And on the other style a vfd, do you utilize a separate switch for all tr controls and also the controls on a bridgeport? Seems I wouldn't need speed controls aside from the one that is variable belt speed
May Pop
Well-known member
I have a static convertor on my ancient Bridgeport mill-1947. It does a fair job, but it does loose a lot of the motors strength. I will do a 1 phase to 3 phase VFD in the future to get some slower speed out of this machine. I dont use it very often but it has worked well for at least 10 years. Original cost for a 1/2-1 HP unit was under $125.
Ron
Ron