3ph motors in a single phase shop
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3ph motors in a single phase shop
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Topic: 3ph motors in a single phase shop (Read 1079 times))
luge007
"What ever, just crash it!" (kid from 1980's Toyota Cienna crash testing commercial)
Plinker
Posts: 293
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Real Name: Matt
3ph motors in a single phase shop
«
on:
November 16, 2022, 07:01:33 AM »
Hopefully this is an easy question to answer for some electrical engineer out there.
I only have a single phase electrical system in my 'shop', yet the Bridgeport Mill I bought (J head) has a 3phase motor. This piece of machinery is the ONLY 3ph motor in the shop and likely the only one that will ever be in there.
My 3 options as far as I can tell are;
1. Have the motor rewound single phase
2. wire in a phase converter (rotary or static) for that single piece of machinery
3. (and the least expensive option) install a variable frequency drive on or near the mill.
SO, my question is, which option would "work the best". To elaborate, all of them WILL work, but what will I give up or gain for each given option.
Thank You in advance,
M
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USA, RI, SK
Ronno6
GTA Senior Contributor
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Real Name: Ron
Re: 3ph motors in a single phase shop
«
Reply #1 on:
November 16, 2022, 08:10:42 AM »
Dunno about options 1 & 3.
As for option 2, converters work but you will lose HP in the conversion.
How about replacing the motor with a single phase unit?
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USA, Stone County, MS
You can lead a man to water, but you can't keep him from urinating in it.
Bubba18655
Plinker
Posts: 159
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Real Name: Jim
Re: 3ph motors in a single phase shop
«
Reply #2 on:
November 16, 2022, 10:56:19 AM »
Get a single phase input to 3 phase output VFD. You just need to watch the HP size of the drive. I think they need to be roughly 1/3 larger than the HP of the motor. Works great. You get speed control and full HP of the tool.
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USA, PA, Shickshinny
KWK
Sharp Shooter
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Real Name: Karl
Re: 3ph motors in a single phase shop
«
Reply #3 on:
November 16, 2022, 10:58:43 AM »
#1 is practically impossible. #2 is feasable but #3 a VFD is the most common and easiest option EDIT for the home shop. That's what I would do.
«
Last Edit: November 16, 2022, 11:20:46 AM by KWK
»
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USA, PA, Camp Hill
Rob M
GTA Senior Contributor
Posts: 6308
Re: 3ph motors in a single phase shop
«
Reply #4 on:
November 16, 2022, 11:09:45 AM »
VFD is the easiest option. I have a vfd running a spindle in the shop , like someone mentioned above, when i increased the motor size , trouble started.. Amazon mislabels almost all their vfds, so id get the most powerful one available .( the wattage needs to far exceed the claimed wattage of the motor)
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Louisiana
KWK
Sharp Shooter
Posts: 590
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Real Name: Karl
Re: 3ph motors in a single phase shop
«
Reply #5 on:
November 16, 2022, 11:23:58 AM »
The Practical Machinist forum is about the best place to get this kind of information. Really good information there. And here as well.
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USA, PA, Camp Hill
pan60
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Real Name: pan
Re: 3ph motors in a single phase shop
«
Reply #6 on:
November 16, 2022, 12:39:01 PM »
as a member i would also recomend The Practical Machinist forum for this subject.
VFD would be the easiest but i dont think i would grab a cheapy. if the machine isnt somwhat newer ( not new but new enough to have well insulated coils ) i would go with a rotary.
«
Last Edit: November 16, 2022, 12:41:02 PM by pan60
»
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USA, Dyer
luge007
"What ever, just crash it!" (kid from 1980's Toyota Cienna crash testing commercial)
Plinker
Posts: 293
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Real Name: Matt
Re: 3ph motors in a single phase shop
«
Reply #7 on:
November 17, 2022, 07:02:45 AM »
Thanks for the prompt replies. I suppose I can get involved in yet another web site/forum. I was hoping to avoid more screen time and spend more time on the machines.
Forums that I am passionate about tend to not so good me in for hours and hours to the point where I get little done from the perspective of making little metal chips.
I WAS told to 2 people that it IS possible to rewind the motor for single phase operation, though I have yet to get a price. Due to the very unusual dimensions of the Bridgeport J-head Mill motor, there are no direct, drop-in replacements available. I HAVE however considered machining an adapter or dummy motor so I an attach a standard frame 2hp, single phase motor, but figured I'd try the 'easy way out' by seeing what others have done first.
It appears the easiest way out is the VFD, but by how much should I 'oversize' the drive? As I recall the Bridgeport motor is 1 1/2hp, 220v, 3ph. I know static phase converters have a 'range' they can provide power for, outside that range and it doesn't work, or it burns up. Anyone know if the VFD is the same way? Can anyone direct me towards a reputable VFD brand? Searching around, there is a bewildering selection on "the big A" online, ALL from China. Makes the VFD cheap, but not to the point of being 'disposable', so I'd like to get this right on the first try if I go this route.
Oh, I looked into rotary phase converters, one sized for 1-3hp, 220v, 3ph motors will cost more than I paid for the Mill.
So yeah, they are expensive, and I got a great deal on the mill.
Thanks guys and gals,
M
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USA, RI, SK
sb327
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Real Name: David
Re: 3ph motors in a single phase shop
«
Reply #8 on:
November 17, 2022, 09:50:37 AM »
I have heard lots of decent results being had from the cheaper vfd offerings. I myself haven’t tried one.
When I got my Bridgeport (for cheap), it was missing the motor. I did a tm motor conversion by making a bracket. That’s been years ago and is still working fine. Plenty of power for things I do.
Good luck getting it sorted, Bridgeports are fantastic machines and rock solid. Congratulations on getting one.
Dave
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USA, OK, Stigler
Dave
Rob M
GTA Senior Contributor
Posts: 6308
Re: 3ph motors in a single phase shop
«
Reply #9 on:
November 17, 2022, 10:00:34 AM »
well , if the bridgeport is 1.5 hp thats 1118 watts , so youd likely want to be in the 1500-2000 watt range on the inverter. ( thats actual wattage written on the drive , theres been a few cases where people order 1500 watts then the label says 1200 w
«
Last Edit: November 17, 2022, 10:27:51 AM by Rob M
»
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Louisiana
KWK
Sharp Shooter
Posts: 590
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Real Name: Karl
Re: 3ph motors in a single phase shop
«
Reply #10 on:
November 17, 2022, 10:59:20 AM »
Do a search with "Practical Machinist" at the end of your inquiry. That usually works. There's been a lot of discussion on the subject.
This website is often useful as well.
https://bbs.homeshopmachinist.net
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USA, PA, Camp Hill
customcutter
GTA Senior Contributor
Posts: 2531
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Real Name: Ken
Re: 3ph motors in a single phase shop
«
Reply #11 on:
November 17, 2022, 11:16:13 AM »
I recently bought my second VFD for my 3ph mill. The first one was an older model when I bought it. The plastic finally broke down to the point that it was no longer useable. I would get a 2-3 HP VFD.
On my old surface grinder I converted a 3HP 3PH motor to a rotary to run a 1.5 HP motor. I had to wire in a starting capacitor to the third leg and an extra start switch. As soon as it starts up you turn off power to the extra starting capacitor. It puts out power on all 3 legs and the 3rd generated leg is slightly higher voltage IIRC. (It might be slightly lower voltage, not really sure. It's been 30 years since I built it. I got the plans from an electrical engineer where I worked a long time ago.) I had the motor so it cost me nothing to build, and worked great when I was using it. I used it to grind folding pocket knives to a known dimension, matching the thickness of titianium that I used when making the frames. Sorry I don't have the plans any longer, but you might find something with an internet search.
A VFD is probably cheapest and easiest. Good luck.
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Valrico, Fl
OTmachine
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Real Name: Keith
Re: 3ph motors in a single phase shop
«
Reply #12 on:
November 19, 2022, 02:47:32 AM »
If you were going to swap out the motor anyway, why not just buy a 3 hp rated vfd for $100 on Ebay. I have some of the Vevor brand that work good for me. Ran my son’s 3ph BP on a Vevor for 5 hours straight machine time doing a work project just to prove out the machine when I picked it up for him. Did some heavy hogging and had no problems. My son has a Teco on this BP now which works good. I usually go 2x the size of the motor. There are some single phase 1 hp BP motors out there, but usually pretty spendy. My .02
«
Last Edit: November 19, 2022, 02:59:00 AM by OTmachine
»
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USA, Central WI
scoutscope
Shooter
Posts: 36
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Real Name: Lee
Re: 3ph motors in a single phase shop
«
Reply #13 on:
November 19, 2022, 02:35:19 PM »
dealers electric.com That is where I got a motor and teco vfd for the price others were charging for the vfd. The motor is a onehp 3 phase motor that will work for my bport. The vfd converts singe phase to three phase and is doing well powering the original mill motor. I have had good luck with it and also the 2hp set I got for my 12x36 lathe. I used the motor as well as the vfd on the lathe and it is working well. I got a bit of programming support from vfd manufacturer. I think the vfd is a great option. Hobby-machinist.com forum helped me a lot on my first vfd conversion. I feel that a good name vfd is worth the investment. I'm also cheap and found a way to get a motor cheap or free in the bargain.
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Cameron, MO, USA
luge007
"What ever, just crash it!" (kid from 1980's Toyota Cienna crash testing commercial)
Plinker
Posts: 293
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Real Name: Matt
Re: 3ph motors in a single phase shop
«
Reply #14 on:
November 21, 2022, 06:57:08 AM »
Wow, thanks for all the input! Looks like I will try the VFD based on cost, space and effectiveness. My main concern was power. I know going with a 2-3hp rotary phase converter, I SHOULD get full power out of the Mill. However they are pretty expensive $300-$500 from what I've found poking around. I suppose I could try to find a used one, but then it's a gamble.
Going with the VFD, (from what I am seeing here), there should be no 'dip' in power as the load builds, up to 'normal' working parameters. Guess I will find out.
My second concern is 'over-sizing' since I was told by a machinist, that back when he ran a 'rotary' sizing was very important. Sizing too large apparently was not good for the unit. Sort of like running a diesel engine with no load, or something called 'wetstacking' for long periods of time resulting in damage. (also unconfirmed, just things I've heard over the years)
I dropped a phone call to a good friend of mine who's a master electrician with much more experience with VFD's and 3ph wiring than I have. It will be interesting to see what HE has to say, since this particular field is more or less his specialty.
(not sure why it took me so long to call him) I'll let you know what I find out after picking his brains.
Next step will be to log into Practical Machinist and poke around a bit.
Anyone else having experience with this topic, please feel free contribute. This thread will be around for a long time, so it may reduce the research time for others too.
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USA, RI, SK
Bubba18655
Plinker
Posts: 159
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Real Name: Jim
Re: 3ph motors in a single phase shop
«
Reply #15 on:
November 21, 2022, 10:21:47 AM »
Make sure to read the manual about opening a switch on the output of the VFD. Some models don't like to open circuit the motor leads. You might need to disable any switches on the mill or use it to control the VFD.
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USA, PA, Shickshinny
sicumj
Sharp Shooter
Posts: 533
Real Name: James
Re: 3ph motors in a single phase shop
«
Reply #16 on:
November 22, 2022, 03:07:25 PM »
I think 2hp single phase motors are around 175 bucks. That is what I would go with if you can find the right frame and shaft size.
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USA, OH, Shiloh
eeler1
Expert
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Real Name: Jon
Re: 3ph motors in a single phase shop
«
Reply #17 on:
November 22, 2022, 04:59:06 PM »
Maybe 10 years ago, so 'old tech' for nowadays. I put a Teco 1ph-to-3ph vfd on my 1&1/2hp (Baldor motor) Burke mill, and it worked great. These vfd's can do all kinds of fancy motor tricks, in fact a bit intimidating unless you intend to work on learning new vfd skills. But I really only wanted it so I could use the existing 3ph motor and have some speed change without having to change belts. I called the company and asked for the most bare-boned vfd that would work for me, didn't need all the bells and whistles, and they recommended a more basic (cheaper) model for me. Rotary phase converters might be more suitable if you had multiple 3ph machines, but for just one, I'd go vfd. Re-winding the motor seems like more work than buying a new 1ph motor and selling the old 3ph motor.
I also preferred keeping the 3ph motor as it MIGHT provide better surface finishes, although I've never done a side by side comparison. Something about the phases causing some small vibration or something. Maybe BS.
I'd contact one of the companies that supply these things and see if you can get a recommendation on a unit that isn't chock full of all them powerful new features that you'll never use. In summary; get a vfd and start making chips.
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West Sacramento, CA
luge007
"What ever, just crash it!" (kid from 1980's Toyota Cienna crash testing commercial)
Plinker
Posts: 293
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Real Name: Matt
Re: 3ph motors in a single phase shop
«
Reply #18 on:
November 22, 2022, 07:09:48 PM »
Well, I poked around on Practical Machinist having found it in a web search for "Bridgeport J Head, 3ph motor control" and found quite a bit of info about VFD's. Trying to search resulted in requiring registration, but by the time I got to the bottom of the next page, I had NO interest in joining. What a bunch of jerks! Some guy had inquired about "some unknown tooling" he'd acquired with a small lathe he's purchased and they chastised him, in more ways than one. First they for all intensive purposes 'yelled' at him for posting about a "hobby machine" in a "Pro machinist forum", when he asked for clarity, he was told to just stop posting, and one other guy told him to "not post stupid questions, read the book, 'how to run a lathe' by South Bend", before he comes back to ask anything. WOW, what an unfriendly lot! I am SO glad GTA is NOTHING like that and (for the most part) much more tolerant of complete noobs who might ask really ignorant questions. I mean everyone has to start somewhere, why the PM forum has to be so intolerant of the uneducated seems to be a colossal failure on their part. "machine snobs"?
I have had a discussion with my Master Electrician buddy with all the VFD knowledge one could ever hope for and he suggested an inexpensive VFD as well in the 1.5-2hp range. So I'll keep the factory 3ph motor, make a VFD mount, wire it up and see how it goes.
My next issue is if I should clean up and possibly rebuild my old machine since it's been sitting for a year, covered in a barn, and has a little surface rust and decades of grime; OR buy a mint used machine with a DRO already on it (that is 1 of 2 in a garage 7miles down the road) for under a grand, then sell my machine as a 'project' for someone cheap. Tough call, since the one I currently have actually has a power feed setup. Anyone need a Bridgeport 'clean-up project' for $500?
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USA, RI, SK
Bubba18655
Plinker
Posts: 159
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Real Name: Jim
Re: 3ph motors in a single phase shop
«
Reply #19 on:
November 22, 2022, 10:53:21 PM »
Try this site. It used t be a very friendly forum with a lot of information.
https://www.hobby-machinist.com/
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USA, PA, Shickshinny
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3ph motors in a single phase shop