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Bridgeport Project

Bed isn't pristine but good enough for me!

PXL_20210609_223547430.jpg
 
architect said:
At the end of the day it won't be able to run after bearing replacement until I located a 220v motor.
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Me too. Keep me/us posted on your motor search. I'll do the same. Hopefully one of us can find a supply so we both win.

Never thought I would ever be so impatient. I can't wait to get at least one of mine working......

What are you looking for in a 220V motor? 1ph or 3phase? Hp?

What is in there now?

Are you considering a VFD?

So many questions! So much to learn!
 
Brent H said:
@Susquatch - you are not too far out of my way (I think). I have a trip to Brantford very soon and will be heading through the Hamilton area if you are having issues. Get a copy of that book on refurbishing a Bridgeport- lots of great info
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I'm about 4 hours West of Hamilton Brent.

Let me know if you ever head toward Windsor. I'm in farmland East of there.

Book was ordered yesterday. Got a copy of the older pulley version too for my Hartford.
 
Brent H said:
@Susquatch - for Ontario - you are close! LOL - I grew up in the Chatham area.
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Geeze..... every time you guys sling the names of places in Ont around, I have to go google them to figure out where you are talking about LOL. Remember the parts Utilathe pickup episode:D
 
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Mcgyver said:
For sure.....and you get a mill with new bearings. Is that a standard NEMA frame or something special? It might be worth comparing the the cost/bother of new motor or rewind option to to single phase step up transformer + a VFD. I did it on a smaller 440V lathe...worked really well and there usually seem to be some used single phase transformers kicking around on kijiji. Not saying its neccesarily the way to go, but worth consideration as an option.
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Can this be done the other way around? 220-1ph power to a 220 VFD to 220/440 transformer to 440-3ph motor? I know the VFD's like to feel the motor current flow to adjust their output, but I wonder if they can be bullied into just doing what they are told.

Wondering about it because I've seen lots of three phase 440 or 550 to 230 step-down transformers around. I think they should work fine stepping the voltage up too. But I know precious little about VFD's so I have no idea if that part would work. I have a call in to TECO about the standard application. Maybe I'll ask them about this too.
 
YYCHM said:
Geeze..... every time you guys sling the names of places in Ont around, I have to go google them to figure out where you are talking about LOL. Remember the parts Utilathe pickup episode:D
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Hey, I was born in Saskatchewan SW of Humboldt. I understand the difference you are talking about. You guys have sections and quarters out west. We farm teeny tiny gardens in acres here in the east.

But I think what is funnier is to draw a line of Latitude from Saskatoon to Ontario. Ontario has polar bears and no roads that far north! In fact the line of Latitude that defines the north border of California passes by just south of me.
 
Susquatch said:
Can this be done the other way around? 220-1ph power to a 220 VFD to 220/440 transformer to 440-3ph motor? I know the VFD's like to feel the motor current flow to adjust their output, but I wonder if they can be bullied into just doing what they are told.

Wondering about it because I've seen lots of three phase 440 or 550 to 230 step-down transformers around. I think they should work fine stepping the voltage up too. But I know precious little about VFD's so I have no idea if that part would work. I have a call in to TECO about the standard application. Maybe I'll ask them about this too.
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I know a certain amount about this, but you could quickly push me past my competence level, so don't view me as the electrical expert. :)

I would say its not a good idea. Transformers want a nice smooth sine wave to work well and the output from the VFD is not necessarily that. The transformer if hooked up properly should not have phase shift, but I'm unclear on how or if it might affect current sensing and its not going to do well with a square wave. There are lots of 3P transformers out there but they tend to be large, I'm not seeing a lot of advantages to this over using a 1P transformer before the VFD...they're not as plentiful used but they are out there and in my observation tend to be small and suited to a single machine application

The disadvantage of transformer then VFD is that I've not see in 600 or 440V the proliferation of cheap offshore VFD's like there is for 240V. Buying quality brand VFD's can be expensive, especially for larger motors. My big lathe is 7.5 HP 600V and one mill is 600 5HP....I'd love to convert everything to transformer -> VFD but the cost of VFD's for these larger motors is significant. So far, I've cheaped out and endure the drone of the RPC :)

The idea of running a step down in reverse for sure works - I do exactly that but with a RPC not a VFD. While it would be nice to convert everything to VFD over time, my main source of 3P is a 10hp homemade RPC. After the RPC, 240 3P goes to some machines, then I run 600 -240 3P step down in reverse to get 600V 3P for other machines
 
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Mcgyver said:
I know a certain amount about this, but you could quickly push me past my competence level, so don't view me as the electrical expert. :)

I would say its not a good idea. Transformers want a nice smooth sine wave to work well and the output from the VFD is not necessarily that. The transformer if hooked up properly should not have phase shift, but I'm unclear on how or if it might affect current sensing and its not going to do well with a square wave. There are lots of 3P transformers out there but they tend to be large, I'm not seeing a lot of advantages to this over using a 1P transformer before the VFD...they're not as plentiful used but they are out there and in my observation tend to be small and suited to a single machine application

The disadvantage of transformer then VFD is that I've not see in 600 or 440V the proliferation of cheap offshore VFD's like there is for 240V. Buying quality brand VDS can be expensive, especially for larger motors. My big lathe is 7.5 HP 600V and one mill is 600 5HP....I'd love to convert everything to transformer -> VFD but the cost of VFD's for these larger motors is significant. So far, I've cheaped out and endure the drone of the RPC :)

The idea of running a step down in reverse for sure works - I do exactly that but with a RPC not a VFD. While it would be nice to convert everything to VFD over time, my main source of 3P is a 10hp homemade RPC. After the RPC, 240 3P goes to some machines, then I run 600 -240 3P step down in reverse to get 600V 3P for other machines
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As I've said before, I'm no expert either. But I do know enough to have a pretty darn good idea of how much I don't know!

I'm not so sure that transformers like nice clean sine waves on their inputs. I think it's more like they like to PRODUCE nice clean waves on their outputs. They act a lot like big inductors (because they are coils), so they naturally smooth out signal chops and noise. I've even deliberately used transformers for that purpose in high frequency applications.

Anyway, after reading what you all have to do in your shop, I find myself thinking that I worry too much about keeping everything common in my shop. I have very little to worry about compared to you. My needs are minimal. Sure, I'd like to have lower speed available on my lathe, and I'd like all my power to be the same and available on the wall, and I'd like to minimize any conversion stuff, etc etc. But all in all my needs are simple compared to yours. A little conversion hardware here and there isn't really a big deal in the big picture.

I love old sayings. The one that comes to mind right now is: "Never let perfection be the enemy of the good."

I think I should just get on with getting a 230V 3phase motor for the Hartford, a 230V 1PH-3PH VFD for both mills, and be happy.
 
I know the basic affects of an inductor, but I thought the challenges were more due to the core - efficiencies, current draw, saturation etc. With a square wave you've got for a moment got DC going in..but I'm 100% prepared to be wrong and will leave it to others who know more about it.

Might be worth an experiment if you've got a 3P transformer? Done safely off course....no second changes with 600V

I like VFD power not for speed control (its the poor cousin of a manual transmission) but for convernience. Its silent and I don't have do gymnastic moves to get across the crowded shop to turn the RPC on. I'd say for sure if you were using a VFD for speed control with a transformer between motor and VFD you'd have issues as a drop or rise in frequencing can really effect the transformer's abilities/performance
 
YYCHM said:
Geeze..... every time you guys sling the names of places in Ont around, I have to go google them to figure out where you are talking about LOL. Remember the parts Utilathe pickup episode:D
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I’m surprised someone of your....generation....doesn’t have an atlas. Heck I even have a road map for Regina :D
 
Mcgyver said:
I know the basic affects of an inductor, but I thought the challenges were more due to the core - efficiencies, current draw, saturation etc. With a square wave you've got for a moment got DC going in..but I'm 100% prepared to be wrong and will leave it to others who know more about it.

Might be worth an experiment if you've got a 3P transformer? Done safely off course....no second changes with 600V

I like VFD power not for speed control (its the poor cousin of a manual transmission) but for convernience. Its silent and I don't have do gymnastic moves to get across the crowded shop to turn the RPC on. I'd say for sure if you were using a VFD for speed control with a transformer between motor and VFD you'd have issues as a drop or rise in frequencing can really effect the transformer's abilities/performance
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Hey, I wasn't pretending to be an expert either! Just reacting with an off the cuff thought about whether transformers need clean sinusoidal inputs. I question things like that a lot and I dream up unconventional ways to do things. It's the way I'm wired...... Lol!

An experiment would be fun. In my younger days I would have eagerly, and perhaps foolishly, taken that on. But it would be better done by a real expert. I gotta try and stay focussed on a direct affordable path to a working mill.

Thanks for taking the time to respond to my crazy thinking.
 
Here's the problem in using a transformer between the VFD and the motor: The VFD senses instantaneous current and back EMF to run the motor in Sensorless Vector mode, which is preferred on a milling machine. SV mode allows the motor to develop better torque at slow speeds by doing these measurements.

The downside of SV mode is that even leads to the motor longer than 2m can seriously affect the sensing required to do the job.

So putting a transformer between the motor and the VFD will completely screw up the SV mode. Check with the TECO/Westinghous folks, but I'm pretty sure that they will tell you the same story.
 
Dabbler said:
Here's the problem in using a transformer between the VFD and the motor: The VFD senses instantaneous current and back EMF to run the motor in Sensorless Vector mode, which is preferred on a milling machine. SV mode allows the motor to develop better torque at slow speeds by doing these measurements.

The downside of SV mode is that even leads to the motor longer than 2m can seriously affect the sensing required to do the job.

So putting a transformer between the motor and the VFD will completely screw up the SV mode. Check with the TECO/Westinghous folks, but I'm pretty sure that they will tell you the same story.
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They say that "Necessity is the mother of invention". At the time that I posed the question, I had not found a single phase to 3-phase step-up VFD. My post was about exploring that idea. My initial words were "...I know that VFD's like to feel the motor current flow to adjust their output, but I wonder if they can be bullied into just doing what they are told." My question was about creating 3ph 400 from 1phase 220 without a Rotary Converter. In any event, the need is moot now that I see that ATO makes a relatively low cost inverter that does this natively.

I also regret selfishly hi-jacking this thread to satisfy my out of control curiosity. My apologies to the OP.
 
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