Hi all,

When I bought my second hand watchmaker's lathe years back I got a small Russian motor with it. It turned out to be a three phase induction motor with six leads wired in a single-phase 240V configuration with start capacitor. There was no obvious speed control possible, so I used a sewing machine motor instead to run the lathe.

A while ago I bought a cheapie Chinese VFD to see if I could use the Russian motor instead. I configured the 6 leads in delta configuration after figuring out what the coil wire pairs were. There was no marking on the wires other than C1 to C6, so I had to guess (and test) the coil polarities.

Some pictures are he https://www.dropbox.com/sc/d8czpdqcvf9x0gn/HE0rbKAkgi

My problem now is that the motor seems to run well and reacts to frequency changes well, but I can stop the pulley by hand with not much finger pressure. I would have expected friction burns and lost fingerprints when doing that..

The WW lathe doesn't need much torque, but surely this motor should be more powerful than a lousy sewing machine motor? I can barely use the lathe as is, it slows down too much or stalls when applying graver pressure, especially if I use the smaller spindle pulleys.

I don't have another motor to test with. Reconfiguring the wiring (swapping coil polarities, or the three delta leads) all lead to even worse performance.

There seems to be no obvious way to open the thing. The only screws besides the mounting ones are to keep a bearing cap in place. I wanted to look inside to see how many poles there are.

Does anyone have any idea what could cause the poor torque? Or am I just expecting too much of it?

Cheers,

Rob

On Mon, 25 Nov 2013 21:13:33 -0800 (PST), teegee
wrote:

Hi all,

When I bought my second hand watchmaker's lathe years back I got a small Russian motor with it. It turned out to be a three phase induction motor with six leads wired in a single-phase 240V configuration with start capacitor. There was no obvious speed control possible, so I used a sewing machine motor instead to run the lathe.

A while ago I bought a cheapie Chinese VFD to see if I could use the Russian motor instead. I configured the 6 leads in delta configuration after figuring out what the coil wire pairs were. There was no marking on the wires other than C1 to C6, so I had to guess (and test) the coil polarities.

Some pictures are he https://www.dropbox.com/sc/d8czpdqcvf9x0gn/HE0rbKAkgi

My problem now is that the motor seems to run well and reacts to frequency changes well, but I can stop the pulley by hand with not much finger pressure. I would have expected friction burns and lost fingerprints when doing that..

The WW lathe doesn't need much torque, but surely this motor should be more powerful than a lousy sewing machine motor? I can barely use the lathe as is, it slows down too much or stalls when applying graver pressure, especially if I use the smaller spindle pulleys.

I don't have another motor to test with. Reconfiguring the wiring (swapping coil polarities, or the three delta leads) all lead to even worse performance.

There seems to be no obvious way to open the thing. The only screws besides the mounting ones are to keep a bearing cap in place. I wanted to look inside to see how many poles there are.

Does anyone have any idea what could cause the poor torque? Or am I just expecting too much of it?

Cheers,

Rob

Are you sure its not a two speed motor? A winding for each speed?

And it is Russian...shrug


__
"A human being should be able to change a diaper, plan an invasion,
butcher a hog, conn a ship, design a building, write a sonnet,
balance accounts, build a wall, set a bone, comfort the dying,
take orders, give orders, cooperate, act alone, solve equations,
analyze a new problem, pitch manure, program a computer,
cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects."
- Heinlein

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This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

"teegee" wrote in message
...
Hi all,

When I bought my second hand watchmaker's lathe years back I got a
small Russian motor with it. It turned out to be a three phase
induction motor with six leads wired in a single-phase 240V
configuration with start capacitor. There was no obvious speed control
possible, so I used a sewing machine motor instead to run the lathe.

A while ago I bought a cheapie Chinese VFD to see if I could use the
Russian motor instead. I configured the 6 leads in delta configuration
after figuring out what the coil wire pairs were. There was no marking
on the wires other than C1 to C6, so I had to guess (and test) the
coil polarities.

Some pictures are he
https://www.dropbox.com/sc/d8czpdqcvf9x0gn/HE0rbKAkgi

My problem now is that the motor seems to run well and reacts to
frequency changes well, but I can stop the pulley by hand with not
much finger pressure. I would have expected friction burns and lost
fingerprints when doing that..

The WW lathe doesn't need much torque, but surely this motor should be
more powerful than a lousy sewing machine motor? I can barely use the
lathe as is, it slows down too much or stalls when applying graver
pressure, especially if I use the smaller spindle pulleys.

I don't have another motor to test with. Reconfiguring the wiring
(swapping coil polarities, or the three delta leads) all lead to even
worse performance.

There seems to be no obvious way to open the thing. The only screws
besides the mounting ones are to keep a bearing cap in place. I wanted
to look inside to see how many poles there are.

Does anyone have any idea what could cause the poor torque? Or am I
just expecting too much of it?

Cheers,

Rob
============

Can you measure the three motor currents?
jsw

On Monday, November 25, 2013 11:13:33 PM UTC-6, teegee wrote:
Hi all,



When I bought my second hand watchmaker's lathe years back I got a small Russian motor with it. It turned out to be a three phase induction motor with six leads wired in a single-phase 240V configuration with start capacitor. There was no obvious speed control possible, so I used a sewing machine motor instead to run the lathe.



A while ago I bought a cheapie Chinese VFD to see if I could use the Russian motor instead. I configured the 6 leads in delta configuration after figuring out what the coil wire pairs were. There was no marking on the wires other than C1 to C6, so I had to guess (and test) the coil polarities.



Some pictures are he https://www.dropbox.com/sc/d8czpdqcvf9x0gn/HE0rbKAkgi



My problem now is that the motor seems to run well and reacts to frequency changes well, but I can stop the pulley by hand with not much finger pressure. I would have expected friction burns and lost fingerprints when doing that..



The WW lathe doesn't need much torque, but surely this motor should be more powerful than a lousy sewing machine motor? I can barely use the lathe as is, it slows down too much or stalls when applying graver pressure, especially if I use the smaller spindle pulleys.



I don't have another motor to test with. Reconfiguring the wiring (swapping coil polarities, or the three delta leads) all lead to even worse performance.



There seems to be no obvious way to open the thing. The only screws besides the mounting ones are to keep a bearing cap in place. I wanted to look inside to see how many poles there are.



Does anyone have any idea what could cause the poor torque? Or am I just expecting too much of it?



Cheers,



Rob

How slow are you trying to run the motor? I purchased one of these cheap (and junk) VFDs, at slow speeds, I could stall the motor out with hand force, and I was playing with a 4HP 3Kw motor and VFD. By slow I'm talking less then 5Hz VFD output. These are not vector drive VFDs, which would drive high torque smoothly at very low Hz output.
Your description makes me think the end housings are spot welded directly to the motor laminations. (sorry, but dropbox requires sign in, so consider this unviewable).
I'm surprised the motor is delta, I assume you ohmed it out and did not find a common Y connection, but 6 isolated windings. Is there 12 terminations?
Sorry I can't be more help.

On Tuesday, November 26, 2013 9:49:11 PM UTC+8, Jim Wilkins wrote:

Can you measure the three motor currents?


I haven't done that, but the VFD display registers 200 mA at most, for the 220V motor. I assume that is some average of all three currents..

- Rob

Hi Fred,

On Wednesday, November 27, 2013 8:23:07 AM UTC+8, fred hababorbitz wrote:
How slow are you trying to run the motor? I purchased one of these cheap (and junk) VFDs, at slow speeds, I could stall the motor out with hand force, and I was playing with a 4HP 3Kw motor and VFD. By slow I'm talking less then 5Hz VFD output. These are not vector drive VFDs, which would drive high torque smoothly at very low Hz output.

I don't need to run it that slow. The torque is bad at higher speeds too.. My VFD is 1.5kW (Huanyang HY02D223B).

Your description makes me think the end housings are spot welded directly to the motor laminations. (sorry, but dropbox requires sign in, so consider this unviewable).

It does? That's odd, it works for me in a different browser, no need to login. Not sure what's going on here..

I'm surprised the motor is delta, I assume you ohmed it out and did not find a common Y connection, but 6 isolated windings. Is there 12 terminations?

I just wired it delta, instead of star (as per http://home.solcon.nl/gjkool/brushlessE5.html, for example). There's three coils, six leads. Total newbie when it comes to three-phase, as may have been obvious

- Rob

On Mon, 25 Nov 2013 21:13:33 -0800 (PST), teegee
wrote:

Hi all,

When I bought my second hand watchmaker's lathe years back I got a small Russian motor with it. It turned out to be a three phase induction motor with six leads wired in a single-phase 240V configuration with start capacitor. There was no obvious speed control possible, so I used a sewing machine motor instead to run the lathe.

A while ago I bought a cheapie Chinese VFD to see if I could use the Russian motor instead. I configured the 6 leads in delta configuration after figuring out what the coil wire pairs were. There was no marking on the wires other than C1 to C6, so I had to guess (and test) the coil polarities.

Some pictures are he https://www.dropbox.com/sc/d8czpdqcvf9x0gn/HE0rbKAkgi

My problem now is that the motor seems to run well and reacts to frequency changes well, but I can stop the pulley by hand with not much finger pressure. I would have expected friction burns and lost fingerprints when doing that..

The WW lathe doesn't need much torque, but surely this motor should be more powerful than a lousy sewing machine motor? I can barely use the lathe as is, it slows down too much or stalls when applying graver pressure, especially if I use the smaller spindle pulleys.

I don't have another motor to test with. Reconfiguring the wiring (swapping coil polarities, or the three delta leads) all lead to even worse performance.

There seems to be no obvious way to open the thing. The only screws besides the mounting ones are to keep a bearing cap in place. I wanted to look inside to see how many poles there are.

Does anyone have any idea what could cause the poor torque? Or am I just expecting too much of it?

Cheers,

Rob

just a tghought. You might have it wired with 2 coils turning it one
way the other coil backwards trying to turn it the other way. Post a
list of what wires you have connected to what. I think you will have
to try trial and error to see what happens, unless you can get it
apart and see the direction each coil is wound.

I had a friend buy a 15hp compressor that was 440 volt. He took it up
to a motor shop and they cut the windings and broughht out the leads
so he could do high or low volts. They mis-labeled them and had 3
windings CW and 3 CCW. he blew the fuse on the telephone pole. He
took it back they re-labeled the leads and and said, opps....sorry.

Remove 333 to reply.
Randy

Super low torque from an otherwise good motor may be a sign that the
motor is wired for higher voltage. Say, a 440v motor will run from
220v, but with a lot less torque. Maybe the Russian motor is wired for
380 volts?

i

On 2013-11-27, Randy333 wrote:
On Mon, 25 Nov 2013 21:13:33 -0800 (PST), teegee
wrote:

Hi all,

When I bought my second hand watchmaker's lathe years back I got a small Russian motor with it. It turned out to be a three phase induction motor with six leads wired in a single-phase 240V configuration with start capacitor. There was no obvious speed control possible, so I used a sewing machine motor instead to run the lathe.

A while ago I bought a cheapie Chinese VFD to see if I could use the Russian motor instead. I configured the 6 leads in delta configuration after figuring out what the coil wire pairs were. There was no marking on the wires other than C1 to C6, so I had to guess (and test) the coil polarities.

Some pictures are he https://www.dropbox.com/sc/d8czpdqcvf9x0gn/HE0rbKAkgi

My problem now is that the motor seems to run well and reacts to frequency changes well, but I can stop the pulley by hand with not much finger pressure. I would have expected friction burns and lost fingerprints when doing that..

The WW lathe doesn't need much torque, but surely this motor should be more powerful than a lousy sewing machine motor? I can barely use the lathe as is, it slows down too much or stalls when applying graver pressure, especially if I use the smaller spindle pulleys.

I don't have another motor to test with. Reconfiguring the wiring (swapping coil polarities, or the three delta leads) all lead to even worse performance.

There seems to be no obvious way to open the thing. The only screws besides the mounting ones are to keep a bearing cap in place. I wanted to look inside to see how many poles there are.

Does anyone have any idea what could cause the poor torque? Or am I just expecting too much of it?


just a tghought. You might have it wired with 2 coils turning it one
way the other coil backwards trying to turn it the other way. Post a
list of what wires you have connected to what. I think you will have
to try trial and error to see what happens, unless you can get it
apart and see the direction each coil is wound.

I had a friend buy a 15hp compressor that was 440 volt. He took it up
to a motor shop and they cut the windings and broughht out the leads
so he could do high or low volts. They mis-labeled them and had 3
windings CW and 3 CCW. he blew the fuse on the telephone pole. He
took it back they re-labeled the leads and and said, opps....sorry.

Remove 333 to reply.
Randy

"teegee" wrote in message
...
On Tuesday, November 26, 2013 9:49:11 PM UTC+8, Jim Wilkins wrote:

Can you measure the three motor currents?


I haven't done that, but the VFD display registers 200 mA at most,
for the 220V motor. I assume that is some average of all three
currents..

- Rob

If you suspect a problem, checking for unequal phase currents with a
clamp-on ammeter is an easy, nonintrusive test. I like to begin
troubleshooting with simple tests that blame or absolve large parts of
the system.

On Mon, 25 Nov 2013 21:13:33 -0800 (PST), teegee
wrote:

Hi all,

When I bought my second hand watchmaker's lathe years back I got a small Russian motor with it. It turned out to be a three phase induction motor with six leads wired in a single-phase 240V configuration with start capacitor. There was no obvious speed control possible, so I used a sewing machine motor instead to run the lathe.

A while ago I bought a cheapie Chinese VFD to see if I could use the Russian motor instead. I configured the 6 leads in delta configuration after figuring out what the coil wire pairs were. There was no marking on the wires other than C1 to C6, so I had to guess (and test) the coil polarities.

Some pictures are he https://www.dropbox.com/sc/d8czpdqcvf9x0gn/HE0rbKAkgi

My problem now is that the motor seems to run well and reacts to frequency changes well, but I can stop the pulley by hand with not much finger pressure. I would have expected friction burns and lost fingerprints when doing that..

The WW lathe doesn't need much torque, but surely this motor should be more powerful than a lousy sewing machine motor? I can barely use the lathe as is, it slows down too much or stalls when applying graver pressure, especially if I use the smaller spindle pulleys.

I don't have another motor to test with. Reconfiguring the wiring (swapping coil polarities, or the three delta leads) all lead to even worse performance.

There seems to be no obvious way to open the thing. The only screws besides the mounting ones are to keep a bearing cap in place. I wanted to look inside to see how many poles there are.

Does anyone have any idea what could cause the poor torque? Or am I just expecting too much of it?

I would get a known good Inverter Duty 3-phase motor and hook it up.
Try it again and see what happens. 1/4 HP and lower are available -
you can go a bit bigger on the motor than the lathe maker calls for,
as long as you've got a shear pin in the geartrain in case you crash
it real good.

Sewing machine motors are even worse, that's got to be down in the
1/30th HP or lower.

I'll betcha the Russian motor is a pile of borscht and that's all
that's wrong with the setup. Was it actually marked 3-Phase, or does
it have a centrifugal Start switch inside? It might be a Single Phase
Capacitor Start, and the centrifugal kicks out the capacitor after
starting.

Though the next time you're tempted to test a motor for stall torque
Do Not grab the pulley - you can lose fingers that way. Gloves,
Goggles, and anchor one end of a hemp or coir natural fiber rope, and
loop it around the pulley like you're using it as a windlass drum. You
can adjust the drag that way.

Oh, and have a bucket of water handy to put out the rope if you test
it too hard.

On Thu, 28 Nov 2013 11:16:15 -0800, "Bruce L. Bergman (munged human
readable)" wrote:


Though the next time you're tempted to test a motor for stall torque
Do Not grab the pulley - you can lose fingers that way. Gloves,
Goggles, and anchor one end of a hemp or coir natural fiber rope, and
loop it around the pulley like you're using it as a windlass drum. You
can adjust the drag that way.

Oh, and have a bucket of water handy to put out the rope if you test
it too hard.


a squirt bottle like a window cleaning bottle works fine for those
small somewhat expected rope issues. However...do NOT use one that
contains WD-40! The expected becomes very much unexpected if that is
used. Truely.


__
"A human being should be able to change a diaper, plan an invasion,
butcher a hog, conn a ship, design a building, write a sonnet,
balance accounts, build a wall, set a bone, comfort the dying,
take orders, give orders, cooperate, act alone, solve equations,
analyze a new problem, pitch manure, program a computer,
cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects."
- Heinlein

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This email is free from viruses and malware because avast! Antivirus protection is active.
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On Thu, 28 Nov 2013 13:11:04 -0800, Gunner Asch
wrote:

On Thu, 28 Nov 2013 11:16:15 -0800, "Bruce L. Bergman (munged human
readable)" wrote:


Though the next time you're tempted to test a motor for stall torque
Do Not grab the pulley - you can lose fingers that way. Gloves,
Goggles, and anchor one end of a hemp or coir natural fiber rope, and
loop it around the pulley like you're using it as a windlass drum. You
can adjust the drag that way.

Oh, and have a bucket of water handy to put out the rope if you test
it too hard.


a squirt bottle like a window cleaning bottle works fine for those
small somewhat expected rope issues. However...do NOT use one that
contains WD-40! The expected becomes very much unexpected if that is
used. Truely.

Don't use WD-40 to clean the brushhes/comutator on an el-cheapo
weed-wacker while it is running either! DAMHIKT
Isopropyl Alcohol would probably work better butbe satisfied to turn
it by hand and let it thoroughly dry before applying power.
---

Gerry :-)}
London,Canada