Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Rewinding a motor stator

Got a bit tired of electronics and as my old hand drill, i only use for
counter-clockwise left-hand drilling, is playing up so I decided to give it
a birthday present of a new coil. It was supposed to be for 240V but running
off 110V via a variac was ok for my purposes, but now the part-bad coil was
causing too much variation and excess current/contact arcing for the ammeter
on the variac.
I removed the relatively blackened coil , that putting a meter over that
coil , in use, confirmed bad in comparison to the other. Cut through the
hank and counted turns , weighed the copper to .2 gm and measured the wire
diameter so I know how many turns and a good idea of the average diameter.
Does anyone know a formula for a better guide for setting up a 2-part former
( for removal) with the right dimensions, to wind a replacement before
squashing and placing in the channels with paper from an old high voltage
capacitor and then swathing in lacquer. Would laying a length of rubber cord
around the placement area inside the motor be a better idea for getting the
winding former dimensions. any other tips ?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/



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Default Rewinding a motor stator

N Cook wrote in message
...
Got a bit tired of electronics and as my old hand drill, i only use for
counter-clockwise left-hand drilling, is playing up so I decided to give

it
a birthday present of a new coil. It was supposed to be for 240V but

running
off 110V via a variac was ok for my purposes, but now the part-bad coil

was
causing too much variation and excess current/contact arcing for the

ammeter
on the variac.
I removed the relatively blackened coil , that putting a meter over that
coil , in use, confirmed bad in comparison to the other. Cut through the
hank and counted turns , weighed the copper to .2 gm and measured the wire
diameter so I know how many turns and a good idea of the average diameter.
Does anyone know a formula for a better guide for setting up a 2-part

former
( for removal) with the right dimensions, to wind a replacement before
squashing and placing in the channels with paper from an old high voltage
capacitor and then swathing in lacquer. Would laying a length of rubber

cord
around the placement area inside the motor be a better idea for getting

the
winding former dimensions. any other tips ?

found a useful table in a 70 year old book.
Wire qauges one way and columns of wires per sq in packing, weight per 100
yards and ohms per 1000 yds. So the former dimensions are determined

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/



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Default Rewinding a motor stator


"N Cook" wrote in message
...
N Cook wrote in message
...
Got a bit tired of electronics and as my old hand drill, i only use for
counter-clockwise left-hand drilling, is playing up so I decided to give

it
a birthday present of a new coil. It was supposed to be for 240V but

running
off 110V via a variac was ok for my purposes, but now the part-bad coil

was
causing too much variation and excess current/contact arcing for the

ammeter
on the variac.
I removed the relatively blackened coil , that putting a meter over that
coil , in use, confirmed bad in comparison to the other. Cut through the
hank and counted turns , weighed the copper to .2 gm and measured the
wire
diameter so I know how many turns and a good idea of the average
diameter.
Does anyone know a formula for a better guide for setting up a 2-part

former
( for removal) with the right dimensions, to wind a replacement before
squashing and placing in the channels with paper from an old high voltage
capacitor and then swathing in lacquer. Would laying a length of rubber

cord
around the placement area inside the motor be a better idea for getting

the
winding former dimensions. any other tips ?

found a useful table in a 70 year old book.
Wire qauges one way and columns of wires per sq in packing, weight per 100
yards and ohms per 1000 yds. So the former dimensions are determined

--


That's pretty cool, I've toyed with the idea of rewinding a motor like that
just for fun but never actually done it.


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Default Rewinding a motor stator

James Sweet wrote in message
news:tajci.19089$%M5.3755@trndny02...

"N Cook" wrote in message
...
N Cook wrote in message
...
Got a bit tired of electronics and as my old hand drill, i only use for
counter-clockwise left-hand drilling, is playing up so I decided to

give
it
a birthday present of a new coil. It was supposed to be for 240V but

running
off 110V via a variac was ok for my purposes, but now the part-bad coil

was
causing too much variation and excess current/contact arcing for the

ammeter
on the variac.
I removed the relatively blackened coil , that putting a meter over

that
coil , in use, confirmed bad in comparison to the other. Cut through

the
hank and counted turns , weighed the copper to .2 gm and measured the
wire
diameter so I know how many turns and a good idea of the average
diameter.
Does anyone know a formula for a better guide for setting up a 2-part

former
( for removal) with the right dimensions, to wind a replacement before
squashing and placing in the channels with paper from an old high

voltage
capacitor and then swathing in lacquer. Would laying a length of rubber

cord
around the placement area inside the motor be a better idea for getting

the
winding former dimensions. any other tips ?

found a useful table in a 70 year old book.
Wire qauges one way and columns of wires per sq in packing, weight per

100
yards and ohms per 1000 yds. So the former dimensions are determined

--


That's pretty cool, I've toyed with the idea of rewinding a motor like

that
just for fun but never actually done it.



Making up a former was easier than I thought.
The first thing to lay down is some loose loops of lacing cord, about 8
loops diametrically , 45 apart, around the former before winding the turns,
then cutting the cord into indivuidual loops and tying off after wire
winding and before removing. So the exact shape of the bulking of the wires
into a hank does not matter that much as the tying-off of the lacing cords
while still on the mandrel would form the cross-secion of the hank into a
circle. I will do the winding today. If it should be wrong in demensions ,
then I've a large drum of 29 SWG wire to have plenty of other attempts. As
always the winding on a coil winder takes no time at all, its the
preparation thats time consuming

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/


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Default Rewinding a motor stator

(via email response) For anyone else too embarrassed to ask on-thread why I
use left hand drill bits. This week an amp, as received from a well
respected UK maker, had a knob effectively seized on. The owner had never
touched them. The grub-screws were brass and overtightened so one nib of the
2 nibs, making a screwdriver blade slot, had broken off at assembly.

Tip
To free seized equipment knobs
For the situation where the knobs are seized onto the shaft by rusted
grub screws,especially where the screw penetrates the shaft;
after you have butchered the grub screw slot try this.
Make up some guide tubes,small enough to just slide into the hole
in the knob containing the grub screw,these tubes drilled on a lathe with
a clearance bore to take a drill bit. This drill bit usually needs to be
extended by brazing onto a longish rod (so the chuck of the
drill misses the face of the equipment).
Use some cutting oil and drill into the grub screw.
Ideally use left hand drill bits and left-handed power drill
rotation, such drill bits are available from specialist suppliers ,
other suppliers may kook at you as though you're trying to wind them up
(anti-clockwise).
To convert a right hand drill bit well enough for this use grind the
cutting face back on the opposite rake angle, swarf clearance
is not relevant here. Often the bite into the drill bit
into the screw or the localised vibration or heating is enough to
shift the screw.
Now use a small "easi out"(maybe this is a UK trade name),but consist
of a coarse left-handed cutting thread on a coarse taper.
Wind into the hole in the grub screw and hopefully extract.
If this fails repeat the first procedure with larger diameter drill bits
until nothing remains of the grub screw,retap a larger hole and use
a larger grub screw for knob reuse.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/





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Default Rewinding a motor stator

I thought that ovalling the axial parts to squash in the slots in the motor
core would be a problem but all went fine, though 7mm diameter when squashed
to a circle, rather than original about 6mm. The hank resistance of 7.1 ohm
compared to 7 ohm was good. I could not decide if the original was 29 or 30
swg but looks as though it was nearer 30 swg.
A rifenement is to lay a dowel or rod axial and outside the core to tie the
hank back to while pushing the axial sections into the core slots. The
overall circumference was too long so the ends of the hank overhanged at the
open ends too much. I will recalculate for 30 swg and have another go. There
was space in the housing to try out my effort so did have a go assembling
and running without lacquering in, and it worked fine.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/


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Default Rewinding a motor stator

"N Cook" writes:

I thought that ovalling the axial parts to squash in the slots in the motor
core would be a problem but all went fine, though 7mm diameter when squashed
to a circle, rather than original about 6mm. The hank resistance of 7.1 ohm
compared to 7 ohm was good. I could not decide if the original was 29 or 30
swg but looks as though it was nearer 30 swg.
A rifenement is to lay a dowel or rod axial and outside the core to tie the
hank back to while pushing the axial sections into the core slots. The
overall circumference was too long so the ends of the hank overhanged at the
open ends too much. I will recalculate for 30 swg and have another go. There
was space in the housing to try out my effort so did have a go assembling
and running without lacquering in, and it worked fine.


Out of curiosity, how much time have you spent reviving your $10US drill?

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
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Default Rewinding a motor stator

Sam Goldwasser wrote:
"N Cook" writes:


Snipped account of rewinding stator.

Out of curiosity, how much time have you spent reviving your $10US drill?


Ohhh - that`s not the point.. We Bwitish will spend forever trying to
keep our old tat working. It`s a national pastime

Ron(UK)
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Default Rewinding a motor stator

Sam Goldwasser wrote in message
...
"N Cook" writes:

I thought that ovalling the axial parts to squash in the slots in the

motor
core would be a problem but all went fine, though 7mm diameter when

squashed
to a circle, rather than original about 6mm. The hank resistance of 7.1

ohm
compared to 7 ohm was good. I could not decide if the original was 29 or

30
swg but looks as though it was nearer 30 swg.
A rifenement is to lay a dowel or rod axial and outside the core to tie

the
hank back to while pushing the axial sections into the core slots. The
overall circumference was too long so the ends of the hank overhanged at

the
open ends too much. I will recalculate for 30 swg and have another go.

There
was space in the housing to try out my effort so did have a go

assembling
and running without lacquering in, and it worked fine.


Out of curiosity, how much time have you spent reviving your $10US drill?



--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above

is
ignored unless my full name AND either lasers or electronics is included

in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.


A change is as good as a rest. I wouldn't take on someone elses motor of any
sort to repair.
I like to have an excuse to dig out my old coil winding machine that I
brought back to working order from a seized rusted mess combined with mice
nest that was in a leaky shed for decades.
I originally thought the hank lay up would have to be over a 2 part former
like a pulley split in two, the awkward way, but with a semicircular laying
up section. Then having to manually lay-up (as the auto traverse flip is
only per item , not per layer) something like 3 turns,6,9,12,14,16,17,18 and
down again to 3 for 190 turns. But I know now that a complicated former and
intricate lay-up is totally unnecessary.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/



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Default Rewinding a motor stator

I like to have an excuse to dig out my old coil winding machine that I
brought back to working order from a seized rusted mess combined with mice
nest that was in a leaky shed for decades.


That explains a great deal right there. Otherwise, motor rewinding is
a difficult and obscure art, at least for most of us. I've been
building electromagnets for demonstrations at the science museum, and
it doesn't take long for even the simplest coil to turn into a mighty
mess if you're not careful.

I have a vacuum pump that's essentially integral with its squirrel-
cage induction motor, and the stator overheats. The fellow at the
motor shop gave me some insane estimate of several hundred bucks to
rewind the thing; I'm ready to try it myself.

M Kinsler



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Default Rewinding a motor stator

m kinsler writes:

I like to have an excuse to dig out my old coil winding machine that I
brought back to working order from a seized rusted mess combined with mice
nest that was in a leaky shed for decades.


That explains a great deal right there. Otherwise, motor rewinding is
a difficult and obscure art, at least for most of us. I've been
building electromagnets for demonstrations at the science museum, and
it doesn't take long for even the simplest coil to turn into a mighty
mess if you're not careful.

I have a vacuum pump that's essentially integral with its squirrel-
cage induction motor, and the stator overheats. The fellow at the
motor shop gave me some insane estimate of several hundred bucks to
rewind the thing; I'm ready to try it myself.


That will likely not be fun, winding machine or not!

How badly/quickly does it overheat?

I assume you're sure it's set for the correct line voltage, if that's
changeable.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
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Default Rewinding a motor stator

m kinsler wrote in message
oups.com...
I like to have an excuse to dig out my old coil winding machine that I
brought back to working order from a seized rusted mess combined with

mice
nest that was in a leaky shed for decades.


That explains a great deal right there. Otherwise, motor rewinding is
a difficult and obscure art, at least for most of us. I've been
building electromagnets for demonstrations at the science museum, and
it doesn't take long for even the simplest coil to turn into a mighty
mess if you're not careful.

I have a vacuum pump that's essentially integral with its squirrel-
cage induction motor, and the stator overheats. The fellow at the
motor shop gave me some insane estimate of several hundred bucks to
rewind the thing; I'm ready to try it myself.

M Kinsler


If you can run it on reduced voltage with monitor lines added or probes to
the stators then the bad one will be substantially lower volts than the
other one. The hot coil may well be the ok one, being forced to take more
current along with the armature, i didn't think to check that and too late
now.

My second hank was too small and the third attempt was Goldilocks.
Waiting for the lacquer to harden and will reassemble tomorrow.
I will write it up with data , dimensions, handy hints discovered along the
way and a few pics and add it to
http://www.divdev.fsnet.co.uk/repair4.htm
probably tomorrow. It should give some idea of the dimensions for a similar
sized motor.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/


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Default Rewinding a motor stator


"Ron(UK)" wrote in message
...
Sam Goldwasser wrote:
"N Cook" writes:


Snipped account of rewinding stator.

Out of curiosity, how much time have you spent reviving your $10US drill?


Ohhh - that`s not the point.. We Bwitish will spend forever trying to keep
our old tat working. It`s a national pastime



It's not just you guys, I've done the same sort of thing on occasion. It's
not so much because it makes practical or economic sense as it is just
because it can be done.


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Default Rewinding a motor stator


"m kinsler" wrote in message
oups.com...
I like to have an excuse to dig out my old coil winding machine that I
brought back to working order from a seized rusted mess combined with
mice
nest that was in a leaky shed for decades.


That explains a great deal right there. Otherwise, motor rewinding is
a difficult and obscure art, at least for most of us. I've been
building electromagnets for demonstrations at the science museum, and
it doesn't take long for even the simplest coil to turn into a mighty
mess if you're not careful.

I have a vacuum pump that's essentially integral with its squirrel-
cage induction motor, and the stator overheats. The fellow at the
motor shop gave me some insane estimate of several hundred bucks to
rewind the thing; I'm ready to try it myself.

M Kinsler


You know, I borrowed a vacuum pump the first time I did some A/C work but I
later found I could buy new surplus rotary compressors designed for window
AC units for $5-$8 and they pull a stronger vacuum than the real vacuum pump
I had! Pegs the mechanical guage all the way down to 30 in/hg which is
plenty lots of things and the price is hard to beat.


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Default Rewinding a motor stator

About 3/4 down this file
http://www.divdev.fsnet.co.uk/repair4.htm
title
Stanley Bridges ? drill repair

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/


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