# pancake generator rewind



## backstay (Feb 3, 2011)

I have only watched an electrician build coils, form them and install. That was after he cooked the motor to be able to remove the old windings. I think it is beyond the inexperienced.


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## SWDweller (Dec 9, 2020)

I worked in a company that had a motor rewind division. Those guys knew far more than I did about the hows and whys. Then there was the bake and dip tank. Baking to remove windings and dipping for keeping everything where is was supposed to be.
New bearings, brushes and warrantee would have me going the replacement route.


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## 460 Delta (May 9, 2018)

Watch this.


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## splatz (May 23, 2015)

460 Delta said:


> Watch this.


Then show your wife this video, if the Chinese girl can do it in a 24 minute video, what's her excuse?


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## 460 Delta (May 9, 2018)

splatz said:


> Then show your wife this video, if the Chinese girl can do it in a 24 minute video, what's her excuse?


The coil winder we were going to get off of Craigslist was snagged an hour before we could get there. 

I was pretty sad about that.


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## Almost Retired (Sep 14, 2021)

460 Delta said:


> Watch this.


that aint her first rodeo ....


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## gpop (May 14, 2018)

SWDweller said:


> I worked in a company that had a motor rewind division. Those guys knew far more than I did about the hows and whys. Then there was the bake and dip tank. Baking to remove windings and dipping for keeping everything where is was supposed to be.
> New bearings, brushes and warrantee would have me going the replacement route.


This one is brush less and has the exciter coil built into the main winding's. I think there was a short between these winding's due to it being overloaded so it got upset during a live rotor flash and let out the magic smoke. 
I understand the basics but have never tried anything like this as i did not know where to buy the parts. On a good note the winding's are less than 6" long so i figure i can skip the baking stage.

worst case is $150 bucks wasted and a $1600 generator head that still needs to be replaced. (no trade in value)


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## CMP (Oct 30, 2019)

I think I missed the barnyard dip and bake portion. As well as the blasting mask. But A for effort.


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## John Valdes (May 17, 2007)

backstay said:


> I have only watched an electrician build coils, form them and install. That was after he cooked the motor to be able to remove the old windings. I think it is beyond the inexperienced.


I agree. If he has not done this work before I would not expect success. Secondly does he have the materials and tools to do this job? Buy a new coil if possible.


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## Signal1 (Feb 10, 2016)

I'd marry her.


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## gpop (May 14, 2018)

John Valdes said:


> I agree. If he has not done this work before I would not expect success. Secondly does he have the materials and tools to do this job? Buy a new coil if possible.



No idea what im doing but unfortunately my old man never taught me how to quit until i failed or f-ed it to a point that it can never be fixed. 

Got the head in the shop and broke down the leads. Worked out the winding pattern and now im cutting out the winding's and cleaning out the slots. I give it about a 25% chance of success at this point. 
Don't really need a lot of tools and amazon sells all the parts required to rebuild it which is 20% of the 25% covered. On a good note i did not need to burn it out as the generator kindly did that for me so its coming to bits with out to much of a fight.


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## Almost Retired (Sep 14, 2021)

i could be showing lack of "paying attention" or lack of "intelligence" ...
but it seems to me that there were only a very few things that were super critical
and none of it was complicated
size of the loop, slots to skip per loop, number of strands in the loop, connecting each loop, connecting the pecker head leads with numbers
the rest of it did not require "electrical" skills


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## Almost Retired (Sep 14, 2021)

Signal1 said:


> I'd marry her.


I like that she comes to work in full makeup, and manicured nails LOL
apparently she can build a house, and restore a lathe as well !!!


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## gpop (May 14, 2018)

Got the case clear now ive just got to find the micrometer that's somewhere in the shop and work out the gauge and the rough length's as im going to have to run the main in groups of 5. 

On a good note we were chatting at work about this dumb idea and someone said they have a junk one laying in the yard. No idea what condition its in but they will bring the stator in tomorrow to see if its the same size. Might get lucky if its the correct size and tests good.


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## mburtis (Sep 1, 2018)

Rewinding is something I've always wanted to try. Post pictures of you give it a shot.


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## MotoGP1199 (Aug 11, 2014)

I have confidence that you can do it with lots of time invested if you have all the data you need. First try, fifth try, whatever. This is how I learn. Please post pictures


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## paulengr (Oct 8, 2017)

gpop said:


> I burnt up the stator on my diesel generator so i wondering if its possible for someone with no experience to rewind one. Basically its broke and as a professional rewind cost about the same as a new replacement so its fix or trash it.
> 
> They sell the wire, nomex paper and varnish so that's part of the battle. Anyone tried anything like this just for the experience.
> 
> If anyone has a winding diagram for a marathon 6kw capacitor regulated pancake that would be helpful so i can check that against what i find when i tear that connection end to pieces.


It is possible but winding is definitely a skill, not something you can learn off YouTube. There are lots of issues though. EASA has all the connection diagrams. But you have to buy a membership. That’s why most shops pay for it. You can theoretically carefully disassemble though, check wire gauges, etc.

If it’s aluminum heat to 650 for 8 hours. If steel 750. Not sure how you have an oven for this. Warning! During burnout at some point most motors ignite. At that point you frequently need to cool it down ASAP. Burnout ovens have water sprays. Doing it by hand might need to watch it the whole time and open doors and have a hose ready if it flashes. Since you don’t have a core lilies machine do a growler test. It’s old school but works just as well for checking the core for damage. On a modern motor if you go old school on it with a rosebud or a weed burner to burn out the varnish you will damage the laminations beyond repair. The core steel is much more thin than 40 years ago.

Winding just requires patience, skill, and good plastic hammers. What you have is random wound. On those we prewind the required turns on a machine but you can just wind on a core then temporarily tape everything together and pound it in. Make sure the coils are absolutely straight before starting. The copper density is so high now that you can’t do it by hand.

In terms of varnish you need to get every little area varnished. It’s simply impossible to just brush on. And we really almost never use varnish. It’s almost always epoxy now. You need to soak it. Motor shops use a VPI tank but you only need VPI itself for medium voltage. You can probably use a drum or bucket do achieve the same thing. Agitate until there are no bubbles at all, not even one.

Then bake out. The temperature profile comes from the epoxy/varnish manufacturer.

IF you can do all that and have the equipment sure you can rewind yourself. Modern motors though just aren’t something you rewind. Generally anything under 25-50 HP is not worth the money unless it’s something very specialty. We don’t even rewind exciter coils.


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## gpop (May 14, 2018)

after removing the light ballasts that will not be re-used. You can spot what they did with the main breaker which explains how they overloaded the generator and burnt the head










Stator pulled. rotor seems to test good but it will be double checked 











cap controlled field coil in the stator as this is brushless










stator as found










breaking the leads free after cutting the string











Field coils are on top so breaking them free to find out wind rotation and connections









Main coils broken free and the jumper between coils marked, Piece of wood is in a empty slot and was used to mark slot one as this involved a lot of counting. If i ever done this again a yellow paint pen is a must to number the slots










Did not take pics as it was dirty job stripping the coils. Basically cut close to the motor frame with a grinder then gently tapped the fiberglass pieces out on the main coil where they were not to tight and removed a couple of strands. Like conduit once you get a few wires out the rest can be pulled as a bundle. (does leave the winding paper in the slot but that can be dealt with later)

Field coils are a lot tighter as they are a bigger gauge so block of wood and a hammer gets them to move. Must admit it was hard work and my girly hand hurt as i started with nippers cutting the wires so i could count them. Once i figured out the pattern using a grinder was a lot less work.


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## Almost Retired (Sep 14, 2021)

keep going, you are about to catch the girl in the video !!
she did it with clean designer coveralls, full makeup, perfect hair, and manicured nails !
LOL


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## gpop (May 14, 2018)

Mate dropped off the gen head he had laying around and its a different size so im carrying on with the rewind.










Ordered all the wire and parts i think i need to assemble this thing which came to just over 200 so this is going to be a expensive can of magic smoke. I have also cleaned up the slots.

Still trying to figure out how to wind the loops as i need 12 loops (of 5 wires) with different spaces between them wound in one go. Don't think your allowed to wind it directly into the case as that would leave twists in the end loops. Oh well got a week to figure it out and come up with a red-neck solution


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## gpop (May 14, 2018)

Got the wire so set up to wind this thing













One set in and starting on the second set of power windings











Ok that went well. Looks like it was rolled on the inner thigh of the virgin mary











seems a shame that i may not have left enough room to get this hunk of junk called the field wiring in the slots











wife says i need a swear jar after getting 2 of the field wire in place so i will have enough money to buy a new genny head

odd of success is now at 18%


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## joe-nwt (Mar 28, 2019)

I don't care what the others say, I'm giving you an "A" for effort!  It looks pretty good in the pictures, hope you fit the field windings in there.


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## micromind (Aug 11, 2007)

Ball-peen hammer......use the round end, not the flat end.........lol.


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## nrp3 (Jan 24, 2009)

I just sold another rotor/stator/VR/brush replacement like all the rest that have failed. So much easier. That said, I give you tons of credit for trying this. I'm too lazy, stupid, impatient, insert another excuse, comment, etc.


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## gpop (May 14, 2018)

I don't need a generator at the moment so this is me playing with something that's broken. 

Option 2 is a 11kw honda genny head i have had in the shed for the last year that need a adapter to make it 2 bearing so i can add a belt drive. Its 3600 rpm and the engines 1800 but can be opened up to 2200 for the extra hp required. 
So i bought a lathe with a bad motor last weekend then blow a ball getting that 1200lb beast into the shed. Got a drive and bought a 1.5hp 3ph motor from a guy off face book for $75 and with a little mod to the mod's that were all ready done to the drive system it should be good to go. I need to cut a tapered shaft using a thing called a drive dog and that looks scary as hell.
I shall watch a few you-tube videos and figure that out .


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## gpop (May 14, 2018)

Was going to post the pic with the field winding in place but there was a pop of lightning and the old centrylink switch just blew-up next to my desk. Funny thing its not plugged in but its still got the old cat 5's connected and now my wifes pc screen refuses to come on. 

Once i figure out whats fried i will try to post the pics.


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## gpop (May 14, 2018)

Got the wife computer fixed and cut the phone line outside so back to the project


field winding half in









field winder install tool











Hardest part of the job was soldering the T leads on. I spent ages getting the coating off the wire then had to use a small blow torch.

test with a ohm meter and found a weak connection so had to redo that. Coils to ground and each other tested good. Not going to meg it till its coated 

Laced the ends











Had to add the terminals and cap to make sure the leads were long enough to reach 










Add smoke affects. This one is to give the magic smoke a nice pink color that will smell of strawberry's. Can warning label also says it will also give you anal warts in the state of California so i wouldn't use it there










the pic is after brushing it on. Didn't have any use for the rest of the can so i poured that on after the pic just to get rid of it. Im looking at some epic smoke when this thing goes postal.

Later tomorrow i will meg it as the stuff takes 8 hrs to dry with out a oven. Wife said "no way" when i suggested baking it in the house.


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## gpop (May 14, 2018)

If i get my lathe working this weekend then im going to start on option B







































This is a good genny head from a EB1100 honda. It just needs a adapter to make it a belt drive.


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## gpop (May 14, 2018)

Well im surprised it worked and did not blow smoke. 

Voltages are a little out at 111-109 and 221 but that may be hertz as i do not have a meter with that option at home. Also the capacitor may be a little low and need to be replaced as that controls the output voltage. I will bring home a better meter tomorrow. (biggest fear is one of the T-lead connections is not perfect and will need to be re-soldered) 

Next thing on the list is to strip and rebuild the control box and make it look pretty. Im thinking some ebay voltage and amp displays, hertz display, one gfci, one 30 twist lock and maybe a temp gauge.


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## MotoGP1199 (Aug 11, 2014)

Good job. 👍 were your nails painted nicely while doing it?


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## joe-nwt (Mar 28, 2019)

gpop said:


> Next thing on the list is to strip and rebuild the control box and make it look pretty. Im thinking some ebay voltage and amp displays, hertz display, one gfci, one 30 twist lock and maybe a temp gauge.


Post your shopping list here. Who knows what surplus may be lurking.


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## gpop (May 14, 2018)

https://www.amazon.com/dp/B00E0LVFC2?psc=1&ref=ppx_yo2ov_dt_b_product_details 5 rolls 22g wire
https://www.amazon.com/dp/B09NS1H4N9?psc=1&ref=ppx_yo2ov_dt_b_product_details 1 roll 18g wire
https://www.amazon.com/dp/B00DGKDOHC?psc=1&ref=ppx_yo2ov_dt_b_product_details 1 can of epoxy
https://www.amazon.com/dp/B082S4CVC4?psc=1&ref=ppx_yo2ov_dt_b_product_details 1 piece of sleeve 3mm
https://www.amazon.com/dp/B082S3J6NP?psc=1&ref=ppx_yo2ov_dt_b_product_details 1 piece of sleeve 2mm
Nomex 410 Insulation Paper 10 mil thick (0.25mm) 3" x 10' (~ 3M) | eBay 20 feet of paper


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## gpop (May 14, 2018)

My winding instructions

main winding counting clockwise from marker indicating empty slot 1 from the wiring end.

4 mt slots (1-10-19-28)
36 slots total
4 banks of 6 slots for main winding
5 runs of 22ga, 10 turns per loop (50 wire per slot)

T4 to wire slot 12
slot 12 cw loop slot 6
jumper 6 to 13
slot 13 cw loop slot 7
jumper 7 to 14
slot 14 cw loop slot 8
jumper insulated to 17
slot 17 ccw loop slot 23
jumper 23 to 16
slot 16 ccw to 22
jumper 22 to 15
slot 15 ccw to 21
jumper insulated to 30
slot 30 cw loop to 24
jumper 24 to 31
slot 31 cw loop to 25
jumper 25 to 32
slot 32 cw loop to 26
jumper insulated 26 to 33
slot 33 ccw loop to slot 3
jumper 3 to 34
slot 34 ccw loop to slot 4
jumper 4 to 35
slot 35 ccw loop to slot 5 
connect to T3

repeat for t2 start slot 12 to t1 finish slot 5

Field wire 

60 loops of 18g 

slot 9 cap wire
slot 9 cw loop slot 2
Jumper 2 insulated to 11
slot 11 ccw loop slot 18
jumper insulated 18 to 27
slot 27 cw loop slot 20
jumper insulated 20 to 29
slot 29 ccw slot 36
slot 36 to cap


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## gpop (May 14, 2018)

I would like to say i would never do this again but i work on old car's, tractors and other stuff where its impossible to get a original part so i probably will.

The main thing i have learnt is the wire will take a lot more abuse and that coating it tough to get off. 
One of the things no one really explains is how important folding the paper is. Fold it wrong and it will fight you, fold it right and it will assist in keeping the wires in place (don't ask me whats right either as its trial and error but it does explain why winders spend a lot of money on a paper folding machine)


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## joe-nwt (Mar 28, 2019)

I meant for the panel goodies when the time comes.

Btw,



gpop said:


> Voltages are a little out at 111-109 and 221 but that may be hertz as i do not have a meter with that option at home.


, if your frequency was anywhere close to rated, your voltage regulator should have compensated for frequency. You may have to adjust the regulator to match the new field windings. 

Then, load testing will tell you how successful you were with your project.


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## mburtis (Sep 1, 2018)

There a channel on you tube you would probably enjoy. It's called hand tool rescue. He rebuilds all kinds of crazy old tools and machines.


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## paulengr (Oct 8, 2017)

The regulator sets the voltage not the capacitor. What you have is an alternator. The rectifier changes AC into DC. The capacitor just smoothed the output. The regulator biases the excitation voltage to control output voltage. It is normally a very simple device. Most just have one to four or five pots and maybe some jumpers. Sometimes the regulator includes the diodes. In a brushless design there are more diodes and a surge arrester and capacitors on the diode plate on the rotor. The engine controller is totally separate. It does all the engine related activity plus control RPM (frequency) including responding to load changes and all the alarm functions and operating the breaker/contactor in many cases. The regulator is often so small beginners don’t even realize what it is. There are simpler methods than an AVR but AVRs are so cheap I rarely see anything else. Don’t expect anything huge or fancy. It’s hard to make voltage regulation complicated. Once you find it often just a little tweak takes care of the issue. But if it’s not responding often this is the reason it failed in the first place. Often we’ve rewound exciters only to do it again because of bad AVRs.


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## gpop (May 14, 2018)

paulengr said:


> The regulator sets the voltage not the capacitor. What you have is an alternator. The rectifier changes AC into DC. The capacitor just smoothed the output. The regulator biases the excitation voltage to control output voltage. It is normally a very simple device. Most just have one to four or five pots and maybe some jumpers. Sometimes the regulator includes the diodes. In a brushless design there are more diodes and a surge arrester and capacitors on the diode plate on the rotor. The engine controller is totally separate. It does all the engine related activity plus control RPM (frequency) including responding to load changes and all the alarm functions and operating the breaker/contactor in many cases. The regulator is often so small beginners don’t even realize what it is. There are simpler methods than an AVR but AVRs are so cheap I rarely see anything else. Don’t expect anything huge or fancy. It’s hard to make voltage regulation complicated. Once you find it often just a little tweak takes care of the issue. But if it’s not responding often this is the reason it failed in the first place. Often we’ve rewound exciters only to do it again because of bad AVRs.



I just rebuilt it and it has a capacitor and nothing else to regulate the voltage


























Google says the size of the capacitor affects the voltage and when is google wrong ....


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## gpop (May 14, 2018)

I just figured out i have no idea how this works.


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## gpop (May 14, 2018)

*The capacitor connected to this coil phase shifts the induced current to produce a magnetic flux that is opposed to the flux from the rotor*. The flux from the excitation circuit in turn induces a current in the rotor coil which is rectified by the diode to strengthen the magnetic field on the rotor. 

Not sure what that means but im guessing the general concept is capacitance equal phase shift so a capacitor that's out of spec affects voltage. 

@micromind @paulengr can one of you dumb this down for me.


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## Almost Retired (Sep 14, 2021)

im gonna guess that it is using DC on the stator excitation field
part of the procedure to re-magnetize the genny (the result of sitting unused for too long) is to disconnect the stator field leads and connect them directly to a 12V battery, it goes on to state that fully charged 12VDC will result in correct voltage out (120-120/240)



https://www.marathongenerators.com/generators/docs/manuals/SP0022.pdf



i think this will help you considerably


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## gpop (May 14, 2018)

So speed and capacitor affect phase angle. Engine was at 57.9 hertz and the book says 61 to 61.5 no load. Once adjusted to 61 htz the voltages came up to 121-125 which means i probably added or subtracted a coil somewhere during the winding. 
ordered 2 made in china quality displays that are going to love that diesel vibration and some pop out breakers to finish the job









CrocSee AC 80-260V 100A CRS-022B LCD Display Digital Current Voltage Power Energy Frequency Power Factor Multimeter Ammeter Voltmeter with 100A Split Core Current Transformer - - Amazon.com


CrocSee AC 80-260V 100A CRS-022B LCD Display Digital Current Voltage Power Energy Frequency Power Factor Multimeter Ammeter Voltmeter with 100A Split Core Current Transformer - - Amazon.com



www.amazon.com





Once its all installed i will load bank it at work to see what she does.


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## nrp3 (Jan 24, 2009)

Some of these I see have a little lower voltage, some are at 250v line to line. Is this mechanically governed? If so, once you have a good meter to check hz, see what it’s at around 62.5 hz.


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## micromind (Aug 11, 2007)

I can't remember any gen 5KVA or less that had an AVR, all are capacitor regulated. Some use capacitors up to 10KVA, above that it's usually an AVR of some sort. 

It's a simple capacitive-inductive circuit, voltage is dependent on RPM and capacitor size. 

Typically it's 60 HZ and pretty close to 120, usually the engine has some sort of mechanical governor that's not all that stable so the no-load HZ is 61 or so, full-load would be around 58 or so. 

I'd say yours is about right.


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## gpop (May 14, 2018)

Started on the control panel
A little sketching on cad, printed 1:1 then attached the paper to a piece of scrap with a glue stick. Drilled all the holes then the skeeters got to bad so i quit for the night. Tomorrow i hope to cut the squares out and at least dry fit all the parts.

Gfci, 30 amp twist lock, 2 displays and 3 pop out breakers.


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## gpop (May 14, 2018)

Ran the house on the genny for 2 hrs with the window rattler, water system, lights, etc. I was surprised that my highest load was under 4kw total. 
Tomorrow i will tow it down to the gas station and get 30 gallons of diesel ready for what could be a exciting few days come Tuesday/Wednesday. 

Still trying to teach the wife how to select which generator she will be using and which button to push to transfer power. I guess im going to have to take some pics and make a step by step guide.


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## just the cowboy (Sep 4, 2013)

gpop said:


> Hardest part of the job was soldering the T leads on. I spent ages getting the coating off the wire then had to use a small blow torch.


Yep that was always an issue, we had a electric three jaw wire stripper just for that, and still used small torch.



gpop said:


> One of the things no one really explains is how important folding the paper is.


We had a climate controlled storage unit for the paper. We bought the paper pre-folded in many sizes but had to keep it for getting damp and losing shape.


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## 277boy (Feb 25, 2015)

Is it typical practice to actually strip the enamel by mechanical means? I recall having seen videos of motor or maybe transformer work where they twisted all the wire together as is and brazed it red hot with an oxyacetylene torch.


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## paulengr (Oct 8, 2017)

277boy said:


> Is it typical practice to actually strip the enamel by mechanical means? I recall having seen videos of motor or maybe transformer work where they twisted all the wire together as is and brazed it red hot with an oxyacetylene torch.


Depends on the wire. Low voltage is so thin whatever method you use to connect it burns off the insulation other than crimp connectors. We TiG. Baldor for instance solders and it’s pretty easy to melt all the solder out during a fault on their commutators. Almost everyone uses “shock cord” (Kevlar) these days and tie wraps all the end windings to secure it. There is an old HE video somewhere showing high speed videos of just how much the windings flex during startup. It changed industry practices and motor insulation failures decreased a lot as a result.


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## gpop (May 14, 2018)

Powered the house over 50 straight from my re-wound light tower generator (hurricane Ian). The leds light hate it especially when i use the keurig but it did what i need it to do and it didn't burn up so that's was a bonus.


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## gpop (May 14, 2018)

paulengr said:


> Depends on the wire. Low voltage is so thin whatever method you use to connect it burns off the insulation other than crimp connectors. We TiG. Baldor for instance solders and it’s pretty easy to melt all the solder out during a fault on their commutators. Almost everyone uses “shock cord” (Kevlar) these days and tie wraps all the end windings to secure it. There is an old HE video somewhere showing high speed videos of just how much the windings flex during startup. It changed industry practices and motor insulation failures decreased a lot as a result.



wish i would have though of tig.


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