HK-4025 12N8P Winding Project

[Stolla]

Now tell me brother, why oh why do you use such thick wire for your first motor? Not as if a little thinner its gonna make a noticeable difference in performance. you're really making it hard for yourself, shh, don't tell anyone, thickest I've used is 1.6!

[HeliFX]

stolla I like torturing myself plus gives my finger a great workout.

honestly its a great way to improve my technique. Seeing all the examples on different forums for 4025 it seem to be the way to go.
i might consider 1.5 for my second attempt.

Originally Posted by Stolla

Now tell me brother, why oh why do you use such thick wire for your first motor? Not as if a little thinner its gonna make a noticeable difference in performance. you're really making it hard for yourself, shh, don't tell anyone, thickest I've used is 1.6!

[_Dekker]

Fully agree with Stolla, 1.7mm as a start is... ehm... a bit enthusiastic
And indeed the copper diameter is the one that counts.
I hope you also check for shorts/bad isolation because the risk of damage increases with wire diameter.
Also, 0.3mm nomex is quite thick. Most guys use 0.17mm. It does not sound like much of a difference but you might be amazed how much space it will give you.

[HeliFX]

whoops nomex paper is 0.13 dekker slight typo error in my last post

my first attempt test winding had no mark or nicks on insulation and passed 1000V megger test no problem. I test each winding as I go stator to wire and between each neighbor winding.

here a bad photo of my second attempt.
its much cleaner and tighter this time around.

Originally Posted by _Dekker

Fully agree with Stolla, 1.7mm as a start is... ehm... a bit enthusiastic
And indeed the copper diameter is the one that counts.
I hope you also check for shorts/bad isolation because the risk of damage increases with wire diameter.
Also, 0.3mm nomex is quite thick. Most guys use 0.17mm. It does not sound like much of a difference but you might be amazed how much space it will give you.

[HeliFX]

so I'm taking the advise of Stolla and Dekker and going with a size smaller then my original plan to using 1.7 mm.

4.5 short transition and so far passed 1000V test

ok guys no laughing its my second attempt.

those transition really threw me off my clean and organized starts.
last tooth started to get pretty ugly in my opinion but I was determine to finish one side.

I'm finding I need to refine my tools ffor the smaller stators like HK - 4025

hey with all this engine winding I can now do one finger push-up no problem

[HeliFX]

Here is my first completed winding HK 4025. Not as clean as I'd like but pretty confident my next motor will be spot on and clean.
Passed 1000V test.

4.5 short transition YY @ 1.5 (more like 1.6 with insulation ) (target Kv 1130)

can someone confirm everything looks correct.

I may have question regarding testing of each separate motor.
Not sure of a easy or temporary method to assembly motor to test before doing final connection.

next phase testing.

[Stolla]

Congrats, your first motor!, I usually do the generator test first, you have to assemble the motor temporarily before joining the two motors, then you can use a drill to spin up motor and measure volts between bullets for each motor, kv should be the same. once you get a good result here you test each motor with your testing equipment, again kv should be very close, can't remember the percentage but mine had been under 1 percent difference. Then disassemble, very lightly glue your windings, here I place couple of drops of epoxy at bottom then heat it up with hairdryer to thin glue so it can seep into the little gaps, once hardened, assemble again, remember to insert the locking pin, I prefer using locktite for the stator assembly but some use epoxy here as well.
Finally test motor again for kv do the 1000 v test on the completed and assembled motor again. Then go fly!

[HeliFX]

thanks Stolla,

I'd be much happier once the motor is working and final stages go smoothly.

few quick question regarding your response.
I take it your referring to Loctite 648 or 620 for final assembly of stator also find the holder has a very tight fit to stator.
Do you sand the holder down to more a slight fit instead ?

I take it you prefer to not too tap M2 screw and just glue the stator.

now when doing a temp assembly for testing motor do you omit the retaining pin and just tap in the stator holder ?

still on the fence with epoxying the windings as I posed a similar question to dekker and he mentioned the same concern I had regarding remove the engine some day can be difficult.

In the event that the two motor Kv do not fall within the 1% is the motor not fit to run and what could be the cause in your opinion ?

cheers

Originally Posted by Stolla

Congrats, your first motor!, I usually do the generator test first, you have to assemble the motor temporarily before joining the two motors, then you can use a drill to spin up motor and measure volts between bullets for each motor, kv should be the same. once you get a good result here you test each motor with your testing equipment, again kv should be very close, can't remember the percentage but mine had been under 1 percent difference. Then disassemble, very lightly glue your windings, here I place couple of drops of epoxy at bottom then heat it up with hairdryer to thin glue so it can seep into the little gaps, once hardened, assemble again, remember to insert the locking pin, I prefer using locktite for the stator assembly but some use epoxy here as well.
Finally test motor again for kv do the 1000 v test on the completed and assembled motor again. Then go fly!

[ZuvieleTeile]

Congrats, Nicely done HeliFX,
I wish I had my wire already . . .

Please let us know, how you do the testing, determining Kv, drill test etc.
Any detail is of interest (at least for me)

[HeliFX]

thanks ZuvieleTeile, not completely happy with it. Need to do it much tighter next time. luckily I have no scratches or nicks on the insulation. Worst is when a scratch happens 2 or 3 teeth into the winding.
Powercroco advises to use high temp paint for cover.

interesting to note as you start actually winding it take some time to find a rhythm and method and refining your tools. By the time you figure it out your done and you can't go back and redo it.

I'm not out of the woods yet. It needs to run which is always nerve racking. Second guessing if your work is correct etc.

I'll be sure to report back with testing results.



wow very unfortunate regarding your brocotts shipment mix up. Look on the bright side you had plenty of time to visualize your winding

Originally Posted by ZuvieleTeile

Congrats, Nicely done HeliFX,
I wish I had my wire already . . .

Please let us know, how you do the testing, determining Kv, drill test etc.
Any detail is of interest (at least for me)

[ZuvieleTeile]

I am visualizing so hard, HeliFX, that I have already tears in my eyes. . .

[Stolla]

Originally Posted by HeliFX

thanks Stolla,

I'd be much happier once the motor is working and final stages go smoothly.

few quick question regarding your response.
I take it your referring to Loctite 648 or 620 for final assembly of stator also find the holder has a very tight fit to stator.
Do you sand the holder down to more a slight fit instead ?

I take it you prefer to not too tap M2 screw and just glue the stator.

now when doing a temp assembly for testing motor do you omit the retaining pin and just tap in the stator holder ?

still on the fence with epoxying the windings as I posed a similar question to dekker and he mentioned the same concern I had regarding remove the engine some day can be difficult.

In the event that the two motor Kv do not fall within the 1% is the motor not fit to run and what could be the cause in your opinion ?

cheers

Depends on motor, you have to clean the scorpion stator and holder from glue residue etc not needed with mx as they use no glue, yes on ltite.
for testing you don't need pin if stator tight as there's no load on motor.
Re epoxy depends on thickness of wire etc, kontronik don't glue wires, I do but very little once motor is done and tested,
I don't tap but use pin and locktite
I think the tolerance on kv may be higher, forgot the figure but it can be due to damaged wire, i.e. short on the same pair, very difficult to find afterwards so if you suspect damaged wire test the pair in question.

[HeliFX]

stolla appreciate your feedback.

stator and holder pretty smooth and clean.

there was one thing I noticed not mentioned all that much is the effect of the length of wire from motor to esc or what is a good distance.
I started with 6 inches. I suppose shorter helps limit resistance but I do recall Kontronik warning users to never shorten motor leads which can potentially effect its performance.

I wonder if this length plays a role on performance.

Originally Posted by Stolla

Depends on motor, you have to clean the scorpion stator and holder from glue residue etc not needed with mx as they use no glue, yes on ltite.
for testing you don't need pin if stator tight as there's no load on motor.
Re epoxy depends on thickness of wire etc, kontronik don't glue wires, I do but very little once motor is done and tested,
I don't tap but use pin and locktite
I think the tolerance on kv may be higher, forgot the figure but it can be due to damaged wire, i.e. short on the same pair, very difficult to find afterwards so if you suspect damaged wire test the pair in question.

[HeliFX]

oh I did have one quick question when testing the 2 motors.

Is ok to have both motor ends (star points) when test each separate motor or will this cause a problem ?

just need to be sure

thanks

[powercroco]

the kontronik warning is caused by their fear, that a lot of users arn't able, to resolder the ends of the litzwires in the right way.

as shorter the connections between batterie -> controller-> motor, as better it is.
not only because of resistance, but also to prevent interferences with rc.


to test both motors single is the best way to find out, if you have made some mistakes.
a good result you have, if the difference in n spec of booth motors is lower than 1%.
the starpoint won't cuase a problem, if the incomming wires of the not used partmotor are insulated against each other,


and:
neat work, congratulation.

[HeliFX]

thanks

I certainly couldn't have done it without the wealth of knowledge you have graciously provided to all of us. Thanks Ralph

not to mention others on the forum - stolla, dekker, JB and to the many available posts

now I'm officially addicted to rewinding motors but I think my fingers won't be happy about this news.

Originally Posted by powercroco

the kontronik warning is caused by their fear, that a lot of users arn't able, to resolder the ends of the litzwires in the right way.

as shorter the connections between batterie -> controller-> motor, as better it is.
not only because of resistance, but also to prevent interferences with rc.


to test both motors single is the best way to find out, if you have made some mistakes.
a good result you have, if the difference in n spec of booth motors is lower than 1%.
the starpoint won't cuase a problem, if the incomming wires of the not used partmotor are insulated against each other,


and:
neat work, congratulation.

[HeliFX]

Is Loctite 648 or 620 what one should use for securing the stator to the holder ?


Are these adequate both are described as high temp retaining compound.

[_Dekker]

I use 648 for motors that I want to last a long time and I do not intend to take apart again to rewind.
For motors that might need upgrading or different specs in the future I use epoxy or just the M2 screw.

Bert

[HeliFX]

I finally had the chance to test out the newly re-wounded 4025.

4.5T short @1.5 mm target 1100
esc: Hobbywing 80A
timing set = 15 degrees
pack: 6S

motor #1 = 553 Kv
motor #2 = 551 Kv
total = 1104 Kv

safe to say I'm good to move on to final phase sealing and glue the motor.
unless someone see something I might have missed

[GMAURO]

Originally Posted by HeliFX

I finally had the chance to test out the newly re-wounded 4025.

4.5T short @1.5 mm target 1100
esc: Hobbywing 80A
timing set = 15 degrees
pack: 6S

motor #1 = 553 Kv
motor #2 = 551 Kv
total = 1104 Kv

safe to say I'm good to move on to final phase sealing and glue the motor.
unless someone see something I might have missed

Why? Normally the total kv is not "motor 1 + motor 2"... If you have chek 550 kv for each motor the final kv is 550 (with little approximations).
But is strange 550 kv for 4+5 yy winding.... My 4025 4+5 x 1.4 yy have motor 1 1124 kv, motor 2 1125kv and total 1127