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Old Oct 17, 2012, 11:39 AM
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United States, WA, Puyallup
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Originally Posted by vinnieg View Post
On the first rewound 5 gram, I wanted to use a 4x2 prop with a 1S battery but the motor would stutter on startup. I tried changing the ESC timing but it didnít help. With a 3x2 prop the stuttering was greatly reduced. So for my first flight I have made a scaled down 15Ē cheap and easy RET foamie. The AUW is 50 grams. I havenít had a chance to maiden it yet due to the weather.

BTW that little bugger really winds up.
The funny thing is in the video I had the prop on backwards. It has some decent power for a 3x2 on 1S. (don't have a thrust stand to measure though)
prop on backwards? dont think many know but thats ideal for pusher type models which I do on all delta wings meaning ya get more thrust........ if you have a thrust scale you can see the diffrence, but ofcourse the proof is unloaded in the air......good luck with the foamy project
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Old Jan 09, 2013, 12:52 PM
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United States, NJ, Edgewater
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I finished rewinding the second 5 gram motor with the 32 awg wire Todd send me. I was only able to get 13 turns on each tooth on the last phase. (A motor with inconsistent turns is better than a motor that doesn’t turn). To test, I first tried to measure the resistance in each phase. Two of the phases were fine but the third one had an incomplete circuit. I must have broken a wire when trying to squeeze in one more turn. So I tried to unwind just the broken phase but it was impossible. There was no room between two adjacent teeth to cleanly remove the wire. I finally gave up and simple ripped out all wire.

Now I’m back to square 1. I’ll try again with 13 turns on each tooth this time. Am I ever going to learn that spending $8 on a new motor is a much more economical than wasting 6 hours on a rewind ?
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Old Jan 09, 2013, 02:12 PM
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United States, WA, Puyallup
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Originally Posted by vinnieg View Post
I finished rewinding the second 5 gram motor with the 32 awg wire Todd send me. I was only able to get 13 turns on each tooth on the last phase. (A motor with inconsistent turns is better than a motor that doesn’t turn). To test, I first tried to measure the resistance in each phase. Two of the phases were fine but the third one had an incomplete circuit. I must have broken a wire when trying to squeeze in one more turn. So I tried to unwind just the broken phase but it was impossible. There was no room between two adjacent teeth to cleanly remove the wire. I finally gave up and simple ripped out all wire.

Now I’m back to square 1. I’ll try again with 13 turns on each tooth this time. Am I ever going to learn that spending $8 on a new motor is a much more economical than wasting 6 hours on a rewind ?


broke a wire? either that or you scraped a wire on the stator corner, real easy to do and can cause a short, thats why ya wanna resistance check after each wind phase>>>>>>>>>>dont give up so easy youll be glad ya didnt
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Old Jan 09, 2013, 05:23 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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!

Quote:
Originally Posted by vinnieg View Post
I finished rewinding the second 5 gram motor with the 32 awg wire Todd send me. I was only able to get 13 turns on each tooth on the last phase. (A motor with inconsistent turns is better than a motor that doesnít turn). To test, I first tried to measure the resistance in each phase. Two of the phases were fine but the third one had an incomplete circuit. I must have broken a wire when trying to squeeze in one more turn. So I tried to unwind just the broken phase but it was impossible. There was no room between two adjacent teeth to cleanly remove the wire. I finally gave up and simple ripped out all wire.

Now Iím back to square 1. Iíll try again with 13 turns on each tooth this time. Am I ever going to learn that spending $8 on a new motor is a much more economical than wasting 6 hours on a rewind ?
We don't rewind motors to save money as much as we do it to get motors that are better than we can buy and to get them perfectly matched to the props we want to use.

It is unfortunate that you had a problem with your first attempt but that has happened to others too.

If you are working the wire too hard to get the turns on, the risk of a shorted turn (common) or broken wire (less common) is one of the reasons to consider using a smaller size wire. To get the last turn or two on it can require threaded turns carefully pulled into place. This post in another thread describes how to get those last turns in by threading them:

http://www.rcgroups.com/forums/showp...4&postcount=55

Good luck with it!

Jack
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Old Jan 09, 2013, 05:52 PM
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San Jose, California
Joined Dec 2007
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Originally Posted by vinnieg View Post

Now I’m back to square 1. I’ll try again with 13 turns on each tooth this time. Am I ever going to learn that spending $8 on a new motor is a much more economical than wasting 6 hours on a rewind ?
Jack said it best; but simply putting it most of us do it for the enjoyment of the rewind itself and oh yea, seeing something dead come back to life.

And yea...after I rewind a motor, I wouldn't sell it, even if my life depended on it.
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Old Jan 14, 2013, 01:12 PM
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I finally finished the winding on all twelve teeth. All that remains is to test the resistance and fire it up. Can't wait to see it run!
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Old Jan 14, 2013, 01:16 PM
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Jack,
I have been using the method you described of pushing a pin through to create an opening for the wire for the last two turns or so.
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Old Jan 14, 2013, 04:30 PM
Jack
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It's a great help, isn't it? They call those the "money turns".

A little oil on the pin helps when it is real tight. You run some risk of nicking the insulation coating but it is worth to get the turns on. Sometimes it is just a case that the room for the strand is there but you can't slide it down past the higher turns.

I use the tip of a APC 13" or so prop and slide it into the slot from the side, between the strands, and that will flatten them back against the arms a little. That helps to get some of the earlier turns to drop down in when you're on you way back down the arm.

Sneak up on it for the first tests, just one or two clicks for a second or two. If it does not start and run clean or if it stutters look for a winding error.

Good luck with it!

Jack
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Old Jan 15, 2013, 09:01 AM
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United States, NJ, Edgewater
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A little oil on the pin helps when it is real tight.
If I used oil, I may have been able to get 14 turns! maybe next time!

The resistance test was a success but in the process of putting the motor back together I lost the c clip which holds the shaft to the can. There is still a good amount of magnetic force holding the shaft in place. Do you think I need to find a mechanical solution for the c-clip or will it be fine when running with a prop at full throttle ?
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Old Jan 15, 2013, 12:33 PM
Jack
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Originally Posted by vinnieg View Post
A little oil on the pin helps when it is real tight.
If I used oil, I may have been able to get 14 turns! maybe next time!

The resistance test was a success but in the process of putting the motor back together I lost the c clip which holds the shaft to the can. There is still a good amount of magnetic force holding the shaft in place. Do you think I need to find a mechanical solution for the c-clip or will it be fine when running with a prop at full throttle ?
You can (and should) test it without the prop first, I do that all of the time without a clip. And if you mount the prop in a pusher manner and make the motor go in the right direction it will push the magnet housing on. Otherwise, the prop might lift it and then the motor won't run.

Jack
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Old Jan 17, 2013, 04:02 PM
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Sweden, Gšvleborg County
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I dont use c-clip on any of my small motors, up to 25-30 grams. On the indoor planes it is much easier to change prop if you first pull off the can from the motor. When the motor is running the magnetic field from the windings helps to keep the can in place.

The only time i have notised that the can pulled out was my first rewinded CD-rom motor when using the crappy ring magnet that is on them original.
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Old Jan 17, 2013, 08:42 PM
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Woohoo! The motor runs great! I ran it with a 4 x 2 prop on a 2s and it was pretty powerful. I don't have a watt meter or a thrust stand but I can say I'm happy with the rewind. The motor was setup as a puller(?) and the lack of the c clip was not an issue. I may have to analyze the sound to figure out the KV. Now its time to make a little foamie for this puppy!


Hextronix 5 gram motor rewind (1 min 23 sec)
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Old Jan 18, 2013, 08:17 AM
Jack
USA, ME, Ellsworth
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Nice job, Vinnie!

Don't let your lack of a watt meter, or the money to acquire one right now, stymie your curiosity. There are some very affordable ways to measure the current that you might already have at hand:

$3 Watt Meter - http://www.rcgroups.com/forums/showthread.php?t=949923

Home-Made Current Shunts for Measuring Motor Current - http://www.rcgroups.com/forums/showthread.php?t=393591

Turn any DVM with a 2000ĶA range into a universal DIY 2000 Amp DC Ammeter - http://www.rcgroups.com/forums/showthread.php?t=1697445

It might be as simple as just snipping off a little piece of wire and doing a little soldering...

The HK specs for that motor show it as a 2A motor on a 2S or 7.4V battery so, if they have that right, it would work out to being a motor that is capable of handling an input power 2A x 8.4V = 16.8W. Surely you want to know how your motor compares to that don't you?

I don't do thrust measurements either for the most part. If I want some info on that I usually look up the prop at flybrushless.com and see the thrust to RPM curve there. That will usually give me an idea as to what to expect from the prop if I can get it up to a reasonable RPM.

Congratulations again on the rewind, welcome to another facet of the RC the addiction!

Jack
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Old Jan 18, 2013, 08:34 AM
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This is awesome! I have one of these and I never knew that meter could be converted into a wattmeter! I'm difinately going to do this. The only thing that bugs me is that I over paid for mine
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Old Jan 18, 2013, 12:35 PM
Jack
USA, ME, Ellsworth
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The $3 version uses the shunt (a piece of wire basically) that is inside the meter. So with that it starts overheating at 10A or more and if used for too long. Lucien's thread where you use a 13" long piece of 10 Ga. is where the real genius starts to emerge for most of us. That gets the shunt (the piece of wire) outside of the meter and opens the door to much higher current levels.

For your motor the shunt inside the meter is fine and, the way it is wired, it also allows you to switch between the volts and current so you get both parts of the Volts x Amps = Watts equation. The voltage needs to be measured under load and at the same time as the current reading is taken to be a vlaid measure of the power (Watts).

If you keep your eye on it online or get the fliers in the mail, the meter gets down to $2.99 fairly regularly...

Jack
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