Scorpion HKII 2221-6 4400KV Rewind

[sutty]

Thanks 1BOHO, that was the plan, to get the log, but I don't know what to make of it now that I have it. Maybe you guys could look and see if it gives away any tells.

Thanks in advance, if you have the time.

Not sure how to check the wye termination now I've epoxied it, since it won't come apart unless I get it hot, and then I might damage something else, and end up starting again. Any thoughts in that regard?

One bullet might be slightly iffy soldering, but it reads zero, and works under no load, but it isn't as shiny as the others. I'll resolder that, but won't run it in the heli until the logs have been looked at by someone who understands such things.

My ESC now smells, but don't know what it is inside it that smells, but it seems to still work. Whether I can now trust it I'm unsure.

Anyway, please let me know if the log for this quickly abandoned and smelly test tells you anything.

FailureSave.csv

Cheers

Sutty

[sutty]

I think I know the answer to this, but it can't hurt to seek confirmation. Is it possible that what caused the death of my previous wind, the original OEM wind of my 2221-6, and the wildly fluctuating graphs in the castle logs, which I examined at the time, and which made me put it on the scrap heap to begin with, could come down to nothing more complex than a faulty bullet?

I was just inspecting everything that could be causing me the issue with this wind version, and that I could get to, like could the motor mount screws have touched the windings, was the soldering to the bullets okay, did the bullets fit properly, etc, and the answer to that last one is no. One of them was sloppy and loose, and I can't believe that I didn't go with new bullets after going to all the effort of doing a rewind. I think I might well have brought the problem with me.

I think it's damaged my ESC too and I don't know if it will be reliable now, but I'll try it out with careful tests. It is apparently still working.

I've done some further bench tests after having changed the bullets for new, and after making sure the soldering is good, and during the bench testing I loaded the motor up pretty good by hand and it never skipped a beat.

I'd love to hear back from you more experienced guys if you can see anything in that log, and if you know if a loose bullet could cause all those problems.

I'm going to go for some really cautious spool ups in the heli over the next couple of days, as time allows. No blades, then tails only, then mains and tails, no pitch, and then finally see if it will lift off.

I'll let you know how I get on.

[1BOHO]

Dont be surprized. It can be that simple.Hopefully that was the problem. The motor screws clearance was also a good simple idea to check. That was a very reasonable idea as to the cause of your symptoms. I hope the castle survived maybe you just heated up the board a bit. In my personal experience with castle I have been a bit abusive in my treatment of them but they haven't failed me as of yet. Hopefully yours will be the same. It may be a wise idea during your winding learning curve to use a mystery esc or something in that price range for initial test or permanent test rig.Even though you tried to avoid it,looks like youre slowly becoming immersed in winding motors anyway..... The one thing I see in the log is the temp quickly rising to over 150*F degrees and the negative ripple, rpm, and watt readings for minimums. Looks like it may have lost its sync or arching with the intermittent phase connection. Just my untested hypothesis worth .02.

BTW in the castle graph viewer app you can export the screenshot to a jpeg, bmp, png, then post it as an attachment. If you want to inject it in the post and dont want it to be wider than the rest of the post open the jpeg or format you chose in paint and reduce the size to 75% then re save it. Then you can post it and it will be an acceptable size when inserted in the post.

[1BOHO]

Weird I no longer see these negative reading when I looked back at the graph minimums :dont know I cant duplicate it now . But opening the CSV file in excel line # 8 reveals 3 resets and says the cause was "prop strike" If that didnt happen maybe that was an interpretation of an excessive current condition where the over current protection was activated. Just another untested .02.

Hopefully someone else has ideas and interpretations that are better. Maybe you should review that feedback with the castle engineers. There is a factory forum here.

[sutty]

Thanks for the answers. I need to get to bed now, so I can't answer in detail, but to explain the session # inconsistency and the prop strike reference, though I'm not sure how that came about, the file was edited to show only one session, because I thought it might be more useful to allow it to be an actual log that could be read in the viewer, as opposed to a jpeg, so you could hover over it and such. Prop strikes could have been when holding the motor in my hand, and catching it before it spooled up properly, and then stopping, to try again and again, etc, but has no relevance to that one log where it went foobah. Sorry for the confusion, I just wanted to cut out all the prior and post dross to make it clearer, and by leaving the wrong session header in I made it more confusing. My bad.

I'll cover the other points tomorrow, since it's 3am here.

Thanks

Sutty

[1BOHO]

The excel data reflects just the session csv. you posted. Hope that helps.

Tommorrow Ill ask u if you held it in your hand in the chopper because I thought this was the log of it acting up while in the Heli.

[sutty]

Right, wide awake. .

Yes, you're right, that is the log of it acting up in the chopper and I thought it was the header text portion saved from the top of the file, the first session, meaning that I'd made a mistake during the file edit, keeping only the data portion of the session that I wanted, but I didn't.

Having reviewed it this morning, checking the original file, you're absolutely right, that header text, which references the prop strikes does indeed belong to that 'in chopper' session, so I was more careful with my edit than I had thought last night, and your assessment is correct.

There was however no blade strike, or similar physical barrier to it starting during the 'in chopper' test, so I'm unclear as to what that could refer to. I'll see what I can find out in that regard. Thanks to the pointer to the Castle forum.

Current limiting was/is set to very sensitive, 50A, which is as low as it will go, so maybe that is related, but I'm glad that was set to low, since maybe that saved the day.

As for getting immersed. Only in as much as there were no wind suggestions coming forth for this motor, other than one which included removing the powder coating, which resulted in the stator falling apart and a lot of additional complexity. I didn't fancy that idea, so I had to come up with my own solution. Honestly, even if this works out in the end, I would much rather have just copied from a known good and working solution, that didn't involve stripping the stator. If that was out there, I would have gone for that in a shot. It wasn't, or at least I didn't find it, so I had to learn enough to work it out myself, and as I said earlier, that was tough without the grounding, and for all I know could easily all have been wrong

If it works out in the end, I will be very pleased, like with the 600MX, and maybe even a tad more pleased than having just copied from a known good working solution, but it's still just copying anyway, just from multiple sources across the net, when having to find out the info just takes a lot longer.

I won't be winding anything else in the near future, but I will certainly be taking away from this the lesson that it is possible, and for any future motor burn outs I will have no fear in terms of giving a rewind a bash.

As for using a sacrificial ESC. Good point, but I also thought I was past that point of risk, having run several bench checks. Live and learn. Hopefully as you say, the ESC will be fine long term too. The smell is fading.

Seriously though, even if it isn't okay, it's no big deal. What's the price of one single ESC for having learned how to wind a motor, and having some fun trying.

Thanks again, I'll keep you updated over the next day or so with regard to the further testing, success or otherwise.

Cheers

Sutty

[1BOHO]

Guess it depends on the esc. My castles cost nearly 400 a pop so burning one up for a 100 dollar motor wouldnt be nice but I know what you are saying. No prop strikes so hopefully the connector issue was the Achilles heel and when you test again everything will work out. Post how it goes.... About the help it comes and goes here but I doubt very seriously if you would have asked Dekker or others about this one they wouldn't have helped same as the Align

G'day
1BOHO

[sutty]

I will for sure. Thanks for taking a look and for the advice.

Cheers

Sutty

[sutty]

Originally Posted by 1BOHO

About the help it comes and goes here but I doubt very seriously if you would have asked Dekker or others about this one they wouldn't have helped same as the Align

I didn't notice this whilst at work this morning, when I first replied. Thing is I don't like to directly ask people, until they actually respond. I was just throwing the questions out there to the forum in general, and if people have the time to consider them and answer, that's great, but targeting anyone in particular puts them under undue direct pressure to respond, which is unfair. Many of the questions throughout this thread were left unanswered, so I pressed on. I'm not, and wasn't complaining, just explaining that I continued on regardless and got to some sort of solution on my own. I know people have their own things to get on with, and probably look in sporadically, and I don't suppose that it's a particuarly well frequented section of HF anyway.

I imagine most people would think, like I did, that rewinding a motor would be way beyond what they could handle, and too expensive to get someone else to do it, so they don't even look in and simply buy a new motor.

Fortunately, thanks to you guys, I now know different. Even if this one doesn't work out, the 600MX just blows me away every day, weather permitting. Maybe this will prove to be the same in the long run. Fingers crossed.

Cheers

Sutty

[1BOHO]

Hi,
Sometimes post get missed so no one may see. I guess Ive been a bad boy coz I'll pm anybody I think may have the info Im looking for Omerco, Dekker, Christian and whomever else that conversations and post spark interest. I never thought of pressure when talking about a model I always though thats what a forum is for but....maybe you are correct. No worries though.I figure if a person is on here they can talk if they choose if not we still have the ability to teach ourselves.In alot of cases personal research is certainly not the worst way to learn. Nevertheless I hope you have the same success with the scorpion. I'm sure you will. What ideas did you come up with for the prop strike flags you got off the log? Are you ready to test her in the bird again?

1BOHO

[sutty]

Honestly I haven't looked. I'm intending doing a series of very careful tests, with ever increasing load, as I described previously, keeping and eye on temps with my IR thermometer. I'm going to mount the ESC on the outside, as opposed to hidden away inside, to make this easier. Last time, because I thought it was working fine, I jumped straight in. This time I will be much more circumspect, inspecting the logs after every run up.

I won't be doing this until tomorrow evening at the earliest, maybe the following evening. If I get chance at work tomorrow I'll have a scount around for possible causes of the prop strike error.

Cheers

Sutty

[1BOHO]

Also consider attaining the other motor constants too like Rm and idle current. U remember we showed you the 4 wire hook up to get your . These numbers become useful in predictions and simulations.

This is very simple with two cheap meters and two 10 ohm 10 watt resistors in series.

Good luck....
TTYS

[sutty]

Thanks. I just did this but using Ron's method for simplicity, since I had the tools.

He told me to short out my power supply, and adjust it to exactly 5A. I did that. It is current limited, adjustable and protected, so no problem there.

He then said, apply that 5A to the windings in turn, whilst measuring the voltage across it, make sure the 5A is sustained. It was, perfectly at 5.00A, according to the power supply.

Here is the result.

Pair 1 0.268V
Pair 2 0.269V
Pair 3 0.270V

So, I know V=IR, so R = V/I so we have

0.268/5, etc.

0.0536 Ohms
0.0538 Ohms
0.0540 Ohms

Means nothing to me. Well I know what it means, but not in terms of performance.

They seem close values, so maybe nothing horrible is going on.

If you know if those are in the ball park, or plain stupid, let me know.

Your time is appreciated.

Cheers

Sutty

[sutty]

Wow, stuff can be fun. I just imagined that star diagram for wye, and realised that I was measuring across the two coils at once. I also knew that I cut the wire to 1m lengths for the wind, after a test wind.

I took note of how much I cut off to finish the motor off. 15cm, leaving each at 85cm. Twice 85cm will be 1.7m.

I just put this into an online resistance calculator for 1.7m of 0.85mm dia copper wire, and guess what the answer is. No, go on, guess.

Okay, I'll tell you.

0.0502705

That's close enough I'd say for a confirmation.

Don't think I did anything stupid there in those assumptions.

Cheers

Sutty

[1BOHO]

Take an average of the three call it that. But if you really want to see how it correlates without the math you can put the motor constants in simulation leaving everything the same but Rm and compare the results of different Rm numbers. That seems like it would be a reasonable way to possibly see the effects. Youre getting bit by a bug

BTW not that it matters now but what I found for actually tested in the 2221 is a YYY 16turns .8mm 3750 KV. Figured since Im looking right at it in my notes I may as well share it. Maybe the next guy can eat and will try that configuration.

[omerco]

Originally Posted by sutty

I didn't notice this whilst at work this morning, when I first replied. Thing is I don't like to directly ask people, until they actually respond.

Most of us are reading most of the threads just not on a daily basis. In this one you are receiving help so far and I'm sure if anyone has anything to add he will.

From my experience here there is no problem asking personally once and in most cases you will be answered. best refer that someone to a specific post or thread.

[omerco]

Originally Posted by sutty

Wow, stuff can be fun. I just imagined that star diagram for wye, and realised that I was measuring across the two coils at once. I also knew that I cut the wire to 1m lengths for the wind, after a test wind.

I took note of how much I cut off to finish the motor off. 15cm, leaving each at 85cm. Twice 85cm will be 1.7m.

I just put this into an online resistance calculator for 1.7m of 0.85mm dia copper wire, and guess what the answer is. No, go on, guess.

Okay, I'll tell you.

0.0502705

That's close enough I'd say for a confirmation.

Don't think I did anything stupid there in those assumptions.

Cheers

Sutty

Could you post a link to that calc please?

[omerco]

Originally Posted by sutty

Wow, stuff can be fun. I just imagined that star diagram for wye, and realised that I was measuring across the two coils at once. I also knew that I cut the wire to 1m lengths for the wind, after a test wind.

Now you can start understanding the advantages of winding a YY pattern or a YYY one: you get the coils parallel to one another hence significantly reducing the IR.

Look at the D and Y diagrams you will also understand why D is preferred.

[sutty]

Thanks 1BOHO, is there a motor sim that you could point me to that most in here are using and I'll see what to make of the numbers I now know. I assume you agree that they are all close enough to be accpetable, since you said just use the average..

Honestly omerco I wasn't making a big deal about the help thing. You have both been very helpful in this thread, and your comments are both very welcome, but it won't change my mind. I very rarely go asking directly unless someone is helping me already. If and when I do I always start off by apologising for the cheek of my direct request. In the main I also like to stay in the thread itself, if I can help it, because PMs defeat the purpose of the forum.

Here is the resistance calculator I used.

http://chemandy.com/calculators/roun...calculator.htm

As it stands, despite much reading, and having already wound two motors, I still have no idea what YY or YYY means. I thought I did, then read something that contradicted the opinion I had, so no, I can't see how that affects things, since I don't know what they both are.

Instinctively I do not understand why Delta would be preferred. There should be no difference as far as I can see, in that for the same KV you need fewer turns, and I assumed that balanced out the difference in the exact same ratio. Indeed I assumed, but never checked, that was how the ratio came about in the first place. In this wind, I did exactly that, changed the number of turns to balance it back out.

I can however see that the single wire motor exit portion would be of higher reistance, but dekker already said that this should be kept as short as possible in either case, so I didn't think it would make a massive difference at a few cm each, perhaps 5cm. Though I can see here that would be 10cm in total, and that would be 3mOhms more than the wind itself, according to that same calculator. I guess only a proportion of that would be the actual difference though, since Delta has some extra too. I also thought that I'd read, in theory, that wye should be more efficient anyway. Not sure if that's right, it's just in the back of my mind.

Wye exists, so it must have its place, so not sure why people choose one over the other. Never found that out. I know why I chose it, because I'd already done one in Delta.

Cheers

Sutty