View Poll Results: On impact or midair (read post for more information)
midair 17 70.83%
on impact 7 29.17%
Voters: 24. You may not vote on this poll

Thread Tools
Feb 23, 2004, 01:39 AM
Thread OP

The unfortunate truth about why cheap brush motors die


Hello folks!
being surprised at how the last two GWS EPS-300c motors died out upon rough landing, I took them apart to find that there was still a little bit of carbon left, but the springy metal piece that holds the carbon to the spinning drum with contacts isn't all that springy any more, at least not enough for a solid contact through which currect can flow easily.
I could fix this. All I'd have to do is take the pringy metal pieces out and bend an angle into them. It would work just fine I have no doubt about it. I'd just have to unsolder the motor terminal wires on the other side of the springy piece and then they could slide out. Then bend, slide in, resolder, and worst of all, put it back together making sure things are nice and snug.
Anyway, I was planning on getting a 400c anyway, so I'm not gonna go through all the trouble.

So the question of the poll, when your GWS motor "burns out" most of the time does it fail on some kind of impact (i.e. landing) or midair?

Thanks!
-Michael
Sign up now
to remove ads between posts
Feb 23, 2004, 02:27 AM
It's the last plane honey
SlowRider's Avatar
Most of mine have been mid-air, my 350's lasted an average of 500 minutes. Went brushless, haven't looked back.


Andy
Feb 23, 2004, 05:21 AM
Registered User
vintage1's Avatar
You know, I have only had one can motor go on me apart fom one that I got S/H that died of bearng bfailure drop of oil would have cured that) and iot also looked like it had been demagged a bit too..

That motor is the first one I bought a couple of years ago, It's siezed up a bit on impact, and so on, and been bent straight a few times, and I was bench testing it - there was a clunk, and it siezed solid. I took it apart, couldn't see anything wrong, but it was wrong ratio and wrong wind for me anyway, with a lousy gearbox, so its in bits in the drawer now.


I don't run cans hard. With LIPOS for my smaller models at sport fly levels, I don't have to. I treat em gently and they last.

I suppose one day I will wear some brushes out, but I haven't yet.
Feb 23, 2004, 07:21 PM
Thread OP
Weird, vintage....
Probably not a junky GWS motor or one of the cheap ones like a regular S300 or S400...
Also, upon talking with my dad, he said that it's not the metal part dnot as springy, it's that when there was carbon inbetween, it was farther apart from the rotor, now that they've mostly worn down it needs to spring farther to keep contact.
-Michael
P.S. But how does the above description relate to impact? Dunno. Whoever votoed "on impact", can you elaborate?
Feb 23, 2004, 11:14 PM
Lawn darts, anyone?
GWS "A" motor on maiden flight, had not been broken in, flew at
WOT 15 minutes, failed on soft landing. Prop/motor froze up when
plane touched down. Found carbon brush had separated from its
springy mounting, got macerated between armature & mag poles.
Feb 23, 2004, 11:46 PM
Thread OP
Wow. That's weird. I would've thought it could've been defective but at the rates these are mass produced i REALLY doubt they could make them that far apart.
-Michael
Feb 24, 2004, 12:55 AM
Clinger, MAGA
rclark's Avatar
All midairs. Flying along and poof. No motor. Deadstick in for sometimes not so good landing as usually went out at a 'not so convenient place'. Averaged about 25 flights a motor (5-6 minutes per flight) on the S300s on 8 cells.... On 7 cells (with the ol' Zero I'd get maybe 50-60 flights) . Went brushless and never looked back.....

My 400 motors however I've only run one into the ground so far after about 150 flights in the ol' Sky Scooter Pro a few years back now...... Acceptable attrition in my mind.... Still use 400 6V motors for some projects...
Feb 24, 2004, 01:17 AM
aeropengquin

The GWS 350 C setup tends to be used in an over amperaged application and fails for whatever reason, fairly soon, and many people just go to brushless.

If you are interested in a low cost replacement I suggest a GWS 400 C for $14.95 at your local LHS. It comes in a very large number of gear ratio's. Use the avail. moto calc routines to set your prop size for max thrust and min current and you should have a reliable low coat solution.

regards, charles
Feb 24, 2004, 01:22 AM
Does anyone hear a cat?
headless's Avatar
My LHS sucks. They charge 26.99 for the freakin 400 and 21.99 for the 350c. Ugh.
Feb 24, 2004, 02:16 AM
Tight is Right
Darren Hintze's Avatar
I always wanted to get more out of those little cans than they really could give so I went through them pretty quick. By far the most flamed in the air.

Even when I backed off a bit and ran only recommended set-ups, they still only lasted me an average of 60 flights (at 8mins per flight that's 480mins -- very close to the other numbers posted).

After a couple failed and shorted -- blowing up both the motor and the ESC -- I also went brushless and rarely use cans anymore (I have a few kids planes we fly very occasionally with gingerly treated brushed motors).

Threads like this remind me just how badly I hated those "burned motor" days.

Darren
Feb 24, 2004, 04:08 AM
flyin' fool
goldguy's Avatar
Come on guys, lets not give the lowly can motor a bum rap here. I have had good success with them, but I treat them right. It's easy with a Whattmeter, the first investment all electronuts should make, saves money.

I read the same complaints about BL as well, they fail just like the cans can, or is that, cans do. Anyhoo, mostly, fried motors are usually the fault of the pilot/builder and not the motor manufactures.

If you strive to keep the volts up and the amps low, you can't go wrong with brushed or brushless.

If you want to stay with inexpensive brushed motors and want an improvement in preformance and efficiency, try the Acro 280BB in your GWS boxes, great motor and replacement bruches too.
Feb 24, 2004, 04:34 AM
Registered User
vintage1's Avatar
Or better still, regear them for 3s LIPO and drop the current to something sane, get the same power, at far less current and higher effciency and treble your flight times!

Not sure how the elevated RPM will relate to brush wear tho.
Feb 24, 2004, 05:03 AM
Here's my take on EPS300/350 failure mode:

https://www.rcgroups.com/forums/show...34#post1635534
Feb 24, 2004, 10:06 AM
Tight is Right
Darren Hintze's Avatar
I don't give the cans a bad wrap. Given that they were not designed for our hobby, and how kits with them have revolutionized RC flying, I think they are fantastic.

But they aren't for someone who flies like I do either.

How is Voltage related to brush wear: Higher RPM = more friction, bounce and wear.

Granted, I don't think either is as detrimental as the higher temps of more current, so until max rev is reached, I'd maximize V.

But I think we've also already had LONG discussions about that.

~Darren
Last edited by Darren Hintze; Feb 24, 2004 at 01:16 PM.
Feb 24, 2004, 01:31 PM
Clinger, MAGA
rclark's Avatar
Quote:
But they aren't for someone who flies like I do either.
Exactly. I know I was pushing the can motors to get the performance 'I' was looking for (although 7/8 cells and less than 10A doesn't seem like I was pushing that hard ) . If I flew them to 'last' (very low amps)-- it would have been 'no fun' flying. Who wants to limp around the field?


Quote:
I read the same complaints about BL as well
I've only had one fail and that was a Hacker B20L (gearbox, rotor, and rear bearing problem) . I've yet to have any another BL fail . Much more reliable -- if you treat 'em right . I have a miniAC motor (oldest of the bunch) that has more than 7000 minutes on it now and still as good as the day I bought it two years ago -- ready to go again this year....


Quick Reply
Message:

Thread Tools