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Old Jul 12, 2002, 03:47 PM
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United States, CA
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Brushless Motor Break-In Period?

Even if not required by the mfr, should a new brushless motor go through a break-in protocol of some sort, or at least a gentle running period, to improve its lifetime or performance?

Advice appreciated.
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Old Jul 12, 2002, 03:54 PM
MKH
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Ohio
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Without brushes, there isn't anything to break-in. Just set it up per the manufacturers instructions, and use it. It's part of the beauty of brushless!
MKH
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Old Jul 12, 2002, 04:08 PM
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Mark Wood's Avatar
United States, CA, Bear Valley Springs
Joined Feb 2000
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Quote:
Originally posted by MKH
Without brushes, there isn't anything to break-in. Just set it up per the manufacturers instructions, and use it. It's part of the beauty of brushless!
MKH
Yup! No BS flying. The best thing I've done since I first started flying was dump the Endo setup in the Big T (Nothing against the Endo. I just got tired of the constant maintenance) and drop in a Jeti 30/3 on DD. Quiet, almost NO maintenance and the plane hauls donkey. Fine by me.

mw
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Old Jul 12, 2002, 04:16 PM
RIP Ric
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Marietta, GA
Joined Jun 1999
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For a third opinion.. no, no gentle break-in required. Solder 'em up and let 'em rip!

This is where even the less efficient brushless motors still outshine a brushed motor - no "break in", and no ongoing maintenance. Mark says virtually - not sure why - unless he means geared, in which case gear lubrication is important.
..a
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Old Jul 12, 2002, 07:00 PM
tic
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should I be disassembling my maxon gearboxes and changing the grease???? it's sealed... and I didn't get any documentation advising to do so.. I'd imagine it would be good for a VERY long time.. unless grease molecules sheer like motor oil..
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Old Jul 13, 2002, 12:59 AM
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Canada, ON, Ottawa
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Tic, you should be replacing the grease in the maxon gearbox an a somewhat regular basis. The gearbox actually screws off of the brass piece attached to the motor. You may need to gently hold the motor in a vice (protect motor with something soft) and then use a set of pliers to twist the maxon gearbox off. Unscrew the same direction as you would a normal screw.

The above assumes you are talking about the 4.4:1 gearbox sold with hacker b40s, Kontronic speed 400/480 series, etc.
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Old Jul 13, 2002, 08:13 AM
RIP Ric
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Marietta, GA
Joined Jun 1999
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I have read instructions on how often the gearboxes should be serviced.. have no idea what I did with the, however.. As a general rule, the sealed GB's tend to go a lot longer between service than an open frame unit.

..a
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Old Jul 13, 2002, 08:18 AM
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BREAK IN.....

Exercising the better part of caution, maybe a little break-in maybe of good use.

There maybe a defect from assembly (i.e. loose metal part in motor) or a bearing may fail prematurely. I suppose a 15-30 minute run-in period would do good just to make sure everything is fine. I would take special attention to the bearings. Remember, these motors achieve very high RPMS.

Doing so will allow you to avoid the destruction of another item or the entire plane due to motor failure.

I remember my car dealer telling me once that breaking in a car is not actually for the engine as these have been broken-in in the factory but more to prevent accidents from failed axles, bearings or in some case, transmissions and entire suspension systems falling out due to poor assembly. (I dont want to hear comments about what brand car I drive!)

The again, you could always return the item on warranty (but that won't cover a crashed plane).

Finally, it is good to break-in a motor, but not a necessity.

Rgds, JT
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Old Jul 13, 2002, 10:42 AM
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Most motors are run at the factory to ensure accurate assembly.
..a
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Old Jul 13, 2002, 09:38 PM
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Just like the cars.

Mal
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Old Jul 13, 2002, 09:52 PM
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As with any mechanical device, a gental and constant run-in period does no harm (ball-bearings and gearboxes are no exception). In the garage I call it "lapping". Lapping should be done with any moving hardened metal such as bushings, rings, rear-axles, valves, and transmissions. This is especially the case when dealing with the close tollerances used in sealed gearboxes that often are mated with brushless motors.

Read over the below link for some ideas on how NASA uses/breaks in bushless motors and their gearboxes (brushed motors will not work in a vacume....there is no air to circulate around the cumutator/brushes for cooling this hot-spot, thus brushless motors are quite popular with NASA)

http://www.grc.nasa.gov/WWW/spacemech/vol1.html

Quote:
For better protection of the gear teeth, the through hardness or surface hardness (or both) may be increased, and the surface finish of the teeth improved through lapping, and prerun-in.
And from another site:

Quote:
"New gears and bearings are lapped at the factory but some are lapped more than others and even with lapping they are still not lapped under the same pressures that driving creates. The loads generated while driving force any microscopic high spots on the gear teeth back into the surface of the metal. This is called "work hardening". Work hardening is similar to forging in the way that it compresses the metal molecules into a very compact and hard formation. This can only be accomplished if the metal surfaces are lubricated and the temperature is not hot enough to change the molecular structure [like running a shiny-new brushless/gearbox combo at 100% straight out of the box] due to the heat alone. If the temperature of the metal gets hot enough to change the molecular structure it will soften the surface instead of hardening it. This may seen like a balancing act but it all happens easily & passively as long as the oil keeps the gear cool while it is breaking in. All new gear sets require a break-in period to prevent damage from overheating. "
Also, when a vendor says they "pre-run" their products, take this with a grain of salt. Case-in-point:
Dealing closely with network-gear maker CISCO (you would think they of all companies would adhear to this) I find a DOA rate of about 5%. Not very good, considering that their equipment is delivered already "burned in" (and not in a literal sense).

Pullin_GS
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Old Jul 14, 2002, 08:46 AM
tic
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But the real question here is.. would you buy CISCO stock here at 14 dollars a share w/ a PE in the 90's.... lol.... very good points on breaking in ANYTHING w/ gears and close tolerances. I didn't do this with my hackers... oh well...
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Old Jul 15, 2002, 02:14 PM
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Brushes obviously not an issue here; mainly concerned about wear-in of gears and shaft bearings which I think has been addressed - Thanks all for your inputs. At the least, seems that an initial period of conservative operation won't be harmful, might actually reveal a latent problem before major harm is done.
Quote:
As with any mechanical device, a gental and constant run-in period does no harm (ball-bearings and gearboxes are no exception).
Shouldn't a break-in, if one even considers it worthy here, be an initial period of gentle but varying operation? Seems that running at a constant condition (speed, torque) would tend to establish clearances and wear patterns happiest at that particular speed, with higher gear/bearing friction and wear at other speeds?
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Old Jul 15, 2002, 03:43 PM
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I would think after a 3 min run in period at 3rd throttle then winding it out for 10 seconds back down to 3rd throttle and back up to full. Should give you a good idea if the motor is "Up to snuff" I myself would do this WITH a prop on and placed into whatever you are going to be flying it in.

Mal
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