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Old Mar 04, 2003, 11:57 PM
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Timing GWS 370 motor a step-by-step tutorial

Since I was in the process of timing another 2 motors, thot I might as well snap some pics ... it's been talked about, but I don't recall any step-by-step picture guide. So here goes:

Tools:
* small wire cutter
* split-ring pliers
* soldering iron

Optional:
* Multimeter
* 2x AA or any other 1-2 cell voltage supply
* patch lead


Step 1:
Mark the side of the can along the red dot - this is for your reference.
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Old Mar 04, 2003, 11:59 PM
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Step 2:
De-solder the capacitors from the can.
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Old Mar 05, 2003, 12:00 AM
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Step 3:
Pry open the 4 tabs that hold the back plate on; I find using a small wire-cutter easier than needle nose pliers, etc. Start out with opening up a little on 3 of the tabs to see if the back plate will start to rotate. Remember you aren't clipping out the tabs, just straightening them out a little.
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Old Mar 05, 2003, 12:03 AM
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Step 4:
With the can in one hand (a piece of rubber grip helps out) and split-ring pliers in the other hand, rotate the backplate clockwise around 10mm. I've noticed on some batches of motor, even with all the tabs straightened, it can be difficult to rotate the plate; look for some glue gunk or maybe even excess solder from the caps - or usually a little more elbow grease does the job. Also, you don't want the plate to rotate freely.
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Old Mar 05, 2003, 12:04 AM
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Step 5:
As a reference, see how the red dot has been rotated clockwise away from the initial position.
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Old Mar 05, 2003, 12:05 AM
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Step 6:
Re-solder the capacitor leads; I find that dremeling the surface a little helps the solder and all to bond nicely. I've not had a problem with backplate being too loose after timing it, but if you're not comfortable with the way it rotates, you can put a dab of CA to secure the backplate in place (makes it hard to rotate afterwards though).
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Last edited by Peter Khor; Mar 05, 2003 at 10:53 AM.
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Old Mar 05, 2003, 12:14 AM
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Timing a can motor

Wow --- thank you! You have shown in a few pictures something that I was never able to do from the written descriptions.
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Old Mar 05, 2003, 12:19 AM
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Optional:
If you have a multimeter, hook up a 2 cell (1 cell should be fine also, above 2 cells it can be hard to hold on to the motor) and measure the current draw as you rotate the back plate; I usually adjust for the same current draw - eg; factory position draws .7A, as you rotate the back plate, the current will drop, and then go up again. As it rises, you will hear the motor rev up noticible. Stop when you reach .7A again. Overall you gain aprox 10% to 14% more rpm for the same amount of current draw. You can also advance it a little more (higher currently draw) but you will burn out the motor quicker - I usually go a little higher (.05 to .1A) and get ~100 odd flights a motor on 7-8 cell NiMh.

Another way is to measure the current draw with the motor 1st running in the intended direction, and then matching that current when you reverse the polarity and rotate the back plate. It's really up to you how far you want to advance the timing, you can just go by 'ear' and listen to the motor rev up. imo the ~10mm mark is about right.

Break in the motor as usual, and you're ready to go!

imo there's a world of difference between running a timed and stock motor; all of the GWS planes will now fly rather well on just 6 cell AA nicads; add more cells (and reduce the prop!) and you can cruise the Warbirds at 1/2 throttle. It' no brushless, but it's a "free" efficiency upgrade that you can perform on the supplied system.
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Old Mar 05, 2003, 12:52 AM
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Some notes:

* The 2 timed motors I've broken so far was due to the failure of a brush wiper(as pictured below). It looks to have still a bit more carbon brush on the surviving wipe. The problem with running the motors in reverse (from factory) is that you're running the comm. against the brush wipes - the 'bumps' and other grime/grit/dirt can snap the wipes when the motor's turning at high rpm.

* Since I have nothing better to do, every 20 flights or so, I remove the motor and while running it on 2 AA cells, I spray out the interior and comm. with motor spray (for R/C cars) and re-oil the bushings - it seems to help keep up the power level the motor produces and lifetime of the motor is markedly improved.
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Old Mar 05, 2003, 12:58 AM
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Picture of the comm. from a broke motor - the dark narrow part in the middle is the usual track for the carbon brush. Note the wider swath of 'polished' and slightly indented portion - this is the last couple minutes of run when the bare copper brush wipe acted as the brush itself - at this point in time, the motor was giving out this metalic, scraping, whine - good thing I was facing the wind when the motor cut around 20' off the ground, set the plane (GWS P-51, btw) down nicely on the tall grass.
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Old Mar 05, 2003, 01:06 AM
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Last picture ... view of both brush wipes; you can see how the broken wipe carved the groove once the carbon brush broke off.

Anyways, have fun re-timing your motors and flyin' them!
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Old Mar 05, 2003, 02:28 AM
now that's a wattmeter...
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Quote:
Originally posted by Peter Khor
Some notes:

* The 2 timed motors I've broken so far was due to the failure of a brush wiper(as pictured below). It looks to have still a bit more carbon brush on the surviving wipe. The problem with running the motors in reverse (from factory) is that you're running the comm. against the brush wipes - the 'bumps' and other grime/grit/dirt can snap the wipes when the motor's turning at high rpm.

* Since I have nothing better to do, every 20 flights or so, I remove the motor and while running it on 2 AA cells, I spray out the interior and comm. with motor spray (for R/C cars) and re-oil the bushings - it seems to help keep up the power level the motor produces and lifetime of the motor is markedly improved.
yes that's exactly what happened to the stock motor on my Wattage F-22....
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Old Mar 05, 2003, 07:11 PM
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W. Bloomfield, Mi
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Timing

Came across your photo review. Thanks, A piture in this hobby goes a long way to helping us,

Michael
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Old Mar 05, 2003, 07:43 PM
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Northport, NY
Joined Dec 2002
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Peter:

Thanks so much... I have played around with timing some old motors but have found that I do a lot of damage to the backplate because the metal is kinda soft.
That photo tutorial is awesome!

-Sean
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Old Mar 05, 2003, 08:33 PM
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Highlands Ranch, CO
Joined Feb 2003
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question

Great post!

I think I might like to try this in the future, but I just maidened my slow stick today (after some touch and go "learning" on a sky scooter). I wanted to break in the motor before flying with it, but couldn't get it out of the gear system it came with. I took out the screws, but it just wouldn't budge. Is there a secret to getting it out?

I hope to be able to break in the motor I'll buy to replace this one and maybe start tinkering around with the timing.
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