ModeratedUser30082018

iTrader: (-1)

I already have a very nice bit on my trinity lathe. Here you can see one fresh turned comm in the middle next to 3 brand new never used arms. 2x Reedy 6T and a cheap 10T paper weight that i bought just today. Safe to say that they dont come from the factory veey good... especially the cheap one.

I also was looking for a dyno... but to my knowledge, they are not real dynos in the sense that they dont measure torque but only rpm per volt... I cant see anything available on ebay. Can you recommend where I can get one at least?

If a magneto charger is not required, do you know where I can have that service provided? I'm sure there are plenty of machines collecting dust.

daleburr

I think you're describing blinky racing, in which case we're on the same page. I don't understand it's popularity. In boosted or mod a decent motor will last a couple of seasons, and you have enough power that there's no need to throw money at it.

miller tyme

iTrader: (5)

LOL, In that I agree completely and I'll add that a little profile tweaking can adjust the power band to make an average motor perform very well

howardcano

iTrader: (37)

I have an old Robitronic that works pretty well on brushed motors. It is a flywheel dyno that measures both torque and speed, so it can calculate output power. These occasionally (rarely!) show up used on Ebay or here on RCTech.

The Robitronic has an internal resistance to simulate NiCd/NiMH cells, so it won't be too accurate if you run your motors on LiPo. But for comparisons between two similar motors the data is still useful.

Racermac73

iTrader: (3)

Lol i forgot about the dynos.. walk down the hallway at a hotel race back then and all you heard were dynos going off everywhere

1spunspur

iTrader: (1)

Yes, the water method is for your brushes it also puts a shiny coat on your com. A silver composite com would be ideal but expensive as mentioned above .there is nothing you can do to stop the wear. that's just the way it is.

ModeratedUser30082018

iTrader: (-1)

1spun, i think you misunderstood. I was referring to the bushes, not the brushes.

I'm not too fond of the idea of just "accepting it because thats just the way it is". I think there is some validity to comm drops.

I still can't find any dynos for sale... anywhere. Are there any write ups of people making their own? Since I have a lathe and mill, im no stranger to metal work... its just the electronics side I'm not sure about. A flywheel is a good idea if I could accurately time it and log rpms. I can't see why such a system would be strictly for brushed or brushless motors. I've also seen some people use a slave motor... again, how power is measured, I'm not sure.

This looks handy, though its only half the picture as its only going to measure electrical power, not mechanical power... so I will have no idea of efficiency.

+ YouTube Video

https://www.youtube.com/watch?v=kfs4Bs3H7gw

gigaplex

iTrader: (2)

I don't think the water method is for the bushes. At least when I used to race silver cans, it was used to break in the brushes

howardcano

iTrader: (37)

Here is the thread on my flywheel dyno for sensored brushless motors: http://www.rctech.net/forum/radio-el...no-thread.html

I have recently acquired a suitable flywheel, and I now need to make a mounting system to hold everything.

I can provide you with the electronics if you can make the flywheel and mount. PM me if you are interested.

In theory, a flywheel dyno can be used on any motor, brushed or brushless. The problems for any particular system lie only in the execution. The Robitronics flywheel is too light for our 540-size brushless motors, giving insufficient data. Also, my dyno uses the motor's Hall sensors to gather the data, and these (of course) don't exist on a brushed motor.

To get accurate timing data, it is imperative to have a direct connection between flywheel and motor. A gear or belt drive has far too much lash, play, and flexibility to get the accuracy I desire. In addition, the time measurement must have resolution on the order of a few microseconds to get the accuracy I desire, and commercially-available systems fall far short of this.

ModeratedUser30082018

iTrader: (-1)

You've been working on that since 2015. Have you sorted it all out yet?

Regarding the electronics, I can manage sourcing parts and soldering... its more schematics and software i'd need help with. For data collection, you don't you use an automotive crankshaft trigger wheel? That should give you plenty of resolution. Hal effect sensors are very easy to set up.

After a quick look through those photos... I hope you're getting a bigger flywheel lol You need a much better bearing supports as well. If the flywheel isn't dynamically balanced then you will destroy your motors bearings. I too am not a fan of the belt or gear drive either. direct shaft drive is the way to go

howardcano

iTrader: (37)

Actually, a better description is that I haven't worked on it for the last year! Everything except the flywheel and mount was done a long time ago.

Yes, the new flywheel is bigger than the Robitronic, and will require a support in addition to the motor shaft. That is all addressed in the dyno thread.

You'll need to set up a suitable sensor for a brushed motor. The Hall sensor/trigger wheel sounds good, or you could just use a cheap/used sensored brushless motor for the sensors.

If you want to pursue this, we should move our conversation over to the dyno thread.

Bar

iTrader: (1)

deleted

sport10

I am surprised all the others forgot to mention properly aligning the armature in the can. I usually reassemble the motor minus the shims and see where the natural magnetism aligns the armature and shim it to match this. Also, the orion V2 was the angled style motors and could get around 40 runs per rebuild.

1spunspur

iTrader: (1)

Great,... you're one funny guy. Howsomever, I used to use a slave motor and volt meter and check the voltage on the slave motor. Higher voltage =higher RPM.

ModeratedUser30082018

iTrader: (-1)

Interesting idea. However I was told that it is better to keep the slave motor an open circuit as to not induce any arcing while breaking in? Or will the volt meter not allow any current to flow, however small?