Cutting a motor commutator & motor tweaks

[EddieO]

My fantom has the 27t motor...I use 2.9-3.5 volts depending on the arm.....bigger comm and/or heavy armature needs to the extra voltage to spin it faster....Anything over 4 volts is just too fast.

In my guide you can see how to its setup to a degree along with how to use your finger.

Glad you like the guide. Sorry I took so long on them, just busy busy busy, but after getting yelled at by a longstanding customer, I made it a goal to get them done....I have a new camera on the way as well, so better pics along with videos.

Later EddieO

[cartronicshn]

Great write up Eddie

[mrG]

I'm hunting down a pulsar charger to run my lathe.

Does anyone see an issue with using this for a power supply, all the numbers look good.

AC to DC 12V 15A Regulated Switching Power Converter Supply Metal Silver | eBay

[Hotrodvw]

I used to cut my comms after every weekend of racing off road. My first comm lathe was actually a mini lathe made for doing jewelry work. It worked great actually. I retired that lathe from comm work, and picked up a real comm lathe last yr. I had a hand full of motors that needed a freshening up as well. I am one of the guys that likes to let the magnets dictate where the comm will ride int he can, and then shim it appropriately from there. I've never worried about brush position (top to bottom) on the comm. It's a transfer of electricity, nothing more. Top or bottom makes no difference in my eyes. I'm more concerned with a fresh, even cut. I clean the end bell and can with brake cleaner and compressed air, as well as the armature itself. I haven't ever been super anal about my motors. They always worked and made the same power, never had an issue. This comm was really worn, took some serious cuts to level her out. I don't run brushed mods anymore, so this was just a matter of freshening them up for the shelf LOL...........and to play with my lathe.
Before


After

[EddieO]

Originally Posted by mrG

I'm hunting down a pulsar charger to run my lathe.

Does anyone see an issue with using this for a power supply, all the numbers look good.

AC to DC 12V 15A Regulated Switching Power Converter Supply Metal Silver | eBay

Those power supplies work just fine to power a run in device along with most chargers. They typically come from military or the like, as they need to be replaced every X hours regardless of failure or not. They are sold cheap even though nothing is wrong with them. Usually all they need is a AC cord hooked up (find old computer cable, cut off female plug and add connectors.....)

Later EddieO

[rex21]

I just bought a com lathe and some other motor related tools, and a motor lot or two. One lot included a Fantom can with the magnets loose inside. I found a Fantom 17x2 arm that looks barely used in another can with no label. Neither had an endbell on them.

What should the correct endbell say on it if I have it here?
What is the best way to glue the magnets back in?

[EddieO]

Thats a Trinity D6....should have an endbell thats says Trinity/Epic on it....good can. Looks to be a RPM blank arm, which is normal for winds over 10 from the racing days.

Later EddieO

[mrG]

So is there a how to set/check your lathe for everything being aligned? I cut my first comm and it looked good. I measured and it was within .0005" end to end. Am I good?

[EddieO]

Pair of calipers....0005 is pretty good tolerance....all you can do is make sure its square....square should cut straight unless something is tweaked, so its not really square.

Later EddieO

[mrG]

So are we shooting for the same diameter all the way through? What is acceptable?

[Hotrodvw]

Just like EddieO said..........yes

[mrG]

Okay so I rebuilt a couple of motors and the second one I did I rotated the endbell 180. I broke it in and put in on a aps dyno charge (I know its not a true dyno) for 2 minute @ 7 volts. It was running quite a bit warmer than the other motor. Thought? I'm a newb with the whole motor lathe/rebuild thing.

[EddieO]

7 volts? We didn't even break in race motors above 5.

I break in everything at the shop at 3 volts pretty much....

Later EddieO

[mrG]

Broke it for 5 min @ 3 volts and then did a test at 7, too much too soon?

[mrG]

Ran them both at 7 volts

[EddieO]

The rpm checker on the unit should take all of 30 seconds or so to get a good reading. 5 volts should be plenty to take a good reading, but even 7 volts works...

I never used the unit much back in the day, I grabbed a few on ebay a while back but only use it to break in motors.

My guess, brushes were not broken in all the way....or you have a shorted armature.

Later EddieO

[Hotrodvw]

I don't know any of us back in the day that broke our motors in. Cut them, fresh brushes, and go racing.

[EddieO]

I broke every motor in I ever raced....was always the key to being fast. Many of the guys used to just buy and run....my dad raced slot cars in the 60s, and told me about breaking them in, so I always did.

My favorite trick was to break them in, then pull them back apart....skim the comm just enough to make a pretty much new surface, reassemble and run in for 30 seconds.....motors were always fastest this way....

Later EddieO

[mrG]

Other than using an ohm meter to check each section of the comm to the adjacent one and comm to the shaft, are there other tests to do?

[EddieO]

You can use a multimeter to check comm segment to comm segment....resistance should be consistent between each (a/b, b/c, c/a). Two other checks....each comm segment to stack (make sure you are touching bare metal on the stack) and each comm segment to shaft.

You can also use an LCR meter to check inductance...same as the first process above.

Some shorts won't always show up though, especially heat shorts or the famous stalled armature. The heat short can sometimes be sniffed out by warming the armature up.....doesn't always work though.

Later EddieO