Skaldiddog's "Progress"

[SkaldidDog]

Thanks for both sides of the coin Gents. I'm gonna entertain the option that I have at my disposal every night...makin' stuff!

All of this depends on my link testing so none of these needs are even material yet. I'll keep you posted.

Thanks again for the tech chat.

J

[JohnRobHolmes]

The basic reasoning isn't what racer got results with cut brushes, it is that Joel isn't the guy that wants to cut brushes and recut them every 2mm of wear.

I'm sure there are plenty of cases where motors will make more power with thinner brushes, 5 slot being one of them. Efficiency tanks when the brush is too wide. When you were thinning the stock motor brushes, I would assume you were removing trailing edge so that the effective timing was more advanced than stock to give the higher power. Neato. You are comparing apples to oranges with brush size though. Power is needed in a crawler at low speeds where brush drag is not a factor, and the lowest resistance interface will rule. Its ALL torque which is made possible with shoving amps through. In a high speed motor we have to balance the contact friction with the commutation period, and as the rpms rise there is more opportunity to gain power with reducing the brush contact area and use rpm to make power instead of torque. If cutting brushes really helped in a crawler we would already be doing it. Thanks for the fun stories about racing history though.


If you want a reversed spring on your motors Joel, we have a source.

[EddieO]

Cut brushes don't require you cut them every run....not sure where that comes from. Like anyone rebuilds there motors anyways....

Assumption wrong.....first the MVP was cut equally on both sides, second reducing the trailing edge doesn't magically increase timing. Old RC myth that was proved not correct long ago. Slot car guys as well have proven it BS. Many companies marketed timed brushes....they didn't work at all in increasing the timing. Go cut the trailing edge and dyno a stock motor....you won't see power increases from the magical timing advance...it doesn't exist.

While race motors are high speed, they are driven at numerous low speeds and in many high amp issues. Not being able to shove amps through would be just as problematic under your idea.....maybe in Oval that theory would work....wait, they hated the v2 motors in oval though.

And maybe you don't cut brushes, but I have....it works in certain applications....its not popular though as 99.99% don't even rebuild the motors when they should...so the telling them they need to cut more brushes isn't gonna happen.

Besides, reducing the brush a bit in width ain't gonna shove juice into the comm any slower with 18 awg wire coming from the ESC...

And your welcome for the history lesson....fun way to learn stuff is by studying history.

Later EddieO

[ROWDY RACING]

Sup Joel how's the weather in SoCal these gays?

[SkaldidDog]

Originally Posted by ROWDY RACING

Sup Joel how's the weather in SoCal these gays?

Raining Men!

[ROWDY RACING]

Originally Posted by SkaldidDog

Raining Men!

Hallelujah!

[Frankenwheely]

Originally Posted by SkaldidDog

Raining Men!

Cocks and Dongs!?

[ROWDY RACING]

Originally Posted by Frankenwheely

Cocks and Dongs!?

#bawznweinaz

[Frankenwheely]

Originally Posted by ROWDY RACING

#bawznweinaz

Finally some posts I can understand. Too much scientific motor tuning made my head hurt.

[JohnRobHolmes]

Removing trailing edge increased timing on our checkpoint team motors, I did it on all five slots and tested with three slots. Neutral shifted three degrees from the mark and speed differential between forward and reverse increased. Front and rear motors required mirrored cuts to make timing self evident and consistent.

I would induce that the stock motors benefited more from decreasing the commutation duration as opposed to timing shift brush cuts.

Don't get me started on thin wire. I'm only talking about brushes here

[EddieO]

John, so even though there is 30 years of racing data that shows a timed brush does not work, your going to sit here and tell me it does? When Mike Reedy, Big Jim, Jim Dieter (worked at trinity and didn't even use the timed brushes), etc all said they didn't increase timing like claimed....if it did, we would ALL of used it.

Removing the trailing edge does not increase timing, it decreases the duration, that's it. You can't magically make the leading edge see timing any sooner regardless of what's done to the trailing edge. On the flip side, if you trim the leading edge while leaving the trailing edge the same you will RETARD timing, as now the the brush is not firing when it normally would. So in your Checkpoints the reason you had to mirror the cut is because the other would of retarded it. In essence it works to retard, but not increase....you can only increase by rotating the position of the brush relative to the magnet center...

I'll agree on the wire...but magically the funnel of power does not get bigger once it hits the brush. I'll argue the non-conductive bottom plate on most motors hampers current flow more than a small brush cut would.

Sorry to clog up your thread Joel...

Later EddieO

[greencrawler]

Here we go again!

[JohnRobHolmes]

I'm going to say maybe you are arguing semantics here, when I'm going by engineering definitions. The average brush position is where timing is calculated in all my books. Degrees of timing are based from ZERO, which is defined as when a motor ideally runs equally in both directions. If I remove trailing edge, I have moved the mechanical zero point by your statement that reverse got retarded - whether or not the speed increases in forward vs an uncut brush.


I guessed wrongly that the trailing edge cut was used to help stock motors, and stated how it affected our motors. This isnt some attack on all of your mentors dude, but you can think that if it helps you stay on your toes.


And Joel, I'm not sorry for anything sweetums. I'm going to send you a pile of decade old brushes loose in a box with a brush cutter so you can practice getting graphite everywhere.

[rockhugger]

This is like one of those epic rap battles.

[xkill]

This got me interested on how to cut brushes!
Google here we go!

[EGRESSor]

just an old drawing



shows a 5mm wide 4mm high laydown brush in blue
1mm cutted trailing edge
so it acts like an 4mm wide 4mm high brush w. 10° advanced timing , shown in green

so you will loose some rpm by the reduced brush/comm overlap of the narrowed brushes
may get some rpm back with the timing advance
may loose some power
may get some efficiency

or not

[stubs179]

It's is like the good old days in here! I like to see the enthusiasm.

And there's no need to apologizes to Joel, its productive information.

[SkaldidDog]

The more info I get the happier I am.

Nice to see you around Christian!

J

[EddieO]

The picture isn't really correct.

The brush is stationary, it doesn't magically move because you trimmed the trailing edge. Timing is based off the brush location to the center of the magnets. At zero timing, your brush is dead center of the magnet. Cut the trailing edge, the leading edge REMAINS at the same point. The comm is rotating, NOT the brush or magnets. The leading edge of the brush will hit the comm slot to the next segment at the same time as before with the trailing edge cut, only thing different is the comm slot will pass through the brush faster since the trailing edge has been trimmed....hence the decrease in duration. The next comm slot will NOT reach the leading edge of the brush any sooner in relation to the center of the magnet.

On the flip side if you trim the leading edge, now you are increasing the time it takes for the leading edge to hit the comm slot, along with decreasing duration AGAIN.

I'd draw a pretty picture if I could, but I can't draw worth a crap...

In stock racing, 1 degree of extra timing was to die for....we used to look for arms that were advanced, even to the point I had a $400 tool made to measure it. Also where the term cranking the comm came from for the cheaters....even just a slight bump in timing would turn a good motor into a rocket.

The proper way to trim the checkpoint brushes would be BOTH sides to reduce overlap...still would of been right around the same size as a standup.

Crawler motors or not, the same principles apply......

Later EddieO

[EGRESSor]

i added a 4mm brush in green with zero timing for you



hope that helps