Skaldiddog's "Progress"

[JohnRobHolmes]

Mechanical brush timing has been defined for at least 100 years by the commutating plane, the mid point between leading edge and trailing edge contact extended in the radial direction. It does not take into account brush angle, relative brush modifications to yesterday's gimmick, or anything else except just the two points. If leading edge was the only factor in the timing then every width of brush would also have a different zero location, which is not the case.



Taken from Hawkins Electrical Guide, published in 1914 and considered to be the standard for all industrial motor definitions since.

 

[EddieO]

Yes, because books from 100 years ago are always still correct about stuff. (though in no way does that picture back up anything you are saying) I have many of those books as well, lots on just motors. Stuff they say can in NO way work, works on our motors. Are these the same books that didn't tell you what a lamination was?

But by all means, you win......I can do nothing but simply shrug my shoulders. The great JRH is always right when it comes to motors..... You can continue to tell your followers timed brushes work...


Later EddieO

 

[JohnRobHolmes]

By your own statement, timed brushes affect reverse direction. How is that not a timing change? Tell me that history is worth studying a few posts back, then dismiss one of the pivotal books that is use as reference in terms and theory? :???:

 

[EddieO]

I explained that multiple posts back...feel free to read it again.

I can't explain it anymore technical for ya, it was explained to me by an RC motor legend who moved on from RC and is now one of the head engineers for the makers of the Dremel tool....

Yes, History is well worth it...you can see how stuff was done, what worked and what didn't. I didn't say to ignore the book, simply that stuff written 100 years ago has changed over time...on the flip side, a timed brush has shown over 30+ years of racing in RC and Slot cars that they DON'T work as stated doesn't magically change because we are using 35t armatures in rebadged race motors instead of 27t armature...

But again....you win. All Holmes Hobbies customers, Timed brushes are the bomb...please use them...

Later EddieO

 

[TSK]

Based off everything I've read in the last couple pages, and based off what my reading comprehention scores say,

Both of you are right.

Timed brushes DO WORK, but only at RETARDING timing.

Court is adjourned.

 

[JohnRobHolmes]

But again....you win. All Holmes Hobbies customers, Timed brushes are the bomb...please use them...

Later EddieO

I've made no statement of performance gains in any of this, but please feel free to continue harping on how much I must love running timed brushes in everything. It makes sitting by my CNC a LOT more entertaining.


To recap, we can't agree on the basic definition of mechanical timing and I win for insisting that books used in electrical engineering are references that can be trusted for information in regards to electrical engineering. So what do I win, maybe you have a box of timed brushes I can install backwards so that timing is affected while I visit the pacific northwest? Fawk that, I'll put one in backwards and one in normally so timing is affected in BOTH directions and 30 years of racing lore will self implode into a ball of burnt stock motors installed in Wraiths. Now everybody can win!

 

[EGRESSor]

first let me say , i´m a fan of both of the greatest motor builders here
i´ve got great motors and parts from both

so please stay technical
no bitch fight , as long as you dont show your tig bits ;-)

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.

the brush itself is still in center with the mags , both side cutted changes nothin but the brush to comm area
one side cutted and the brush to comm area is of center , but the uncutted part of the brush is still in Center with the mags

just think about a brush as wide as the comm diameter , cut it to the half wide , that reduces the brush area to the half , and changes the Timing

i´m not sure how much rpm´s you will loose by the narrower cutted brush
and how much you will win with the Timing advance
maybe the same at the end , i dont know

 

[EddieO]

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.

Sure looks like it....

And yes, come to the PNW...enjoy our rain...and just think weed is legal here!

Later EddieO

 

[JohnRobHolmes]

In the case of the five slot Checkpoint, cutting the trailing edge did in fact help performance because the brushes were too wide and overdriving the coils causing amp ripple. I could have cut either side, but cutting the trailing edge ensured that visually zero timed motors actually had a few degrees built in to help brushes wear better. Very specific case, and back when people insisted on zero timing and I was being sneaky to increase brush life. We were able to increase brush life two fold with the modification on visually zero timed motors. The proof of timing changes occuring was the wider RPm gap between forwards and reverse with trailing edge cuts VS symetrical cuts. If reverse has become slower, then forwards has been advanced by definition of how timing affects forwards and reverse speeds.


So I am saying that trailing edge cuts are beneficial for performance in the case of checkpoint or laydown brushes combined with 5 slot armatures. But it's not the timing shift that is the end goal, it is the duration reduction. The timing shift was just part of moving the face a bit.

 

[SkaldidDog]

All bent out of shape...

Ok E/T, here are the links I'm planning on shaking out for a couple of weeks. Single bend close to the rear. Bend angle and position places the distal link section parallel-ish with the shock at full twist. More acute bends caused binding.



Full twist.




J

 

[JohnRobHolmes]

Tight tolerances dude! Looks really well planned out with how the bends follow the shocks close at full twist.

 

[SkaldidDog]

Tight tolerances dude! Looks really well planned out with how the bends follow the shocks close at full twist.

Learning that bend cost me a set of VP links. We'll worth the lesson. The next set can get a little closer...I think.

J

 

[SkaldidDog]

Mo bigguh hangers and servo bling

I finally got sick of looking at my scraps of aluminum acting as my servo/servo horn mount washers. I found a scrap of faceted 3/8 7075 rod and sliced off some new washers. Quick fix and sunk cost. My kind of mods.





Blue Voodoos are coming along nicely. The take about 15-20 packs to break in depending on the rock. I like my small "hangers" on my silvers so I stepped it up a notch on one of my blue sets. These are actually the side wall crest from a blue that Frankenwheely gave me a while back. I like the way they work vs the small block hangers. Next set of blues will have them on both sides of the tire. As usual going to push the cost benefit ratio until I need to stop.

Pre glue...



Post glue.



They will definitely increase the life of the inner row of pins. Perfect for long crawls.

80Gator;-)

 

[TSK]

Links look great and I've never noticed that support bushing/flange thing you use to secure your servo horn.

And those sidewalls remind me of Leopards.:ror:

 

[JohnRobHolmes]

Sunk costs? You sound like an edumacated man!!

 

[SkaldidDog]

Links look great and I've never noticed that support bushing/flange thing you use to secure your servo horn.

And those sidewalls remind me of Leopards.:ror:

That "washer" is new. More artistic than anything.

Sunk costs? You sound like an edumacated man!!

I'm the king of sunk costs.

Man overboard!

J

 

[crawl-o-matic]

Do they change the tire flex at all? I like it"thumbsup"

 

[SkaldidDog]

Do they change the tire flex at all? I like it"thumbsup"

None. I tested this after I glued the first few on. I pressed the "corner" of the tire and noted how far down the sidewall the bump went before it stopped. Same distance with or without big hangers. Next set will have outer lugs that don't go as far down the outer side wall. Too much of a snag risk. Just a little corner lug may be perfect. Gotta try it before I can rule it out.

J

 

[ROWDY RACING]

None. I tested this after I glued the first few on. I pressed the "corner" of the tire and noted how far down the sidewall the bump went before it stopped. Same distance with or without big hangers. Next set will have outer lugs that don't go as far down the outer side wall. Too much of a snag risk. Just a little corner lug may be perfect. Gotta try it before I can rule it out.

J

You can send me those and make a new set. :mrgreen:

 

[SkaldidDog]

Really? May I?

Thanks.


:ror: