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Old 11-06-2003, 11:00 AM   #61
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Quote:
Originally posted by seaball
good pic,

it does bring to light something else, at least for me. and that is this:

though exaggerated, it is easy to see that timed cuts take formerly alligned brushes and, basically, misalign them.

after the many claims i've read about aligning the brushes and the profound effects that this has on overall power #'s, i'm wondering how affective this method is. i do undertand the inverse proportionality between torque and rpm when timing is changed, but wouldn't overall power #'s decrease from poor alignment? or does advancing the timing alter the amount of current that the motor will draw, in turn, making a generally more aggressive motor?

uh oh.

keep in mind that realigning the hoods after the cut is made will negate any timing effect that the cut was intended to accomplish.
seaball - No, timing the brush will not 'misalign' the brush. The brush face has a specific contour molded into it. The contour of the brush face is designed to match the curvature of the commutator. The brush hoods are aligned so the brush face makes complete contact with the commutator. Cutting the brush to advance or retard the timing only effects where the brush touches the commutator and not how the brush face is aligned with the commutator.
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Old 11-06-2003, 11:09 AM   #62
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OK hear we go. I may be eating crow on this one.

I only tested one motor and used three fresh brush sets. To really figure this out, more motors and more brushes will need to be tests. (any body want to send me more motors? Putnams are prefered. LOL, yeah, that the ticket)

There will probably be lot differences on the brushes I used. Slight comm wear might also impact each test, as I didn't freshen the comm between runs. The total run time is much less than one battery run so is probably not an issue. The motor showed no noticable increase in temperature during this test. It was warm after the initial break in and stayed about the same. I did at least three dyno runs for each configuration and made sure that at least run 2 and run 3 did not have any significand difference. (break in might not have been completed prior to first run, I did look at the brushes to make sure they where fully seated.)

Motor orientation:
End bell up, shaft down, looking at the shunt end of the brush.

Brush Cuts:
What I call a leading edge cut is removal of the right side of the brush, or the side of the brush that sees the comm first.

Trailing edge cut is removal of the left side, the part of the brush that sees the comm last.

Forgot the measure the width of the brush face after cutting. I did it on a jig and the width is approximatly the width of a demel stone cutoff wheel.

Motor/brushes:
Almost new monster pro with trinity 4503 brushes.
Fresh cut on the comm with 300 second break at 2.5v (that's what my power supply gives me, an old computer power supply) in for each brush, no comm drops for break in or dyno runs.
Brush hoods aligned for center brush wear and contact.

Dyno:
Fantom powered by a 12.5v lawnmower battery with fresh charge and zero voltage/amp drop during test.

Tested at 5V.

Results:
4503 Full face, red+/grn- springs
Power: [email protected],688rpm
RPM: [email protected]
Torque: 892 gm/cm
Effic: 53%@14568

4503 Leading edge cut, red+/grn- springs
Power: [email protected],086rpm
RPM: [email protected]
Torque: 836 gm/cm
Effic: 68%@14719

4503 Trailing edge cut, red+/grn- springs
Power: [email protected],713rpm
RPM: [email protected]
Torque: 887 gm/cm
Effic: 57%@13,673

Conclusions:
Full face is best, but with slightly less efficiency then a trailing edge cut. Trailing edge cut has slightly less power at slightly higher rpm, but with 4% more efficiency. Speculation: removing the trailing edge will slightly reduce the brush wrap and improve efficiency.

Leading edge cut sucked. The only thing good is much better efficiency. It did get to max rpm faster, but at a much lower max rpm
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Old 11-06-2003, 11:11 AM   #63
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Hey Mike D, what stock motor did you use at the Halloween Classic race. Also what pinion and spur did you use for your 1/12th scale car and your TC-3 if you could tell me I would greatly appreciated it thanx.
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Old 11-06-2003, 11:32 AM   #64
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Quote:
Originally posted by noline
Hey Mike D, what stock motor did you use at the Halloween Classic race. Also what pinion and spur did you use for your 1/12th scale car and your TC-3 if you could tell me I would greatly appreciated it thanx.
noline - I used Putnam's Monster motors for both sedan and 12th scale. That was the first time I ever ran his motors... I was very impressed.

As for setup and gear,
sedan: blue/green brush combo, red springs, rollout ranged from 1.00-1.12, I ran 1.06 in the main
12th scale: blue/green brush combo, green springs, 1.77 rollout.

Let me know if you need any more info.
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Old 11-06-2003, 12:18 PM   #65
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i just this thread and maybe i missed it, but... which is the leading edge? trailing edge?

thanks.
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Old 11-06-2003, 12:24 PM   #66
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go back a couple of pages, we're talking about brush cuts.
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Old 11-06-2003, 12:34 PM   #67
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Quote:
Originally posted by sands
go back a couple of pages, we're talking about brush cuts.

found it. thanks
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Old 11-06-2003, 12:43 PM   #68
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Quote:
Originally posted by RCInfinity
I hope we answered your question. Did you have something in mind as far as motors go?

Yes, Definitely, i'm pretty impressed with the stuff posted here about putnam.

with regards to motors, i also run 19 and mod, so i'd like to see some disscussion with regards to this.

also, with the new 19T motors coming out, im pretty curious, there are alot of variations now.
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Old 11-06-2003, 01:18 PM   #69
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Default Sources for Putnam Products???

Where (online) can we find PP?
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Old 11-06-2003, 01:20 PM   #70
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Quote:
Originally posted by Geppetto
Where (online) can we find PP?
http://www.putnampropulsion.com
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Old 11-06-2003, 03:17 PM   #71
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www.rc4less.com is a good source for Putnam brushes and motors.
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Old 11-06-2003, 04:42 PM   #72
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thanks miked,

you may be on to something. however, as i understand it, brush alignment is not defined as the brush face aligning, or seating on the com, but that the force provided by the brush itself be aligned or directed at the center of the com or arm.

by your definition, the brush hoods could be aimed almost anywhere, and the brushes would eventually break in providing total contact or a full seat. the brush hood alignment tools are out there to keep this from occuring.

in theory, if enough material was removed from the width of the brush, say over 50%, the brush could not direct any force at the center, as it would be offset, and the spring force would inhibit rotation of the com. the brushes would sort of be in shear. if the com were removed, the faces would actually not contact each other, but slide past each other like scissors. regardless of the contact patch, i would not think this scenario to be considered aligned.

i am not trying to be overly critical here for my amusement, but because some people swear by going to the extent of aligning each hood by the wear patern of the brush. insisting that cocking of the brush will exhibit noticeably poor perfermance. which is like within a few .000ths. wouldn't this phenomenon be seen with timed brushes as well?

our timed brush cuts are along the lines of what....030 or so? a typical dremel disk thickness? that's not really negligeable, is it?
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Old 11-06-2003, 05:19 PM   #73
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Default recycled jpeg

perhaps, to explain my concerns.
Attached Images
File Type: jpg advance cut.jpg (26.0 KB, 393 views)
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Old 11-06-2003, 06:37 PM   #74
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Quote:
Originally posted by JDM_DOHC_SiR
So whena re ya going to play with the other motors you know which ones
Ive already started on them...Just got to do some fine tunning!!

ea
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Old 11-06-2003, 06:42 PM   #75
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Default Re: recycled jpeg

Quote:
Originally posted by seaball
perhaps, to explain my concerns.
Small problem guys...you are showing the rotation backwards in the pics if your looking down the motor from the endbell end....I had to go get a motor to look for myself... The cut is correct that is an advanced cut..but your showing rotation backwards.

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