reedy mvp
09-17-2003, 02:26 PM
#31
i reem the bushings also and align them.
when you test a motor before and after
reeming and aligning the difference is and xtra 400 to 600 rpm and the efficiancy goes up plus power in the combustion engine that is call volumetric efficiancy!
when you test a motor before and after
reeming and aligning the difference is and xtra 400 to 600 rpm and the efficiancy goes up plus power in the combustion engine that is call volumetric efficiancy!
09-17-2003, 02:47 PM
#32
how do you align the bushings? I just tap them back into place until they are flush with the end of the can.. I couldnt imagine they could get any more aligned then that. Either way, they will always end up seating themsleves that way in a run or two.
09-17-2003, 03:56 PM
#33
something i've been doing lately is this.
i'll take the arm out of the can and reassemble the motor w/o it. i then take a precision drill blank (at .125 of course) and slowly insert in each end noting where it naturally wants to go. i've seen many motors that have bushings that don't align with each other. the endbell side is usually the culprit, and can be realigned by just moving the blank until it visually lines up.
another benefit to doing this is to feel the axial drag the bushings cause. once i'm as aligned as i can get it, i'll try to gauge the friction. i then spin this blank with metal polish or buffing compound using a dremel or drill press to both polish and reem the id of the bushing. once done correctly and cleaned up, the blank slides back and forth like it's on ice. it is important not to go too far with the reeming as radial slop will induce vibration and kill rpm's
something else i've noticed is that a motor that is held together and spun free is not necessarily free when assembled with screws. it's very difficult to notice drag in the bushings with an arm in since the magnetic field is so strong. by using a small drill blank, you can nearly eliminated this effect. i will always take any new motor apart and make sure a blank slides freely, or it will before i put the arm back in. i also feel that it's good to use about the same amount of torque on the screws each time you assemble a motor. that plasic endbell can distort and you may bind up, a motor that you thought was free.
people are always talking about how many amps a motor is pulling. more, more, more. well aligning, and polishing the bushings will certainly bring better performance to a motor, but this is one tuning tip that will DECREASE the current draw. that is a result of increased efficiency.
i'll take the arm out of the can and reassemble the motor w/o it. i then take a precision drill blank (at .125 of course) and slowly insert in each end noting where it naturally wants to go. i've seen many motors that have bushings that don't align with each other. the endbell side is usually the culprit, and can be realigned by just moving the blank until it visually lines up.
another benefit to doing this is to feel the axial drag the bushings cause. once i'm as aligned as i can get it, i'll try to gauge the friction. i then spin this blank with metal polish or buffing compound using a dremel or drill press to both polish and reem the id of the bushing. once done correctly and cleaned up, the blank slides back and forth like it's on ice. it is important not to go too far with the reeming as radial slop will induce vibration and kill rpm's
something else i've noticed is that a motor that is held together and spun free is not necessarily free when assembled with screws. it's very difficult to notice drag in the bushings with an arm in since the magnetic field is so strong. by using a small drill blank, you can nearly eliminated this effect. i will always take any new motor apart and make sure a blank slides freely, or it will before i put the arm back in. i also feel that it's good to use about the same amount of torque on the screws each time you assemble a motor. that plasic endbell can distort and you may bind up, a motor that you thought was free.
people are always talking about how many amps a motor is pulling. more, more, more. well aligning, and polishing the bushings will certainly bring better performance to a motor, but this is one tuning tip that will DECREASE the current draw. that is a result of increased efficiency.
09-17-2003, 04:23 PM
#34
Originally posted by seaball
something i've been doing lately is this.
i'll take the arm out of the can and reassemble the motor w/o it. i then take a precision drill blank (at .125 of course)
something i've been doing lately is this.
i'll take the arm out of the can and reassemble the motor w/o it. i then take a precision drill blank (at .125 of course)
09-17-2003, 05:14 PM
#35
Tech Elite
Reaming the Bushings
Guys;
Do you ever have any problems with the Arm contacting the Magnets after a Ream.
I have a Friend who has several P2K's that have had this problem without being reamed. Bushing wear?
I guess I should order a Drill Blank and Reamer too. Surely couldn't hurt. At least a Reamer in fractional sizes is reasonably priced compared to its Metric counterpart.
Most important part of any Thread is that we ALL learn something from the discussions.
Do you ever have any problems with the Arm contacting the Magnets after a Ream.
I have a Friend who has several P2K's that have had this problem without being reamed. Bushing wear?
I guess I should order a Drill Blank and Reamer too. Surely couldn't hurt. At least a Reamer in fractional sizes is reasonably priced compared to its Metric counterpart.
Most important part of any Thread is that we ALL learn something from the discussions.
09-17-2003, 07:55 PM
#36
Most important part of any Thread is that we ALL learn something from the discussions.
09-17-2003, 08:51 PM
#37
Check the magnets?
I have seen several p2ks that have had loose magnets,the last one was from a bad crash.You have too look real close to see the
loose magnet or you can try and move the magnet from end to end in the can--also have been able to reglue them back with epoxy or jb weld. Hope this might help you.
loose magnet or you can try and move the magnet from end to end in the can--also have been able to reglue them back with epoxy or jb weld. Hope this might help you.
09-18-2003, 10:55 AM
#38
I disagree with holycow saying that armatures find thier own centres when in use. Hmmmmm. I have no reason to doubt that his motors fly though, cos even motors with weak magnets can still be quick
Armatures move towards the pinion end under acceleration and towards the endbell side when under braking. In either case, the armature is moving away from the ideal magnetic field position, which cannot be good. I enjoyed reading about the co-efficients of expansion - not that I ever thought I'd need to think about this kind of thing when running my Reedy MVP I'm certain that your futre experiments will make a good read, so carry on - we'll all still learning! Fair do's, you guys are pretty cool for boffins!
09-19-2003, 06:15 AM
#39
centering
uh oh, conflicting information again. while it might me posible for different types of motors to exhibit different characteristics, i would think that our 05 size brushed electric motors would all react the same way regarding the centering issue. now we just need to agree on exactly how. 
and perhaps, if we are lucky, someone will tell us why.
in the past, i had inferred, from the importance that people place in shimming the motor to the center, that we do this to counteract the motor's natural tendency to push out of the strong section of the magnetic field. i do believe that i had made an incorrect inference, and that it does indeed find it's center all by itself. note that i am not stating a fact here, but having been told this by a trustworthy source, i decided, as usual, to verify this. the very next time i broke a motor in after a rebuild, i shimmed it very loosely or not at all, and watched it run in. by taking my finger, i noticed that i could push the arm either way, and it would indeed recenter. now i usually like to state physical reason for this, but i do not know the reason that the arm is attracted to the strongest point in the field. uh, i'm guessing that the forces that rotate the arm in the can are attractive, versus repulsive.
will someone with more knowledge on the specifics of the subject clarify the happenings of our motors under power?
while it might me posible for different types of motors to exhibit different characteristics, i would think that our 05 size brushed electric motors would all react the same way regarding the centering issue. now we just need to agree on exactly how. and perhaps, if we are lucky, someone will tell us why.in the past, i had inferred, from the importance that people place in shimming the motor to the center, that we do this to counteract the motor's natural tendency to push out of the strong section of the magnetic field. i do believe that i had made an incorrect inference, and that it does indeed find it's center all by itself. note that i am not stating a fact here, but having been told this by a trustworthy source, i decided, as usual, to verify this. the very next time i broke a motor in after a rebuild, i shimmed it very loosely or not at all, and watched it run in. by taking my finger, i noticed that i could push the arm either way, and it would indeed recenter. now i usually like to state physical reason for this, but i do not know the reason that the arm is attracted to the strongest point in the field. uh, i'm guessing that the forces that rotate the arm in the can are attractive, versus repulsive.
will someone with more knowledge on the specifics of the subject clarify the happenings of our motors under power?
09-19-2003, 06:49 AM
#40
That was a very diplomatic response, dude
I suppose with certain armatures that fit the can/endbell relatively snugly, the armature is pretty close to the magnetic field centre, even at either extreme of it's movement - it make little practical difference. However, on armatures (like most armatures!) that don't fit so snugly, the movement with no shims is very pronounced - you can see the pinion move out whilst accelerating and back in when breaking. No doubt it tends to settle somewhere between the 2 extremes at a given/steady rpm on the bench, but I bet that this position is NOT the magnetic centre - but a position just off it ie the magnetic field is opposing the force that throws the armature of the 'true' magnetic centre, but not overcoming it entirely. As the revs decrease, the arm gets closer to the magnetic centre, but only when the armature comes to rest does it then sit in the magnetic centre. That's what I deduce after too many years
09-19-2003, 11:10 AM
#41
sea ball
i think that the magnetic field created by the current flow in the motor is strongest where the material is more dense thus the electrical force created by the magnetes is stronger in the center where the mass is largest. note this is a hypothetical guess
on the fact that an electric 05 motor is nothing more than a generator producing power from current applied to it rather than a slave motor driving it to create a current like a generator where there is an electrical field where its most conductive.
i hope i put this into word correctly!
basically the motor centers it self were the field is strongest!
seaball i understand how it works i dont know if i explained correctly.
i think that the magnetic field created by the current flow in the motor is strongest where the material is more dense thus the electrical force created by the magnetes is stronger in the center where the mass is largest. note this is a hypothetical guess
on the fact that an electric 05 motor is nothing more than a generator producing power from current applied to it rather than a slave motor driving it to create a current like a generator where there is an electrical field where its most conductive.
i hope i put this into word correctly!
basically the motor centers it self were the field is strongest!
seaball i understand how it works i dont know if i explained correctly.
09-19-2003, 11:36 AM
#42
thanks horatio.
man, i too have read/heard the same thing that supports your belief. and yes, it's entirely possible that my experiment was not controlled enough to get valid results. therefore, i will add myself to the list of folks who want an answer...and the physics behind it.
will someone step up to confirm what facts have been stated thus far?
fyi - the experiment will happen. we've been rebuilding our track for this sunday, and i've just not had the time i thought i would. me and my empty promises.
man, i too have read/heard the same thing that supports your belief. and yes, it's entirely possible that my experiment was not controlled enough to get valid results. therefore, i will add myself to the list of folks who want an answer...and the physics behind it.
will someone step up to confirm what facts have been stated thus far?
fyi - the experiment will happen. we've been rebuilding our track for this sunday, and i've just not had the time i thought i would. me and my empty promises.
09-19-2003, 11:45 AM
#43
whoops. it takes me so long to post that others sneak them in before i hit send.
were getting there speedxl. and that's only because it supports my view! ha. just kidding.
keep it coming techies. uh...wait, isn't this an mvp thread???
were getting there speedxl. and that's only because it supports my view! ha. just kidding.
keep it coming techies. uh...wait, isn't this an mvp thread???
09-19-2003, 12:55 PM
#44
seaball i wasnt sure i wrote in a way to be understood i guess
you understood it!
let me know if i wrote it right!
you understood it!
let me know if i wrote it right!
09-19-2003, 01:26 PM
#45
Tech Elite
Armature shifting under load
Guys;
I have seen this on my Dyno while doing pulls. The Dyno Flywheel will shift to one side during spool-up.
Really the idea is to minimise the shift to keep the Arm in the "Sweet" spot, without having it too tight and increasing drag.
Does that "Sweet" spot move depending on whether or not the Armature is energized, this I do not know. Maybe one of our resident Electrical Engineers can answer that question. (wasn't being funny)
Thanks,
I have seen this on my Dyno while doing pulls. The Dyno Flywheel will shift to one side during spool-up.
Really the idea is to minimise the shift to keep the Arm in the "Sweet" spot, without having it too tight and increasing drag.
Does that "Sweet" spot move depending on whether or not the Armature is energized, this I do not know. Maybe one of our resident Electrical Engineers can answer that question. (wasn't being funny)
Thanks,
