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Arm winding #2


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#151 havlicek

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Posted 23 November 2013 - 04:27 PM

Thanks Steve (BTW...how've you been?).  Of course, this is only the Cliff Notes (abridged) version.  There are a bunch of small(er) steps in between these ones...like removing the powder coat from the outside of the stack before clamping it up.  That's especially important with the LaGanke clamps, because they're machined so well that the arm wouldn't come close to fitting if you left it on there.  Anyway, instead of just the arm, I'll do the whole motor up...and using the stock magnets/end bell hardware.  Speaking of magnets, even the regular magnets that came with these are OK for a lot of stuff...MUCH better than the 16D magnets.  I think this pair measured around 740 on my meter, but as importantly...they were near dead-bang perfectly matched, only being off by around a point.  This should be a nice smooth running motor, with lots more top end and grunt off the line, but with a little more glide through the corners than say an Arco-equipped 26D.  With the extra revs, a little gearing adjustment is all that will be needed for tons of fun!

Oh yeah, this motor is 50T/#28 and should be around .3 ohms.

 

-john


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#152 Gator Bob

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Posted 23 November 2013 - 05:11 PM

John, that 26 looks Great, nice wind. :good:


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#153 havlicek

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Posted 23 November 2013 - 06:02 PM

Thanks Bob, now get back to work on that motor :)

 

-john


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#154 SlotStox#53

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Posted 23 November 2013 - 07:02 PM

Very nice abridged "How To" John :good: will come in handy... Was gonna ask if you had removed the powder coat from the stack... Actually good to hear the standard 26D magnets are actually pretty good.. Have never played with one before and always hearing that the "Arcos" were the in thing , have never felt how good they can be.. WIll remember that.

 

What did you use for the tail & comm spacers John? Ally tubing?



#155 havlicek

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Posted 23 November 2013 - 07:54 PM

Hi Paul,

 

     The stock magnets are fine for making a very solid/smooth running motor, even though the Arcos are like 50% stronger.  Like I said though, this pair is extremely well-matched, and that's important too.  Also, the airgap in these things is fairly tight right off the bat, but of course I'm going to see about shimming them in just a tad (.004" per side) and see how that works.  In any case, smoother high revving motor can be very nice "drivers" as opposed to the "lightswitch" motors that are all-ballistic all the time :)  "He who stays on the track, often wins the race".  Not that the motor won't be fast...it definitely will be!

 

 

 

What did you use for the tail & comm spacers John? Ally tubing?

 

I have several different types of brass and aluminum tubing here for spacers and cut them to length on one of those el-cheapo mini cut off saws.  Mostly it's metric thin wall from K&M.

 

-john


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#156 havlicek

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Posted 23 November 2013 - 08:28 PM

...and some more progress:

 

Tie the arm and ready for epoxy:

ArmTied1_zps9f05326e.jpg

 

Mix up some epoxy and, after warming the arm for a couple of minutes...apply sparingly

 

EpoxyMixed_zps6129a131.jpg

 

After the arm comes out of the oven to cure the epoxy...time to true up that nasty com (the Kirkwoods are way out of round the way they come)

 

ComCutStart_zpsfc373ab9.jpg

 

...after a bunch of going slow, the com is all trued up.  After truing, I carefully run the back of an X-Acto blade down the slot to clear out the gunk:

ComCutDone_zps2e6e39a7.jpg

 

Next little, but important detail: true up the com end and the tail spacer.  First, a careful couple of twists with the heavy cutter and then finish with the fine one:

TrueComamptail_zps8c7796a8.jpg

 

You want to see an even/flat end on both the com and the tail spacer so the arm rides nice an d smooth in the setup:

TrueComDetail_zpscacc09bd.jpg

 

Time to check the arm, now that the com is clean and the connections have been welded.  The arm comes in at .317 ohms (exactly) per pole:
CheckResistance_zps683ae76c.jpg

 

All that's left on the arm end of the job is to balance it.  This one...I'm going old school.  A quick check reveals the arm isn't far off, time to get out the RGEO balance block.

 

Before that, I'll do a little on the setup.

 

-john


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#157 havlicek

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Posted 23 November 2013 - 08:36 PM

With all the basic makings for a fast motor already there, it won't take much to get this baby singing soprano:

StockSetupOpen_zps520970ac.jpg

 

Remove the hoods and brush tubes ("heatsinks").  On these ones with the flat hoods, you can still solder them together.  I put a little blob on the tubes:

BrushTubeSoldered_zps6e5d29ca.jpg

 

...then a little bit on the hoods:

BrushHoodSoldered_zpsf24f71f9.jpg

 

Reassemble the hoods and tubes with the slightest bit of Nokorode flux in there and quickly heat the hood until you see the solder flow...then get AWAY before you melt stuff.  You can just barely see that there's a good solid connection between the hoods and tubes.  This will help keep everything in place if stuff starts to get hot AND provides a good solid current path besides the springs...couldn't hurt right?

 

hardwaredone_zps472de382.jpg

 

-john


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#158 SlotStox#53

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Posted 23 November 2013 - 09:10 PM

Great armature so far John :good: Always good seeing you do the whole motor setup , is the tool that you use to cut the comm & tail spacer a specific slot tool or regular hardware type gadget?



#159 havlicek

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Posted 23 November 2013 - 09:59 PM

The one I use for the heavy cuts is by Go Fast and is really just a carbide end mill with a hole bored through it's axis for a 2mm shaft.  It's very sharp and I only use it carefully by hand.  A few easy twists is all it takes, but you need to be careful on coms with it becauswe it could dig in and damage it.  The other one is a piece sold all over (I got mine from Scott at PCH) with diamond grit on the end.  That one I got with a 2mm hole on one end and the other is sized for the larger 36D shaft.

 

-john


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#160 SlotStox#53

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Posted 23 November 2013 - 10:15 PM

Thanks John, thought I recognized the diamond grit end one for doing motor bushings , it was the end mill one I didn't know :) Can never have enough tools :laugh2:



#161 Bill from NH

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Posted 23 November 2013 - 11:05 PM

The diamond coated tool was originally sold by Magnehone & came in three different versions. 1,) .078" on both ends, 2.) .078" one end, 3/32" axle on the other, 3.) .078" one end, 1/8" axle on the other. I have one of the later. Magnehone has been sold several times in the last fifteen years. I think I read RGEO now owns their rights. Rick B, will know for sure.


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#162 havlicek

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Posted 24 November 2013 - 09:06 AM

The Go Fast tool, is really probably meant most for tail spacers, and it will cut those down PDQ.  The thing about the diamond tool is that the fine diamond grit on it's ends will clog/foul very quickly on coms, so you do a twist or two...clear it...a twist or two...clear it etc.  If you actually have to change the length of the com, rather than just true it up, it's a tedious and inefficient process, even more so on tail spacers.  So I just use the diamond tool to do a final cleanup and use the Go Fast tool for the "heavy lifting".

 

-john


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#163 havlicek

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Posted 24 November 2013 - 11:55 AM

Okey dokey, time to finish up the 26D step-by-step motor.

 

Back on the arm, it just needs some balance work.  While dynamic balancing is the best and most accurate way to have at this, you CAN do fine work with a set of razor blades and a solid balance block such as the one I got from RGEO Rick.  This process is completely dependant on the shaft, because that's what you're "registering" the arm's balance against.  If the shaft is not true/straight/round..."fuggedabowdit" as they say in Brooklyn! :)  You need to go slow, check and recheck as you drill...BE CAREFUL when you drill if you're using a hand drill instead of a drill press and a jig to remove material.  One slip and all your hard work is for nothing!  You also have to understand that mass produced factory arms will not have the kind of attention paid to balancing as you can apply.  I'm not talking about balancing services, you expect them to "get it right", but when there's several hundred arms to be balanced, they're more likely than not going to go for..."meh...that's good enough"!  In any case, this arm was pretty easy to balance and you want to get to the point where the arm will roll super slowly from one end of the razor blades to the other with the slightest itty bitty nudge, and not loping past one pole as if that one might be a bit "heavy".  That's exactly what I got here, and I was very satisfied that balance was good!  If the arm is as good as you can manage, I figure you should be confident enough to put your name on it.  I don't do that if it's sent out for dynamic balancing because I figure I might just screw things up.  With static balancing, if I have the slightest suspicion that one pole or the other just might be a teensy heavy, I'll engrave that pole as "insurance".

 

ArmBalance_zps1b6defa6.jpg

 

So with the arm done, it's time to head back to the setup and finish that off.  Even though the "hole" was fairly tight stock, I whipped up a pair of .004" shims to see what those would do.  ***On setups like the Mabuchis where the magnets are held in by one clip and a set of tabs on the other side, too much shimming will result in the magnets being closer on the clip side than the tab side, because the tabs will only let them move inward so much.  From what I've seen, .004" shims are thin enough to not cause that to happen.  If you need to shim much more than that, it might be time to flatten the magnet retainer tabs and go with two spring clips so everything remains concentric as possible.  Anyway, I wound up with a total difference of .024" (.012" per side) after shimming, which is fine for these fairly imprecise setups.  The math sounds OK, but the reality is that you could wind up with more on one side and less on the other, even though the Mabuchi cans are generally really well formed.  Another potential problem is that the bearings in these things are NOT precision pieces :)

 

While everything was apart and the magnets were out of the setup, I took the opportunity to drill the can and end bell for screws.  Those tabs WILL break, may as well take care of business beforehand and act preemptively.  I know they're not "correct", but the Mura 0-56 screws are the best.  They're small enough to not interfere with most installations, very strong and...er...I like the way they look   :pardon:   Anyway, you also need to remove any burrs from inside the can after drilling and get any steel drillings/filings out of there before final assembly.

 

SetupWork_zpsa075383c.jpg

 

Now, with the final assembly done, it's time to make some adjustments.  Of course, beforehand, you need to be sure the brushes DO NOT get hung up on the tubes.  They should fall out of the end bell by just gravity, but not be sloppy either.  I tested the arm first with the stock springs and it draws just under an amp at 6VDC, but seems like it could use a bit more spring tension (I'll sometimes use a toothpick to put a bit more pressure on each side to see how the motor "likes" that).  So I decided to go with a pair of Mura extra light springs, which are a little stouter than the stock ones, but not THAT much.  Also, with these small brushes, the amount of pressure per square unit of measure will be greater than with the larger 36D size brushes.  Imagine a woman stepping on your toe in flats...and then the same woman stepping on your toe in 6" spiked heels, uh...you get the picture of the physics involved :blush:   Anyway, going with the Mura springs which have a larger diameter at the coil, I installed a set of post protectors...not so much for the heat because the motor doesn;t get too warm at all, but because the springs fit better with the larger diameter posts.

 

26DComplete_zpsbd784ff2.jpg

 

Result?  The motor is a screamer (relatively speaking) drawing just over an amp and running nice and smooth thanks to investing the time to get the balance as good as possible.  I also spent the time to get the arm as perfectly centered in the field as possible.  Install the arm with no brushes and no spacers...give it a spin and see where it "lands".  Add some spacers and try again, until there's as little "slop" as possible without the arm being bound AND it's not pushing towards one end or the other.  It should spin freely and not "want" to be closer to the end bell or can end.

With everything as good as you can get it, install some new leads and put your name on it...I call this one "done".  Lastly, when installing the leads, I like to install the bottom lead from the inside of the tab and heading up where it will need to go when installed in a chassis.  Whoever installs the motor may just say "thank you" when they notice that :)

 

-john


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#164 havlicek

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Posted 26 November 2013 - 04:31 PM

I had a few minutes this afternoon, so having gotten back some arms from balancing, I put together a couple of motors:

TwoWhistlers_zps908f7919.jpg

 

These arms were from the last group of "private stock" :D I documented here.  On the left is a stormin' Hawk (ceramic mag version...my fave).  At 35T/#27, we're well into the performance zone.  The little Hawk is a great motor, and in this version is a GREAT motor!

On the right is a nice clean EBD Mabuchi FT16D done up at 55T/#29.  I kept this all vintage (Arcos) ...except for a pair of Mura Xtra Light springs, which are a bit stronger than the stock ones.  Even the com is an NOS Kirkwood, and it sings a lovely tune indeed!

 

I just have a Mura Green Can left to assemble, but that one will need a little more TLC, so I'll get to it when i can block out some quality time :)

 

-john


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#165 sidejobjon

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Posted 26 November 2013 - 09:08 PM

John ,
I thought the H was for Havlicek .Great looking work man .
SJJ
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#166 havlicek

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Posted 26 November 2013 - 09:45 PM

John ,
I thought the H was for Havlicek .Great looking work man .
SJJ

 

 

It is John...but in the case of the Hawk, it kinda works on two levels :)   These are all for a group of motors I plan on auctioning off to support Slotblog as a kind of "end-of-the-year-special", so I'm making extra sure I've crossed all my "T-s" and dotted my "I-s".  Thanks for looking in!

 

-john


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#167 Gator Bob

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Posted 26 November 2013 - 10:52 PM

John,

The motors look great and the detailed build tips 'rock'.  :good:...  AND.... 26D motors have a unique siren sound to them ... :D 

 

On the Mura 0-56 screws .... Nice choice.


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                            Bob Israelite

#168 SlotStox#53

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Posted 27 November 2013 - 12:25 AM

Beautiful motors John :D Will have to keep an eye out as your auctions are awesome!!

 

Really like what you did to both the Hawk and the FT16D :good: both sweet sounding mills for sure !

That 26D came out just ...Wow ! :D



#169 havlicek

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Posted 27 November 2013 - 07:25 AM

Thanks Bob and Paul.

 

 

 

 AND.... 26D motors have a unique siren sound to them ...  :D

 

Yes they do!  Actually, I think all the Mabuchi motors have a "different sound", but in particular the 26D and I'm pretty sure it's in no small part due to those bearings.  Anywho, the cans are all really nice on the Mabuchi's...thin and light for such "full" cans, plenty strong because of their one-piece "drawn" forming and surprisingly straight and true.  

 

 

 

Really like what you did to both the Hawk and the FT16D  :good: both sweet sounding mills for sure !

 

 

They are.  I'm pretty sure that 55/29 was a popular race wind back then, and with good magnets still makes for a really solid motor.  The Hawk (as I've said before) seems to me to be the logical successor to the C-can, which is of course still pretty optimal.  The Hawk isn't quite as flexible as to what arms you can stuff in there, but that short stack with a solid wind makes for a wonderfully fast and inexpensive motor.  I much prefer the ceramic versions, but the solid neo versions can work...they're just pretty close to the edge because of the ridiculously strong magnets.  I like a motor that can wind and breathe without sweating and boy howdy can this #27 Hawk do that!

 

 

 

That 26D came out just ...Wow !

 

 

Thanks!  With all three Mabuchis I kept things very close to all-period.  I really don't see the benefit in adding modern parts to the things when there are many modern motors that are (of course) better out of the box.  I have built many "bastard" Mabuchis with a mix of parts when people ask for them, and that's a fun thing to do for sure, but the best is when you stay as close to what "could" have been done back then.  This 26D is a beauty and there are still a good supply of plain-jane blue wire 26D parts out there.  They're actually fun motors stock, but they REALLY take well to rewinding.  This one in either a Dynamic or scratchbuilt chassis would be a real handful of fun :)

 

 

 

On the Mura 0-56 screws .... Nice choice.

 

 

Thanks again Bob...but I'm sure there are those out there who would rip them out and replace them IMMEDIATELY if they got their hands on the motor, but that's an easy-enough thing to do.  So it's not like I "ruined" anything ;)  These screws are pretty stupidly expensive for what they are, but I have never found the exact same screw from any source outside of slots...and believe me I've looked.  These have thread-cutting type threads made for plastic, they hold really well and are fairly close to a "flush" fit without countersinking...which wouldn't really work with a flat-bottomed screw head anyway.

 

Just have to get busy over the holiday to get the Mura Green Can motor done, so I can get the group up for auction to support the Blog!

 

-john


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#170 havlicek

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Posted 28 November 2013 - 09:13 AM

I just saw where Steve O'Keefe did-up a beautiful period build/rewind of an old Revell AND documented it with great pictures.  I never saw any of the "Arm-Winding"  threads as being only about what I do and hoped they could be part of a general reference about rewinding and building motors, and Steve's work could easily have been posted here as a great source of info.  Just in case anyone hasn't seen the build, it's right here:

http://slotblog.net/...-race/?p=514861

 

-john


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#171 havlicek

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Posted 28 November 2013 - 09:35 AM

...and BAM!  The Mura "Green Can" rewind is all done:

MuraGreenCan_zps1e1b738e.jpg

 

The arm (previously shown) is a 33/27 "mid wind":
CArmComp_edited-1_zps1336193b.jpg

 

...It's been dynamically balanced and I also had Alpha take a "skin cut" grinding the stack just enough to true things up.  Winds in this category are plenty fast, and in such a "bullet proof" setup as the Mura have tons of "safety factor" built in.  The motor draws about an amp and a half at 6VDC and current draw is rock solid right up to full-tilt boogie (12VDC), not changing much (a good sign).  The can bushing was pretty worn, showing visible slop when moving the arm shaft by hand, so I popped in a new 2x6mm bushing.  The end bell got a set of bussbars and only the small aluminum heatsinks that installed mainly as spacers to keep the brushes riding fairly high on the com.  The only other mod I did was to groove the hoods for shunts if anyone ever feels like installing a pair...though they won't be needed for this wind.  ***Only two modern touches were a set of shorter magnets to keep weight down a bit, and they're a very good match size-wise for the stack...and a set of Camen springs.  The motor sounds wonderful :)

 

-john


John Havlicek

#172 Pablo

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Posted 28 November 2013 - 12:34 PM

Cool stuff !! Glad you got over the HO madness !! I thought we were losing you there for a while :D


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Paul Wolcott

#173 havlicek

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Posted 28 November 2013 - 02:56 PM

Thanks Pablo...the HO stuff was crazy alright.  No doubt it got easier, but I started wondering what the heck I was thinking.  In the end, they're all the same, just smaller and smaller  :umnik2:

 

-john


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#174 Pablo

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Posted 28 November 2013 - 03:11 PM

My friend Bill says it's like racing cockroaches   :laugh2:


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#175 Bill from NH

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Posted 29 November 2013 - 03:21 PM

How many friends named Bill have you got? :laugh2:


Bill Fernald
 

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