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#1 havlicek

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Posted 10 November 2017 - 05:20 PM

Lately, my motor work has gotten kind of schizophrenic, and I like that.  Whilst rummaging through my "pile o' stuff", and more specifically the FT36D portion of the "pile", I came across a set of Arco magnets.  Upon further rummaging, I located the matching shim so I was pointed in the direction of an FT36D build.  My Champion cans look pretty sorry and all would need a strip and repaint, so I dug out a very nice Cox can.  These things tend to stay really nice because of the durable chrome plating, and of course...any Mabuchi FT36D can is the same as any other except for the outside finish/paint.  Then, upon even FURTHER rummaging, I came up with a Champion end bell...and those things are rare...not "medium rare"...but rare!

So I put together an arm blank, and it's "off to the races" so to speak!

IMG_2303.JPG


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#2 Geary Carrier

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Posted 11 November 2017 - 12:09 AM

Hi John,

 

What are you using for the armature shaft?

 

 

Thanks,

g


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#3 havlicek

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Posted 11 November 2017 - 06:23 AM

Hi John,

 

What are you using for the armature shaft?

 

 

Thanks,

g

This was a stock Mabuchi stack and shaft.  I stripped it coated the lams with epoxy after warming the blank so it would seep-into the cracks, cleaned off the excess after curing (all so the lams wouldn't let go) and then pushed the shaft for can drive.

There is no "available" shaft material for the Mabuchi FT36D, other than from more modern Mabuchi round can motors, and many of those have flats ground onto the end.  ***I have pressed Mabuchi FT36D lams onto 3/32" drill blank axles by only pressing a few at a time (*IT"S TIGHT!), but that opens up more problems than it's worth.  For one, while you can use a 3/32" axle bushing in the can, using one in the Mabuchi end bells is a problem.  There's precious little material around the end bell area, so the bushing needs to be turned for a snug fit and then keyed to the end bell so it stays put.  Then too, pinions would need to be slightly reamed to fit, most people I sell motors to don't have the tooling to do that.

I've tried all sorts of other drill blanks including a few off-size regular and metrics and they're all either under or over the bizarre Mabuchi FT36D shaft size.  I know Philippe has explained why Mabuchi used (*and has kept on doing so right up to today) such a weird size, but it really seems to be a size ONLY used for these little motors.  ***Some other manufacturers (I think Igarashi???) used/use the same shaft size as well for motors in this general size category.  Weird!

***Anyway, the Mabuchi FT36D shafts are generally very nice...straight and round for the most part.  The "modern" Mabuchi shafts used in their "360" sized round can motors are also really nice, although often (*not always) too short if you cut off the flat ground into the end.


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#4 Geary Carrier

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Posted 11 November 2017 - 11:55 AM

Hi John,

 

Thanks for all the excellent info.

 

g


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#5 havlicek

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Posted 12 November 2017 - 06:28 AM

Mags and shim are epoxied-in for a nice tight air gap.  Using spring clips doesn't do a good job of centering the magnets on these things...actually, it doesn't work that well on the 26D Arcos either.  An unusual thing here for a Mabuchi...when you now spin the arm in the setup, it actually feels like there's a set of magnets in there, and with the magnets being Arcos, it's all vintage.  :)  Anywho, this big old motor could go different ways...anything from a drag motor to a stocker to the "surprise under the hood" for an old R2R to a scratchbuilt anglewinder (*yes, FT36D anglewinders have been done!).

IMG_2306.JPG


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#6 havlicek

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Posted 12 November 2017 - 07:32 PM

Of course, every good motor needs a good armature.  This is a good motor, so I made it a good armature.  At the risk of seeming immodest (*and I REALLY don't want that!), this isn't just a good armature, it's about as good as it gets for an FT36D.  It's a 45/28 with modest CCW advance.  That would be beyond what a period motor considered "prudent" would be, but not near as hot as some of the "imprudent" ones.  It could be a drag or a road motor, but either way it's ridiculously faster than any stock Mabuchi.  At .265 ohms (exactly!) and with a set of Arcos...it'll haul beans.  :)  I made sooper sure that the epoxy went everywhere it really needs to go, especially that tricky place out at the stack ends behind the crowns, and that the coils are fully saturated.  Com was double knotted too.  In these motors, a #28 worries me!

IMG_2308.JPG IMG_2307.JPG


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#7 slotbaker

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Posted 12 November 2017 - 09:15 PM

Awesome...

:heart:


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#8 olescratch

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Posted 13 November 2017 - 03:12 AM

Well done!  


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#9 John Streisguth

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Posted 13 November 2017 - 06:52 AM

John, if you ever want drill blanks made to a custom size, check CENCO in Allentown PA.  They can make any diameter/length you want at a reasonable price, especially small lots.


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"Whatever..."

#10 havlicek

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Posted 13 November 2017 - 07:44 AM

Thanks for looking-in guys!

 

 

John, if you ever want drill blanks made to a custom size, check CENCO in Allentown PA.  They can make any diameter/length you want at a reasonable price, especially small lots.

 

 

Hi John, yep, I've been to their site!  Even at "reasonable prices" for small lots, the economics of these things don't work.  As great as it would be to have good drill blank shafts for these motors, there are VERY few (if any!) folks who would happily pay the price.  Certainly removing the Mabuchi lams from the stock shaft and pressing them onto new shafts is not a big deal, but the Mabuchi lams have a nasty habit of "letting go" once removed.  It seems that they were originally a tight fit, so the shaft holes are too loose when trying to re-press them.  ***There are probably lams out there for RC or other uses...somewhere, but those too would have to be "gifted" to make any of this do-able, and that ain't happening!  :)  


John Havlicek

#11 havlicek

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Posted 13 November 2017 - 08:46 AM

Oh and I forgot to mention that I tried a little something different here.  While permanently writing on this end bell material is impossible, I engraved the "H" logo...filled it in with marker, and then sanded off the excess with #400 paper.  This all left the writing below the surface (*sorta like a printing plate negative image) and on material roughed-up by the engraving.  I *think* it will stay there (?), and seems to look OK.


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#12 Geary Carrier

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Posted 14 November 2017 - 02:10 AM

Hi John,

 

Was thinking about shafting for Big Blocks and decided to do a little investigating.

 

I got some 2.3mm M2 drill blanks from McMaster and they measured:

001.JPG

 

Measured the stock Mabuchi shaft:

007.JPG

 

So the 2.3mm drill blanks are 2 tenths smaller in diameter. These are nice shafts being RC 60+ with a measured TIR of < 1 tenth. The way they fit the stock bearings leads me to believe that they will work just fine.

 

Tried to push out an old shaft and bent it so I decided to make a fixture that would pull them out:

024.JPG

 

027.JPG

 

I epoxied the stack after straightening the lams with the original shaft still in place and pulled the shaft out in the direction away from the sharp edge of the lams. The shafts came out quite easily and nothing is bent.

 

This is the epoxied armature and shaft before pulling; the shaft was shortened further before pulling.

035.JPG

 

This is the epoxied armature and shaft after pulling; notice the dimples from the cone point set screws that hold the shaft during extraction.

039.JPG

 

This is the epoxied armature stack with the drill blank loctited (RC 620) in place, you can see the laser markings on the drill blank. The drill blank is a tight slip fit and the type of joint that is well suited for RC loctite.

036.JPG

 

Next up is powder coating and then on to more fun...

 

thanks,

g

 

 


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#13 havlicek

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Posted 14 November 2017 - 06:07 AM

Good work Geary!  I tried "liking" this, but after one other "like", the site is telling me I've reached my quota for the day!?  Anywho, I have used those shafts (*might even have a couple left around here somewhere).  They were nice alright.  With the original shafts not being a very snug fit in the Mabuchi bushings, and many of the Mabuchi bushings being slightly worn, I was getting a pretty sloppy fit of the finished arms.  If yours fits well, then you should be fine.

Epoxying the stack before removing it is the only sure way to re-use Mabuchi lams, so good choice there too.  As you discovered, there's a right direction and a wrong direction when pushing or pulling out shafts because of how the lams slightly deform when they were first pressed.  Good to see you digging-in!


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#14 havlicek

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Posted 16 November 2017 - 05:26 PM

Sooooo, since the original setup here went to a kuh-raaaaa-zeee drag motor with a new arm.  I took this nifty #28 wire arm (*which is super fast for these motors) and installed it in a nice clean old K&B Royal Bobcat.  The magnets got shimmed way in, and the arm was a dead-cinch drop-in.  Result, it howls like a love-sick wolf on a Saturday night with no wolf single bars out in the bush.  Or something like that anyway.

Yes, it could still be a drag motor, depending on the rooolz, but I think this wind in this motor could go about any direction (*as long as it's counterclockwise as viewed from the end bell ;) )

 

IMG_2313.JPG

 


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