Author Topic: Northern Pacific (NP) W-5 Mikado Project  (Read 11773 times)

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mmagliaro

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Northern Pacific (NP) W-5 Mikado Project
« on: April 28, 2014, 04:03:56 PM »
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Since Tony Hines asked about fitting the Maxon motor into a Kato Mikado, I figured now is the time to split this off from the discussion about molding lead weights and begin a proper project thread on my Mikado.  This will be an NP W-5 using a Kato Mikado
and the GHQ W-3 pewter kit.   I expect this to be a straightforward kit build with perhaps a few detailing and drivetrain
tweaks, hopefully not a massive scratchbuild.

For starters, here is the new Maxon motor fitted into the Mikado chassis.  It actually drops right in and aligns with the worm
coupling with no shimming needed!  You do have to grind some metal off the inside faces of the frame where the motor goes
in order to make it fit.  I pulled out the drivers, gears, valve gear, everything, took the frame halves apart, and
then flat-filed the insides until I got enough clearance for the motor.  You could probably do it with a Dremel and a metal grinding bit
without taking the chassis apart, but this makes things neater.  Plus, I didn't have to tape everything up to protect against metal shavings in the gears.

The two blue solid state devices are 4.3v 1W zener diodes.  I put then back to back, in-line with one lead of the motor.
This drops a fixed 4.3 volts.  This is a 12v motor, but it actually starts turning and moving the engine at under 0.5 volt,
which can be very annoying!  By knocking 4.3 volts off there, it operates in a more comfortable range for DC,
and the headlight will come on at full brightness before the engine starts to move.  If you use a DCC decoder, you can
program the speed steps, I'm sure, to avoid this problem and the diodes wouldn't be necessary.  The motor draws so little
current that even a 1/2 watt zener would do the trick.  But I had these handy and they are still small.

Also shown: my home-made weight comprised of tungsten plate and lead, weighing 20g vs the stock weight's 10-12g.



Note the big flywhee on the back.  That is a 12mm.  The original Kato is about 10mm and is much thinner.  I had to
grind out some of the frame below the flywheel to allow clearance for it.  The trick to getting it onto the backshaft of the Maxon
1024 motor was to first sleeve the shaft with some 1/16" OD K&S tubing.   It won't fit over the shaft as it.  You will need to
drill out the tubing with a #62 bit.  Once I pressed it on (just finger tight), I put a drop of green Loctite on the tip to fix it.

Now, the tubing will actually be TOO BIG to fit inside the flywheel.  So I ran the motor and held a file against it, checking frequently until I turned it down to just about 1.5mm to match the flywheel bore. 
I prefer to do it this way because I find it a lot easier to get a perfectly true sleeve than to bore out the flywheel and keep it
true.  Plus, this way, if there was any error when you bored out the tubing, you will correct it when you turn it down with the file and the flywheel will turn perfectly.

You need to be able to press the flywheel on with your
fingers.  The motor shaft cannot tolerate any pushing or twisting.   Again, LocTite will fix the flywheel.  The trick is to get it snug
so it won't wobble, but not so tight that you need to really "press" it on.

Here's the turning of the shaft sleeving:




Here's some video of the mechanism running.
I put a black mark on the flywheel with a sharpie so you can see how slow it turns.  And remember, this one does not
use a gearhead, even though I normally like gearheads.

https://www.youtube.com/watch?v=k25MU0kFZUg
« Last Edit: June 30, 2017, 05:16:22 AM by mmagliaro »

Ed Kapuscinski

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #1 on: April 28, 2014, 05:13:44 PM »
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Siiiick. Looking forward to another awesome build thread.

SkipGear

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #2 on: April 28, 2014, 05:38:39 PM »
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Max,
 For future reference, K&S now has metric tubing. It makes creating adaptors very easy now.

http://www.ksmetals.com/26.html
Tony Hines

Chris333

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #3 on: April 28, 2014, 06:29:42 PM »
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I usually find the correct OD and ream the center out to meet what I need. 

Also looking forward to the build  8)

mmagliaro

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #4 on: April 28, 2014, 06:41:50 PM »
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Thanks Tony and Chris.  I didn't realize they made metric tubing.  I just tend to use what I have on hand.
I never seem to have sleeving that is quite the right size.  Sometimes, Eldon throws a little piece of sleeving in with the motors I buy from him, so I have it ready-made.  But this Maxon was just in my stash.  (You know it's serious when you actually
have a "stash" of precision coreless motors, ha ha.  But in all seriousness, they are expensive, so I snap them up whenever I stumble on a good buy.).

I am amazed at how good this one runs.  That 1024 is just so whomping powerful.  I just clocked it at
.068 scale mph.  I did not make a mistake on the decimal point.  It took about 1 hr and 15 min to go 3 feet.
I am seriously tempted to remove the flywheel, and give up that room so I can put a 4:1 gearhead on it.
The engine is geared way too fast anyway, and I suspect I would be even happier with its performance
with the huge torque boost of the gearhead.



delamaize

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #5 on: April 28, 2014, 10:20:52 PM »
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I'm watching this build........make my W3 build look like childs play!!

Looking forward to this one!!
Mike

Northern Pacific, Tacoma Division, 4th subdivision "The Prarie Line" (still in planning stages)

mmagliaro

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #6 on: April 29, 2014, 01:52:19 AM »
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I'm watching this build........make my W3 build look like childs play!!

Looking forward to this one!!

Actually, Mike, I am really hoping this will be a simple build.  The W-5 is identical to the W-3 except for the location
of a few appliances, some piping, and the compressors sitting on the smokebox front.  This gives is a larger,
beefier appearance, but it is in fact the same boiler.  So this should be a straight-ahead GHQ W-3 kit build,
with some detail rearrangements, not some unholy monster like the SP&S 4-6-2 was.
In fact, I am hoping this will be one of those engines that anybody with a W-3 kit can do.  It's time
we had more W-5's in the world.

Lemosteam

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #7 on: April 29, 2014, 02:23:32 PM »
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"It's time we had more W-5's in the world...."

...He said as I make the sign of the Keystone... :facepalm: :D

Can't wait to see more Max!

strummer

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #8 on: April 29, 2014, 06:50:22 PM »
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Siiiick. Looking forward to another awesome build thread.

I'll second (or third or fourth) that.

Mark in Oregon

Lemosteam

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #9 on: May 02, 2014, 06:47:06 AM »
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Max,
 For future reference, K&S now has metric tubing. It makes creating adaptors very easy now.

http://www.ksmetals.com/26.html

Now hold on there Tony,

I picked up some 1mm, 1.5mm and 2mm K&S tubing last night.  The bad news is that the tubing is sized to the O.D. and each has a 0.225mm wall thickness.  That calculates to 0.55mm, 1.05mm and 1.55mm ID, respectively.  So for those metric motor shafts, the extra 0.05mm of clearance is too loose and the tubing will be cocked or eccentric.  Boo hiss...

VonRyan

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #10 on: May 02, 2014, 08:35:14 AM »
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Even if this project is "Simple", if it's a Max project, it's gonna be a good one.
Cody W Fisher - Modeler of the PRR, PRSL, GWR, SZD, and DRG

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Switchboard Technician - 33rd Signal Construction Battalion (reenacted)

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hegstad1

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #11 on: May 02, 2014, 08:56:56 AM »
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A couple of things I would keep in mind if I were doing this conversion.  You may have already thought of them but to me they are key spotting features of the W-5.  first,  the sandbox is different.  The W-5 has a more square look to it.  The W-5 has a delta trailing truck.  The W-5 has a longer tender.  For this last one, the dimensions of the USRA tender are the same.  I would sand off the rivet detail and re-do it with Archer decals and then rebuild the coal bunker using the W-3 casting as a guide.  Lastly.  Become good friends with Gregg Scott and he will give you all the appropriate parts so you don't have to do it yourself.
Andrew Hegstad

mmagliaro

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #12 on: May 02, 2014, 01:51:22 PM »
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A couple of things I would keep in mind if I were doing this conversion.  You may have already thought of them but to me they are key spotting features of the W-5.  first,  the sandbox is different.  The W-5 has a more square look to it.  The W-5 has a delta trailing truck.  The W-5 has a longer tender.  For this last one, the dimensions of the USRA tender are the same.  I would sand off the rivet detail and re-do it with Archer decals and then rebuild the coal bunker using the W-3 casting as a guide.  Lastly.  Become good friends with Gregg Scott and he will give you all the appropriate parts so you don't have to do it yourself.


Thanks, Andrew.  Yes, I did take note of all that you mention (sand dome, delta truck, and tender, especially).  Plus,
the walkways are different, the cab is shifted 12" from the W-3, and there are some other things.
I supposed I glossed over this when I said "just a few applicances", ha ha!  To me, if the valve gear, drivers, and wheelbase are right, and the overall boiler length and shape are right, the rest is "details".

That 28' tender means that the Kato underframe should work perfectly as-is (as opposed to the early W-3's where you
need to chop a piece out of the tender chassis to shorten it).

The delta truck can come from the GHQ L1, or even an old Trix truck.  As for the tender - definitely, sand it up, reshape
the bunker and then use the rivet decals.  Thank goodness for those Archer rivets.  They make so much
more of this possible!

Cajonpassfan

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #13 on: May 02, 2014, 01:58:40 PM »
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Andrew, that's one good looking locomotive, and a great looking model!
Max, I'm going to follow this build, you always inspire me with your steam projects.
Best, Otto K.

mmagliaro

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Re: Northern Pacific (NP) W-5 Mikado Project
« Reply #14 on: May 02, 2014, 05:19:51 PM »
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Andrew, that's one good looking locomotive, and a great looking model!
Max, I'm going to follow this build, you always inspire me with your steam projects.
Best, Otto K.

Andrew's W-5, which first appeared on the forums several years ago, is the whole reason I'm building one.
I wasn't even doing NP back then, but I saw that and never forgot it.  Now that I'm doing NP/SP&S, I
still haven't forgotten, and I'm a gonna build me one.   Andrew's model is simply beautiful.