Northern Pacific (NP) W-5 Mikado Project

[mmagliaro]

Remotoring, take 2.

Although the Maxon 1024 worked great, I was not happy with the high speed and the slow-downs on hills with a heavy train.
I also felt that while it could creep at amazingly low speed, once it got up into the "normal" slow range or about 2-5 mph,
the motion of the drivers just wasn't uniform enough.

Fixing the binds in the mechanism discussed in my other thread helped, but not enough.
So now I have switched to a Maxon 1017 motor + 4:1 gearhead.  The 1017 is 7mm shorter, allowing room
for the gearhead.  I had to give up the flywheel.  But the gearhead's performance more than makes up for it.

The top speed at 12v is 37 mph.  That sounds a little on the slow side.  But I was actually surprised that it was only 37
when I measured it.  I thought it was going faster than that.  I think I have become accustomed to engines
running at low speed because I prefer them that way, so 37 doesn't seem slow to me.

Here's a video of it.   I am really thrilled with this.  NOW we're ready to start engine building!

https://www.youtube.com/watch?v=VDGP1Rmcrbk

[strummer]

Max

As usual,you da man! Am looking forward to watching the next phases...

Mark in Oregon

[dnhouston]

Sweet!  I am still drooling.  That is some amazingly smooth slow speed.

[mmagliaro]

Thanks, guys.   Sometimes you just get lucky.  The motor is great, to be sure, but putting it into an already excellent-running mechanism like the famed Mikado really puts it over the top.  I don't think I've ever been able to make one run as good
as this thing.  The responsiveness and feel as it starts out and picks up speed is hard to describe or capture on video.

Havin' fun!

Collecting photos and parts.   The build will come soon enough.

[Chris333]

Max, how does this run compared to your 2-10-0 with the 6 volt Faulhaber 1016 + 4:1 gearhead?  Is the Maxon 1017 12 volts?

My Kato mike is pretty much the oldest N scale steam that I still have and it could use a new friend 

[mmagliaro]

Max, how does this run compared to your 2-10-0 with the 6 volt Faulhaber 1016 + 4:1 gearhead?  Is the Maxon 1017 12 volts?

My Kato mike is pretty much the oldest N scale steam that I still have and it could use a new friend 

This one beats the I1.  The I1 is no slouch.  It can run at under 1 mph.  But this one definitely has an edge for
smoothness and even better overall responsiveness and slow speed uniformity of motion.
 The Maxon is rated at 0.75W maximum vs the Faulhaber's .42.  Stall torque beats the Faulhaber
as well.  Many of the Maxons beat the Faulhabers in these smaller sizes because Maxon uses neodymium magnets,
but Faulhaber still uses samarium cobalt, which does not produce as strong a magnetic field in the same space.

As for voltage: I am utterly confused.  I *thought* this 1017 was a 12 volt.  But looking at the data sheet, it should only
be able to spin about 11,900 rpm at 12 volts.    With the Mikado's 36:1 ratio x my 4:1 gearhead, that's 144:1
With 63" drivers, I only get a top speed of about 15 mph, but I am definitely at 37.
So check me.  Maybe my math is wrong, or the Mikado's built-in ratio isn't 36:1
(or maybe this motor is a 6v and I'm driving it to 12, so I'm getting 24,000 rpm out of it, but I really don't think
so.  That seems impossible, especially as quiet as it is).

[peteski]

Going by the catalogs I have motors of certain sizes come in several voltage ratings.  So hypothetically a 1017 motor could have windings for 6V, 12V or other voltages.  The 1017 number only denotes its physical size.  Nominal voltage should be specified elsewhere on the motor.

[mmagliaro]

Going by the catalogs I have motors of certain sizes come in several voltage ratings.  So hypothetically a 1017 motor could have windings for 6V, 12V or other voltages.  The 1017 number only denotes its physical size.  Nominal voltage should be specified elsewhere on the motor.

Yep, I know.  And the voltage is not denoted in the motor's number on Maxons.  That's one thing that infuriates me about the numbering on Maxon motors.  They usually have some cryptic number on them that does not match up to any number in their catalog.
I called about this and a Maxon rep was able to look it up and tell me what it was, but it took several days for
them to get back to me.  Basically, when they do a large run for an industrial customer, they give the motor a custom
number, and they record what that number really maps to in their catalog, but there is no way for a second-hand
purchaser of said motors to find out what's in there.

Faulhabers have a very clear numbering system that denotes voltage, gear ratio (if any), bearing type (ball bearing or bronze friction),
and other choosable parameters.
BUT.... I notice that the terminal resistance of the motors is given on the data sheet.  Bwa ha ha ha.  I can measure and figure it out.

Be back soon.

I'll tell you this, if my calculations are correct, that motor would have to be spinning at 29,600 rpm for me to get 37 mph, and that
just does not seem possible.  It's a good motor, but that's 11,000 over it's maximum allowable RPM, and I would expect it to be
screaming (which it's not), if it didn't just self-destruct, that is.

Maybe the Mikado ain't 36:1.  I'll check that again too.



-- M

[Chris333]

I have a couple Maxons from MTL Z locos, but I'm guess you got yours from Eldon. I can just do the same. Plus then I don't have to fit the tiny gear on the shaft.

[mmagliaro]

Chris,
I actually DID fit the tiny gear on the shaft.   I took one of my spare plastic Maxon 16:1 gearheads (I grab these when I can if they are cheap so I can harvest extra parts from them).   Inside, right at the nose, there are 3 blue plastic planetary gears.  They come right out and they are the perfect size for pinions.  I just pushed one of those onto the motor shaft after grinding the shaft against a cutoff disk to get
it just a bit smaller so it would fit.  Drop o' Loctite, and it was good to go.

Measurements:
Confirmed:  The Kato Mikado's internal gear ratio is 36:1
Measuring my 1017's terminal resistance, I get 20.5 ohms, which maps to one of the two 6v models they make.
So it must be a 6.  It has a rated no-load rpm of 13,000, and I would bet with the gearhead it is able to do that
because there is so little load on it.  But that means that at 12v, I am revving it up to, yes, 26,000 (or more like 29,000 according to
my engine's top speed measurement).

It sounds crazy, but it sure does run smooth and quiet.   I suppose since the gearhead shields it from all the shaft loading,
as long as the coreless basket (the logical "armature") doesn't fly apart and the bearings don't burn up, it can handle it.

The current draw is miniscule, even up hill with a 20 car train... about 40 ma.  The maximum rated continuous current
on this motor is 170 mA, so it's loafing.

Well, I a gonna leave it just like it is as long as it runs this good.

Chris (and all), I am going to do a photo  thread on how to cut down these gearheads to make 4:1 out of 16:1, and how to
use the planetaries as pinions.   When I get some time....

[glakedylan]

I am going to do a photo  thread on how to cut down these gearheads to make 4:1 out of 16:1, and how to
use the planetaries as pinions.   When I get some time....

I am so looking forward to this! it will be studied very carefully and a guide  through the process of several locomotives.
thanks for what you have already posted and for those still to come.

appreciation,
Gary

[GaryHinshaw]

What a slick machine.   Does it get hot to the touch after running at 12 V for a while?

[mmagliaro]

What a slick machine.   Does it get hot to the touch after running at 12 V for a while?

No.  Certainly not.  There's an important thing about DC motors that most people completely overlook, and that is,
it's all about current, not voltage.   A motor will draw a minimum current at a certain voltage, just to spin with no
load on it.   But the more load you put on it, the more current it will draw.  It's not like a simple fixed resistance.

As long as you don't pass too much current through the brushes and the windings, you are fine, regardless of the voltage.
The thing is, in conventional motors, usually if you drive them at double their nominal spec voltage, the resistance of the armature coil wire is low enough that it will happily draw more current than the wire can handle and burn itself out, even with no load on the  motor.

But not so in these coreless beauties.   On the bench with no load, this motor only draws 5 ma at 12 volts, even though it's a "6v nominal" motor.  And it is rated at a maximum current of 170 ma.    Holding the shaft in my fingers on the bench, squeezing as hard as I can, the load still only gets up to about 80 ma. 

Under load in my engine, up hill with 20 cars in tow, it only draws about 40 ma.

So even at 12 volts, it is drawing way below its rated current, and it doesn't even get warm.
The only danger is that the thing is running at speeds way above the stated maximum rating, so I would worry that the bearings
can't take it, or the spinning "basket" could physically fly apart at these speeds.  But it seems to be doing fine.
Since I've run Faulhabers at speeds and voltages well above theirr maximum for years, I'm willing to let this Maxon go and
see what happens.   If it fails after 20-30 hours of running, then I'll know never to try that again.  But I highly doubt that will happen.

[GaryHinshaw]

Thanks Max.  I agree that it's about the current and the bearings.  If it's rated at 170 mA and you're drawing 40, and if you're not hearing any significant noise, you should be fine.  Once again: a very nice machine!

[mmagliaro]

Hello again everyone.   It's time to get back to the NP W-5!

First, here is the chassis with the second powerplant that I eventually settled on, a Maxon 1017 + 4:1 gearhead,
rather than the original 1024 with no gearhead.   The motor is covered by some tungsten and lead plate in this photo:




Next, I began working on adjusting the boiler so it properly fits onto the frame.  Since we last visited this project,
I had the good fortune to receive a care package from Gregg Scott at GHQ containing the actual W-5 (not W-3) castings that he
made for this engine.  He advises me to let folks know that he does have more sets of these parts, and will consider making them
available for sale depending on the level of serious interest people show in this project as I move along on it.

I will be documenting this step-by-step, and this thread will be your W-5 "instructions" if that kit does become available.
It will require some work.  If Gregg does make the W-5 available, it will be a set of parts with the expectation that you
will use prototype photos and drawings and craftsmanship to build the engine.  There will be no "kit instructions".

I am hopeful that what I present here in the coming weeks and months will be enough encouragement and documentation for
people to want to try more of these.

Now... on to the project.

I am building this using W-3 parts and the extra W-5 parts.  I am using the W-3 instructions somewhat
as a guide, but what I need to do here is a hybrid between that kit and the W-5 prototype information I have.












A word about this boiler height thing:

Getting the boiler on the frame correctly, at least to me, is critical at this point because it will become the reference upon which everything else is based (location of appliances, piping, distances of other parts away from the drivers, etc).  I
paid special attention here so I can keep the overall proportions right.