Author Topic: The Stephenson Rocket  (Read 1797 times)

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mmagliaro

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The Stephenson Rocket
« on: September 01, 2021, 02:32:29 AM »
+14
Okay, so Ed dared us to see who would try to make a 19th century locomotive, specifically the Stephenson "Rocket" from 1829.  There is a Shapeways printed boiler and tender available for it.

The very idea of building something so unusual, and so small, and actually being able to make it RUN piqued my interest.

I will use the Shapeways boiler and tender parts, and whatever I can scrounge from anywhere.  I'm not out to do a 100% scratch build like the 0-6-0 was.  The challenges of making this tiny thing look good and work well are quite enough.

I do have one rule for myself.  It MUST propel itself.  No putting a motor in a car behind it to push. 

So, without further adieu, let the games begin.

First, here's what we're building...



Note how the wheels look a lot  like wagon wheels....

Aside from getting a motor and gears small enough for this thing, the other thing that struck me about some of the completed ones I've seen (in N Scale, that is) is that they use commercial wheels that just look all wrong.  They have a counterweight on the face, the spoke count and size is all wrong.  Now I'm not out to bash anybody who managed to get theirs to run at all.  But I wanted to try for better looking wheels.

So I made this:




"Oh no!  He's at it again!"

No... I did NOT completely scratch build this thing spoke by spoke.  I searched high and low for N scale "wagon wheels" because that's essentially what the loco wheels looked like in 1829 - wooden wagon wheels with an iron rim around them.
I got all manner of plastic, etched brass and other wheels.  But they just didn't look good enough, or weren't round enough or strong enough, to be convertable into a working loco driver.

Then I came upon Stony Smith on Shapeways, who has a nice-looking plastic wagon wheel.  I asked him if he could change it to N Scale, and he was happy to do so.  But when he heard what I was trying to do, he suggesting trying to see if Shapeways would do it as a lost wax brass casting.  And they DID IT.
(Unfortunately, the smaller wheels in brass came out with spokes that were too chunky, but the one big driver looked good.)

So that's what my wheel center is made from.

Here is the rest of the story....








What's coming next...

1. I have several different spoked carriage wheels for N Scale coming from Japan that looked promising in the photos.  Hopefully, I can adapt those to make the tender wheels and the trailing engine wheelset.

2. I have found some 4mm and 5mm diameter pager/phone vibration coreless motors that
would run for hours without burning up their brushes (and some that happily burned up in an hour, as well! )
And I have a 4mm gearhead coming that I hope to mate to one of those.

To be continued....


Chris333

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Re: The Stephenson Rocket
« Reply #1 on: September 01, 2021, 04:27:47 AM »
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peteski

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Re: The Stephenson Rocket
« Reply #2 on: September 01, 2021, 04:53:07 AM »
+1
Between your new build, and u18b's Shay thread, I'll be spending a lot more time on TRW following you guys (with bated breath).
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craigolio1

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Re: The Stephenson Rocket
« Reply #3 on: September 01, 2021, 06:39:05 AM »
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I’m so excited for this!

MK

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Re: The Stephenson Rocket
« Reply #4 on: September 01, 2021, 09:14:20 AM »
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He has gone mad...again!   :D

Cameron_Talley

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Re: The Stephenson Rocket
« Reply #5 on: September 01, 2021, 10:03:02 AM »
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Super excited to follow this one, this is great!  I was able to see the real thing at the Victoria and Albert Museum in 2005:


C855B

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Re: The Stephenson Rocket
« Reply #6 on: September 01, 2021, 10:24:19 AM »
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I am interested in how Max is going to achieve enough gear reduction in that tiny space. As we all know, small motors = very high RPM.

Otherwise, once you apply power to it, it's going to take off like... uh... a Rocket.  :facepalm:

mmagliaro

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Re: The Stephenson Rocket
« Reply #7 on: September 01, 2021, 11:09:16 AM »
+1
My hope is that the tiny 4mm gearhead I am waiting on will get me a 16:1 reduction and will still be short enough to lay down in the tender so that a worm off the gearhead will sit right over the rear tender axle, under the water barrel.  Fom there, I'll put a worm on it and drive a spur gear on the rear tender wheel with somewhere between 15 and 20 teeth.  Even at 15,
that would be 16 x 15 = 240:1.   The motors I am testing are about 15,000 - 20,000 RPM.  Worst case, 20,000/240 = 83 rpm, which on a 32" wheel works out to only 8 mph. 

I want to make it go as slow as I possibly can to take all the load off the motor, and also to get some hope of smooth performance out of what is going to be admittedly be a "not a Faulhaber" quality motor.  Plan B would be a series of compound spur gears inside the barrel to get a multi-stage reduction (and no gearhead).  The whole thing would probably have to be built on a tiny brass plate with mod 0.15 gears (finest I can get custom made).  Since the motor is going to have to sit right where the coke pile goes, I'll just make a humped shroud to cover the motor and cover that with ground up black stuff.

And yes, they used coke for fuel, not coal, at least in 1829.

I have a Sanyo 4mm coming that is supposed to be a 6v motor, which would be really nice.  Most of these things are 2.7, 3, or even 1.5v.  While I can use a zener or resistors to limit the voltage, I'd rather keep that to a minimum.  There's no room for anything in this tiny model.  Getting enough weight in it, getting a motor and gears in it, and getting pickup from the 6 wheels - hoo boy.  This is seriously a science experiment that could well turn out to be physically impossible.  But I'll give it a go.

wvgca

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Re: The Stephenson Rocket
« Reply #8 on: September 01, 2021, 11:25:02 AM »
+1
i do have a dewitt clinton, and a john bull [in ho scale], but they came pretty well built ...in n scale this should be .. uh... interesting [ Guests cannot view attachments ]

Ed Kapuscinski

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Re: The Stephenson Rocket
« Reply #9 on: September 01, 2021, 11:51:35 AM »
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Yessssssss.


NtheBasement

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Re: The Stephenson Rocket
« Reply #10 on: September 01, 2021, 02:46:59 PM »
+1
Will our hero @mmagliaro come out of this with any hair left on his head?  Will he go blind?  Will he be carted off by the men in the clean white suits?  Come back next time for a new episode of That would be extremely cool if you pull it off!

peteski

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Re: The Stephenson Rocket
« Reply #11 on: September 01, 2021, 06:29:07 PM »
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I'm wondering how you will achieve reliable electric pickup from such a lightweight model, with relatively few areas of contact with the rails.  Will you have it pulling a sort train with all its wheels picking up power (similar to what Minitrix did with their Adler set)?
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mmagliaro

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Re: The Stephenson Rocket
« Reply #12 on: September 01, 2021, 06:40:23 PM »
+1
I'm wondering how you will achieve reliable electric pickup from such a lightweight model, with relatively few areas of contact with the rails.  Will you have it pulling a sort train with all its wheels picking up power (similar to what Minitrix did with their Adler set)?
No.  It has to be able to run on its own.  I will have 6 wheels total.  No traction tires.
I have the same concern that you do.  I may not be able to even get this thing up to 20g, and that's probably not enough to make for reliable pickup.  I plan to use tungsten everywhere I possibly can, including the coke tender load, which can be tungsten powder, covered with a thin veneer of better looking crumbles.  I may have to resort to something like cutting out the whole bottom rectangle of the tender and replacing it with a rectangle of tungsten plate.

Maletrain

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Re: The Stephenson Rocket
« Reply #13 on: September 01, 2021, 07:24:04 PM »
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Make a mold of the tender print and cast it in type metal?  Might not be too hard to do if you make the mold open on the bottom, invert it, and fill it with the lead alloy - so no air venting to worry about.  Then mill out whatever volume you need on the inside?

Chris333

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Re: The Stephenson Rocket
« Reply #14 on: September 01, 2021, 08:17:12 PM »
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If it came from Shapeways you could always get it made in brass.