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Questions Again: RC, scratchbuilding, batteries.

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  • Member since
    December 2006
  • From: Florissant, Missouri
  • 493 posts
Questions Again: RC, scratchbuilding, batteries.
Posted by hoofe116 on Friday, January 4, 2008 10:17 PM

Hello Board,

I'm working on my first scratchbuild project, a stationary engine based on a Echo boiler & cab. While it will never be scale-correct nor technically accurate, I want to shoot for as close as I can get as part of the learning curve. (Pipe diameters, valve mechanisms, waterfeeds, backhead/boiler/cylinder detailing, etc). Stuff one never considers until one gets started thinking. It will be an operating unit, I've retained the motor and live axle. And the sound system (for now). It has a smoker that generates a respectable amount of foul-smelling smoke. At first I thought the motor was shorted--that kinda smell. Only worse. Perhaps like a fire in an old septic tank.

Question 1: Would I be well-advised to enroll on a scratchbuilder's board like My Large Scale, or post here? I note Mr VSmith is on both and is a helpful person. My thinking is, they have a beginner's section and the responses might be more numerous. This is, after all, advertised as a General Discussions board. I don't like memberships on boards in general, and multiple boards in particular. Call it a personality deficit.

Question 2: I have surfed the web in search of DIY electronic modules. It's called 'Board Bending' now. Taking a sound module out of a teddy bear and reworking it to make other noises. Problem is, all those forums seem to be music-oriented. Riffs from Spinal Tap don't fit my plans. (And hurt my ears). Is there someplace Out There that caters to model RR roll-your-own electronics? I want to investigate the feasibility of building my own boards. For one reason, I can make them in odd shapes to fit better. For another, I can use recyled parts from used electronics stores. It may ultimately be cheaper to buy the off-the-shelf stuff, however.

Question 3: The Kicker: Youse guys--well, some of you--said, "Go battery & RC! It's the hassle-free-est!" or somesuch pitch that appealed to my aversion to wiring and cleaning track. But NO ONE ever mentioned the five-boxcar (I exaggerate a little) Battery-Toting consist that a poor engine must drag about the layout. So, how does one estimate the number of batteries to design in? In my case the consists will be short, five cars probably, max. The runs will be short, on the order of perhaps 40' if my best intentions come to pass. Shunting cars will be the focus. Indoors, not to be repetitive. In the case of the stationary engine-to-be, those clever Chinese had a sound card, a smoke generator and a remarkably tractive floor train loco running on two D cells. How long it'd run on a pair is an open question. When set up, I'll run it off a power cube. When one starts adding up the current draw from a sound board, a motor-control board, a decoder(?)--unclear on that detail at the moment--lights on engine and in firebox, and oh yes, the motor itself, well, that could be a lot of juice for say, six C-cells in a tender. Larger batteries are out there, but they have the defect of not fitting into anything smaller than a boxcar, so far as I can tell.

Thoughts, please?

Les W.

 

 

  • Member since
    September 2003
  • From: Centennial, CO
  • 1,192 posts
Posted by kstrong on Friday, January 4, 2008 11:37 PM

Question 1: MLS is a great site (as are the other sites out there). I'd post your questions and progress in the Model Making forum. Post here as well. Many folks hang out at multiple fora, but you invariably reach different people and get different insights at each.

Question 2: I have no idea. Interesting idea, though. I've used sound boards from toy trucks as diesel loco sound systems before.

Question 3: Batteries can be squoze into remarkably small spaces, especially with today's battery technology. I use AA Nickel Metal Hydride (NiMH) batteries, and fit all the necessary electronics in the loco's tender, with room still left for speakers and sound if I wanted. If you're interested in switching, then you don't need a lot of speed. I've done 2 dedicated switchers which run on 9.6 volts (8 cells). Everything else I've done runs on 14.4v (12 cells)

Later,

K

  • Member since
    February 2005
  • From: Peak District UK
  • 809 posts
Posted by cabbage on Saturday, January 5, 2008 9:40 AM
Q1: Not a bad idea.
Q2: Sorry I can't help you there -I have been deaf since the age of 7. I do like music however and I have a hifi system with 3 feet wide speakers...
Q3: This is where I can help you!

a: Weigh the loco (plus tender) and convert the weight to Kilogrammes.
b: Work out how fast you would like the loco to travel at (scale) speed.
c: Convert the (scale) speed to real speed in Metres per Second.

d: The power required in Watts is: Kilogrammes X 9.81 X Speed in Metres per second.
e: Divide the Watts by the Voltage to give you the Amperage.

Thus for a one hour run time, would also be the Amp hour rating (Ah)

f: Take the number of axles in your loco, and divide the weight by the number of axles.
g: Multiply that by, the number of Driven axles X 19.

h: That is the total weight of the train that your loco can pull.

This is the formula originally proposed by Henry Greenly in 1924!

Ok -quick run through...

Let me use the example of my MEYER locomotive.

a: 5.35Kg
c: 0.15mS-¹
d: 7.87W
I use a 6 Volt SLA so the answer is:
e: 1.31A
The MEYER has 4 axles
f: 0.66Kg
The MEYER has 4 driven axles
g: 0.66Kg X 4 X 19

The total weight of rolling stock my MEYER could pull easily is therefore
h: 12.54Kg

Please note that this is theoretical maximum, however it has been proved that the MEYER is capable of a push of 105 Newtons. I doubt the Tenmille plastic couplings were ever intended to take that sort of tensional force!!! Three of my locos CAN push my son (38Kg and 1.42m) along the kitchen floor on a wheelie stool -but there is quite a lot of wheel slip at the start....

regards

ralph

The Home of Articulated Ugliness

  • Member since
    December 2006
  • From: Florissant, Missouri
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Posted by hoofe116 on Saturday, January 5, 2008 1:27 PM

Thank you for the comprehensive reply and the examples. I now have a better understanding of drawbar pull. I'm not conversant with metric, but there're lookup conversion tables on the web so that's not going to be a problem.

Sorry to hear of your hearing problem. I'm losing mine more rapidly than I thought. Comes from years of working in machine shops and around jet aircraft. As an aside, that's one reason why these $289, 16-bit sound cards have no appeal to me. I have '2-bit' hearing. (That's a play on slang--'two bits' used to mean a quarter, or 25 cents--it means 'cheap'). Actually, being around an engine all dressed-out in sound is annoying after a few minutes because it's hard to hear anyone speaking when the thing's going.

What 'model' train experience I have was with the old immediate postwar Lionel. Those heavy diecast suckers never thought of stalling. Wheel-slip was the big problem.

I had to smile when I read 'meters per second'. The picture of one of my proposed scratchbuilts going that velocity--short of falling from a tall building--struck me as humorous. I want slow. Tractive effort isn't a concern right now. I need to run stuff and see how it all sorta fits together.

The math insight is a big help.

Les W.

  • Member since
    February 2005
  • From: Peak District UK
  • 809 posts
Posted by cabbage on Saturday, January 5, 2008 3:50 PM
Well if it is any help....

0.15mS-¹ is 15cm per second or 5.9 inches per second or a (scale) speed of 5.9mph (@16mm to the foot scale). Most of my locos run around the track at between 4 and 8 (scale) mph.

I would advise you check what American Customs Units to Metric conversions are -as I am positive my Imperial to Metric conversions are different. e.g. the Imperial Gallon is 4.53 Litres and there are 454 Grammes to an Imperial Pound...

regards

ralph

The Home of Articulated Ugliness

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