Noob Scratch Builder Attempts N Box Cab Loco

[Dwight in Toronto]

Thanks Ed. 
And thank you Pete, for applying the pressure!  I wanted the guard rails to look beefier than the hand grabs, so in this case I opted for the thicker brass wire.  If I’d have had a slightly thinner wire on-hand, I would have used it.

But yes, that is precisely the sort of feedback that I welcome.  I’d like to think that, at some future date, some other first-time scratcher will stumble upon this topic and realize that .02” brass wire is comparable to 3” pipe IRL.  Good stuff!

[Scottl]

I don't have much to add other than you have done a fantastic job!

[Dwight in Toronto]

Scottl - thanks so much, man … appreciated!

Since this entire build was a ‘learning experiment’ on my part, I decided to have a shot at fabricating a brass ladder leading up to the roof:




For this, I again used the .012” brass wire.  I wasn’t sure how to go about it, so I tried putting a piece of 3M clear double sided tape on a smooth glass work surface.  I then cut and formed the two uprights, pressed them face down onto the tape, and then nipped off 8 pieces for the rungs.
The top, middle and bottom rungs were lightly soldered into place (what fun THAT was!).  The remaining rungs were affixed with tiny drops of CA.

I have to mention here just how invaluable a digital caliper is.  The utility, versatility and overall modelling benefits of these devices was being heartily endorsed by a couple of TRW fellows several weeks ago, so I picked one up (less than $30 Cdn at a local electronics/specialty retailer).  I am SO thankful that I trusted their sage advice.  This tool has been invaluable throughout almost every aspect of this project, and I strongly echo the recommendations to add one of these to your workbench.

Twenty four hours later I gently pried the ladder off the tape, and found that some of the CA had ‘spiderwebbed’ as a thin film across the inside corners of several rungs.  Careful chipping and scraping with a long-pointed Xacto blade eventually cleaned up the worst of it, but a few remnants remain in a few spots … I forced myself to stop while I was ahead.

The ladder has a slight outward bow, and at some point I’ll probably try pressing it inward, but for now I deem it good enough.  The grab bars on the roof were the finishing touch on this segment.

I edited this segment to point out that I decided to add a second brass lamp housing to the rear of the model.  The upper light will be a red LED serving as a marker lamp; the lower unit will be the reversing headlight.

[peteski]

That is some prerry fancy soldering/gluing Dwight.  Are you sure you're a noob?!

Also, I believe you have a caliper.  Micrometer is not very useful for our hobby use.

[Dwight in Toronto]

Thanks Peter - right you are.

I changed ‘micrometer’ to ‘caliper’.  I also changed the earlier error where I referred to the Kato chassis as being 4-axle.

You question my noob-ness … perhaps my careless mistakes are evidence enough!

[Dwight in Toronto]

I mentioned earlier that I needed to be able to remove the roof to facilitate access to the LED’s.

Like many modellers, I’ve never liked the idea of permanently affixing LED’s within the shell, with their wires being ‘tethered’ to the chassis-mounted decoder.  Some of our brethren have devised  admirable phosphor/bronze ‘flex arms’ that press against copper contact pads; others use tiny plugs & sockets, and there are undoubtedly other approaches (which would be great to hear about).

Not long ago, there was a topic covering roll-your-own streetcars wherein bbunge described how he uses styrene tube as an LED holder.  I decided to use his technique on the box cab.

As shown in the pic, this simply involved solvent-gluing a short length of styrene tube on the inside wall of the shell, precisely behind the exterior headlamp location.  I had blackened the tube with a Sharpie, and then reinforced around the seam with diluted Tamiya putty.  You can see a 0402 LED being inserted into the front “retainer tube” with tweezers:




Here’s how the LED’s ended up - an 0402 warm white in the front lamp, an 0603 red LED in the rear/upper retainer tube (as a marker lamp), and another 0402 white in the rear/lower retainer tube that illuminates in reverse.  I used a small dab of sticky-tac to help keep the LED’s anchored within their retainer tubes:




Should I ever need to remove the shell to get at the decoder or service the chassis, it’s simply a matter of sliding off the roof, picking out the sticky-tac ‘plugs’, and slipping the LED’s out of their retaining tubes.

Speaking of sticky-tac, I use that @#%& for everything!  In this project alone, its holding the LokPilot decoder and the pc board snug against the chassis.  It’s also being used as “cable management”, to keep the various pc board wires away from any potential pinch points.  I’m always reluctant to snip off any unused decoder wires, so those too get wrapped around, tucked out of the way, and held in place with a small dab of sticky-tac.  Very useful, and endlessly re-useable, stuff!

[CR4100]

I love this project!

Do you have any plans to fill that empty space inside with weight for better pick up and traction?

[Dwight in Toronto]

CR4100 … I’ve put several hours of running time on that Kato chassis, and not once has it ever stuttered or faltered in any way at all.  In future use, if it needs a bit of extra weight, it will get it.
There’s sufficient space in the cab to drop in some contoured lead tape/ribbon, for instance.

[Jim Starbuck]

This is a wonderful project Dwight. I appreciate the creativity you implemented here.
You couldn’t have picked a better mechanism for it. These little Katos are absolute gems.
Nicely done!

[Dwight in Toronto]

Mr. Starbuck - so nice to hear from you; thanks for the confidence boost!

A short stint on the LokProgrammer brought the three LED’s to life.

First, a pic of the front headlight:




Here’s a pic of the rear red marker lamp (toggled by F3):




And here’s the rear headlight, which illuminates only in reverse (the red marker light is also lit up, but appears kinda washed out):

[CNR5529]

Well executed project Dwight!

One question for you, couplers?      some z scale couplers would look nice and fine on this tiny unit.

[peteski]

Well executed project Dwight!

One question for you, couplers?      some z scale couplers would look nice and fine on this tiny unit.

. . .or wait for those true-scale couplers which will be available soon.

[peteski]

I mentioned earlier that I needed to be able to remove the roof to facilitate access to the LED’s.

Like many modellers, I’ve never liked the idea of permanently affixing LED’s within the shell, with their wires being ‘tethered’ to the chassis-mounted decoder.  Some of our brethren have devised  admirable phosphor/bronze ‘flex arms’ that press against copper contact pads; others use tiny plugs & sockets, and there are undoubtedly other approaches (which would be great to hear about).

Not long ago, there was a topic covering roll-your-own streetcars wherein bbunge described how he uses styrene tube as an LED holder.  I decided to use his technique on the box cab.

Funny thing is that over 35 years ago I thought I had a clever idea.  That was before Internet or online forums. It was also before white LEDs were even available, and DCC was not on my radar either.

Even back then I liked to  have realistic constant-lighting on (DC) models. So I build those 4- or 6-diode constant lighting circuits popular back then, and used the Miniatonics 1.2mm diameter 1.5V tiny incandescent light bulbs for illuminating my models. Asa bonus, those bulbs had a lens-shaped end which produced a nicely focused bright light. Like a real headlight.

Since I fully expected those tiny bulbs to have fairly short life, and since I like  to make my models easily serviceable, I used brass tubes epoxied inside the shell to hold the bulbs in place, yet make it a breeze to replace them if burned out.  Here is an example.



The 4 bulbs are head lights and ditch lights, while the tubes under the roof (only one is fully visible) are for the strobes on the loco's nose.  Those are long tubes located between the roof and cab's interior ceiling.  Nice thing about using brass tubes is that unlike plastic tubes, brass is completely opaque, preventing any light bleed.

In my example I also custom-etched PC boards to make the replacement even easier.  Lamps only have short leads which can be unsoldered at the PC board, without disturbing the full wire harness inside the shell.

I don't remember if I read about this technique somewhere, or if I came with it on my own, but it is interesting seeing something similar used by other modelers decades later.  Not that white LEDs should ever have to be replaced during the model's lifetime.

[Dwight in Toronto]

I have indeed been thinking about couplers, and I was going to get into that next. 

All along, my plan was to only put a MT coupler on the rear.  I might be able to hit my LHS tomorrow.  But I really like Peteski’s suggestion to use the new N-Possible device.  I’ll switch to that in the Fall.

Peter - that’s an interesting tale how you were using the retaining tube concept for loco lighting all those years ago.  Of course, styrene tubes won’t short out the LED when the solder joints touch the inner cylindrical surface.

[peteski]

Peter - that’s an interesting tale how you were using the retaining tube concept for loco lighting all those years ago.  Of course, styrene tubes won’t short out the LED when the solder joints touch the inner cylindrical surface.

That's true - that's why I slipped some insulation over the bare light bulb leads.   
Brass tubes also have thinner walls, which sometimes makes a difference in N scale tight installations. But plastic tubing is suitable too.