Best Of SP&S 4-4-2 Atlantic project

[victor miranda]

Hi Max
some where in my warren of n-scale bits and pieces
I have some white 0402 SMD LEDs. ( think of them as tiny lamps)

I tried setting one at the bottom of a plastic headlamp casing.
I think it was from a b-mann 0-6-0.
I don't know what happened to that assembly.

I powered up the LED and...the whole headlamp glowed.
fiber optic light does not have the glow effect.

mv lenses are nice.
I miss them.

given the careful art required to install tiny LEDs
I am thinking any other way may be better.
I figure once I find out a good way to make a LED headlamp
I'll change my mind.

I have to make a comment, I like your lamp contact.
I tend to do it with the flex side on the shell.
You put the flex on the chassis.
why I never thought the other way was possible... dunno.

[victor miranda]

hi David K. Smith

I am going to have to keep an eye on small parts.
they keep managing to be my idea of expensive
so I have tended to steer away from them.

I apprecate the heads-up on that.

back to the lamp. 
strain relief is part of the issue.
I know epoxy can seal and give strain relief
what I want is easy to build and repair
should repair become a concern.

the small shrink wrap may be the key.

victor

[DKS]

they keep managing to be my idea of expensive
so I have tended to steer away from them.

Expense is relative. If they have something you really need, and you've already exhausted other sources, then "expensive" can quickly become "affordable."

[Lemosteam]

DKS thanks for splainin to Victor what I wrote.

[peteski]

I have some comments about installing LEDs directly in headlight housing.
Most steam loco bodies/headlights are molded from black plastic which is opaque enough to block the light from the LED mounted directly in the headlight.  Some headlight are also metal castings (for example in Model Power locos). If not (or if the casting is light colored resin), then coating the interior of the headlight with 2-3 coats of black paint followed by a silver or white layer of paint (for reflectivity) before installing the LED does an excellent job of blocking any stray light from shining through the body of the headlight.  Just make sure that the previous coat of paint is dry before applying the next coat.  To verify that the paint is opaque enough, just power up the LED and temporarily place it inside the headlight while checking for any stray light.  If no light shows through, apply the silver or white paint.  I have done this numerous times and had no problems with light leakage.

As far as magnet wire leads go, I use them quite often in my models.  Yes, they are somewhat fragile, but the way I install them I never had one break yet.

In the example we are discussing here, the headlight wiring is confined to within the loco's shell. It runs between the LED and the permanently-mounted contacts (also in the shell).  In this type of situation I hook up the LED to the contacts using magnet wire, then I glue the entire length of the magnet wires run to the inside of the loco's shell using CA glue. If the clearance is tight then I route out a groove in the shell and glue the magnet wires inside that groove.  Since the wires are permanently bonded to the shell, they will not break.

Here is a ditch light installation where the magnet wire is glued to the shell along its route.


The above photo also shows a small printed circuit board used as an interface between fragile magnet wire and regular insulated wire.  This method can be used when a more robust wiring is needed. The circuit board which I use makes it easier to join the magnet and flexible wires together, but it is not needed.  The flexible wires can simply be soldered to the end of the magnet wire, then the junction area can be encased in epoxy glue.  I have also done that successfully but I have no photos.


As far as enclosing the magnet wires in heat-shrink tubing, that is not the only option. I often just strip a piece of regular wire insulation (which at that point is just a piece of fine plastic tubing), then I thread the magnet wires through that tubing. No heat shrinking is needed as the insulation is already pretty fine.  Here is an example of LED with magnet wire leads where the wires are then encased in a piece of yellow wire insulation.  Simple and effective! 

This photo also shows that I used black paint to prevent the ditch light LED light from shining inside the locomotive. Since the loco's body is molded from gray plastic  (which allowed some light to shine through it) I also painted the inside of the body black (as described above) before installing the LEDs and encasing them in epoxy).



The model in these photos has been in service since 2004 (and taken apart quite often to show off the camera installation) and the magnet wires have not broken yet.  Nor I expect it to break anytime soon, since they are all either glued to the shell and/or protected by the yellow tubing.

[SkipGear]

High headlight solution.....

Brass tubing for the light housing.
A couple pieces of channel for the mounts.
Number boards from the GMM steam kit if needed.
Wire 0402 LED with magnet wire, dip in CA to insulate.
Mount in back of housing.
Fill housing with Micro Krystal Cear
Let dry.

Result.....




I need to make another one of these actually. This was done before I found a good Yellowglow LED that I liked and it has too much bluish tint, even with some Tamiya transparent amber paint burried in a layer of the Micro Krystal Clear.

[DKS]

I've found a way to solder wires to 0402s with relative ease. First, I bond them to a piece of stainless steel (such as an old ruler) with CA. Then I solder on the wires--it's much easier with the LEDs fixed in position. Finally, I pop them off the stainless with the tip of a knife, and dip them in acetone to clean them up.

Some photos of the process are here (scroll down for the part on wiring): http://1-450.blogspot.com/2009/06/on-roll.html

[mcjaco]

I think this thread has set the record for most times the term "robust" has been used.... 

[peteski]

I think this thread has set the record for most times the term "robust" has been used.... 

That was a very ROBUST post Matt!   You must have not used magnet wires...

Like DKS, I found a way to immobilize the LED during soldering. But instead of CA glue and a metal ruler I simply use double-sided tape and a piece of wood.  Also the Radio Shack soldering paste (non-caustic, for electronic soldering) is a vital part of soldering wires to SMD LEDs.  Of course so is the bright workbench illumination and a good magnifier (for me it is an Optivisor with #7 lens plate).

[mmagliaro]

Ahem, to get this thread back to the steam loco construction project (instead of a debate about SMD LED techniques   )
... some more work on the rods.

The expansion link on the right isn't done yet (the little brass curved piece at the far right that is not connected to
anything).  You can see where it's going from the finished one on the left. 

I have been measuring the analogous Kato Mikado counterparts of these parts.  These are all now
thinner and smaller than the Kato ones.  Of course, this is a brutal magnified image and the parts aren't blackened
yet.  But I still think they look pretty good.  I have about 3 custom pieces to make that were never
even modeled on the Rivarossi valve gear.  That's coming next.

[mmagliaro]

08-Nov-2012  Just to catch up on where this project is.

1. Valve gear all finished on both sides.  (only one side shown in these pics below)
2. Started grafting Model Power tender truck side-frames onto the Bachmann trucks (rear truck shown below)
3. Fixed the pilot wheels, so they have the raised discs in the center of the wheels
4. Finished up all the fine tuning of the boiler - sanding, shaving, and skimming here and there with JB Weld to get
the surfaces smooth and proportioned correctly.  You may not notice, but look at the side of the firebox, especially, compared
to earlier photos.
And... it still RUNS!  (yay)

Next up, figure out how to attach the boiler to the frame without some big screw or hole showing in the top, make something
to put on the back of the cab to hide the rear of the motor, and then the serious work of detailing the boiler can begin.

I split this into 3 posts so that you can get individual scroll bars on each photo

[mmagliaro]

Photo 2:

[mmagliaro]

Photo 3 (tender truck)

[Lemosteam]

Max, got room for a small piece of ferrous metal epoxied to the chassis and a small rare earth mag (with not too much pull force) epoxied to the boiler at each end?  maybe one down by the smoke chamber up fron and one in the cab or firebox?  Drill out one of the domes and add a metal screw to the chassis where the dome is and put a magnet there?  Down low where the two air tanks are?

Looks really great by the way!  handmade rods- YOU DA MAN!

Added:  Only one criticism- you GOTTA hide that coil spring above the trailing truck.  Just add some mass?  Is it really holding up that cab and motor??   
I figure you are going to add some farme under there to close off the opening.

[mmagliaro]

Heh, yes, that coil spring is actually holding up the engine.  I have always had that in there after I
upgraded the motor, because the motor is too darn big and heavy.  Even all the weight of the pewter boiler can't quite overcome it.
Choosing the right spring so the engine is balanced nicely was an engineering project all by itself.   Once it is painted
black and the large horizontal air tanks are in place below the walkway and cab, I doubt it will show much.

Perhaps I can sneak some thin styrene "walls" around it painted black to look like part of the frame under there.