CESM - "Darth Vader" Signals Available

[dcutting]

For Pt. 1, see this thread: https://www.therailwire.net/forum/index.php?topic=39859.0

I'm just finishing up my searchlight signal kit shipments, so it's time to get a move on on the darth vader signals. I learned a ton from the searchlight signals in terms of how to design for ease of manufacture and assembly. Here it goes.

Targets

This is one of the most important parts of the signal so it's taking up most of my time. The searchlights were a disaster for manufacture because I had to manually place almost 400 - 0404 SMD RGB LED's and then reflow them in my skillet. I then had to coil up 38AWG magnet wire and stick in a bag for the modeler to install. Not fun for me or the modeler. Moving on to the darth vader signals, here's the latest revision of the 3-light head:



The idea is for these to be 10 mil (approx 0.25 mm) rigid PCBs (flexible PCBs aren't really feasible because of the high tooling cost). The PCB will be thin, but all of those circles in the drawing are holes in the board that tabs on the hood will fit into. With some glue or solder between the hood and that red metal rail you should be fine.

The LEDs are mounted to the front of the board and are 0201 size (0.65 x 0.35 x 0.25 mm!!!). Originally I had hoped to mound LEDs on the back of the board but the smallest reverse mount LED I could find was a 1206. You really won't notice the difference here and if you wanted to reverse mount an 0603 LED in a hole on the back of the board you would have to to it manually. I don't think you want to do 1500 of those.

I'm working on getting a pre-twisted 5-conductor 38 AWG magnet wire bundle together. I need 5 conductors so I can make the 4-light versions of this signal head. I am trying to find PCB assembly houses that can solder on all of the wires for us and so far the hunt is going well. The wire isn't very expensive at all; a quarter will buy you enough for one signal head. With that wire pre-soldered and the LED's pre-installed everything should go together much smoother. As an added bonus, the wire that I've requested a sample of has each wire as a separate color so it's easy to trace down the mast and there's no guessing. The wire has the same insulation as wire from ngineering - it's easy to strip with a soldering iron.

The hoods will be made from brass, and I will 3D print a forming tool. After the forming tool, there will be tabs that key in to the holes along the copper strip on the PCB so you get a perfect form. The white circles around the LED pads are just silkscreen - you can use them as a template for micro-glaze lenses if you wish, or just paint black over them. The PCB will have a black solder mask layer so only touch-up painting on the edges will be needed. That being said I'm seriously considering removing those circles.

Control

I had good results with my searchlight decoder, so I'm just going to roll a new version of the firmware for this type of signal, that will allow you to mix and match different numbers of lenses on each head. The hardware will stay the same, but I fully intend to get a board house to assemble and program the boards instead of doing it all myself (there's still a lot of decoders to program down in the basement).


I'll go into details on the hardware for the actual signal masts in my next major post - I'm still working on the specifics there.

David Cutting - CESM

[C855B]

Very good. I was looking at doing a similar design myself, particularly the 0201 LEDs front mounted on a PCB target. Great minds and all that.

What I'm after versus what the larger audience might want... I'm modeling the UP in 1970, which means the "original" snow hoods. IIRC, modern targets are 24", the targets from my period are a mix of a few 24" with mostly 36". The older signals are cast US&S backs. I suppose what I'm requesting is simply a version with 36" targets, and I'll worry about the backs and brackets.

You're doing the really hard part, however, and I would be good for over 100 if you were able to execute the larger target. If there are other "classic" UP fans who could offer additional info and/or correct what I think are 35 or 36" targets, chime in!

[nkalanaga]

...Mike:  I think what you're after is also what the MILW used in electric territory, so what I would like.  On  the other hand, the modern style would probably be close enough for my few signals.

[C855B]

Oh, that's right. The wider targets in general with standard visors were also found on other roads... ACL is one that quickly comes to mind.

There's an idea for you, David - generic 24" and 36" "loaded" targets that could accommodate both hoods and visors, with clear backs for cast and at least two styles of modular cases.

I was in Cheyenne yesterday, and was reminded of the unique look of the big targets on short masts. Very distinctive!

[Philip H]

Since I model the era where the Vaders got installed . . . these look great!

[dcutting]

What I'm after versus what the larger audience might want... I'm modeling the UP in 1970, which means the "original" snow hoods. IIRC, modern targets are 24", the targets from my period are a mix of a few 24" with mostly 36". The older signals are cast US&S backs. I suppose what I'm requesting is simply a version with 36" targets, and I'll worry about the backs and brackets.

You're doing the really hard part, however, and I would be good for over 100 if you were able to execute the larger target. If there are other "classic" UP fans who could offer additional info and/or correct what I think are 35 or 36" targets, chime in!

I can do the larger targets if there is enough demand. The minimums for these signals are going to end up at several hundred just to get the price down to about a dollar a board. Pre-orders will decide if it happens.

Here's my latest version. In order to better hide the wires and increase the size of the vias to something that is able to be manufactured, I removed the track of copper underneath the hood. That opens up a ton of space which I filled up with vias. Now I should be able to get the casing over the back of the signal. I just ordered a test from OSH park to give it a go... they will be very thick but that's not a problem as they are just to check dimensions, etc.

[nkalanaga]

For folks who actually want a signal system, "several hundred" should add up fairly quickly.  In my case, all I need are 2 single-head and 1 dual-head, for a junction, so I'll wait and see what turns up.

I planned on adding my own hoods to NJ International signals, but haven't been able to find any for several years now.  Nobody I ask about them seems to be able to get them.

[dcutting]

I've done some more development with these boards. First, I'm working on getting the cost down. Considering the tiny size of the boards and the delicate processes involved, I thought it would be an unwise decision to ship this job out to China for quote there. Too much risk involved. And I think many of us would enjoy the "made in the USA" stamp.

That being said, the cost just to get each target made and the LED's assembled is going to be just shy of $3 in a quantity of 800. Add the cost for me to design/build plus operate the automatic wire soldering machine that I have in the works here and you can add another $1.50 per head. My business wasn't supposed to be a non-profit (key: wasn't supposed to be ) so add a little profit on there. We're talking $6.00 a head folks. And that's just a PCB, 3 LEDs, and four leads of magnet wire.

So... unless I'm mistaken I should be looking for Chinese options. The question is, what's the sweet spot for a signal head like this? Thoughts?

David

[nkalanaga]

A quick Google search turned up an NJ International 3-light LED dwarf signal for $16.78, and a two-head mast signal, 3 over 2 lights, for $33.99.  Anyone who can put the head on the mast should be able to assemble a mast kit, as that would be primarily a tube and ladder, so $6.00 a head doesn't seem out of line.

The dwarf signal is just a short piece of tubing, a flat mounting base, and a head, so at $6.00 a head, that means the tubing, base, and assembly cost $10.78.

[Philip H]

I'm with @nkalanaga on this - $6 a borad with the parts is very reasonable - especially if the signal heads they go into keep the cost around $30 a piece.  The roll your own factor isn't likely to bother anyone here.

[dcutting]

That's more promising to hear. I'm working with a supplier in China at the moment and it looks like they will be able to slash the part cost by about half. The cost will probably sit in that $6.00 range and I'll feel much more comfortable about the margin.

[robert3985]

The "original" sized snow-shield Type D's are what I'm looking at.  Although UP is removing them from the mainline between Ogden and Evanston nowadays, they've been in place since the late 1930's, and are exactly what my 1947 thru 1956 era calls for and will save me a shirt-load of work.

The ones I need are the three-light heads, which control this ABS section of the UP.

As my layout grows, there are at least two signals every twelve feet and since I am designing my own etched kits to build proper UP cantilever bridges (in three styles) as well as platforms and ladders for the equally frequent signals on masts, being able to purchase the targets already wired up and ready to install will greatly reduce the time it's taking ne to get my signal kits ready to build.

The best (and only) kit for UP cantilever bridges was Traincat's, and with a little work and added detailing, they could be made to be acceptably accurate, except for the kit signal "heads", which were miserable.  Unfortunately, he is still out of production, so for me, designing and having kits produced is my only option.

My only concern with your product is the thickness of the target since I've been scratchbuilding my D-type heads out of .005" brass, which is thin, but still noticeably thicker than the prototype sheet metal.

Here are some photos that might be helpful concerning "original" D-type Signal Heads which I took at Morgan Utah before it got replaced with the modern version.

Photo (1) - "Original" D-type 3-light target front view:


Photo (2) - "Original" D-type 3-light target & back cover view:


Photo (3) - "Original" D-type 3-light Signal Head left side view showing back and mounting/aiming hardware:


Photo (4) - "Original" D-type 3-light Signal Head right side view showing back and mounting/aiming hardware:


Photo (5) - "Original" D-type 3-light Signal Head right profile showing "Darth Vader" hood contour:


Photo - (6) - Official UP Plan View & Measurements of Original D-Type Signal Head:


When I scratch built my signal heads, I built the backs oversized to accommodate my planned-on LED installation I'd put in 'em later when I started signalling my layout and I've never been 100% happy with the resulting look.

However, with your product, even if the target is a bit thicker than .005", perhaps a Shapeways "back" and mounting hardware would be more scale-sized.  That's a trade-off I'd be willing to do if the target isn't "too" thick.

Photo (7) - Here's a close up of my scratchbuilt UP signal bridge at the west end of Echo Yard showing the first D-type signal head that I scratchbuilt:


Photo (8 ) - Here are later, improved scratchbuilt signal heads on an improved Traincat bridge kit on my friend Nate's layout:


In any case, "original" D-type signal head circuitry and lighting at $6.00 each is a bargain in my mind, and will greatly reduce the amount of time I need to properly signal my layout.

Cheerio!
Bob Gilmore

[peteski]

Photo (3) - "Original" D-type 3-light Signal Head left side view showing back and mounting/aiming hardware:

Bob, what is the function of that midget  rear-facing light?

[dcutting]

Bob, I think we discussed these earlier. That is 100% within the realm of possibility but this is a part-time venture for now and my bandwidth is not very good. Let me release these and then take a look at those. I will probably not be able to do the 1, 2, and 4 light version of the modern one until later either. Sorry guys.

I made some progress. I've ordered a test set of components from sculpteo that includes the arms, casings, foundations, and caps. I've also ordered the 1/16" brass tube from mcmaster carr. In addition, I've been playing around with the soldering machine/jig and I've ordered most of the parts for it.

Target wise, $6.00 per target board+magnet wire assembly will be quite feasible even in low quantity with a Chinese supplier. There's 120 boards in a panel and I can make as many of those as I want... the cost will go down with volume because the LED's become cheaper. Board thickness wise, the best that I can do is 0.5mm. That's the lowest this supplier will do. I can go down to 0.2 mm thick if I do the boards here in the states. The problem is minimums would be 750-1000 parts and the cost would be higher. I'm not really ready for that kind of volume. I think the 0.2 board will also be very delicate assuming they get any thinner and I'd be worried about them snapping. 0.5 should be thin enough for all intents and purposes. Correct me if I'm wrong.

David

[robert3985]

Bob, what is the function of that midget  rear-facing light?

@peteski

Peter,

I've often wondered about that too.  I've done a bit of research and have come up completely dry, but...my guess is that it's safety related, illuminating the platform and/or ladder for signalmen to more safely come up and work on the signal head at night.  This is completely a guess and I have zero documentation or anecdotal evidence to back me up.  However, on a dark, cloudy night it might be a lot safer to know you're approaching the top of the ladder if you have to repair a signalhead...like on this signal at Henefer Utah:

Photo (1) - Type D signal just east of the Henefer overpass at Henefer Utah:


Maybe somebody else in the TRW crew knows what it's for.

Cheerio!
Bob Gilmore