3D-Printed Signal Heads

[C855B]

@Mark W 's proof-of-concept here demonstrated surprisingly good results in modeling 3-color vertical signal heads with the Photon 3D printer. It's a great start, much improved over SW versions due to the minimum thicknesses of SW output.

Like I said in the other thread, I'm no expert especially with dimensions other than the couple I have in my 1:1 collection, so any and all correction or enlightenment is encouraged.

Random signal modeling notes, in no particular order:

• Three popular target widths, 24", 30" and 35" (36"?). 24" is mostly modern.
• Top and bottom target radii are centered on the top and bottom roundels. One significant exception is a "slim" 24" type seen on ex-SOU lines (and probably others), where the radius "clips" the bottom of the lamp housing, and the bottom lens has maybe a couple of inches of target below the lens ring. I hoped to have photos of local versions, but I didn't move fast enough when the PTC Vader-izing crew came through town two years ago.
• Consider 2, 3 and 4-color variants. Lens center-to-center is 12"
• Outer doublet (lens) is 8-3/8", the retainer ring is about 1-1/4" wide and 3/8" thick.
• Visors - there are several shapes of visors, but by and large they amount to short, medium and long. Modern long in the picture below.
• Hoods - two major distinct versions, modern, and not-modern ; the profiles are different. There are some variations in the older style including things like a top baffle. The older style is still found on UP mostly on intermediate signals. UP, GN and I believe the Canadian roads used the old-style hoods as intended for snow defense.
• Shop-built hoods exist, with rounded square corners rather than the radius top. Very rare in the US... unless it's the RR you're modeling. Seem to be common in Europe.
• Hoods and visors are not mutually-exclusive. I have seen photos of old-style hoods with a short visor over the bottom roundel.
• Backs, as mentioned previously, can be lumped into three styles - cast "one piece" (housing with a single door), modular square aluminum (early Safetrans and other makers), and Safetrans plastic modular (round-ish with mounting ears).
• The most vexing problem (to me) in modeling is building heads with SMD LEDs in quantity. Proofs-of-concept, OK, but multiply the effort by 50 or 100 or more and it becomes a task of diminishing returns.
• We'll need mounting brackets and bases. @Wutter has a good Safetrans base on SW, the relay cases and different base from Showcase Miniatures solve the mounts, but pole brackets will need to be developed. Modern pole brackets (photo below) with wire feed-through may be a challenge; old-style typically has external conduit making the job a lot easier.

By sheer coincidence, last night I was dinking around with PCB software trying to create a micro-PCB with three 0402 LEDs that would slip into a 3D-printed back. 0201 LEDs aren't necessary in this case as there's plenty of real estate for the easier-to-handle 0402 size. My design concept was a 0.012" two-sided substrate, component placement on front, with vias (connections between the front and back layers) bringing the connections - R-Y-G and common - to pads on the back for wires. This, I think, works well with Mark's hollow-back concept. I would expect the board to be commercially-produced as a populated fret with multiples of RYG micro-boards in 1/16" strips you would cut off as needed. I would also populate the fret with a small handful of less-common configurations such as R-Y, R-G, R-Lunar, and R-Lunar-Y. Maybe also a R-Lunar-Y-G or two, not as rare as one would think, as here are two on UP at Kearney, NE (two left lower heads), and the 4-indication heads were standard practice on Soo Line.



The PCB software I was trying to make work was awful and there was not, for instance, a way to plot a small plated-through via, nor was there a convenient tool for routing (as in machining cutouts, versus circuit paths). If somebody here was handy with a CAD package that exported finished Gerber files, we might be able to do this. None of my handful of CAD apps will do Gerber.

I'm hoping this to be a community effort. @Mark W has certainly taken the feasibility lead, now we need proto references ( @robert3985 and @draskouasshat , I'm calling you) and somebody with Gerber file capability. I'll do what I can in finding additional photos and maybe blueprints, the latter has proven challenging. With Gerber files in-hand I can certainly front finding a reasonable PCB assembly house to do the LED frets.

Don't everybody jump on me all at once.   

[peteski]

Remember that you should be able to utilize the metal mast for a common return for all the LEDs on all the heads. That would cut down on the wires threaded through the mast.

For easier soldering you might be able to use thin-wall brass tubing from Special Shapes Co (now a division of K&S Metals).

[C855B]

Remember that you should be able to utilize the metal mast for a common return for all the LEDs on all the heads. ...

I would rather not, honestly. Mast commons create a wiring exception and complicate assembly, especially if the heads and brackets are in resin and we're relying on non-soldered assembly in general. Also elevates risk of scraping a bit of insulation off in assembly and shorting against the tubing. After putting together a few Showcase searchlights with CA it became apparent that making the structure (bridge or mast) part of the circuit was more trouble than an extra wire in the twist for each head.

I did forget to mention the Special Shapes tubing in my notes (although said in the Weekend Update thread). My preference is the Ngineering tubing, with just a skosh more room.

[Mark W]

Here's the second print-ability test.  Hoods turned out perfect this round!

The shield measures 3.96mm which scales to 25". 


https://i.imgur.com/Yu4ZI4l.jpg

The centers are 'pre-drilled' based on the concept of fiber optics.  But assuming LED's will win a strong preference, we'll have to find the best way to mount them.  I could likely do two holes side by side to orient a .402 LED, and a properly shaped cavity for them.   That would require manually threading the leads for each light, quite the tedious and finicky task.

Another option could be something like the Digitrax Signal Circuit board, except without the weird mast.  Put the LEDs on a very small, thin PCB, and the 3D printed shield with hoods would simply glue to the face of it. This would sacrifice the back detail, but make these a lot easier to build. 

[Mark5]

Promising!

[Philip H]

Another option could be something like the Digitrax Signal Circuit board, except without the weird mast.  Put the LEDs on a very small, thin PCB, and the 3D printed shield with hoods would simply glue to the face of it. This would sacrifice the back detail, but make these a lot easier to build.

Honestly that’s gonna he my preference. Painted black - and needing only a couple on masts and maybe a dwarf or three, I’m not looking for super detailed versions.

[Chris333]

There she is again.

[C855B]

... That would require manually threading the leads for each light, quite the tedious and finicky task.

... Put the LEDs on a very small, thin PCB, and the 3D printed shield with hoods would simply glue to the face of it. This would sacrifice the back detail, but make these a lot easier to build.

You don't need to sacrifice the back detail, just make it a 2-piece design for a "sandwich". That was the direction I was going - 3D or etched target and hood/visors, mini-board with the LEDs in the middle on thin PCB material, then a detailed back of your choosing to cover or straddle the mini-PCB. I just need somebody to step-up for the PCB drafting to supply to a board house for manufacture (etching AND components). IOW, we're not going to solve the whole thing as a practical end product until the PCB part of it is fully fleshed.

When I get to the studio tomorrow I will take pics of the two vertical-color signals I have, with dimensions. I have a 2-light Safetrans modern modular and a 3-light modular aluminum square box design similar to (or copied from) the 1st-gen Safetrans. This will give us a leg up on two out of the three major back styles.

[Lemosteam]

You really don't need a PCB.  If you pre-wire (or buy pre-wired) LED's your design could have an "0503" 0.5mm long by 0.3mm wide x 0.3 deep recess with a hole in the middle.  Drill or grind three holes at the led spacing on the tube to feed each set of wires down.
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[narrowminded]

You really don't need a PCB.  If you pre-wire (or buy pre-wired) LED's your design could have an "0503" 0.5mm long by 0.3mm wide x 0.3 deep recess with a hole in the middle.  Drill or grind three holes at the led spacing on the tube to feed each set of wires down.
(Attachment Link)

Maybe just mill a slot in the tube that's the length of all three led's.  Might make feeding the wires easier.

What's the tube diameter?

[draskouasshat]

Ill see what i have for drawings but all of my stuff is on standards of the location, construction, and wiring. Ill do some looking or measuring but i won't be back in the field for 3 weeks due to start up construction meetings.

Drasko

[jereising]

Gorgeous, just gorgeous!

So much progress in so little time.

[Mark W]

I played around with some ideas and put together this quick mock-up of a possible ?elbow mount? signal.


https://i.imgur.com/lcq6yVl.jpg


https://i.imgur.com/A6KxRPB.jpg


The idea is you thread the LED wires through the elbow and down the mast like so:


https://i.imgur.com/ZRQtw7n.jpg

If it is possible to mount the 3 SMD LEDs on a 2.5mm wide x 6.5mm tall x 1.5mm thick PBC, where the ground is shared making just 4 wires to feed, I think this could work! 

[Jbub]

I played around with some ideas and put together this quick mock-up of a possible ?elbow mount? signal.


https://i.imgur.com/lcq6yVl.jpg


https://i.imgur.com/A6KxRPB.jpg


The idea is you thread the LED wires through the elbow and down the mast like so:


https://i.imgur.com/ZRQtw7n.jpg

If it is possible to mount the 3 SMD LEDs on a 2.5mm wide x 6.5mm tall x 1.5mm thick PBC, where the ground is shared making just 4 wires to feed, I think this could work!

Why do I feel like I'll be using this meme a lot?

[C855B]

Your mission, Mr. Phelps, should you choose to accept it...





Pretty nifty, Mark. Obviously these shots are of a two-lens signal, just add an additional lamp module for a standard 3-color. What you have already is a pretty good rendition of the earlier Safetrans and GRS with the square lamp cases.