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Post by Rob Albritton on Nov 21, 2017 18:10:00 GMT -5
A little thing I have been working on. This will be a signal bridge for my Gotthard layout. The majority is 3d printed using a Formlabs Form 2 SLA printer. This type of printer uses a photo reactive polymer that hardens when it is exposed to a very specific light color. A laser traces the part layer by layer and the part "grows" out a vat of goo. The walkways had details that were too fine for the printer, so I made brass photo etched inserts. I initially left off the ladder and safety cage because I did not think it would print, but after some experiments, I think I got a pretty good result. Next step: the signal heads. They are made from photoetched brass with LED lights. I did try to make them in the printer, but even the black resin was slightly transparent with these super bright LEDs, so I had to go back to metal to keep the light from bleeding through the resin. This is an exciting project because it shows the level of detail possible by mixing techniques. Enjoy! -Rob(A)   |
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Post by ztrack on Nov 21, 2017 20:07:28 GMT -5
It looks excellent! The safety cage loos great!
Rob
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Post by markm on Nov 22, 2017 12:27:16 GMT -5
An interesting project and I'm impressed by the detail. Regarding the super bright LEDs, have you tried cutting the current on them? I like running signal LEDs at 10-25% of rated current. This allows me to lower the intensity and to match the intensity between colors.
Mark
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Post by Rob Albritton on Nov 22, 2017 13:56:31 GMT -5
An interesting project and I'm impressed by the detail. Regarding the super bright LEDs, have you tried cutting the current on them? I like running signal LEDs at 10-25% of rated current. This allows me to lower the intensity and to match the intensity between colors. Mark Hi Mark, Yes - tried that, but the problem isn't the intensity of the light - its that the resin is not fully opaque. I also tried painting the part, but the LED still glowed through to the other locations. Sigh. I wish there was an easier solution! Fiber optics are also out because of the number of lights - sometimes as many as 11 per head. The fiber optic bundle would have been HUGE. Its bad enough with magnet wire. |
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pmx
New Member
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Post by pmx on Nov 23, 2017 18:28:11 GMT -5
Fiber optics are also out because of the number of lights - sometimes as many as 11 per head. The fiber optic bundle would have been HUGE. Its bad enough with magnet wire. You say that fiber optics are out, but what size fiber are you working with? The fiber core of singlemode fiber is on 9um and multimode can be 50um a 62.5um. Of course then you'll have the issue of how to diffuse it at the signal head... Just thinking out load. ~Paul E |
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Post by Rob Albritton on Nov 23, 2017 23:02:24 GMT -5
This will give you guys a better idea of the Hybrid Phot etched Brass and SLA 3d printer technique. This is before paint and signal heads:  |
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Post by markm on Nov 24, 2017 10:18:16 GMT -5
Looks like it's progressing nicely. I'm not familiar with the Swiss signals heads, so I'm anxious to see what they look like. Have you considered direct write PCBs for the signal heads? I haven't tried the technology yet myself, but it could help simplify LED mounting and wiring.
Mark
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Post by Rob Albritton on Dec 15, 2017 16:57:48 GMT -5
Finally done! Signal bridge #1 is complete. I learned quite a bit from building the first one that should make them go quicker and with higher quality in the future.   |
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Post by jhrailroading on Dec 15, 2017 22:42:09 GMT -5
Looks Great! It has such fine detail with all the photo etchings. Are there a couple different colored LEDs in each signal head?
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Post by Rob Albritton on Dec 20, 2017 22:38:49 GMT -5
Looks like it's progressing nicely. I'm not familiar with the Swiss signals heads, so I'm anxious to see what they look like. Have you considered direct write PCBs for the signal heads? I haven't tried the technology yet myself, but it could help simplify LED mounting and wiring. Mark Hi Mark (and all) While the SMD LED on brass head is tedious, it is working well. The Magnet wire is #38, so this stuff is about the size of a human hair. I have made some improvements in the design: 1) I designed a wire chase on the inside of the legs of the bridge. This has allowed me to almost make the wires disappear down the sides of the signal bridge. 2) I made a jig to help me build the signal heads. The FormLabs printer really worked well for this. I'm using Rhino for the CAD design and a FormLabs Form 2 printer. So far, this thing has been accurate down to about 0.04 mm on a 10mm part from CAD to finished product - Amazing! Assembly time has improved dramatically too, but I cannot stress how delicate these things are. I want to get them installed on the layout ASAP because I think that's the safest place for them. The legs are the strongest part, so I'm not worried about derailments, but the signal heads are delicate. Here are a few pictures of the progress - enjoy! Attachments:
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Post by Rob Albritton on Dec 20, 2017 22:42:21 GMT -5
Oh, the signal does indeed work - here is the Green light!   |
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Post by markm on Dec 20, 2017 22:54:26 GMT -5
Rob,
Nicely done. The final signal heads seem radically different from the first post, but they do look like something I'm familiar with now. There is something I do to reduce wiring that might be useful to you. I wire two LEDs as reverse polarity. This way two wires gets you:
Red + -
Green - +
OFF - -
Mark
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Post by jhrailroading on Dec 20, 2017 23:34:28 GMT -5
Wow! This is awesome. It shows just what can be done with those chip LEDs.
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Post by smr on Dec 21, 2017 5:51:28 GMT -5
Wow! This is awesome. It shows just what can be done with those chip LEDs. I am deeply impressed, Rob, really good work. For those who don´t have Rob's talent and patience, there is a little shop in Germany: www.rolfs-laedchen.de Best, Sven |
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Post by Commodore on Jan 8, 2018 11:02:04 GMT -5
Great job, Rob
I've been waiting for new pictures and additional posts.
...But we've all been awaiting video of running trains on the Gotthard line.
Can't wait to see what you've accomplished 🤑
Thanks in advance!
Rory
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