You have undying faith in me. I hope I can live up to it.
Built the second HVAC unit today and found something out about post-print-processing. After the pieces printed last night I didn't want to fuss with them so I just dropped them in the alcohol soak and planned on trimming all the supports today. If I'm not trimming I can pull off a complete print and start another in just a couple of minutes. As soon as you remove the print from the platen, it's ready to go again. But… it isn't fully cured yet and sitting in the alcohol caused the part to soften and swell a bit. It was spongy and the fan blades had expanded until they started to buckle. I put it under the UV hardening lights and stabilized it. I was able to press the bottom flat when I CA's the fan to the housing and put it in my woodworking vise. I also found out why none of the cross-bracing printed. The faces were reversed in the SketchUp drawing. The STL file does not recognize the opposite side face. Depending on how the shape was created the inside surface can be expressed on its outside. That fixed shape is now downstairs being printed.
Here are two units. The 3rd fan is done and I'll have it all printed tomorrow. That means the fourth unit will be done probably on Monday. You can see the misshapen fan blades. I'm not going to scrap it. It's not going to be that obvious on the building.
But the 3rd fan came out fine since I didn't leave it in the solvent too long. My 99% isopropyl came from Amazon today. I mixed it with the remaining 91% I had so it's running about 95% which is good.
While all these parts were printing I got the lighting installed in the main building. Here's how it looks when it's all on.
And here it is in a darkened room. Plenty of light!
Now let's talk about how I did it.
I was mistaken in thinking that the lights didn't need current limiters. I tested two set in series and they turned green and went "Poof!". Plan B. I made a series of four, 3 LED unit strings each with its own CL3N2 LED driver. I tried using six sets in series, but my voltage source was petering out and they were dimming. The LEDs units are already in a string array, but the lead spacing was much too narrow. All of the work was cutting the leads and splicing in some red/black power cord. I like the red/black since all of this is DC and needs to be polarized.
This was a test. I tested each array before I pulled off the backing strip and sticking them down. I use shrink tubing at every joint and wire are tied to the cross strips with electrical tape. I may rethink that and use zip ties. I saw some tape already unwrapping.
These four parallel circuits had to be joined to one, so I used ferrules and Euro-style junction blocks. These are disconnect blocks and can be separated. It's overkill, I know, but it's what I have in the parts boxes left over from layout construction. I'm still using junction blocks that I got when building layout #1 in Germany. I wanted the last connector to definitely be a disconnect type so I could remove the roof fully if I had to. I had entertained the thought to run the wires underneath the strips through holes in the strips, but it would greatly complicate the soldering job. As it is there were lots of joints to be made.
Then I went to put the roof on which is the first time I did since all the stuff was in there. The roof wouldn't go on. The cross strips were impinging on that big 3/4" cross-member. It worked with just the trusses, but not with the strip in place. I broke its glue joints and fastened it lower just under the upper roof support blocks. I used a screw instead of glue because I had to pull the sides in forcibly. The previous glue job wasn't all that good anyway since it slipped while drying and one wall was 1/8" further out so there was a gap when the roof was one. In this image you can see that far strips with lighting right on top of the cross brace.
Moving it straight down didn't quite work either since the light units sat right on top of it and it was still pushing up the roof. I then move it two bays to the left and re-screwed it. I have filler drying on the errant screw holes. It now works and still pulls the walls together. I didn't want to go any lower since it would get into the gantry area. I may spackle the screws so they'll disappear. That brace really doesn't ever have to come off.
If I didn't put the trusses on the roof, they would have held the walls tight, and that's how I originally designed it. But with the trusses in the roof (which make it much stronger) those long flex walls needed some help.
I then tested the entire array and it all worked correctly. The wiring is very conspicuous, but the lights are so bright they're not so obvious when it's in the building. I may paint those wires the same color as the trusses to make them disappear.
I'm going to run the leads from roof to the basement using a tube that will simulate roof drain piping. I'm going to maybe print some roof water collectors and have some pipes leading down inside like is done with most big buildings. Next week I'm putting the building back on the layout and starting to put in the windows. I don't want to do them in the shop since carrying the beast is not easy and the windows would suffer.
