WIP: 1:3 scale Star Trek type 4B beta computer

[NormanF]

I do not remember what the inspiration for this was, but I started work on the 4B beta computer about half a year ago and then nothing until recently. Then I though, "Hmm, maybe I should do thread on the build". So here it is. Some of the pictures are a bit blurry. Sorry.

Here is the computer in question:


I got the dimensions from here, TOS Computer props - REVISED and in HD in TOSGRAPHICS Forum, and did some simple division to get the new dimensions. I decided on 1:3 by converting the diameter of the indicators from 5/8" to 5mm so I can use LED's. It is not exactly 1:3, but close enough. The plan is to use an ATMega flashed with Arduino to drive the display. The computer tape slot will have an optical sensor in it that will turn the large light in the center on when a tape is inserted.

The first step was to cut a bunch of pieces of sheet styrene (why isn't "styrene" in the dictionary?) and start gluing them together.

The base with some reinforcements in the corners because I did not have anything better to make sure they are square:


The top of the base with the slot for computer tapes roughly cut:


The base and top together:


Upper section:



Here is the front marked for drilling. I messed this up when I drilled the holes and they do not line up correctly. I used a drill press, but it is not perfectly aligned and for something like this you really need something with an x-y table which won't fit on mine. I know this is the bad one because of the marking are on the front. Also, that bottom row of indicators is too low. I will take a picture of the new one tomorrow.


So that was done in July. At that point I got busy with other stuff. And then I thought a small CNC engraver would have made the face really easy to do and will help with the circuit board. So I got ShapeOko and spent a lot of time getting that together. Then I talked myself into getting a 3d printer to make stuff for the ShapeOko and to also make prop parts. I finally got that calibrating and printing half decent so I can start working on this again.

 

[brandomack]

Lookin' good!

 

[NormanF]

Warning: Wall of text ahead, but I thought I would go through some of the decision making.

The first idea was to use some sort of colored glass or plastic to make the indicators. I looked around and could not find anything adequate. Smooth-On sells a clear resin, but I feel like I suffered lung damage just from reading the warnings, Crystal Clear® Optically Clear Casting Resin from Smooth-On, Inc. I wanted to use the colored indicators so I could use white LED's to light them and they could easily be driven by a matrix display driver. The new plan was use colored LED's. The bad news was that different color LED's typically require different bias resistors. Luckily, most of the LED's I chose were close enough that I only needed two different values of resistors, but it was still annoying and was making the circuit and programming more difficult. That was about the time I took a break for the ShapeOko and 3d printer. Then a month or two ago I saw Steve Neill using Castin Craft "EasyCast" epoxy to make a part for the prototype phaser Kenny made for JJ Trek so I thought, Ah ha!" So I ordered some. And then I found a thread on here that recommened against that product and found out that Smooth-On sells a "this won't give you cancer from visiting our website" clear resin too (EpoxAcast 690), but I already had the easycast.

I started playing around with the stuff to see how to color it without having to buy their expensive tints. Acrylic paint worked as did some ink, but then they would not be clear and would not look right. I went to Michael's and found some more affordable tints, but just red, blue, and yellow. I tried making green. Yellow and blue did not make green, they just made some really dark color. I had some green So-Strong tint from Smooth-On but it reacted with the the hardener or the resin and turned a very nice blue. My green tint has been sitting around for a while and hoping that it was old I went to my semi-local Smooth-On distributor and got a So-Strong sampler. On the way back I bought a bag full of white LED's. Tried the blue and red and they worked great. Tried the green and it turned blue again. :angry

My options at this point were:
1. Try using clear acrylic paint as a tint.
2. Visit Amazon and see if I can find cheap, green tint from the manufacturer.
3. Make the indicators and then try dying them.
4. Go back and buy Smooth-On's clear epoxy (the most expensive option).

I went to the local hobby store, bought some clear green Testors acrylic and had a go. Success! There were some downsides though. It smelled when I mixed it, sort of a cross between ammonia and whatever carrier they use for their paint. The other downside is that I either mixed it wrong or that never gets as rigid as when I use the tints. For what I am doing that is a non-issue.

One thing I noticed during the testing is that this stuff might be rough on molds. I say might because I was using the first mold I ever made and it was a tin based rubber so it might just be age, but the last two time I saw rubber come out with the cast part. I still have the original if I ever feel nostalgic and need to make a new mold. Anyway...

I got a paper cup, filled the bottom with clay, jammed a bunch of LED's in and made a mold.



I need to make yellow, blue, red, green, and amber indicators.

The first ones I cast were yellow. The funny thing was that after I poured the epoxy I though there were huge bubbles at the bottom, but it was just the lens affect. So cool!


No need to show the red or blue. I currently have the green ones curing. I have noticed that when I mix the resin the color looks great but when I pull the parts from the mold they are a lot lighter because they are so small. For now I am going to stay with them. Maybe after I test them with actual lighting I will have to recast them with more tint.

Next up: make a master and mold for the big indicator in the middle. Then it gets tricky. When it is off it looks red, but when it is on it looks amber. I assume it was red and then a way too bright light was on behind it. And of course I have to redesign and test the electronics and then break out a soldering iron. I might try to make a PCB with Eagle and the ShapeOko or just to point to point wiring. I also need to make the knobs and switches. I used the 3d printer to make a full sized knob and it was ok, but not so much with the scale knob. I was still calibrating the printer when I made that so it might turn out better if I try again.

 

[Albertese]

Awesome project!

I've been thinking about doing a similar project but half the size (1:6) and probably not lit. Alternately, I was thinking of building whole sets at 1:24 and making them scaled for that... But I have too many irons in the fire already so I haven't decided which angle to take it.

In any case, I think this looks great and I can't wait to see it progress! Keep up the great work!

--Alex

 

[NormanF]

I took a picture of the current front piece for the computer. I made it several months ago.


I laid this out and drilled it totally differently. On the first one I just drew lines with pencil, then I marked the intersection and used a center punch to make an indentation for drilling the holes. It was close but you could see that nothing really lined up completely. For this one I laid everything out on the back side but instead of using pencil I used a scribe. At the intersections I used a pin vise and the smallest bit that came with it to drill a hole. Then I switched to larger bits and finally regular toolbox sized bits in a power drill.


I did draw some lines with a Sharpie, but that was to make sure the hole for the large indicator was the right size and square especially in the corners.

And of course I made some tapes for it. These are just some styrene cut to the right dimensions and then I used sand paper for the angled top and rounded bottom.


So that was all stuff from months ago. I pulled the green indicators out of the mold this morning. One had a big bubble in it but that is why I made a mold for eight at a time.

Edit: I also need to drill the holes in the face a tiny bit wider as the indicators do not fit at all. The colored LED's, at least the yellow, did fit so I am not sure what happened. I could test the white LED's, but that won't change the fact that the indicators don't fit. I got some metric bits on Amazon so that should help.