Fabricating Step by Step a GEO Tricorder Cam and Technical Designs for the Lower Compartment


Here is a step by step pictorial of how to make the cam for the mid compartment.

Start by marking the cam design on the end of a 1 inch aluminum rod.



Next using a band saw make two straight cuts down the length of the rod to creat node of the cam.







Then cut it to length.



Now using a belt sander loaded with 80 grit start refining the shape. I use two scrap pieces of aluminum to manipulate the piece back and forth to make the rounded end shape.









Now start refining the finish with 180 grit sand paper. Work on the two flat sides first.



Next with a sweeping motion work on smoothing the fat round end.











Fun project diversion

Smooth the surface further using 220 grit sand paper.



Last step is polishing the piece with Brasso.








Compare shot.




The thing you can do with a bandsaw, Steve! That roughing work on the bandsaw with round stock is quite dangerous; be careful. :worried:

Truly astonishing work with very simple tools.


I’m just glad the debate is over and we can put that mystery to bed… Or can we? Here is a new thing to wonder about. What was the real world item that they grabbed the cam out of to make the original prop?

Now I have to make the rest of the GEO tricorder for it.



Consider this…a WWII toy. I think it looks like it could have come from a toy aircraft and WWII toys were aplenty in the 60’s.


OK, I’ll throw a little gasoline on that fire :imp: Maybe it’s not a cam at all, but a rectangle with rounded corners?

Nice work on the cam. I don’t know how dangerous it is to cut aluminum that way, but I’ve ruined two band saw blades cutting round acrylic for phaser parts. The plastic melts and jams the blade.


Yes sometimes my methods a frightening but I can usually get the desired results. No risk, no gain LOL. There is no CNC in use in this shop. I and going to do that dark wear band using a dark gray paint that I have for the Phaser-1’s.

Rob, your absolutely correct that the back side could be any shape at all. We are presuming it’s a cam but who knows? We have one shot using one close-up to work with and build on.

I’m just glad it matches the shot of the original prop as well as it does. I am pleased at how this worked out as well as giving this whole subject finally some closure.

Steve P


So if I do a Hero GEO Tricorder what should the lower compartment have in it for goodies? Any thoughts?



My first pass at the lower compartment technology. Totally not canon but keeps with the genneral “look” of TOS.



That’s awesome, Steve! I was trying to rack my brain for ideas, but other than what AA/DST did for theirs I couldn’t think of anything, lol. That’s definitely the sort of thing I could envision being in there, though. Good use of the space, and it gives enough different things one could fiddle around with :smile:


I like to look at the different tricorders and modular and totally programmable to the specific type.


That makes perfect sense to me, sir! I totally agree, each type of Tricorder should’ve been modular and mission-specific with interchangeable components for whatever the mission called for :sunglasses:


Yeah, who knows what the original part was. I think we were mostly just using the term “cam” to refer to a general shape. It doesn’t necessarily mean this came out of an engine. Though hobbyists do build small working scale engines; I have seen some interesting machining videos on how they make and assemble the parts. It’s quite possible this was just a hobby model engine camshaft that somebody sliced up and stuck in there.

This is excellent. I love the soil sample tubes and especially the creative repurposing of the phaser meter display!


I wanted to use something (the meter display) that connects the phaser technology into the rest of the Star Fleet equipment. I just thought it would make a neat cross-over moment.

I’ve been looking at all kind of things that have cams in them… vintage 16mm film camera and projectors, sewing machines but no matches.



Second idea using the phaser side dial as a hatch for the soil sample chamber on the analyzer.
The idea is to take the far left soil sample vials and load them into the hatch for analysis.




Love the concept sketches! If you didn’t want to take up space in the middle for the sample hatch you could add an aluminum bezel to the soil sample storage area on the left - in my mind it makes sense for the tricorder to be able to analyze all 4 tubes at once, in the same way that it will be able to access all 4 of those memory discs at once.


I like the idea of being able to put the individual soil samples in the middle chamber. Again, I’m all about having more thing to tinker with inside the compartment. The more features to play around with, the better :slight_smile: If I actually owned a bonafide TOS Tricorder with such kewl features that is, lol.


So here is an opposite view of the cam unit. I have given it a name. The ground penetrating radar generator. I am going to make it spin like a radar antenna. My theory of operation is that it will map geological anomalies on the planet surface. What do you all think of that?


Works for me! I like it :smile: Btw, I’ve been looking into the soil sampler in the middler chamber.

Just to test it, I took one of the vials included with my AA/DST Geo Tric and inserted it in the dilithium crystal chamber in the side of my Wand Co. Phaser, perfect fit!

So, if you could find yourself a wrecked Wand Co. Phaser you could salvage the P2 side dial (with its metal housing) from, that would solve how to get that to work. Just an idea.


Your right, I just checked out mine, a perfect fit.