An expired patent by J. H. Trerise from 1902 is the inspiration for this gadget.

During our research, sadly we did not find any mention anywhere on the internet or in books that this gadget was ever made or sold. It may have just been made by the inventor J. H. Trerise and may have not been widely manufactured.

Miners Pocket Transit original Patent Drawing <

While building the 3D files there were certain impractical things about this transit compared to the more standard and earlier Brunton Pocket Transit. We have changed certain elements of the design to correct problems we saw with the device and have also made changes to fit it for the medium 3D printing.

Throughout the design we tried to use brass parts for the metallic ones to make sure that they did not interfere with the magnetic compass needle.

Parts Needed *

Paper Print files

Original SVG Files

PDF Version of the same files

Tools Needed

  • 3D Printer
  • Inkjet Printer or Laser Printer may also work
  • Scissors (However, it is better to use a Craft Cutter)
  • Pliers
  • Diagonal Cutting Pliers
  • Exacto Knife
  • Soldering Iron
  • Hot Glue Gun
  • Contact Cement
  • Flat Head Screwdriver
  • Technician Q-tips

3D Printer settings

Dowload the STL Files and print them with these settings. It is reccomended to print them all separately rather than as one large print.

  • STLFiles/HBody-MinersPocketTransitUS712869.stl - Generate Support: Touching Buildplate. Adhesion: Skirt. 1.9 Hours
  • STLFiles/ArmTop-MinersPocketTransitUS712869.stl - print veritcal. Generate Support: everywhere. Adhesion: Raft 1.08 Hours
  • STLFiles/ArmBot-MinersPocketTransitUS712869.stl - print veritcal. Generate Support: everywhere. Adhesion: Raft 0.9 Hours
  • STLFiles/FlapTopBot-MinersPocketTransitUS712869.stl - print two copies. Generate Support: No. Adhesion: Skirt. 2x 17mins = 0.53 Hours
  • STLFiles/BottomDisk-MinersPocketTransitUS712869 - flip so top is bottom. Generate Support: off Adhesion: Skirt 1.78 Hours
  • STLFiles/TopDisk-MinersPocketTransitUS712869.stl - Generate Support: off Ahdesion: Skirt 1.8 Hours

Local Copy Of STL Files

Assembly Instructions

All parts Labeled

Full Assembly Instructions with a step by step guide.

Gadget School Lessons

Figure out the scale.

The original patent did not have any indication of the size of the object other than it said "Pocket". We printed on paper a series of blow-ups of the original drawing to get a feel for how they felt at different sizes before proceeding.

Do the small stuff first.

The first time Viktor tried to layout the gadget in FreeCAD it was a disaster. He did the large parts first then tried to get the little details like the hinges right. This created large multi-hour test prints. In the end he prototyped each of the smaller parts using much smaller pieces that would 3D print in just a few minutes instead of tweaking a larger part. After that it was much easier to build the whole thing.

Think about what is dependent on what.

The whole idea behind parametric CAD software like FreeCAD is that one can make changes to one thing and it should ripple throughout the design. By carefully considering what part is the root part and where it lives this made the whole project go slightly smoother.

Make needed changes

In the beginning Viktor wanted to keep the design as close as possible. But as the project went forward it was obvious that some things just wouldn't work as a 3D print with PLA vs having the whole apparatus made from Brass.

This mean things had to get larger.

At one point Viktor realized that this thing might not be practical. And it may not have ever been made or used by anyone including the original inventor. He decided to make some changes that would make it slightly more useful. The main changes being where the scales and verniers were placed.

The scales are very dependent on the ability of the printer used to print them. Having 0.1 degree accuracy even with the vernier scales is very difficult. The scales become so tiny at this scale that they can be hard to read.

The magic of Vernier scales

A vernier scale is a way to get higher accuracy out of a instrument than a normal scale would allow. It works by taking the normal subdivisions and making a second set of subdivisions that happen at 1/x the distance. Each subdivision is done 1/x short of where a normal mark would occur. See this article for a full explanation.


* This page may have affiliate links for some items. Each product that we have linked to is a product we have actually ordered and used. We will only link to items that are highly recommended by us.

About Gadget School

Gadget school is where Viktor, Enida, and all the collaborators at SFAQT show how they make the gadets featured in their adventures.

Viktor Criterion is an Inventor and Adventurer and is the co-founder of the "Super Fun Adventure Qest Time" Laboratory. Though not normally mad or evil (and we're not touching that whole genius thing after what happened last time!) he can be obsessive. Victor can be a bit donkey-headed when attempts are made to dissuade him from new projects. He believes that life and work should be fun but is realist enough to know that fun is really just a perspective.

Einida Ecxs is co-founder and Laboranteur of SFAQTLabs. She has an almost supernatural skill in being able to find esoteric objects. She also has an almost infinite amount of patience which is a highly regarded skill in the world of Inventing.

SFAQT is the name of the laboratory where Viktor, Einida, and friends do their experimentations.

It can mean SuperFunAdventureQuestTime, or SectionForAutomatedQueryTesting. The definition changes with the task.


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