2016-02-19 (F) Weekly Summary

This week had variety which was more than I could say for the last month or so. Saturday through Monday were about the compass but that has been put on hiatus due to lack of steam. Some of the posts were not very exciting because not much was happening, it felt like I was chasing my tail instead of making progress.

A pretty good system had been established for making good compasses that spun well and pointed north. Fine tuning a custom compass was a lot of guess work but the clear jars made it a little easier to see what was happening. The picture below shows the very finicky work of adjusting the post to be exactly the desired length. Each time the jar had to be opened, the spinner was removed then the post was pushed or pulled a fraction of a millimeter.

Fine tuning with a pair of forceps

Constructing the compasses went from a simple printed spinner with magnets pushed inside to a procedure which involved drilling, grinding and gluing. The last compass needed the ceiling glued to the lid of the jar, a hole drilled in the base, the post needed to be trimmed and sharpened, the magnets were glued to the spinner, a rubber O-ring was wrapped around the spinner and finally the post was glued to the inside of the jar and had to cure in a ventilated area so the jar wouldn't fog. Each of these steps had a good reason and represented something I had learned about constructing compasses but it was a lot of work and time each build.

Tools needed for each copy of the compass

The final compass produced looked pretty good and spun well. It didn't make a lot of noise when it was shaken but it didn't make any noise when it faced north either. Some of these steps were learned hastily so it may benefit the project to let it settle for awhile.

Good looking compass but not fully functional

A one-day project was dragged up which was a model for spur gears. Gears I had modeled previously were simply triangular teeth, which were easy, but beveled teeth like the ones in this gear were tougher in the sense that modeling was more difficult and tougher in the sense that teeth like this last longer in use. I also liked the animation which was a close-up of two gears although the looped animation was only enough frames to show rotation between the angle of two teeth on each gear.

Gear teeth close-up

A new project started with bicycles. Two bikes were purchased with the intention of turning them into a single recumbent bike. Recumbent bikes are notoriously expensive and I am notoriously keen on building expensive things on the cheap. My goal is not to build the best recumbent bike in the world, there are scores of engineers better qualified. My goal is to build a recumbent bike from thrift store bikes without welding. Also, the process must be repeatable so anyone can build one of these bikes after a trip to the hardware store and Salvation Army. No fancy tools and no hard-to-find parts.

Bikes purchased to make a single recumbent bike

The first factor to consider was that I would be climbing onto a girls' youth bike so damage to the frame, like drilling or cutting, might weaken it too far. Instead a couple types of clamps were purchased so the threaded sockets could be used to attach more bike parts. A couple sizes were picked but the 1" IPS split ring hanger worked the best. This will probably be the case with most bikes which have the simple cylindrical tube frame. Carefully selecting these parts was important since the whole build is dependent on them.

Hardware store parts purchased to try combining bike frames

After selecting the mission-critical part and deciding it was probably doable a graphic was made to outline the whole plan, step by step. Following the steps exactly is not the point but planning the procedure in my head was the point.

Animation describing bike upgrade process

The larger bike, granny style, was cut up with an angle grinder. A reciprocating saw would also have worked well. Old inexpensive bikes were, and still are, made of steel so a simple cut-off wheel was more than enough to cut the desirable parts from the bike. While looking at the available parts it occurred to me that the original plan of keeping a short piece of tube attached to the cranks might not be the best solution so the pipes touching the cranks were left intact. For now.

Upper bike frame broken down into pieces

Changing gears, pun intended, to this bike project has been a relief. I know that a project seems most difficult at the seventy percent point but the compass was feeling like a dead end. I know it isn't but I was out of ideas of how to improve the model and the few ideas I had didn't feel promising. The last time I set this project on the back burner I came back with a lot of new ideas and modeling skills. If I can repeat months from now I will be happy.

The rest of the weekly summaries have been arranged by date.

First time here?

Completed projects from year 1
Completed projects from year 2


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