Just a short update. I’ve now got the parts I need to start on the new electromagnet testing platform. As my options for metalworking are limited, I’m planning to use an old dumbbell shaft as the basis of the roller.
In the picture are a pair of 1″ pillow block bearings, and some 1″ shaft collars. I can use different weights for the flywheel, and have some aluminium plate of various thickness to fashion the braking disk.
I’m planning to build this up using the frame of my old Elite Crono fluid trainer, so that I can put the Mk I cable operated setup back onto my Tacx trainer. Have been missing the ergo functionality when it’s raining outside! ;)
Well, my initial results have been somewhat disappointing!
Since the last post I’ve wound some of my own electromagnets, and been trying different options out on the testing platform.
These prototypes are using various gauges of enamelled wire wound around a section of 1/2″ mild steel bar for the core. The whole lot is then wrapped in electrical tape just to hold everything in place temporarily.
By replacing the original permanent magnet assembly on the Tacx resistance unit, I’m limited to around 20mm deep by 45mm diameter per magnet (although I could probably get away with increasing the dimensions a little in each direction). However, the bottom line is that I’m way off the amount of braking force I need per magnet, so I don’t think it’s really going to make a significant difference.
So I think next week I’ll change tack slightly, and put together a new testing platform. Starting from a clean slate I think it would look something like the following diagram;
Spoiler alert – I don’t have access to metalworking machinery – so be prepared for an even more agricultural look ;)