Homebrew Sideswipers 1 & 2.
My two Cootie keys. Both are using the same principle but one is right-angled. They are built from parts of some K4VIZ bugs which I had. The bugs were good but I have a Begali and an Alberto Frattini and so never used the VIZ bugs. My apologies to TOM, the owner of Vizkey.
I use the Cooties as single-levers mostly (with the two terminals separated electrically), through a JA3KAB bug keyer. This produces perfect dits with manual dahs. It is cheating really, hi hi. My pure Cootie skills are not that great and I need more practice.
I use 6mm disk molybdenum magnets for adjustable tension at the end of the bar. These can be purchased cheaply from RS components etc. I have found that the best way to mount magnets is to embed them in a brass cup as shown. You need to drill out the brass collar to a few thousandths less that 6mm, and hammer the magnet home. Glue does not work !
The resultant magnetic pull on the bar results in around 0.25mm repeatability of the rest position, which may be too wide for QRQ . But using the keys as sideswipers or bugs, this small gap is okay. The keys have a marvellous light touch.
The next step is to make a key with two parallel bars and pivots, one bar for each contact, so that the rest position of each contact would return exactly to the same position each time. This would mean a very precise centring can be achieved. QRQ in dual lever mode could be up to 50 wpm or so. [9V1VV].