Artemis SA-1 speed problems

In answer to a message from 52tiger asking how I got some oil into an Artemis SA-1’s motor bearings.

For background, my Artemis started momentarily slowing and then picking back up to speed. The occurrence of this problem increased over time.

I had help from Ivan at Coolgales in the UK, where I bought the deck and via him  Frank Schröder in tackling this. With their help via Email the problem was traced to the motor bearings drying out and the feedforward motor controller fighting against the increased drag.

The motor is a brushed DC type from Switzerland, bearings are sintered and meant to be self lubricating but that’s a trifle optimistic. I actually removed the motor pulley with a bit of even and prolonged finger pressure as the glue had softened over time and it slowly came off the shaft so I was able to trickle a little oil down it to soak into the sinters. Frank had suggested a brand called “Liquid Bearings” but they’re in the US and wouldn’t ship to the UK, I found a UK source of NYE lubricants synthetic oil 181B that wasn’t far off in its characteristics and is made for sintered bearings. I have a 25μl Hamilton syringe with a blunt ended needle from my days working in a laboratory and this came in handy for applying the oil so it trickled down the motor shaft, especially once I’d glued the pulley back on with Loctite 648 (it’s what I had rather than chosen for the job), I left enough of a gap between the bottom of the pulley and the plinth for the needle to pass through so I could add more oil later if necessary, happily this also lined the tape up with the middle of the tensioning roller. initially I added 100μl in 4 doses letting each one soak in before adding the next.

This cured the speed problem after letting it all stand for a few days and then running the motor for a bit, I add another 25μl whenever the motor gets a bit noisier. I’ve had no further speed issues over the last couple of years.

If 25μl is unfamiliar it’s 0.025 cubic centimetres or a couple of drops.

During the diagnosis I bought a cheap laboratory power supply that can supply either constant current or constant voltage. It confirmed the problem wasn’t with the Artemis supply and once the cure had been affected I tried it again, the Artemis deck lost a lot of it’s appeal when using this supply which showed how effective the original feed forward supply is.