Sunday, 10 January 2016

Unplug your Machines when not in use

If your machine has a bakelite foot controller you should never leave it plugged in when not in use. 
Singer tells you this in (some of) their manuals.
From Singer 201K manual

How they Work

These controllers use a stack of thin carbon discs which are compressed by the button you step on to allow current to flow. A friend of mine in Canada has a blog which explains this in detail:

Why Unplug?

There are three good reasons I can think of to unplug your machines:
1. Over time current starts to leak and this can make them hot. This heat can build up enough to start a fire, which can happen when you aren't home or when you're asleep in bed.
2. The higher voltage ones (220V/240V) were fitted with a capacitor to prevent AM radio interference. When this breaks, it short circuits and the machine suddenly goes at full speed. Yes it can happen when you're not at home! 
3. Your machines are fascinating to kids, who love to play with them. If the machine is plugged in, kids are more likely to be injured. When my machine isn't in use I unthread it, place a piece of fabric under the foot, foot down and needle down.

You can certainly tune bakelite controllers so there's less danger, but the best thing you can do is to get into the habit of unplugging them when you're finished sewing. Don't be frightened of these. They're original to the machines and perform very well, so there's no reason to get rid of them. Knowing how they work is valuable.
A few years back I did an entry on fixing them up. Not as comprehensive as archaicarchane's, just removal of the capacitor.

What do they look like again?

Not all carbon disc controllers look like this:
Singer Bakelite Foot Controller

Some of them look like this:
Husqvarna controller from early 1970s
Even clam shell controllers use carbon discs: My daughter's 1970 Singer has them, and a generic Taiwanese replacement I opened up also had them.
I was surprised they all didn't use coiled (resistance) wire, but they don't.
That's all. You've been advised to do it and told why, the rest is up to you. Have fun!


  1. I bought one of those cheap (AU$35) Chinese sewing machine motors on eBay recently to try them out. The foot pedal that comes with them has 4 or 5 separated metal foil layers. As you push down on the pedal more of the layers come in contact with each other and increase the speed. (PS I don't recommend these at all - it took three of them cannibalized to get one working model.)

    1. I'm wary of anything made in China, Ronson. After everything breaking after a short time or never working at all, one learns. Three controllers to get one that worked is a 66% failure rate. The Japanese had it down to 0.3% for electrical goods just 15 years after the war ended (the Brits got down to 3%).
      It's been 30 years since we started buying things made in China and quality hasn't improved at all for the cheaper things. Apparently you can get good quality made there, but the price is almost the same as what is made here.

  2. thank you for this, I have all my sewing things pluged into 1 poe\werboard and turn it off as i leave the room , but I will unplug the old machine as well

  3. Thank you for the tip I will unplug in the future