Presser bar

Upgrading foot pressure adjuster

Old machines usually come with a simple thumb screw for a foot pressure adjuster. Nothing wrong with it in itself, simple and effective.

But I am fussy. On machines where I tend to change foot pressure frequently, I like to have a more modern adjuster that goes in steps.

These adjusters are very common on Japanese machines from 1950s through 1980s, and sometimes you can even pick them up in job lots of bits and pieces. I always salvage them from machines destined for parts, too.

My 1902 Singer 48K is one of those old machines that is due an upgrade.

The first thing to note is that this adjuster does not have a hole in the centre for the presser bar to poke through. No, the new adjuster has a piston with a closed end, so the presser bar must be short enough so that you could lift the foot on the highest pressure setting. This means that the original bar is too long.

Fortunately I’ve got a few presser bars lying around, so I found one of the right length. The original spring can be used with some modifications.

The new adjuster is designed to work with two springs: a soft one for low pressure settings and a hard one for high pressure. The soft spring also pushes the piston all the way up when the pressure is released.

It is up to you how much of the range you want to allocate to the soft spring. It depends on the length of the hard spring – it kicks in when the soft spring is fully depressed.

In my case the hard spring was a bit too short for my liking – it only kicked in at number 3. I wanted it to kick in a lot earlier on this machine, at 1. This adjuster makes steps of half a number, so I would have two steps on the light spring (0 and 0.5). So I added a short spacer on the bottom. It is a piece of a hard spring with a larger diametre than the regular one. Now the soft spring fits into the spacer spring.

Where to get soft springs of the right diametre? In the same place where you get the adjusters and everything else – strip them from old machines. Or buy them separately – there are companies selling ready-made and made to order springs with any measurements and stiffness, but that’s not cheap. So remember to keep anything that looks remotely useful – you never know when it will come in handy! 😃

See also this post on replacing the presser bar.

5 thoughts on “Upgrading foot pressure adjuster

  1. Hi Elena, was just wondering what the little sponge is for. Plus the needle for your sewing machine article was very interesting too.

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    1. The sponge was to stop the noise. There used to be some felt there originally but it perished in the last 120 years. Read the post on Singer 48K for details – there’s a link there.

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      1. Cheers – well that makes sense. Now I wonder if I can use that on hubby! 😉
        I think as we seem to have a little extra time on our hands a revisit to your machine sections will be good bedtime reading!

        Liked by 1 person

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