Tag Archives: vintage singer stop motion

Mar10

The handwheel and the stop motion on a vintage Singer – part two

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Following on from the last post, we’ll now look at how to replace the handwheel, or if you like the balance wheel, which is a process that can make no sense at all if you don’t understand what’s what.

Before we get stuck in though, I need to stress that what follows applies only to the classic Singers with the big chromed knob in the middle of the handwheel.  You’re on your own with anything more modern.

Right … assuming that you’ve had the handwheel off for whatever reason, put a couple of drops of sewing machine oil on the end of the shaft before you slip it back on and give the wheel a spin to spread the oil.  And now for the interesting bit.  You need to put the stop motion clamp washer back where it came from, and it can go back on four different ways – two with the projections on its inside facing into the shaft …

And two with them facing outwards …

So which is the right one?  The answer is that it’s one of the bottom two i.e. it goes back on with the projections on the inside of the washer facing outwards.  But that obviously still leaves two possible ways to fit it, and here’s why you need to get it right …

As we said in part one of this epistle, the two projections on the inside of the washer locate it on the shaft, such that both shaft and washer always rotate together.  But it’s those three sticky-outy bits on the outside of the washer that we need to concern ourselves with now, and in engineer-speak, sticky-outy bits like that are called lugs.  That’s why in some parts of the country you hang your glasses on your lugs, and the orifice into which blokes insert their little finger before wiggling it theatrically is their lug ‘ole.  But I digress.

Let’s have another look at the stop motion clamp screw, and at that small screw in its head which you have to unscrew before you can take the clamp screw off.  That’s called the stop screw, by the way.  Now, if your nice shiny chromed knob is still like it was when you took it off, the underside of it will look like this …

And it probably won’t surprise you to find that if you screw the stop screw back in, like you will when you put this all back together, it’ll look like this …

Now you have to pretend really hard.  You know how you took your stop motion clamp screw off by unscrewing the stop screw, then unscrewing the stop motion clamp screw itself so that it came off and the clamp washer fell out?  Well, imagine that you could somehow magically remove both knob and washer without unscrewing anything, such that they came off in your hand together, exactly as they were on the machine.  If you could do that, they would look like this …

Except for one thing.  The washer would be the other way up.  For clarity, I’ve taken these close-ups with the washer reversed so that it sits against the head of the screw.

What you’re looking at there is the relative position of the stop screw and the washer when you’ve released the clutch in order to wind a bobbin.   Remember that when you do that, the washer stays put on the shaft?  Well, now you can see why when you de-clutch a vintage Singer, you can only unscrew the knob about a third of a turn.  Yep, the stop screw comes up against one of those three lugs, and that stops you unscrewing it any further.  That’s why it’s called the stop screw.

Now, when you’ve wound your bobbin and you want to revert to normal sewing, what you do is screw your stop motion clamp screw in, i.e. you rotate it clockwise.  You can be forgiven for now thinking “Ahah, so the stop screw hits another lug and stops me tightening it any further?” because that’s what it looks like in this next photo.  But that’s not actually the case.

In fact you tighten the knob until you’ve squashed everything together tight enough to squeeze up the slack and lock your handwheel to the shaft.  That’s what stops you rotating the stop motion clamp screw any further – not one of those lugs.  Everything needs to be clamped together by the stop motion clamp screw before you’ve turned it far enough forward for the stop screw to hit one of those three lugs like it has in the picture below.

Gosh.  At last we’ve arrived at how this all relates to which way round that washer (which, remember, is upside down in those two pictures) goes.

Hurrah!

To sum up the story so far, when we come to put everything back together, we need to meet two conditions.  Things need to be so arranged that when we slacken the stop motion clamp screw, we can turn it anti-clockwise far enough to release the pressure on the handwheel so it becomes free to rotate round the shaft, but not so far that we risk the washer getting out of position.  That’s the first condition.  The second is we need to ensure that when we tighten the stop motion clamp screw, everything squashes up enough to lock the handwheel to the shaft before that little lock screw hits a lug.

Unfortunately, those two conditions are only met with the washer one particular way round.  And which way round is that?  Who knows …

Fear not though, dear reader.  All is about to be made clear.

Hopefully …

First of all it helps if we can increase the odds on the washer staying put on the end of the shaft while we screw the stop motion clamp screw back in place.  The way I do that is to have the two slots in the end of the shaft horizontally opposed to each other, and if they’re not like that already, it’s just a case of putting a screwdriver across them like in the picture above and levering the shaft round to where we want it.

What we do then is put the washer on the end of the shaft with the inside projections facing outwards, we check that the little stop screw isn’t protruding through to the back of the stop motion clamp screw, then it’s just a case of carefully screwing that back onto the shaft.

Screw it in as if tightening the clutch for normal sewing, then try screwing in the little stop screw.  If it won’t go all the way in, don’t force it, because it’s telling you it’s not happy with the way things are aligned.  In that case, back out the stop screw, remove the stop motion clamp screw and try again with the washer rotated 180 degrees round the shaft.

If the stop screw will go all the way in, hold the handwheel and turn the knob clockwise as far as you can.  If that leaves you with a handwheel which is locked to the shaft, hold your breath and try unscrewing the knob as far as you can.  If the handwheel rotates freely when you can’t unscrew the knob any further, it’s your lucky day.  You got it right first time.  You’ve met both conditions.  Rejoice, put the kettle on and break out the stale shop-cake.

If the stop screw goes all the way in but something (it’s actually a lug on the washer) stops you tightening the knob before it’s screwed in far enough to lock the handwheel, you need to try again.

It’s a comfort to know that if everything worked properly before you took the handwheel off, it’s just a case of you getting that washer back on the right way and all will once again be sweetness and light.  You have a 50% chance of getting it right first time.

Mar5

The handwheel on a vintage Singer and the stop motion – part one

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Picture of Balance wheel of Singer 99K

According to the old Singer parts lists, that big spokey wheel on the end of your vintage Singer is the balance wheel.  According to most folks who use a vintage Singer it’s the handwheel, so it’s the handwheel as far as we’re concerned here, and we’ll be looking at its removal and replacement, with a bit of a detour on the way.

But why, pray, would anyone want to take the thing off?  Well, you could be taking a machine apart because it’s in a disgusting state and cleaning it will be so much easier if you take off some of its bits.  Or maybe you want to change the handwheel for a different one?  You’re bored and it might be more interesting than cleaning the oven?  Who knows.  Whatever the reason, people do take their handwheel off.  Oh yes. Then they put it back on, and the funs starts when they find that the clutch doesn’t work.

“The clutch?” I hear you say.  “What clutch?”

Well, the clutch is what lives behind that big chromed knob in the middle of your handwheel, and without the clutch your machine would be nowhere near as user-friendly as it is.  That chromed knob is what is properly called the stop motion clamp screw, and it’s called the stop motion clamp screw because that’s what it does.  It stops the motion and it clamps things together.

When you hold the handwheel and turn the stop motion clamp screw clockwise, as you do for normal use, it clamps the handwheel to the shaft onto which it’s fitted, so that when the handwheel turns, so does the shaft.  On the far end of that shaft is the linkage to your needle bar, which goes up and down as the handwheel turns.

That upping-and-downing is the motion, which you stop by unscrewing the stop motion clamp screw when you want to wind a bobbin.  Unscrewing it stops the motion at the far end of the machine, so that your handwheel can drive the bobbin winder round and round without also driving the needle up and down.

Most people call the stop motion clamp screw the clutch knob, because unscrewing it disconnects the drive in the same way that pressing your foot on the clutch pedal disconnects the drive to your car’s wheels.  Let’s take a look behind it …

picture of stop motion clamp screw on vintage Singer

To do that, you need to remove the stop motion clamp screw, and you do that by first unscrewing that small screw in it.  But don’t unscrew it too far, or it will fall out and roll under the table, you won’t find it, and next time you Hoover it’ll be gone forever.  Unscrewed about as far as in that picture is plenty far enough.  If you can now unscrew the knob, that’s what you do.  The thread on it’s about 6mm long, by the way.  If you can’t unscrew it all the way so that it comes off, back that little screw out another half turn and try again.

As you take the chromed knob off, one of two things will happen.  More often than not, a steel washer-type thing will fall out from behind it.  Sometimes though the washer stays in place, in which case what you see when you take the knob off looks a lot like this …

picture of stop motion clamp washer in place on Singer 99K

So how does it all work then?  Well, it’s one of those things which is a doddle to expain if you’re sitting next to me with a machine in front of us, but trying to explain it on the interweb is not so easy.  Fear not, though, gentle reader.  We’ll manage.  Make yourself another coffee, maybe even grab a biscuit if you’re not still on the diet, then take what follows one sentence at a time.

In the picture above, you’re looking at the end of the shaft which runs through the arm of  the machine.  Two projections on the inside of that washer engage with slots in the end of that shaft, so obviously when the shaft goes round, so does the washer.  And vice versa.  Note that the handwheel is fitted on the same shaft.  It doesn’t go round with it, though, because it’s not fixed to it.

If you gave that handwheel a spin, it would just rotate on the shaft, which would stay put, as would the washer (if you put a finger on it to stop it falling off the end).  Just to labour the point, there’s no connection here between the handwheel and the shaft, so turning the handwheel isn’t going to turn the shaft, which isn’t going to move your needle up and down.  As shown in that picture, the motion is stopped.  That’s how things are when you’re bobbin-winding.

Now, if you replace the stop motion clamp screw (the chromed knob) and tighten it up, you’re back to normal – rotation of the handwheel drives the shaft which drives your needlebar up and down (and your feeds dogs backwards and forwards). That happens because tightening up the stop motion clamp screw clamps the handwheel to the shaft, so that whatever’s turning your handwheel also turns the shaft, and you can start sewing.

And at this point, anybody really thinking about this is going to be wondering exactly how the clamping of handwheel to shaft comes about, because it certainly isn’t obvious.  Here’s how …

That’s an exaggerated cross-section through the clutch area, and this is a simplified explanation.  The purple’s the chromed knob, and the red’s the important bit – the stop motion clamp washer.  In the diagram, the knob is unscrewed as for bobbin winding i.e. the motion is stopped.  Nothing’s held tight against anything, so when the handwheel turns, it just spins round on the shaft, which stays put, as does the washer and the knob.  All that happens is that the handwheel turns on the shaft.  Nothing else moves.

As we saw earlier, the washer is connected to the shaft by those two projections which sit in slots in the end of the shaft, such that if the washer turns, the shaft must too.  Those two projections are so arranged that while the washer can’t rotate about the shaft, it can move along it, but only very slightly.

Now imagine that purple knob being shoved hard over to the left, so it closes up the tiny gaps between itself, the washer, the handwheel and that step in the shaft, and squashes everything tightly together.  Squash hard enough, and you have a handwheel which is clamped to the shaft.

In practice, your stop motion clamp screw does the squashing. Tighten it up, and handwheel, knob, washer and shaft effectively become one, so turning the handwheel turns the shaft which makes your needle go up and down. That’s what happens every time you change from bobbin-winding back to normal sewing, and the key to it all is that washer.

OK, that’s the theory and the practice of the clutch, and by now your head probably hurts.  Mine certainly does from trying to explain it, so we’ll knock off here and continue in part two …