How does a sewing machine produce fancy stitches? It’s a combination of stitch length, zig-zag, needle position and reverse feed, and every fancy stitch can be reproduced manually, although it can be a very tedious process.
- Skip to particular sections:
- Fancy stitches done manually
- Fancy stitches with modulated zig-zag width
- Cam-driven zig-zag
- Combinations of geared zig-zag and cams for fancy patterns
- Adding stretch stitch
- Adding patterns to the back-and-forth step
- Computer revolution
- And the winner is…
Fancy stitches done manually
Older manuals will even tell you how to do it, and older machines used to have a dynamic zig-zag width lever that would return to zero when released (but you could lock it at a different width too), such as on this New Home 509 by Janome:
Fancy stitches could then be done by varying zig-zag width while sewing:
Setting the needle left, right or centre would make one-sided or centred designs. If you only modulate zig-zag width while sewing as shown above, you’ll produce filled shapes. But if you also change needle position as you go, you can produce wiggly curves that are made up of zig-zag stitches:
The only problem with this method, is that you’ll need a third hand to guide the material while your other two hands are busy twiddling the knobs!
Automatic fancy stitches
Which is why automatic switching with cams is so much better! 🙂 Modern machines have this bit computerised, but the movement still remains the same, only now instead of cams, we use motors and actuators.
Fancy stitches with modulated zig-zag width
These stitches produce filled shapes. The machine keeps stitching in zig-zag, and the cam makes it change zig-zag width in a certain pattern. Changing needle position makes the pattern have a left or right straight edge, or be centred, as for example on New Home 509 shown above, or on my New Home 580.
The cams for this mechanism are rounded – the width of the “collar” represents the zig-zag width.
The cam collar changes the zig-zag width between minimum and maximum, so where the collar is smallest, you get straight stitch sewn at the currently set needle position. This is how pattern 11R in the table above gets its straight bits. The note under the table says that it only works with the needle set to the right, so what happens in other needle positions? The straight bits are moved to where the needle is set, but the zig-zag is always going left, so it is getting smaller and smaller and blends completely into the straight stitch when the needle is set left. There is also an 11L cam that does the opposite, so only works properly with the needle set left.
Here are the two No.11 cams (yes, they have miraculously changed colour). The left one will produce deeper zig-zag spikes because the “arms” are longer. Notice the position of the start mark – a white tick on the top of the cam. These marks correspond to a positioning pin in the mechanism, so that the pattern always starts in the zig-zag left position. The “arms” in the 11L and 11R cams are displaced with respect to those marks, and that’s how the machine knows when to zig-zag.
These patterns are sewn with the zig-zag width lever set to zero, it controls the minimum zig-zag width in the pattern. Increasing zig-zag width with the lever, changes straight bits into zig-zag ones.
This also allows to do blind hemming and overedging in one operation (good for lightweight fabrics), and make picot hems.
But zig-zag is also a sort of fancy stitch produced from straight stitch by changing the needle position, someone figured. So it can be done with a cam! And then we can make wiggly curves too, because such a cam system would be able to position the needle freely for every stitch. This idea proved very popular, both with interchangeable and built-in cams, I am not sure who invented it first. Singer started using it in their 300 series.
Such cams have to position every stitch. The profile corresponds to the needle position between left-most and right-most. For example, the zig-zag cam (left) simply alternates between left and right, without anything in between. The blind stitch cam (centre) makes several stitches in the right-most position, then one stitch in the left-most. These two cams allow to work out all the details of pattern stitching in this mechanism and design new patterns. I’m leaving it to you as an exercise. 😉
The zig-zag width determines the width of the pattern, and needle position puts this pattern left, right or centre, just as it does for plain zig-zag, which is also just another pattern done with a cam…
Compared to the modulated zig-zag method, we get less variation in a cam-driven system because the pattern remains the same when the needle position changes. However, we can get squashed patterns here, which is particularly useful for small stitched zig-zag.
Machines with cam-driven zig-zag always need a zig-zag cam. Sometimes it’s built in and you have to switch between the zig-zag cam and “the other” cam, sometimes it is removable so that a pattern cam fits in its place. But either way, you need it in order to sew plain zig-zag.
Combinations of geared zig-zag and cams for fancy patterns
And then someone thought, hang on, why can’t I have both – an independently geared zig-zag mechanism, and cams to change the needle position automatically? But of course you can! Behold New Home 551 by Janome.
In this model zig-zag can be overlaid over the cams. The cams are internal, but they have the same structure as the Singer “Fashion Disks”, and they drive the needle position, which cannot be altered manually on this model. Here is what happens:
Adding extra zig-zag makes the pattern bolder.
These two scallopped stitch samples areactually different patterns. The upper one, when stitched without added zig-zag, produces single line scallops, whereas the lower one is designed for satin scallops sewn with zig-zag. However, adding zig-zag to the first scallop pattern pretty much produces the second. So why have two patterns? May be because the second pattern, which already starts out with zig-zag scallops, can produce much bolder (thicker) ones with extra zig-zag than the first one.
Sometimes adding extra zig-zag even changes the design:
Singer 401G and 319K series come with several knobs and levers for creating fancy patterns. I find them the most confusing machines going. The effects combine in unpredictable ways, so unless you meticulously write down everything you try, you will never be able to reproduce that lovely pattern you once stumbled upon… At least, the 319K manual has several pages showing some of the combinations you can get, but the 401G manual just tells you to experiment… :-p
Adding stretch stitch
Stretch stitch is a triple back-and-forth stitch: the machine makes two stitches forward and one in reverse. This can be applied to any stitch – straight, zig-zag or any fancy pattern we’ve seen so far. Some machines have a separate stretch stitch button or lever, so the user can add this back-and-forth movement to whatever stitch they are sewing. Other machines have it built-in, then the menu would typically show a selection of stitches formed with pre-set combinations of zig-zag, needle positioning and stretch stitch:
In this menu, “Tricot Z.Z.” is the stitched zig-zag formed by changing the needle position, while the “Feather” stitch is stitched zig-zag with added back-and-forth stretch. “Blind hem” here has a zig-zag edge like the one produced by the 11R cam on a New Home 580 with a bit of added zig-zag, but here I think it is done with one cam that moves the needle position. The “overlock” stitch is the mirrored blind hem with a straight edge and added stretch. “Buttonhole” is in fact a set of three separate stitches, so it does not count. 🙂
New Home 551 also has a stretch stitch lever, so here is how the patterns change with added zig-zag and stretch:
Adding patterns to the back-and-forth step
But what if, instead of always making two steps forward and one step back, we could specify any back-and-forth pattern? And combine it with needle positioning, perhaps?
Yes, it has been done! Again, a lot of machines have this system, and I don’t know who invented it first. Such cams have two layers, one to drive the needle position, the other to drive the feed (forward or reverse).
The above cams are from Frister & Rossmann and Kenmore machines made by Jaguar. The top layer drives the feed (forward to reverse), while the bottom layer drives the needle position (left to right). Look at the right most cam: the feed can be driven in fractions, it is not a strict forward or reverse division, like in the left-most and central cam.
The left cam just does the triple zig-zag stitch with a simple zig-zag pattern for the needle and the usual two forward, one reverse pattern for the feed. Both the needle position and the feed are switched between their extremes.
The middle cam does a fancy zig-zag where some stitches are shorter than others, so the needle is placed at left, centre and right. The feed is still switched between two extremes (full forward or full reverse), but in a different pattern than for triple zig-zag: six forward, two reverse (worked out from comparison to the triple zig-zag cam).
The right cam is a really fancy one. Both the needle position and the feed are driven into intermediate positions in order to make many little stitches along a curved line. Putting the feed into fractional positions simply means reducing its speed, it’s like working a stitch lever on old machines that goes from 4 to -4, where 0 stops the feed completely. The dogs are still moving up and down, so it’s not the same as drop feed, but they are not pushing the material in any direction.
Some models also have a few cams built-in, for the most common utility stitches: stitched zig-zag, blind hem, that sort of thing, and it takes two-layer cams on top. This allows to use the feed drive pattern from the top cam with any of the built-in patterns.
Picking 3-step stitched zig-zag, here is how it is transformed:
The waffle is done with the classic stretch stitch – 2 stitches forward, 1 stitch back (2-1 feed pattern, but giving a different result than on New Home 551 above due to a different alignment with the needle position). A weird looking baby scribble on the third row is produced by a 5-2 feed pattern, the right half of the forth row is a 4-2 feed pattern, and the left side is that fancy fractional one, as designed for the fancy stitch on the bottom row. 🙂
There are a lot of new possibilities now, but at the same time, only very few combinations actually make sense.
You see where this is going, don’t you – instead of built-in cam stacks or boxes of external cams, we install a computer that controls a few levers to change the needle position and the feed, implicitely changing the stitch length with it. It all boils down to these two; any stitch at all can be produced with the needle position and the stitch length levers worked simultaneously. You’d need a few extra hands and unbelievable reflexes to do it manually for each stitch, but for a computer it’s easy.
Memory Craft 6000 by Janome has an interesting combination of computer-controlled stitches with manual modulation.
Produced in 1986, it has sufficiently advanced electronics to control the motion, although it does not have a fancy colour screen of modern machines. But no modern machine that I know of, has continuous manual dials like this:
Both dials can be engaged or disengaged by pressing the central button. When disengaged, computer defaults are used which are actually very sensible, something you would normally set yourself.
When engaged, the top dial controls the pattern width for zig-zag and fancy stitches, or needle position for straight stitches, with a lovely wide range of 7mm. The bottom dial controls stitch length or zig-zag density when LENGTH is illuminated, but press the button again, and some patterns can be shortened or stretched by adding extra stitches. How cool is that! 🙂
By the way, Janome’s New Home XL-II (900) can do it as well, with cams and gears only! Pattern elongation is done by altering the speed of rotation of the cam, so that the number of stitches per rotation is changed.
But the coolest thing is yet to come. The manual controls in Memory Craft 6000 can be used continuously while sewing, similar to those old machines that only offer manually produced fancy stitches. That’s great because I can modify stuff as I go.
But also, when storing stitches in memory in order to make combinations, they are stored with all their manual settings, so there is no need to “translate” anything into digital form. Those manual controls appear to be not so manual after all!
And the winner is…
Which system is the best? The computerised one, of course – I hear you say. Well, it certainly is the most flexible one with so many lovely possibilities. But it’s expensive, prone to failure, and once the electronics are gone, you lose the whole machine, it won’t even do your basic straight stitch or zig-zag either. So my Memory Craft 6000 is only going to be used for the fancy stuff, not regular sewing.
Ok then, the next best thing: double layer cams that can do so many lovely stitches. That’s a great system, I agree, but you need a cam for absolutely everything, including plain zig-zag (unless the machine has a separate independent mechanism for zig-zag, like Haid & Neu Primatic). So if your machine has built-in cams only, the choice of stitches will be limited.
The older models with other types of cam drives like the ones we started with in this post, offer fewer possibilities and cannot do really fancy stuff. But in return they allow to modify existing stitches in different, yet mostly sensible ways by adding independently driven zig-zag. And most importantly of all, should the fancy stitch mechanism fail either because its plastic gears crack or because you lose your box of extra cams, the basic functions of straight stitch and zig-zag will remain unaffected, and you won’t lose the whole machine.
For me, there are no winners or losers here, in fact it is not a contest at all. Each type of machine is best for a particular range of tasks, so the best choice will depend on the types of sewing you do most… as always!