Singer 306K – crossover into 3d printing!
My Creality Ender 3 V3 SE 3D printer is pretty well used, not so much for decorative knick knacks, but for useful things, repairs to objects,extending the use of thing etc. I have got it sorted out and can print whatever I like, either from other people’s designs, or my own designs drawn on Fusion 360. So I make stuff for my sewing machines quite regularly, most of which is not relevant to most people.
My Singer 306K sewing machine which I bought in January 2025 for $40 is responding well to my efforts to rescue it from ignominious disposal. I have it working well and am now starting to tweak some of the many things that can be tweaked. The basics like end float on hook drive shafts, needle height, needle timing with the hook,feed dog height, stitch length adjustment are all looking good, but the bobbin carrier has a distorted spring which makes the bottom thread tension difficult to adjust accurately. I have a new tension spring winging its way from Omaha, Nebraska via Portland, Oregon to NZ which should fix the problem.
In the meantime I am trying to get my head around the complexities of the swing needle mechanism, which produces the zig zag stitches and a few other decorative stitches. There are slight adjustments required for the “bight” (the width of the stitch produced by the swing needle). The bight seems to be very slightly offset to the left. The control for the stitch offset also appears to be off by the same amount the other way. Neither is a game changer, but eventually I want to get it right. My 129 page adjusters manual will get some good use.
The 306K was well used by someone who made sails, but despite this is in remarkable condition for its age, just like me. It is a year older than me, being made in 1954 ( same as me). It also came with a box of accessories, including two extra throat plates for straight stitching and embroidery, several heavy duty feet for various specialist jobs, and a cute little box of “Fashion Discs”.
This picture shows the box and the 6 discs on a sampler, each disc is on top of the stitch pattern produced by the disc.
The 6 discs provided give a really good range of decorative stitches, but Singer saw fit to produce about 30 discs for this class of machines. Most of the stitch patterns are pretty useless for what I intend to use the machine for, only one caught my eye, disc 20 – Curved Mending Pattern. This pattern is a simple wave pattern. I also need to test the needle position at the extremes of the bight and needle position control, and there is no disc designed to do this.
There are 3D printing enthusiasts out there who have produced replicas of various disks, and of the full set. A search for Singer Pattern Disks or Fashion Disks on any of the special sites will show many possibilities. I was intrigued by this one which allows the user to design their own discs and print them.
A fashion disk is a pattern of 18 stitches, repeated as the disk rotates and a cam follower translates the shape of the cam into movements of the swing arm for the needle, changing the position of where the needle goes through the material. 18 stitches is a bit limiting, but is adequate for most usage. The Thingiverse object above is a Fusion 360 design of the generic zigzag disc #1, but designed parametrically, so that various aspects of the print can be changed to suit the requirements. There are 18 parameter lines in the parameter file, each one specifying the offset of the needle from one side of the possible positions. Offsets can be from 0-12, and don’t have to be integers. All you have to do is work out what numbers to put in! The generic zigzag discs has offsets of 12,0,12,0,12,0… for 18 in total.
My first simple requirement was for something very similar, but with some extra stitch positions in the centre line. So my first disc used 12,6,0,12,6,0,12,6,0… and so on to produce a slight variation on the zigzag which I call Sawtooth, after the shape of the teeth on my favorite hand saw. Probably not much use decoratively or even as a useful stitch, but great for me to examine the stitch positions relative to the centre line in a paper test.
My next requirement was for something similar to the #20 disc mention above. I have no real idea what the actual form of that wave is, but I decided to use a Sine Wave. Sounds easy, but it took me an hour or so to figure out the method.
Rather than try to explain how, I wrote this small program in Python to generate the 18 offsets required for the sine wave.
i=10
import math
while i < 360:
s=math.radians(i)
x=round((math.sin(s)*6)+6,2)
print (i,x)
i=i+20
These are the 18 offsets it produced and that I used to generate the disc.
10 7.04
30 9.0
50 10.6
70 11.64
90 12.0
110 11.64
130 10.6
150 9.0
170 7.04
190 4.96
210 3.0
230 1.4
250 0.36
270 0.0
290 0.36
310 1.4
330 3.0
350 4.96
Finally I generated a disc that had all 18 offsets set to 6, the mid point. This disc effectively produces a straight stitch even if the bight control is set to maximum, or the needle position is set to the left or the right.
The discs took about an hour to print all 3 and the settings provided worked on my printer using my saved settings for the filament I used.
Altogether a very satisfying fusion of 3d printing, sewing machines and some interesting sums!
These photographs show the three discs on the stitching they produce and some close-ups of the stitching.