3D Printing Singer Type A Fashion Discs
Back ground
I have spent a very happy few days combining my two main hobbies at the moment, namely rescuing/restoring a Singer 306K Automatic Swing-Needle Sewing Machine, and learning as much about 3D design and 3D printing as I can and putting it to good use. This post is a hopefully a definitive write up on what I started in a previous post Singer 306K – crossover into 3d printing!.
My 306K came with a set of 6 Fashion Discs in an original box, which was in delicate condition. I thought it would be nice to find some copies of my discs and put the originals away in their box to keep them safe and in good condition. Being on a limited income, I decided to make use of the resources I already had rather than buy discs from all over the country and the world.
At this stage I don’t need many stitch patterns, but I can see a couple I don’t have that I would like, and can think of a couple I would like that don’t yet exist. So I looked for 3D printing files that I could download and print. There are a few out there, but some of them seem a bit iffy. However I found one example on Thingiverse that appealed as it allows you to design your own discs – Singer Parameterised Fashion Disc by Niclasf. Rather than providing ready to print files of some or all of the available discs, this download allows the user to design their own discs, or clone existing discs and the create the 3D print files if they have a bit of knowledge. Read on for some of that!
What is a Fashion Disc? Well it is what allows a swing-needle sewing machine to sew decorative and useful stitches. It is a plastic disc or cam that has lumps and dips on it, and the disc rotates once every 18 stitches the machine makes. Each of the bumps and dips pushes a cam follower, or allows the cam follower to drop into a dip. The cam follower is connected to a swing arm in the needle head, that moves the needle from side to side as the material moves through the machine, producing a pattern of stitches. When the cam follower is closest to the centre of the disc, the needle is over the left of the stitch pattern, and at its furthest away from the centre, it is over to the right.
The stitches can be sewn very close together, or far apart, and can be sewn wide or narrow, however the pattern is limited to 18 stitches repeated over and over. With some thought, a good sewer can get very creative.
How the print model works
The niclasf download from Thingiverse consists of a 3D design drawn in a package called Fusion 360 by Autodesk. Fusion is a sophisticated package almost unlimited in what it can do, and the full version comes with a hefty pricetag. Fortunately for the keen amateurs out there, it is free for non commercial use.
The design uses a feature called Parametric design. which means that an object can be designed so that dimensions and positions of various parts of the design can be based on parameters rather than fixed values.
The parameter file has 18 stitch position in the pattern, each of which can be set to any number from 0 to 12 (not just integers). The parametric design uses these numbers to vary the height of the “teeth” or cam positions, 0 being close to the centre, 12 on the outside. Below is a picture of a zigzag disc (number 1 in the set) and the stitching it produces. You can see 18 stitch positions, 9 teeth and 9 dips, this would be specified as 12,0,12,0,12,0,12,0,12,0,12,0,12,0,12,0,12,0 in the 18 positions.
If you want to produce another existing disc, you have to work out where each stitch has to be and calculate the position within the range 0 to 12.
The 18 numbers below would produce a cam that would sew a continous wave pattern, like disc 20 in the set. In fact these numbers represent a “Sine Wave” covering 360 degrees in 20 degree steps, and the sine values changed into the range 0-12. The disc produced by these numbers is shown under the numbers.
0.0,0.36,1.4,3.0,4.96,7.04,9.0,10.6,11.64,12.0,11.64,10.6,9.0,7.04,4.96,3.0,1.4,0.36
This disc looks round, but you can see slight undulations around the perimeter, and the disc is offset from the hole in the centre. The stitching under the disc is what this disc produced.
My improvements
1. As you can see from the photograph above, the discs produced need to be labelled, as there is no indication what the disc does, and the difference between disc 20 above, and disc 4 “Scallop” (shown below) is not great. The original discs have a number and a picture to show what they are.
In the picture at the top of the page you can see the labels I have 3D printed into the discs. This was acheived by
a. adding a user parameter called discid, with No Units, a numeric disc number, and a comment which makes up the rest of the text on the label. This can be put into the parameter.csv file for each disc like this
discid,,1,Zigzag
pos1,mm,12 mm,
pos2,mm,0 mm,
pos3,mm,12 mm,
pos4,mm,0 mm,
pos5,mm,12 mm,
pos6,mm,0 mm,
pos7,mm,12 mm,
pos8,mm,0 mm,
pos9,mm,12 mm,
pos10,mm,0 mm,
pos11,mm,12 mm,
pos12,mm,0 mm,
pos13,mm,12 mm,
pos14,mm,0 mm,
pos15,mm,12 mm,
pos16,mm,0 mm,
pos17,mm,12 mm,
pos18,mm,0 mm,
tolerance,mm,0.2 mm,
b. another addon was downloaded and added on to Fusion 360, called ParametricText. This allows text to be generated from system and user parameters.
c. sketch2 in the model was edited. The star was removed, and a text field was added. I made it an arc shape by following a guide line.
d. I used the new modify menu option “Change Text Parameters” and created a parametric text parameter attached to the text field just created “#{discid:.0f} {discid.comment}”
e. I use the modify menu item “Compute All” each time I change the text parameter
2. niclasf also decided that the discs could be improved by rotating the disc pattern by 2 degrees. He explains why on his Thingiverse page, but doing this means the discs cannot be used back to front, which means that directional stitches like Disc 5 Arrowhead cannot be sewn in the opposite direction.
This is controlled by a parameter called d108, which can be changed directly, or added to a parameter file.
e.g. “d108″,”deg”,”0 deg”,”degrees offset ”
3. the tooth profile wasn’t correct. The top of the tooth was fine, but the side of the tooth has a concave radius, and it was set to 20mm. The original used a radius of closer to 5mm. Again this is controlled by a parameter called toothRadius. e.g “toothRadius”,”mm”,”5 mm”,” ”
4. I added a slight fillet to the back of the discs edges, just 0.5 mm. If there is a slight elephant foot during printing this negates it.
5. I rotated the model so that it lies flat on the x-y plane, with the text face up. This is so that a bug in Cura does not leave the model to be printed at a slight angle after rotation, ruining the print. The object is printed in this orientation so it saves having to rotate it.
How to use
- Download the Fusion model of Parametric Singer Type A Fashion Disc from Thingiverse.com
- Open the singer_type_A_fashion_disc.f3d file in Fusion 360, which already has addons ParaemeterIO and ParametricText installed.
- Download a parameter csv file or create your own parameter csv file based on the one from Thingiverse.com
- In the modify menu, click on Import/Export Parameters (CSV)
- Choose Import and hit OK in the dialog box.
- Navigate to your downloaded or created parameter csv files, select a file and open it
- Wait until the dialog box says “Finished reading and updating parameters” (my version still shows the progress wheel, ignore it) and press enter or click Ok. The disc should change shape to your chosen disc.
- On the modify menu click on Compute All (or use CTRL-B) to make the text from the parameter file appear on the model.
- DO NOT SAVE (this would overwrite your original model), but use the File menu option to Export the model as an STL file into the location you use for your printable .STL files. Give it a meaningful name!
- Use Cura or whatever slicer you use to take the STL file and print it in your chosen filament, on your chosen printer using your parameters.
Printing
I use a Creality Ender-3 V3 SE printer, and I print these discs using Creality Ender PLA filament. Whatever printer and filament you use, it is probably better than this combination.
My printer has been carefully set up, the print bed is very level. I have worked out the temperatures for the bed and extruder for the material. I do not use glue or tape on the build plate, just clean it with IPA to remove finger grease. I have a Z offset of -0.2 beyond what the firmware calculated, and my prints adhere to the plate and do not have elephant feet.
The object is printed text side up, and I use Ironing (maybe a CURA thing?) on the upper side to smooth off the print.
I use Gyroid infill, at 10%. The top and bottom and walls have 3 layers, these things do not have to be strong. I always keep my print speeds down at 50mm/s or less, so my prints are quite slow.
Finally
A picture of the discs produced during development. All these discs worked, but I was not happy with how they looked. The second photo is the final set on a storage stand. I made the stand magnetic, but a 306K is made of aluminium, so the only place it will stick is on the lid of the box over the knee controller! Doh!
Downloads
I have published this thing on Thingiverse.com, including all 33 of the .STL files for the clones of Type A Fashion Discs 1 thru 32 and 37.
3D Printable STL files for sample discs
These files are STL files of the 11 discs produced so far, already generated for you to print. If you have a friend with a 3D printer, give them a copy of one of these files and they can print off a disc for you. Please test it by hand (no motor) before using it!
The first 7 are copies of discs 1,2,3,4,5,6,20 from the standard singer set.
Disc 100 is a straight stitch disc. Yes, regardless of machine settings this disc will produce straight stitching. Maybe use it with your straight stitch throat plate. It may also be quieter when doing straight stitching, the zigzag disc can be quite noisy.
Disc 101 is a variation of Disc 1 ZigZag, with an extra stitch position in the middle of the ZIG but not the ZAG. I find this reduces puckering or tunneling when a short stitch length is used.
Disc 105 is a similar variation on Disc 5 Arrowhead, for similar reasons.
Disc 200 NZ Fern is a design by myself, and is a simple representation of the Silver Fern logo used absolutely everywhere in NZ, especially sports teams shirts!