Week 17 - Wildcard week

Individual Assignment:

• Design and produce something with a digital process (incorporating computer aided design and manufacturing) not covered in another assignment, documenting the requirements that your assignment meets, and including everything necessary to reproduce it.

For this week's assignment I had several ideas, but I found it difficult to decide on something, that would fit into one week and not consume too much time.

I ended up testing a knitting machine, with the goal to design a dual-color knitting pattern, program the machine and use it to knit a cap.

Introduction

Knitting machines aren't new inventions. They have been around for ages and the basic principle is yet simple and ingeneous. There are circular machines for endless "tube-like" knitting and flat bed machines for knitting back and forth and producing flat product, that can be later sewed together.

There is a certain number of moveable hooks, where each hook contains one stich / loop of the knitted product and a carriage that goes either around or back and forth to do the knitting.

Fortunately, I have a colleague, who owns a knitting workshop with many different machines. She was very generous for giving me the opportunity to test one machine and teaching me how to use it. Special thanks!

The machine I used is the Brother KH-940. It is digitally controlled, has a memory with preprogrammed patterns and free memory for own pattern designs. It can be operated by hand or with the help of an electric motor drive.

One common misconseption is that machine knitting is not handcraft. It does indeed involve a lot of manual work, at least when operating knitting machines for home use.

Another interesting fact about knitting machines is, that they age very well, are robust and have a long life, when well maintained. There is quite some community around them and many first generation digital machines are still in use. They are the only machines I know, still used for production and using punch cards!

Designing the pattern

The idea for the patter is derived from this logo:

I went into Inkscape and played with different arrangements of this logo.

The left pattern looks appealing to me, so I exported the base shape (one quarter) of the pattern. The next step was to "pixelate" the graphic, because the knitting recepie is like a binary code 2D matrix. First I looked for a tool in Inkscape, but didn't find anything useful. I looked on the internet and found Stitch Fiddle, which does exactly that. I had to answer a few questions and could upload my image.

After decreasing the number of colors and adjusting the size, I got a nice chart, that I can use for programming the machine. Because I wasn't sure about the type of yarn I would use and what the width of each column would result to, I saved two patterns (one 50 x 50 and the other 30 x 30).

Note

Another approach for creating the pattern is adding a 50% transparent image as background into an Excel sheet and filling cells with color.

As it turned out, my pattern design wasn't very suitable for dual-color knitting, because both colors should be used in the pattern within relatively short distances from each other. Otherwise long threads will appear on the backside of the piece. This can be avoided by using a special accessorie (ribber), which knits a rib pattern on the backside, but setting it up for multi-color knitting turned out to be too time consuming, so we decided to go for a more simple pattern for the first approach. Nevertheless, we used the ribber for the elastic pattern in the beginning.

The simplified pattern has only a size of 11 x 13 loops and depicts just the simple logo. It will be repeated continiously.

Note

Because we were not going to make a rib pattern on the backside and would have to accept long threads, I was advised that a cap would be more appropriate than a scarf, as the threads won't be visible.

Programming the machine

Programming can be done, either by entering a binary code line-by-line via the interface on the machine or by sending a file via a special software and adaptor cable.

Because the pattern had been simplified a lot, I programmed the machine using the buttons. First a memory space is selected (927), then the width and height of the pattern is entered and lastly all lines are filled by pushing the black and white buttons according to chart.

Note

When using the ribber for multi-color printing a different carriage is used and the color has to be changed every second row. A color changer accessorie is used for that. However, as we were not using the ribber for the pattern, we could use a carriage, with two colors and both colors were knitted simultaniously in each row.

Setup

A test piece using the "einband" type of Icelandic wool, showed us that 31 stiches would result into 10 cm of fabric. To reach the desired circumference of 49 cm, we would need to cast on 152 stiches.

First the needles where selected by pushing them outwards (76 to each side of the bed's center).

The yarn is thread in between the two beds and into the groove on the carriage.

The size of the stiches is selected to "0" on both wheels and the carriage moved to the other side.

Now the stiches have been cast on and the comb can be inserted from below and locked. Weights are placed on each side to pull the farbic down during knitting.

Rib

Now we knit a purl - knit stich pattern for 16 rows. To do so, we select the stich size "2" and push the selector buttons on the carriage.

The counter is useful to keep track of the rows.

After eight rows of hand operation, I tried the motor drive as well. It is quite fast!

Dual color pattern knitting

When the 16 rows are finished, the ribber is removed and the carriage reset. Also the front piece of the carriage needs to be changed to allow for dual color knitting and the second yarn inserted.

Now the pattern is activated and the selector wheel is set on pattern knitting (KC), as well as the MC button pushed.

After one pass of the carriage, the needles are selected automatically by the machine, so that they appear in two rows (different indent). Now the pattern is repeated over and over until you stop.

I knitted 72 rows and then it was time to bind off the stiches. This is done by hand with a small tool and one has to be very careful not to miss any stiches.

Here is the workpiece removed from the machine, but still hanging on the comb.

Now we have a rectangular piece of fabric. For more advanced knitting, I would have introduced decreases to shape the cap, but that is the next level.

Finishing

For sewing the ends together, I used another special machine, where always two loops of the opposing ends are placed on a circular needle rack. It is basically a sewing machine controlled with a foot pedal, that holds onto the stiches.

The last step is to bind of the loose ends and pull the top of the cap together, as well as rinsing it in soap water and letting it dry.

I'm pleased with the result.