April 26, 2009

Casually piling up stuff… not so simple

Picture of the hat My mother has been feeling under the weather for quite a long time now, and although I really wanted her to come to our “Passejada amb Barret” (Walk with a hat) I was not sure she would be able to make it.

Finally she made a big effort and joined us, and I arranged special transportation for her, a rickshaw bike that carried her and some delighted little friends when she was too tired to walk.

She asked me for a hat for the event, one that would show her blue hair, so I came up with something (in inspiration quite similar to last years creation for her) mounted on a head band and with the look of casually piled up ribbon and wire mesh. I did this hat (a whimsy you may call it) in 6 hours on the evening before, so I hope you will take that into account when you look at it.

The head band underneath is a simple thin metallic one, and I covered it with black elastic velvet from Mokuba. The blue velvet ribbon on the other hand is vintage and has a thin wire embedded, and the wire mesh is a modern material very light and can be pulled and stretched.

I kept on twisting, turning, looking and positioning the wire and the velvet until I liked the position. Once everything was pinned I sewed the whole thing in place, bit by bit, very carefully, so as not to destroy the feeling of flow and airiness.

Halfway through the process I realized the whole thing was not stable and I was afraid that a gust of wind would make it tumble so I added a wire for stability. The wire runs as an inverted u inside the structure and finishes as a circle on the underside. Just that tiny circle sitting on the head gives lots of stability. Of the wire I only covered the under circle and painted with a blue felt tip pen the wire that runs through the structure to camouflage it.

So there you have it… considering the time frame available I’m happy of the result, but I must confess that the front view in the best. 

April 18, 2009

Straw braid sewing: the machines


Although it is possible to sew straw braid with an ordinary free-arm sewing machine (check out this ebook by Jane Smith if you want to know more) , when sewing narrower straw it is much easier to use a machine that has been designed for the purpose (like my Corsani, above in the picture). Much of what I’ve learnt about these machines has come from reading old patents, there’s a wealth of information there.

This is what makes these straw braid sewing machines different from your household machine:

  1. They are chain stitch machines (just one thread, no bobbin)
  2. They have a special guide system for feeding the braid and holding the work in place
  3. The needle and plate are all the way to the left to make working easier
  4. They are set on a special table with a big cutout on the middle front so there is space for the hat as it grows, and for you to manouver.

Drawing from patent 218413Some of these special machines have additional special features that were designed and patented by their inventors to make the sewing of straw easier.

To start, there is a mechanism that Willcox called in his patent a “vibrator”, and that has been implemented by every manufacturer afterwards. The mechanism is used when sewing the “button” of the hat (where the hat starts with a tight spiral). When sewing this small spiral the operator of the machine is forcing the straw because the curve is very tight, without this invention the straw can get damaged as the presser foot is pushing down on the straw when the operator is pulling. and it is very difficult to keep the work flat. This “vibrator” contraption is a very clever invention that lifts the presser foot as the needle goes down, pressing down again as the feeder goes into action, thus allowing the operator to easily turn the work.

Here is the text from the patent explaining the workings of the invention.

Excerpt from patent 218413Excerpt from patent 218413

Another interesting invention is the lever that allows the tension of the thread to be easily changed to a tighter tension. This is useful because when one starts sewing the button of the hat (the center of the spiral) the stitch length shortens because of the tight angle at which one is sewing, that often causes loose loops on the underside of the work. Before this invention one had to manually change the tension, setting a tighter tension at the beginning and then stopping the work to set a looser tension as the work progresses. With this invention you can switch between a tigher and looser tension with the flick of a lever (without stopping the sewing).  Below are the drawings and explanation for this invention.

Drawing from patent 309514

Drawing from patent 298315

Excerpt from patent 298315Excerpt from patent 298315

I also wanted to mention that there are essentially two types of straw sewing machines, those that do straight stitch, and those who sew in zig-zag. From looking at the patents I know that there were machines that did a hidden stitch, but those don’t seem to have survived the test of time because the ones in use today are the visible stitch ones, machines that are more than one hundred years old and are still (amazingly) working. The zig-zag machine on the other hand (some are still available in the market) allows one to sew edge to edge and avoid wasting material.

Soon I will write some more on the subject… stay tuned.

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