26-02-2013, 03:46 PM
Computerized embroidery
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Introduction
Computer-controlled embroidery also called machine embroidery is a kind of Computer-aided design and manufacturing (CAD/CAM). We shall introduce some (1) basic principles, (2) existing hardware and (3) existing software and also include some information about computer-controlled sewing. More technical information about computerized embroidery is available in other articles available indexed in the computerized embroidery category.
See also:
• Fab lab, an introduction to end user-created design and fabrication (including a description of many other types of computer-controlled machinery)
• Computerized embroidery in education
• Stitch Era embroidery software, a partial "how to" guide to this free embroidery software suite, split over several articles, e.g.
o Stitch Era - simple digitizing,
o Stitch Era - adjusting stitch sections,
o Stitch Era - lettering,
o Stitch Era - vector graphics, ..
• Concepts of computerized embroidery (rough draft as of May 22, planned as a short lexicon)
• Elna 8300, the embroidery-only model we bought in may 2011.
Professional Computerized embroidery machines are specialized machines that can create embroidery from computerized designs. Such machines exist for the home market, for the small independent professional and for mass production. Many home sewing machines can be turned into an embroidery machine by adding a hardware module. Many modern sewing machines (including the ones for the home market) can be computer-controlled and are also known as computerized sewing machines. Good sewing machines can sew, embroider and quilt. I.e. you get three machines in one.
Design software exists in various form, either as special-purpose tools for various design stages or as complete design suites. Embroidery designs can be stored in a multitude of proprietary file formats and are now often sold over the Internet. Free designs files are difficult to find, i.e. few are available under an open "source" licence. Converter software between various file formats exists, however depending on your sewing machine you will have to make an effort for finding the right tool.
Let's now have a look at hardware-software interaction. We probably can distinguish between the following kinds of models with respect to computer control of the embroidery machine:
• computer-controlled (directly from a computer). These exist in industry.
• computer-controlled (via file upload, i.e. specific firmware in the machine will read a proprietary CNC file and execute it). That's the solution existing in mid and high-end home machines (in the $500 to $10000 range). A good model (like a Swiss Bernina that can both sew and stitch will cost around CHF 3000.-). Entry-level computerized embroidery-only machines are not as frequent and a bit cheaper.
• Computer-powered, i.e. the machine will have more than a single motor and stuff is synchronized with a computer instead of complex mechanics. Typically, low and mid-end home sewing machines. These machines cannot execute sewing or embroidery design files.
Bernina Aurora 450 with embroidery module
In computer-powered or computer-controlled home sewing machines, “the computer directly controls several different motors, which precisely move the needle bar, the tensioning discs, the feed dog and other elements in the machine. [...] The computer drives the motors at just the right speed to move the needle bar up and down and from side to side in a particular stitch pattern. Typically, the computer programs for different stitches are stored in removable memory disks or cartridges. The sewing-machine computer may also hook up to a PC in order to download patterns directly from the Internet. Some electronic sewing machines also have the ability to create complex embroidery patterns. These machines have a motorized work area that holds the fabric in place underneath the needle assembly. They also have a series of sensors that tell the computer how all of the machine components are positioned. [...] The sewer simply loads a pattern from memory or creates an original one, and the computer does almost everything else.” Computerized Sewing Machines, retrieved 13:07, 15 April 2011 (CEST). With that kind of machines, a user can focus on design and the needs to learn how to interpret orders from machine like replacing the threads.
It can be argued that computer-controlled embroidery machines are older than computers, i.e. models made between the two WWs used punched paper ribbons for control. Machines that were controlled in real-time by a "puncher" through a pantographs have been invented at the end of the 19th century.
According to Wikipedia and other sources, the first modern day computer controlled sewing machine was built by Orisol in 1987 for making shoes, i.e. much later than embroidery machines.
More or less according to Wikipedia, the basic steps for creating an embroidery are as follows:
• Get or create a digitized embroidery design file preferably in some kind of editable format. Typical formats are .emb, .exe, .dst, .cnd and .fdr.
• Edit the design and/or combine with other designs (optional)
• Translate to machine executable code, i.e. a stitch file (this is optional if the original format is already machine-readable). Typical formats are .pes .art, .pes, .jef, .sew and .hus (see below)
• Load the final design file into the embroidery machine
• Stabilize the fabric and place it in the machine
• Start and monitor the embroidery machine
Creating a digitized embroidery file itself includes at least two steps:
• Create a drawing in a format that will remain editable. Some software also allows to import bitmap and vector formats which then can be translated (with some manual intervention).
• Then digitize (translate, punch) to a (preferably) editable stitching format. A stitchable design includes embroidery-specific information like stitches and thread color. However good formats define stitching lines and fills (columns and areas) that are parameterized with stitching information such as the filling patterns, density, stitch density etc. Professional digitizing is difficult. Non-professional lower quality digitizing is fairly easy with good software (I learned in a few days...).
• If needed, translate an editable stitch file to a machine-specific format.
Specialized low-end software does this in two steps. Get a drawing or picture. It first will be vectorized (you may have to assist with that as in any other bitmap tracer). You then can have it auto-digitized. Either in the middle of this process (after vectorizing, better) or after that (limited resizing), you then also can resize, combine, rotate, etc.
Consumer embroidery machines
Criteria for selecting an embroidery machine
• Overall mechanical quality, in particular reliability and precision.
• Hoop-size (frames for the embroidery area) is critical. 14x20 cm is expected for mid-level machine and many folks consider this as a must-have minimum. So-called Jumbo hoops (e.g. 40x26cm) exist on high end sewing/embroidery machines and multi-needle models. There also exist a third-party market for hoops. However, on some machines, jumbo hoops are difficult to use since designs must be split so that the hoop can be turned around. Finally, one also needs a tiny hoop (free arm hoop) for embroidering on tight places
• Stitches / minute (SPM). Should be at least 500. Typical range is between 400 and 1000, e.g. a Elna 8300 can do 750/minute.
• Built-in fonts, patterns and designs may make a difference to people who prefer designing on the machine (as opposed to using a software on PC).
• Needle threader (helps putting the thread into the needle or does it without assistance)
• Thread cutter
• Support for standard USB flash drives (keys) and direct PC link
• User interface quality and functionalities. It should allow for simple editing like translation, rotation, resizing, time/stitch counting, design tracing of a design.
• Free (or cheap) software
• Slide speed control
• Automatic detection of fabric and thread tension regulation
• Sensors that will tell you if something went wrong, in particular broken threads.
• Dealer support and pricing
Kinds of machines
As of April 2011. Information below can change rapidly and we may not update !
With respect to sewing and embroidery functionality we could distinguish four kinds of machines:
• Sewing machines only (not discussed here)
• Sewing machines with an embroidery module or combined sewing/embroidery machines
• Single-needle embroidery (only) machines
• Multi-needle embroidery machines
Entry and mid-level pure embroidery machines