GEOSYNTHETICS Quick-Reference Guide for the Sewing of Geosynthetics

Question : How do I sew geosynthetics? Answer: It’s surprisingly easy. Just follow these simple instructions. First take the two pieces of geosynthetic fabric and hold the edges together to make either a prayer seam, "J" seam or butterfly seam (see page 3). Guide the fabric into the machine and depress the orange button to start sewing. The machine will then start stitching the fabric, and pulling the fabric into the machine on its own. At this point, all the operator does is hold and guide the machine as the machine continues to feed the fabric on its own. The operator doesn’t pull the machine along, the machine does that itself. Pulling the machine will cause the needle to bend, and that could result in costly downtime, broken needles, broken loopers, broken throat plates or loss of timing on the machine. That’s it. Pretty simple. Now here are a few helpful hints to increase your productivity. Sewing tip # 1: Use three people. Three people make the job move faster and reduce the chance of job downtime. The first person holds and helps support the weight of the two pieces of geosynthetic fabric and aligns the two edges of the fabric. The second person holds and guides the sewing machine, being careful not to allow the weight of the fabric to put excessive stress on the sewing machine needle, causing the needle to break. The third person helps support the fabric after it has been sewn and checks the quality of the stitching. Sewing tip # 2: Two sewing machines at the job site. It is much less expensive to purchase a second sewing machine as a back up than to pay idle workers and idle earth moving equipment should the first sewing machine be down for maintenance. Sewing tip # 3: Keep the wind from blowing the thread off the cones. On windy days, the thread may have a tendency to ravel off the cones. What you can do is cut the feet out of ladies’s nylons, snip off the toe and put them over the thread cones to keep the thread cones to keep the thread from blowing in the wind. Sewing tip # 4: There is a short learning curve using a sewing machine, so try to choose the same people to operate the sewing machine throughout the project.

Question : What equipment do I need? Answer: Determine how and where you are going to use the equipment. Are you going to sew at the job site? Or will assembly be done somewhere else and then the geosynthetic fabric brought to the site? What are the engineering specifications of the project? Is the material light to medium in weight, or heavy weight? Your answer will determine what equipment you will need for the job.

On the job site: Use a hand held machine with 3/8-inch capacity. Use a sewing machine that sews a two-thread double locked stitch (Federal Stitch Type 401) for security of the stitch and seam strength and quality.         Federal Stitch Type 401

Extra-heavy fabrics and off-site sewing: Be sure it allows you the option to sew both in the field or in the factory.

Use a machine for heavy-duty fabrics with a ¾-inch capacity. Use a sewing machine that sews two rows of stitching (Federal Stitch Type 401). The second row offers increased seam strength. Use a machine with adjustable stitch length. This gives you the versatility to sew different fabrics with the proper seam strength. Be sure it can handle the hard knocks of your job site. Rugged, dependable construction is a must.

These are three different seam types used. 1) SSa-1 (prayer seam), 2) SSn-1 (J seam) and 3) SSd-1 (butterfly seam). The project specification may indicate which type of seam to use for the job.

Features Rugged, portable unit Easy-to-adjust stitch length (3-8,5 SPI) 3/8" sewing capacity Upper and lower fabric feeding mechanisms Double thread stitch type (Federal Stitch Type 401) Can convert to single thread stitch type (Federal Stitch Type 101) Electric or pneumatic motor 1200-1700 stitches per minute Optional equipment: Thread stand to hold one-pound thread cones Metal box that holds up to two portable machines.

Picture shows the battery operated Style 2200MB

Features Easy-to-adjust stitch length (3-4 SPI standard, 5-8 SPI optional) ¾" sewing capacity Two-needles for sewing two parallel rows simul-taneously (Federal Stitch Type 401) 9/32" spacing between rows of stitching Up to 1800 stitches per minute Eliminates wasted fabric from overlapping For in-plant or field use (tabling or hanging assembly optional) Can be mounted horizontally or vertically.