Equipment For Repairing Traction Kites
If you are shopping for a new sewing machine, take samples of all the materials you use (ripstop, dacron reinforcements, webbing) to the store for testing.
The machine should do straight stitching and zigzag, and have a reverse; anything else is a nice extra. Some people like a triple zigzag: 3 diagonal stitches to the right, 3 diagonal stiches to the left, but you may find this stitch only on expensive machines. No need to spend the money for one feature that is more a cosmetic characteristic. Straight stitches work fine. Focus on a machine that has the power and foot petal accuracy you're looking for.
It is good to practice your sewing on some scrap material prior to doing it on your kite. Using the foot petal while simultaneously guiding the fabric into the machine is an acquired skill that will take you some practice to get good. Do not rush this process since you spent a lot of time to get the materials to build, or repair, your kite, and poor sewing will make, or break, your kite project. If you get a run-on, it can be a bit scary at first, but don't be afraid to stop, unpick the threading, and continue on.
To start and reverse a row of stiching (backstitching), just reverse once for a few cm and then sew back over the run to the end and stop. You will need to do this at the start and end of your seam. On the machine you will find a button to do this easily.
Most machines will perform the basic job of sewing ripstop. The beginning kitemaker does not need to purchase a new(er) or special machine just to make kites. Most kitemakers, including many professionals, use home models, and some use 10-20 year-old machines to produce award-winning kites.
You should be able to adjust both the top and bottom (bobbin) tension, that is, top and bottom tension devices should be accessible, and you should know how to adjust them. If your dealer says "don't touch the bobbin tension" or "you can't sew on ripstop with a home machine," find a new dealer. You probably will need to adjust one or both tension devices for ripstop.
Keep in mind that with computerized machines you can change the width of the zig zag stitch only by entering the new width, while on mechanical machines you change the width by turning a dial, an advantage if you do much detailed applique work.
Ripstop is slippery, and there are a couple of feet which help move multiple layers through the machine evenly. The first is called a walking foot, and it grips the fabric from above much the way feed dogs on the bottom do. It is an accessory foot for most machines, but some Pfaff models have a built-in walking foot.
The teflon foot is another accessory foot that works well with ripstop.
Universal needles come in several sizes, usually labeled with both American (9, 10, 11, 12, 14, 16) and European (65, 70, 80, 90, 100) sizes. Size 80 (11 or 12 depending on brand) is a good choice for 3/4 oz ripstop. If you're sewing through heavier material, such as leading edge strips, dacron reinforcements, or webbing, use a heavier needle. Many times you may have used double-sided tape to hold the material so keep this in mind. Most sailmaker supply shops offer size 19/120 for V-92 size thread as their universal needles. This size is typically not sold in general fabric stores.
Always use a new needle when sewing your kites...dull needles don't work as well.
Most kitemakers use a polyester thread when sewing kites. Do not use nylon thread as it is more difficult to locate, and is too slippery for the kite application. The best option is bonded polyester thread. It resists UV rays very well and is very strong and tough. This is available in many sailmaker stores and kite shops.
Dabond 2000 UVR bonded polyester or American Star Ultra Dee bonded V-92 polyester are excellent threads. Both are highly resistant to UV, mildew and very low stretch.
Edges of ripstop fabrics need to be sealed by heat, hemmed, bound, or enclosed in seams to prevent fraying. If you will be hemming, binding, or enclosing an edge, it isn't necessary to hot cut the fabric: you can cold cut, which is usually faster. A good tool for cold cutting is the rotary cutter, which looks like a small pizza cutter, and is available at most fabric and quilting stores. It can be used freehand or against a ruler or pattern piece, works best with straight lines.
For hot cutting, woodburning tools or soldering irons are the usual choices; buy the highest wattage you can afford for faster cutting.
The preferred surface for hot cutting is glass. Large pieces of glass are expensive; check with glass dealers or building salvage yards for used shower doors and windows. Masonite and Formica are also used, but be careful with very high wattage tools, as there can be a fine line between cutting the fabric and heat sealing it to the surface.
For cold cutting, the rotary cutter (looks like a pizza cutter) is the most popular tool; it's especially useful for straight lines. Special mats are available for use with rotary cutters to preserve the cutting edge.
Ripstop Nylon - This is the most common material used for stunt kites as well as most single line kites. There are several problems when working with ripstop, including the difficulty of cutting it accurately and sewing it. The advantages are its strength and resistance to tearing. The best way to cut ripstop is with a "heat knife" or soldering iron. Remember to do the hot cutting in a well-ventilated area - the fumes are unhealthy.
Ripstop Polyester - Ripstop polyester (or ripstop dacron) is becoming more common in the kite world. It's main advantage is higher strength for a given weight. It also stretches less than nylon. Most common brand name is Icarex.
Nylon Taffeta - Nylon taffeta is often used in single line kites. Taffeta usually isn't coated and the porosity of the fabric adds stability to many kite designs.
Solid Fiberglass Rods - These are flexible, very strong, and inexpensive. They are also fairly heavy. These are often used when flexibility is an asset, such as in dragon kites. Solid fiberglass is also used in many small fighter kites in the cross spar.
Fiberglass - Flexible, fairly strong, moderately expensive. A typical fiberglass tube with outer diameter of 6 mm weighs 30 g/m. Withstands "unintentional groundwork" better than carbon. For a given radius, these are stiffer than solid fiberglass rods.
Poly-carbon Fiber - This material is also known as graphite. Stiffer, more expensive, but generally preferred. A typical carbon tube with an outer diameter of 6 mm weighs 20 g/m and has stiffness ("a measure of the ability to resist deflection by a load") 2.5 times that of fiberglass. Again, for a given radius, stiffer than fiberglass tubing.
Aluminum - Between fiberglass and graphite for flexibility, and less expensive than most graphite. It is far stronger than either fiberglass or graphite.
Dowels - A good material for beginning kite builders.
Arrow shafts - These can be found almost anywhere and come in a wide range of materials, including wood, graphite, fiberglass, boron, aluminum, and just about anything else you can think of.
Composite shafts - If the spars listed don't have the combination of flexibility and strength that a kite requires, combinations of materials can be purchased. However, these tend to be very expensive.
Kevlar Spectra - The basic cores of most stunt kite lines. These are extremely strong fibers that can vary in breaking strength from 75-1000lb. They are called "zero stretch lines" because they stretch less than 4% of their length before breaking. Kevlar is more sensitive to UV-light than Spectra. One problem with Spectra is that its melting point is so low that friction against ANY other type of line will cause it to melt and seperate. It is still preferred by most stunt kite flyers.
Dacron - Another polymer, which is often used to sheath the core lines to prevent cutting (most of them are very rough). Braided Dacron is generally preferred by single line flyers. Typical stretch is about 15%.