Stringing Machine Selection Guide 2005
Buying a stringing machine is one of the most important purchases you can make for your business. It is also one of the most difficult. With the plethora of machines, technologies, and features available, selecting a machine is a daunting task. [Note from the Webmaster: USRSA members can also view this information using our on-line stringing machine comparison tools.]
Our Stringing Machine Selection Guide will guide you through the minefields and help you choose the best machine for your business. Below we explain the essential machine features, and the linked charts display the features of almost every professional machine on the market.
Most machines are designed to string racquets for all four racquet sports (tennis, racquetball, squash, and badminton), but a few are sport specific.
Machines are available with or without stands, and those with stands are often adjustible for height.
The charts lists machines with 2-, 4-, 5-, or 6-point mounting systems. This refers to how many places they support the frame. There are many subtle differences in mounting systems. The three most common types of mounting systems are the 2-point, 4-point and 6-point, though each of them is safe.
6-Point Mounting. Fans of 6-point systems will tell you that more points of contact must be better. Six-point systems do support the frame in more places, which means it is a little easier to lock the racquet in place so it does not slide back and forth during stringing. It also allows a better view of the grommets at the head and throat of a racquet. Six-point systems can require fewer adapters for frames of different shapes. Finally, some of these systems have side arms that can be adjusted simultaneously, making it easier to center a racquet.
2-Point & 4-Point Mounting. Fans of two-point and four-point systems suggest that it is quicker to mount a racquet on these machines because there are fewer mounting points to be adjusted. They will also say that these systems offer more support at 6 o’clock and 12 o’clock, (the two most important points to support), because the amount of surface contact with the frame is greater at these locations.
Turntable Lock. This allows you to stop the turntable in one position. Helpful for calibrating and tying knots.
360-degree Rotation Turntable. Allows you to turn the racquet all the way around during stringing.
3-D Rotation Turntable. Allows the turntable to tilt so that each string gets pulled straight through the grommet. This is designed to reduce the friction of the string against the grommet when tension is being pulled.
There are two main types of tensioning systems available today — lockout and constant pull. Lockout means that the machine pulls the string to the desired tension and then locks the length of the string until you clamp it and release the tension head. So, as soon as you lock the length of the string, it starts equalizing and losing tension. Constant-pull machines pull the string to the desired tension, but when the string starts to equalize and lose tension, it pulls a little more again to stay at reference tension. Constant-pull machines generally achieve slightly higher stringbed stiffness (we find the difference to be about 5 percent to 10 percent).
Drop Weight. These machines use a lever (with a weight attached to it) to pull tension on each string. Moving the weight on the bar determines how much tension it pulls. These machines qualify as constant pull because the weight continues to pull the string as the string stretches.
Hand Crank. Tension is pulled by hand crank. These machines lockout when the desired tension has been reached.
Electric. These machines require electricity to pull tension. Most of these machines are constant pull, but a few allow you to choose between constant pull and lockout modes. Some offer multiple pull speeds and a pre-stretch mode.
Linear Pull & Rotational Tensioners. Machines that pull tension in a straight line away from the machine are said to be linear pull. The alternative is a rotational tensioner, which wraps the string around a spool, then rotates the spool to pull tension on the string.
Diablo/Nosecone. The string is wrapped around the diablo or nosecone before it is put in the tension head, allowing the tension head to grip the string more gently.
Foot Tension. Foot-activated tension head.
Manual Calibration. Allows you to adjust (correct) the pulling force manually, as opposed to a few machines that are designed to calibrate themselves automatically.
Diamond Coated Tension Head. Grips the string with less pressure.
Tension Sets. Three types: dial tension set, +/- key tension set, and numeric keypad.
Knot Tensioning. The machine can be instructed to pull the last string before a knot tighter than the reference tension to allow for the tension that is lost between the clamp and the knot.
The clamping system is meant to hold strings in the racquet under tension. If clamps slip, or allow strings to slip through them, a string job can be ruined. There are many different clamps, but we will only discuss three here.
Flying Clamps. These clamps are not attached to the machine. They use one string to hold tension on another string. They generally do not hold tension as consistently as the other two types of clamps. The low price tag makes them attractive to new stringers testing the waters.
Fixed Clamps that Swivel. These clamps are attached to the machine and can be turned in any direction, especially helpful when stringing fan patterns. They also allow you to switch from main strings to cross strings without having to remove and replace glide bars. There are two kinds: dual swivel, dual action fixed clamps that require you to lock two levers to clamp a string; and dual swivel, single-action fixed clamps that require you to lock one lever. 360º glide bar clamps are clamps that rotate 360 degrees, but they are mounted on glide bars. Single swivel fixed refers to machines with only one clamp attached to the machine. Machines with this type of clamp will generally require a starting clamp or flying clamp for part of each string job.
Fixed Clamps that Don’t Swivel. These are clamps that are attached to the machine by glide bars, but can only be turned in two directions (90 degrees and 0 degrees). These require removing and repositioning glide bars to switch from main strings to cross strings.
Diamond Dust. Holds a string with less pressure, avoiding string crushing.
Sometimes, little things can make the difference between whether you love a machine or hate it. These extra features might sway your decision one way or the other.
Categories indicate whether the machine weighs less than 50 pounds, between 50 and 75 pounds, or over 75 pounds. Heavier machines can be more stable and solid, but they can be less convenient when moving or traveling.
This final category indicates which supplies and tools are included with the machine. For descriptions of each tool, see the USRSA Racquet Service Techniques book.