TENNIS.com gear editor Justin diFeliciantonio and his technical advisers answer your equipment questions each day. Click here to send in a question of your own.
Does a racquet strung on an electronic machine come out any differently than if it’s strung on a manual machine? My stringer uses an electronic one, but there are other stringers in my area who use manuals. Just curious.—Caitlin S.
The major difference between electronic and manual machines is how they mete out tension. Regardless of reference tension—i.e., the poundage you request from your stringer—electronics typically string tighter than manuals.
This is largely because electronic machines are built with constant-pull tensioners. CPTs integrate on-board computers, which continually stretch strings until reaching the desired reference tension—and then continue stretching, maintaining that tension until the stringer disengages the mechanism. (The tensioners function automatically; stringers simply place the string against the tensioner to tighten it.)
Older manual machines, on the other hand, stretch strings using lock-out or “crank” mechanisms, which are operated by hand. These are able to…crank out string jobs reliably, but only if the stringer is skilled enough to navigate a number of potential pitfalls.
Of those pitfalls, one is that lock-outs can record friction as tension, especially when pulling cross strings. (The crosses must be tightened across the mains, remember.) Indeed, depending on string type and stringer competency, this can lead to less actual tensioning and more “give” in the stringbed.
An additional complication with manuals is that tension can change depending on how fast each string is pulled. “Electronic machines usually will have standard pull rates. I’m able to set my machine to pull slow, medium, or fast,” says Joe Heydt, a USRSA Master Racquet Technician out of Omaha, Nebraska.
“But with a manual machine, it’s a little bit more of a craft. Because if you want accurate, reliable tensions, not only do you have to make sure that you’re pulling well, but you always have to make sure you’re pulling at the same pace every time. If I have five cups of coffee and string a racquet on a manual machine, it’s going to come out very differently. Whereas, with an electronic machine, there’s less of a human factor.”