Yesterday, I took my rackets to a new stringer who was hesitant to string my AT700LTDs at 28lbs (I normally have them strung 28-30lb). Obviously, he didn't want to be liable if the frame was already damaged and snapped during the stringing process. However, he did point out something quite interesting... On the bottom end of my racket head there was some faint indentation/grooving of the string between the grommets (due to previous stringing at such a high tension). I had to admit that I hadn't noticed it before, and I guess repeated high-tension stringing will eventually compromise the structure of the frame. Has anybody else had this issue (do pro rackets have this problem and they ignore it as they can always just replace a broken racket?). He ended up putting a soft "rubber" so the string puts pressure on that instead of the actual frame. Hopefully that small adjustment also makes the racket more head heavy . Hope everyone can understand what I'm talking about - will try to provide pictures tomorrow!
I believe it's something about the mould of the GEN2 AT700 or something? I've seen quite a lot of posts regarding the durability of the GEN2 AT700's.
yes, i saw the same thing happened on a customer's racquet. it is a at800-off. he like it at 30lb. to avoid this problem, you need to replace the grommet almost every 6~7 month. not a lot of stringer will do it for you for free. also same problem happen to my ar80. however it was string at 20lb but the string was on and i did not use it for more than 10 year. so the string also made a groove on the frame.
@random-prson: my AT700s are both limited (which supposedly has a high[er] quality), so hopefully this isn't the issue @silentheart: the issue isn't with the grommets themselves (which probably become distorted over time too), but with the space between the grommets on the frame (where previous string has "cut" a visible indent into the actual frame)
yes, the string did cut actual indentations on the frame from B9 to B11. Especially the section with 3 strings.
most of the time it is related to grommet condition. If a grommet had degraded, the stress will go the other area.
it happens when you string at such high tension. especially in mp frames my Ti10s have little grooves as well. your main concern would be the strings eating your grommets and your 10/2 o'clock thats where at700s seem to have the most problems. =(
This is a common problem with inexperienced stringers stretching the N/S posts when using a suspension stringing machine. It has nothing to do with the grommets. Stretching the two posts in the mistaken belief that it will protect the frame from distortion is a very common mistake stringers commit. The old Armortec series are very easily dented or damaged this way. The posts, when stretched, are the culprits, but would otherwise do no harm with no no stretching.
This is a problem with the AT series. I have never encountered such problem with Ti-10s, NS-9000, X2 Gold, . . . , etc. The AT's graphite is too soft around that area.
The damage may not be visible, maybe microscopic. The posts have a different surface structure on the sides that face the inner side of the frame. They actually have a built-in shock absorption strip that feels hard but is ideal for absorbing shocks from stringing. It is not disimilar to that of today's hard-feeling car dashboard instead of the old soft dashboard. Stretching the frame with the two posts will render their shock-absorbing property useless.
I have tried stretched and unstretched ways of stringing the ATs. Both method yielded the same result: namely, the bottom part of the graphite got dented inward.
I have seen many old Armortec frames being dented this way. It is always the posts being responsible. I myself have strung many old AT700s, AT800DE, and AT800OF and have not dented even one todate. Maybe, the mounting of the frame is also important.
Sounds like stringer errors. Even at low tensions, lets just say <24lbs I have seen rackets done by inexperiecned stringers, customers rackets have gouges in them! (ouch).
As much as I like high tension strings also, the first and foremost piece of information here is that the strings are being tension considerably higher than the recommended tension for your racquet. The racquet was not engineered to withstand these tensions.
I have to disagree with the comment on the engineering. My guess is they take the actual test results and put in a safety factor of at least 1.3 to protect themselves. So recommended and engineered are two completely different numbers.
I also have to disagree about the engineering comment. The recommended tension is more like a safey to cover themselves as druss mentioned. It's more used for stringers who are not that experienced.
I agree, it is a bit of a safety to cover themselves (and so the racquet "plays as designed") is reasonable but stringing a racquet 20-25% (or more) outside of the max recommended tension and finding damage to the racquet is also not to be unexpected. This is why this voids your warranty. Nothing can "protect" you from an inexperienced stringer if you leave your racquet with them....