Thread: Yonex the lack of QC?
03-16-2012, 08:17 PM #1
Yonex the lack of QC?
I seldom post here but I think this might be worth posting. I have had a pair of less than 1 year old rackets (AT600 & Cab35) and both developed cracking sound inside the cones. I am familiar with loose cones and had to reglued all my MIJ Yonex rackets the last 2 decades, including the AT600. The cracking sound of my Cab35 has developed to a point I have decided to reglue it with epoxy, and this is what I have found.
From what I can tell, the gaps of these cracks are so wide they should be spotted in the factory. Obviously the worker decided to glue it over instead of trashing the wooden grip. I have learn from experience MIJ Yonex aren't as great as most have praised, but this is new low, and certainly deter me from buying in the future. Hopefully the shop won't give me a hard claiming the 1 year warranty which still has 1 month to go.
Also, I have discovered the cones of both AT600 & Cab35 are glued on one side only. I can tell they simply squeezed a large drop of glue on one spot then put the cone on. IMHO, this is very poor practice because the cones will never provide the full support the wooden tip needs when stressed. The glue should fully fill the gap between the cone and the wooden tip. No wonder there are so many broken grips over the years which can be avoided if Yonex Japan did their homework.
03-17-2012, 01:26 AM #2
have u written to yonex to complain?
or send this to them for repair?
i am not yonex..so no worries.if..u do it....
i seriously.. think yonex..will benefit..if u r their director of QA/QC.....
thanks for sharing
03-17-2012, 04:33 AM #3
And why would it have been like this already in the factory? If it was standard practice we would've had more reports I presume ...
03-17-2012, 04:57 AM #4
The reason is that even if I press the wood toward the shaft, two of the 4 gaps are still pretty wide. That means they weren't developed due to stress, the gaps were there before the glue was applied in the factory. I am only an end user so cannot tell how wide spread this practice is. I do know that the way they applied the glue was wrong even with a perfect grip. Also, the inner surface of the plastic cone have many ridges gripping the glue. That means the engineers knew what they were doing, but the factory workers not (or don't care).
From what I can tell, the glue used on the cone is rather thick and flexible, while the glue fixing the shaft inside the wood is rigid & brittle (like regular epoxy). The longest crack is 3/4" long and I can see the shaft has detached at least as deep. Sadly even if I glue the cone back, the strength will not be there because the stress will fall mostly onto the plastic cone instead of working as a single unit.
Why nobody has ever reported similar case? Guess most people simply not paying attention to fade cracking sound until the rackets failed. My sister couldn't hear it when I showed her. I am not even a frequent player or hard hitter.
03-17-2012, 05:16 AM #5
Ok, I almost wish it was standard practice to glue like that. Still have one AT700 with broken handle of which I for the life of me cannot separate the cone from the handle ... (so I can insert a replacement handle).
I do quite often though read about people complaining about cracking noises coming from that area but still seems a minority ...
03-17-2012, 05:24 AM #6
You may heat the cone up with a regular hairdryer then twist it off with a rubber glove. It will take some patient and practice figuring out how hot will be enough to soften the glue but not enough to damage the finish, but it is doable.
03-17-2012, 05:31 AM #7
The plastic cone really needs gluing to the handle over the entire interface, IMO, and preferably with a flexible glue. I've had cracking under Yonex cones a great many times.
03-17-2012, 05:34 AM #8
I have been thinking that too. Should I use flexible or rigid epoxy? Any reason flexible glue is preferred? I remember on my old rackets like Cab9 & WB30, flexible glue wasn't used.
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