Yonex QC factors

[macattack]

There's been a lot of talk about how bad Wilson's quality control is, as well as the QC of most major racquet companies these days. And often in those threads Yonex is help up as a company that has much stricter QC standards.

I completely agree that Yonex does a much better job than most companies (Angell, excluded of course, but they're a special case) when it comes to static weight and balance. I have two RD-7s. One pre-97 logo and one post-97 logo so they're definitely not from the same batch. The weight and balance are both bang on, exact. However, with the swing weight there is a 20 point difference. The newer one is 345 and the older is 325. That's huge. So do manufacturers generally NOT take swing weight into account when creating tolerances for their factories?

(P.S. love my RD-7s and love Yonex so not hate meant by this post)

 

[vsbabolat]

Are all the yonex RD-7 you have the same grip size?

 

[macattack]

They're both 4 3/8. I don't have one of the 4 1/4 grips that was lighter. That was my first thought, so I double checked.

 

[moon shot]

For a handmade product the swingweight can't be anything but a guess without measuring it. Static weight and balance set the general range.

The issues would be
1. If measured how do they fix when the layup is complete?
2. What to do with product that can't be brought to spec?

It is a similar issue to camera lenses, even well over a grand they have no optical bench testing in factory.

 

[macattack]

For a handmade product the swingweight can't be anything but a guess without measuring it. Static weight and balance set the general range.

The issues would be
1. If measured how do they fix when the layup is complete?
2. What to do with product that can't be brought to spec?

It is a similar issue to camera lenses, even well over a grand they have no optical bench testing in factory.

That makes total sense. I thought there was something they could do to make sure the consistency of the layup produced a certain swing weight, but that could just be ridiculous. Haha. I know how racquets are made, generally, but I know little beyond that.

 

[Dragy]

Guessing, but I'd likely believe it's more about technology. You are not likely to rework and adjust the produced frame but for some pre-designed option like handle weights. If your technology provides low deviation from target specs, you can apply strict QC criteria. If your technology is less precise (which doesn't mean "bad", and may be even better in some qualities, or determined by desired layup), you can either apply same strict criteria and trash a lot of frames, or widen the "OK" range.

Anyways, things like flex, size and form, feel of the stick should be secured, while mass and balance deviations can be tweeked by nit-pickers we are here. Just remember to get a slightly lighter stick to have room for customization - with most of market dominated by 300g unstrung sticks, you'll get any profile you might desire to further tweak it to desired specs.
For mass customer base, meanwhile, specs are not that crucial to pray QC. Many just get 1 stick and play, not even pair...

Add: my AI98 was 312g 31,6cm unstrung, my DR98 was 308g 31,3cm unstrung. Not "dead on"

 

[moon shot]

As Dragy intimated it is about technology, specifically engineering the assembly process in a way that creates less deviation.

Here is the blog post about camera lenses I found informative: https://www.lensrentals.com/blog/2016/02/optical-quality-assurance/ Spending $5,000 on a lens you still get a product that has compromises.

 

[RobS]

Ignorance is bliss! I liked my racquets much better when I was just using a scale and a balance board. You're most likely to get racquets that match closely for weight, balance and swingweight when they all come from the same production run. I typically buy a pair of racquets at a time and pick out the pair that has the closest matching serial #'s. When I find a pair close in #, they are typically very close, if not an exact match, in overall spec. The swingweight spec in manufacturing is theoretical. It counts on the material weights, thickness, quantity and assembly to be exact. There's the potential for some deviation at every step from the raw materials to the application of the paint. Manufacturers could pay material suppliers for tighter control, specify additional QC steps in the factory, give factory workers more time to allow for greater precision, automate more of the processes, scrap more racquets, etc. All of this adds cost and if the manufacturers can't pass it on, it's not going to happen. I've been to manufacturing plants (not tennis) in the US, Mexico, Japan and China and I'm honestly impressed at how well racquets are made. Anyone with engineering and factory experience would probably agree. It's not easy mass producing products with great accuracy when several of the steps are manual, your labor isn't highly skilled and your trying to hit a reasonable price point.

Being realistic, I'd speculate that 95%+ of the racquet buying public has no idea what swingweight is or that their racquet may not exactly match the specs written on the throat. I match my racquets but not because I see a significant impact on my game. I just enjoy the nuts and bolts, hands on aspect of it and have engineering burned into my brain. On the other hand, I know guys who played high level college and low to mid level professional tennis who keep it as simple 'I like 11.1 unstrung and 8 or 9 points head light' and would never think of putting a racquet on scale or RDC machine.

 

[Power Player]

Thats all well and good but SW is one of the most important specs to know. It is a PITA to track down an RDC machine, but upping my SW has made a marked improvement on my game.

 

[macattack]

Thats all well and good but SW is one of the most important specs to know. It is a PITA to track down an RDC machine, but upping my SW has made a marked improvement on my game.

Agreed. I totally understand now that it isn't easy to control at the factory, but swing weight is big for me. I'm lucky that my local tennis shop has an RDC. Now, I'm not so picky that I can tell the difference between 345 and 350 SW. I know I'm not that good! But 345 to 325 I can tell immediately. And unfortunately with the static weight being the same on both it's going to take some tricky lead placement to get the lower SW RD-7 up to 345 without exploding the static weight or ruining the balance. And to be honest, even 345 is a bit low for my liking, though I doesn't bother me too much.

Oh well. All my PT10s and original Prestige's are pretty close to matched! 365/32.5/355 (ish)