Manually Measuring Swingweight

E

esm

Legend
Irvin said:
This has been bothering me so I though I reply again. Maybe I should not have said it was a promotional video. The developer contacted me and said he developed a SW machine and asked if I would try it out and provide feedback. That’s all he ever asked for feedback before he started marketing it. He never asked me for anything else and said I could keep the SW1. I was not asked to create a video and put it on YouTube but I did. I wasn’t asked to post a review on a Facebook group but I was happy to do it. And had I not have come across this thread I would not have mentioned it here. It is a great simple product and I’m glad to have had the opportunity to get one.
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In any case I am glad you have mentioned this product in another thread a couple of weeks ago.

I really do hope this product takes off - maybe just need some help to promote this product outside the US, cos you know there are people outside the US playing tennis. Lol

I thought if it a requirement to declare your YT if it is a sponsored and/or promotional video. (Not sure, but that’s what I read…)
 
Irvin

Irvin

Talk Tennis Guru
People on YouTube post links to Amazon items and get a kickback for all the sales from those links. I think that’s what the promotional items are all about. You can watch a YouTube much any more without seeing a commercial so 99.9999% of the ‘you tubers‘ and getting kickbacks one way or another. Want to know how to boil an eggs there are several people that want you to watch a 6 or 7 minute video on how to do that. None of my videos have commercials.
 
B

BoxbeamsFTW

Semi-Pro
Irvin said:
Decently? LOL SwingTool is only as accurate and the measurements you put into it. If your hang point or your balance measurements are off by 1 mm your SW is off. If you’re using SwingTool, measure the SW on 2 different cross strings and tell me which one you feel is the more accurate. They won’t be the same because of the error in your measurements, there’s no comparison.

if you want the SW1 to give you the same results you can measure the SW on any other SW machine and match the results you get on that machine to the SW1. But why would you want to do that?

Now for the inevitable question. No the app is not available for android devices yet.

EDIT: This device was developed by a mechanical engineer that for some reason wanted a better way to measure SW. so he made a better SW machine. Only took him a year and a half. And no it wasn’t me. LMAO
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Damn you! :-D I've been eyeing an Alpha SW machine for the longest time. For about $650. Even though if I'm nice I can go to a local shop with the Yonex Precision Scan for free. Can't measure twistweight though. This is fantastic! So glad someone went out and invented it.

Haha, "for some reason". Edit: oops US price was much higher than I initially thought.
Irvin said:
Not sure what you mean. Are you having issues with the SW1? Or do you just have issues? LOL I see a new thread starting soon about gadget-a-holics.
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Oh gawd haha.......

Btw, I miss your profile pic of the minion already... :whistle:
esm said:
Or maybe I can purchase a new one and have it delivered to you, and then you can send me your used/trusted one to the UK. Then we are all both happy in the end. Lol
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Hahahaha, well that could work but I'm not sure how you would benefit haha. :laughing:
 
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PrinceYonex

PrinceYonex

Semi-Pro
bfroxen said:
What a day! Just got back from the courts, and I have lot of work to do. I hope to have more ready tomorrow or Wednesday at the latest.
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Awesome. I’ll check back on your site in the next day or two to see if it’s back in stock. Good work and congrats on the success.
 
J

jmnk

Hall of Fame
BoxbeamsFTW said:
Damn you! :-D I've been eyeing an Alpha SW machine for the longest time. For about $650. Even though if I'm nice I can go to a local shop with the Yonex Precision Scan for free. Can't measure twistweight though. This is fantastic! So glad someone went out and invented it.
Click to expand...
And what prevents you from measuring twist weight on that yonex precision scan machine?
 
B

BoxbeamsFTW

Semi-Pro
jmnk said:
And what prevents you from measuring twist weight on that yonex precision scan machine?
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Oh I was mostly referring to the Alpha and others like it. Well, if it's possible I don't immediately know how to do it. But I'm not mathematically-minded either.

The Precision Scan measures the left-hand and right-hand static weight from what I understand. This is just for fine-tuning customisations but not twistweight I believe. Like when one side of a racquet feels better or heavier for some players. It does it quite well and is indeed quick though. The numbers are quite different than twistweight readings too btw and don't add up to the total static weight of the racquet. They will range around 70-90g and can be either nearly matching or up to about 5g different.

On another note, it does give a Performance Swingweight as determined by Yonex it seems. In my experience it seems to be a combination of SW and static weight taking into account the balance point.
 
Irvin

Irvin

Talk Tennis Guru
jmnk said:
And what prevents you from measuring twist weight on that yonex precision scan machine?
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SW is the sum of the square of the perpendicular distance from the SW pivot times the mass in the racket. Therefore it would not matter if weight were located at 12 o’clock or 3&9, that mass is always the same distance from the SW axis when a line drawn from 3 to 9 is parallel to the SW axis.

TW is the sum of the square of the perpendicular distance from the racket centerline times the mass in a racket.

Mass at 3&9 is father from the spin weight axis than it is from the swing weight axis. Therefore when the racket is turned 90 degrees from vertical you will get a higher reading. The difference between the 2 readings is the twist weight.

The Yonex precision scan has a 3 digit readout and if you’re measuring a tennis racket you will always get hole numbers in the readout. So you measure the swing weight at 330 and the Spin weight at 343. Does that mean the twist weight is 13? The swing weight could be anything from 329.5 to 330.5 and the spin weight could be anything from 342.5 to 343.5 so the twist weight could be anything from 12 to 14.

The readout on the iPhone when measuring inertia on the SW1 goes down to hundredths. So if the swing weight measured 329.63, and the spin weight measured 343.47 we could say the twist weight was 13.84.

Not saying you can’t measure ball park TW on the Yonex but it’s not accurate enough to start mataching rackets.
 
Irvin

Irvin

Talk Tennis Guru
Here is an actual measurement of swing weight (bottom) and spin weight (top) measurements. 335.33 (spin weight) minus 322.64 (swing weight) gives us a difference of 12.68 (twist weight.)
https://imgur.com/rr6e8RX
If I had 2 or more racket I could include them in more groups and easily see the differences in SW and TW.
 
Wheelz

Wheelz

Hall of Fame
Yeah, the twistweight feature is the best. The iphone app is still good, but the twistweight puts it over the top. Thanks for the video
 
A

AA7

Hall of Fame
RF_PRO_STAFF said:
I got two problems.

1: I don't live in the USA.
2: I don't have an iPhone.
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I don't have an iPhone either.. which is starting to **** me off b/c swingvision does not work in Android neither I think.... but I already told my wife that I will need to borrow her phone...... it took me a while to explain... "I got this gadget...that measures some aspects of the tennis racket.. but only works on iPhone...." she was pretty much rolling eyes and implying "I am not interested in your nonsense tennis stuff, just use the phone I don't care..."
 
RF_PRO_STAFF

RF_PRO_STAFF

Professional
AA7 said:
I don't have an iPhone either.. which is starting to **** me off b/c swingvision does not work in Android neither I think.... but I already told my wife that I will need to borrow her phone...... it took me a while to explain... "I got this gadget...that measures some aspects of the tennis racket.. but only works on iPhone...." she was pretty much rolling eyes and implying "I am not interested in your nonsense tennis stuff, just use the phone I don't care..."
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And there is problem number 3 for me: don't have a wife either.

I'll just wait for when an Android version will become available + shipping to EU is possible.
 
J

jmnk

Hall of Fame
BoxbeamsFTW said:
Oh I was mostly referring to the Alpha and others like it. Well, if it's possible I don't immediately know how to do it. But I'm not mathematically-minded either.
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any device that measures the swingweight can also measure the twistweight. Although indeed some rudimentary math may be needed if such a device does not do the math for you.

BoxbeamsFTW said:
The Precision Scan measures the left-hand and right-hand static weight from what I understand. This is just for fine-tuning customisations but not twistweight I believe. Like when one side of a racquet feels better or heavier for some players. It does it quite well and is indeed quick though. The numbers are quite different than twistweight readings too btw and don't add up to the total static weight of the racquet. They will range around 70-90g and can be either nearly matching or up to about 5g different.
Click to expand...
the left-hand and right-hand static weight is a cute gimmick on that Yonex machine - but that is not needed for measuring twistweight. that being said the idea of having two (or in this case three) static weight measuring sensors is a useful one - it allows the device to give you a balance point of an object.

BoxbeamsFTW said:
On another note, it does give a Performance Swingweight as determined by Yonex it seems. In my experience it seems to be a combination of SW and static weight taking into account the balance point.
Click to expand...
That "Performance Swingweight" is another Yonex gimmick. They clearly invented some formula that likely takes into account swingweight and static weight and balance. It does not really mean anything. But hey, Babolat invented a 'racket flex' thingy with arbitrary way of measuring it, and arbitrary point at which it is measured - so it's not like there's no precedent.
 
J

jmnk

Hall of Fame
Irvin said:
SW is the sum of the square of the perpendicular distance from the SW pivot times the mass in the racket. Therefore it would not matter if weight were located at 12 o’clock or 3&9, that mass is always the same distance from the SW axis when a line drawn from 3 to 9 is parallel to the SW axis.

TW is the sum of the square of the perpendicular distance from the racket centerline times the mass in a racket.

Mass at 3&9 is father from the spin weight axis than it is from the swing weight axis. Therefore when the racket is turned 90 degrees from vertical you will get a higher reading. The difference between the 2 readings is the twist weight.
Click to expand...
I have no idea what you are trying to say here. If you are trying to explain to me what a twistweight is - that's cool, but I'm fairly sure I know.

Irvin said:
The Yonex precision scan has a 3 digit readout and if you’re measuring a tennis racket you will always get hole numbers in the readout. So you measure the swing weight at 330 and the Spin weight at 343. Does that mean the twist weight is 13? The swing weight could be anything from 329.5 to 330.5 and the spin weight could be anything from 342.5 to 343.5 so the twist weight could be anything from 12 to 14.

The readout on the iPhone when measuring inertia on the SW1 goes down to hundredths. So if the swing weight measured 329.63, and the spin weight measured 343.47 we could say the twist weight was 13.84.

Not saying you can’t measure ball park TW on the Yonex but it’s not accurate enough to start mataching rackets.
Click to expand...
you may want to read up on measurement accuracy, precision, and significant digits. The fact that a given device _can display arbitrary number of digits following a measurement_ does not really mean much. Let me give you an example.

Let's say you measure a radius of a circle with a measuring stick that has 1cm resolution. You get 20.5cm where obviously 0.5cm is your estimation since you can't tell exactly given your measuring device. Now you calculate the area of the circle: area = 20.5*20.5*pi. Since you have multiple calculators you use one that can display 10 decimal digits so the built in values for the pi is 3.1415926536. Your resulting area is
1,320.2543126754. Great. Now you do the same on a second calculator that can only display 2 decimal digits. So the value of pi is 3.14, and the resulting area is 1,319.59.

Now, are you going to say that based on your measurement of the radius the value for the area of 1,320.2543126754 is _more accurate_ than the value of 1,319.59? I hope you are not trying to imply that.....

Disclaimer: the SW1 device discussed here looks absolutely cool, and based on a very solid physics principles.
 
esgee48

esgee48

G.O.A.T.
Get a cheap older model iPhone such as an iPhone8 or iPhone6. Cheaper than a GF tho there are advantages to having one...:happydevil:
 
tim-ay

tim-ay

Legend
esgee48 said:
Get a cheap older model iPhone such as an iPhone8 or iPhone6. Cheaper than a GF tho there are advantages to having one...:happydevil:
Click to expand...
there might also be some advantages to cheap older girl friends, as long as you can still keep their software up to date
 
Irvin

Irvin

Talk Tennis Guru
jmnk said:
Let's say you measure a radius of a circle with a measuring stick that has 1cm resolution. You get 20.5cm where obviously 0.5cm is your estimation since you can't tell exactly given your measuring device. Now you calculate the area of the circle: area = 20.5*20.5*pi. Since you have multiple calculators you use one that can display 10 decimal digits so the built in values for the pi is 3.1415926536. Your resulting area is
1,320.2543126754. Great. Now you do the same on a second calculator that can only display 2 decimal digits. So the value of pi is 3.14, and the resulting area is 1,319.59.
Click to expand...
I have a set of scales that measures grams in whole integers and another jewelry scale that measures down to 1/100 of a gram. Both scales will give me the same readings time after time. I have reason to believe both are somewhat accurate. If 1 says a racket weighs 337 g and the other says the same racket weighs 336.63 g, and I use one of those scales to match 2 rackets, which one is more accurate? Each scale could be off in either direction but both are consistently off.

EDIT: BTW if you use 3.14 for pi you’re introducing a 0.05% error.
 
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E

esm

Legend
Irvin said:
I have a set of scales that measures grams in whole integers and another jewelry scale that measures down to 1/100 of a gram. Both scales will give me the same readings time after time. I have reason to believe both are somewhat accurate. If 1 says a racket weighs 337 g and the other says the same racket weighs 336.63 g, and I use one of those scales to match 2 rackets, which one is more accurate? Each scale could be off in either direction but both are consistently off.
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ah, so....... what was the issue in your #68 post....?
 
Irvin

Irvin

Talk Tennis Guru
esm said:
I recall seeing somewhere that the Yonex Precison Scan measures the SW to one decimal point?
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It does on a badminton racket. It can measure weight to x.01 g. But there is 3 digits. If you’re measuring a tennis rackets SW there is no room for anything to the right of the decimal point.
 
E

esm

Legend
Irvin said:
It does on a badminton racket. It can measure weight to x.01 g. But there is 3 digits. If you’re measuring a tennis rackets SW there is no room for anything to the right of the decimal point.
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Do you have on that is actually measuring a tennis racquet?
 
Irvin

Irvin

Talk Tennis Guru
esm said:
Do you have on that is actually measuring a tennis racquet?
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I assume you meant one rather than on. No I do not, nor do I have a Yonex precision scan. That’s just a video I found on YouTube.

EDIT: I did just look at another video on youtube and the precision scan has a 4 digit readout so it can get down to 0.1 kgcm^2
 
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K

Kozzy

Hall of Fame
Managed to snag one of these on the restock earlier today. Super excited! What a great idea and great looking product.
 
esgee48

esgee48

G.O.A.T.
The app makes use of the "gyroscope" inside the iPhone. The issue with Android products is the proliferation different parts and sensitivities from the manufacturers. If the code is based on C/C++, it can be compiled for Android. However, there is a BIG IF whether it would work correctly; it would depend on the tech inside the phone.
 
bfroxen

bfroxen

Rookie
ryushen21 said:
Any idea if he will offer this for android phones?
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I don't have any current plans to develop an Android app, but if demand justifies it, I will. I did verify that Android supplies a precise timestamp with the gyroscope data, so there's a chance that it will work as well as the iPhone app. Unfortunately, it's not a simple matter of recompiling.
 
J

jmnk

Hall of Fame
bfroxen said:
I don't have any current plans to develop an Android app, but if demand justifies it, I will. I did verify that Android supplies a precise timestamp with the gyroscope data, so there's a chance that it will work as well as the iPhone app. Unfortunately, it's not a simple matter of recompiling.
Click to expand...
Actually many Android phones have better gyroscope sensors than the iPhone one. So the sensor itself is not the issue. But I can certainly see that doing the entire app for Android is not that trivial...
 
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