Matching Swingweights

[Shroud]

I have 2 racquets that weigh withing .1g of each other with one being 386.9 and the other being 387g. I used 2 scales and the head weight and the tip weight are identical except for the .1g. I can live with that, but does that mean the swingweights are close? Guessing not because the lead is in different places. Some has more at 12pm, etc. Is there a method to match swingweights, or is it close enough? I think I saw Irvins method but thought it was too complicated or needed wood, or both.

 

[GodlessEndeavor]

Without getting too technical, the only way to be sure is to measure the swing weight and go from there. You can't calculate swing weight from balance / head weight / tip weight, nor can you be 100% sure it matches if those things match.

 

[Mten]

The lead being in different places could contribute to the swingweight being closer. I've done a lot for clients were rackets were roughly the same static weight but off on balance & swingweight so have had to add to 12 on one and lower on the other to match it up. So I wouldn't give that as a reason for it to be different. But essentially the only way to know for sure is to measure swingweight properly. If you don't have access to a swingweight machine there are other ways to do it fairly accurately you will find on this board I'm sure. I remember I had a pair of rackets with identical balance & weight that were well off in swingweight before.

 

[esgee48]

Easiest way is to find a pro shop snd have them measure the specs. If you want to spend more, buy a SW1 and adaptor to measure SW and TW. If you only have a few frames to measure, I would use a pro shop. If you have dozens of frames and are buying/selling all the time, the SW1 kit is more cost effective. The TW app or the SW app would also work if you’re careful, but is very time consuming.

 

[Irvin]

I have 2 racquets that weigh withing .1g of each other with one being 386.9 and the other being 387g. I used 2 scales and the head weight and the tip weight are identical except for the .1g. I can live with that, but does that mean the swingweights are close? Guessing not because the lead is in different places. Some has more at 12pm, etc. Is there a method to match swingweights, or is it close enough? I think I saw Irvins method but thought it was too complicated or needed wood, or both.

If tip and butt weights are close then weight and balance are close. The only way to be sure about SW is to measure it.

 

[Shroud]

If tip and butt weights are close then weight and balance are close. The only way to be sure about SW is to measure it.

Without getting too technical, the only way to be sure is to measure the swing weight and go from there. You can't calculate swing weight from balance / head weight / tip weight, nor can you be 100% sure it matches if those things match.

The lead being in different places could contribute to the swingweight being closer. I've done a lot for clients were rackets were roughly the same static weight but off on balance & swingweight so have had to add to 12 on one and lower on the other to match it up. So I wouldn't give that as a reason for it to be different. But essentially the only way to know for sure is to measure swingweight properly. If you don't have access to a swingweight machine there are other ways to do it fairly accurately you will find on this board I'm sure. I remember I had a pair of rackets with identical balance & weight that were well off in swingweight before.

Easiest way is to find a pro shop snd have them measure the specs. If you want to spend more, buy a SW1 and adaptor to measure SW and TW. If you only have a few frames to measure, I would use a pro shop. If you have dozens of frames and are buying/selling all the time, the SW1 kit is more cost effective. The TW app or the SW app would also work if you’re careful, but is very time consuming.

Thanks everyone. I actually have a SW1 from Biffridi and just never put it together and used it. perhaps thats a new project. FWIW I live in the redneck riveria and no shops have a RDC to measure the swingweight. Will see eventually how close they are.

 

[Irvin]

I actually have a SW1 from Biffridi and just never put it together and used it. perhaps thats a new project.

I thougt you had a SW1 you purchased some time ago. Get it out and set it up as I remember it doesn’t take that long.

 

[McLovin]

I actually have a SW1 from Biffridi and just never put it together and used it.

Also, as an FYI: @bfroxen said in response to a question I had in the SW1 thread...if you're just matching swingweights of N frames, you don't need the SW1 to be perfectly calibrated. The numbers may not be the real SW, but that doesn't matter: All you care about are that the SWs of frame 1, 2, N... are the same.

 

[tim-ay]

Thanks everyone. I actually have a SW1 from Biffridi and just never put it together and used it. perhaps thats a new project. FWIW I live in the redneck riveria and no shops have a RDC to measure the swingweight. Will see eventually how close they are.

If projects take 5 min then it’s a project. just Nike that thing.

 

[GodlessEndeavor]

On a second thought, it might be possible to check whether racquets have the same swing weight without measuring it.

If I wanted to do that, I'd use something similar to the setup presented here: https://twu.tennis-warehouse.com/learning_center/howto_swingweight.php

I'd set up the two racquets side by side on the same table, swing both of them at the same time as accurately as possible - either eyeballing it or setting up a vertical obstable (e.g. a box under the table) to start the swing from.

If you then look at how the two racquets swing, any swing weight difference should become apparent by one racquet swinging faster than the other. If they keep aligned all the way until they stop (or close to it) then the swing weights should be similar (assuming their static weight and balance match - you have to check that first).

 

[dr325i]

I have 2 racquets that weigh withing .1g of each other with one being 386.9 and the other being 387g. I used 2 scales and the head weight and the tip weight are identical except for the .1g. I can live with that, but does that mean the swingweights are close? Guessing not because the lead is in different places. Some has more at 12pm, etc. Is there a method to match swingweights, or is it close enough? I think I saw Irvins method but thought it was too complicated or needed wood, or both.

I'll give you a different example, I have a 2022 Boom MP that matches the SW and balance of the new 2024 Boom MP I have been testing, but the static weights are 10g (yes, ten grams) apart (new one is lighter).
The way the rackets are made is all manual and easy to introduce variations - from putting the graphite layers together, putting appropriate pieces at the exact spots (small shifts introduce SW variations) to putting commercial weights manually...
I've had the situations where two frames were identically matched static weights of the same model with a significant SW mismatch.
I even had two of the same model frames that were completely matched in static weight, balance and SW and felt different (could be mismatch on the TW, flex, etc. that made them feel different or, more likely, all in my head...)

 

[Vicious49]

On a second thought, it might be possible to check whether racquets have the same swing weight without measuring it.

If I wanted to do that, I'd use something similar to the setup presented here: https://twu.tennis-warehouse.com/learning_center/howto_swingweight.php

I'd set up the two racquets side by side on the same table, swing both of them at the same time as accurately as possible - either eyeballing it or setting up a vertical obstable (e.g. a box under the table) to start the swing from.

If you then look at how the two racquets swing, any swing weight difference should become apparent by one racquet swinging faster than the other. If they keep aligned all the way until they stop (or close to it) then the swing weights should be similar (assuming their static weight and balance match - you have to check that first).

It would take him less time to setup his SW1.

 

[Shroud]

It would take him less time to setup his SW1.

long story but all that stuff was packed up by people who had no clue what it was. Will take time to find everything in the totes in the garage. And then find the bbs. Even finding a place to set it up will be tricky I think. But given my present situation, time is one thing I have.

 

[tim-ay]

long story but all that stuff was packed up by people who had no clue what it was. Will take time to find everything in the totes in the garage. And then find the bbs. Even finding a place to set it up will be tricky I think. But given my present situation, time is one thing I have.

now that IS a project! Looking for bits in multiple boxes is painful. But you’ll love the Briffidi if you can find it all.

 

[Shroud]

now that IS a project! Looking for bits in multiple boxes is painful. But you’ll love the Briffidi if you can find it all.

as expected, I think I found it all except the calibration ring. Right, its the base, tube, and calibration ring?

 

[tim-ay]

as expected, I think I found it all except the calibration ring. Right, its the base, tube, and calibration ring?

I think he changed the design from when I got mine. The OGs had a rectangular piece that went on the end of the rod for the heavy calibration. I see on the website he has changed that up to an expanding rod? Not sure which you have.

 

[Shroud]

I think he changed the design from when I got mine. The OGs had a rectangular piece that went on the end of the rod for the heavy calibration. I see on the website he has changed that up to an expanding rod? Not sure which you have.

I have the long tube and just ordered the telescoping new one. Will have to put the project on hold for a bit.

 

[GodlessEndeavor]

It would take him less time to setup his SW1.

Probably yes. I thought I'd write the idea anyway in case it helps anyone else in the future.

 

[bfroxen]

I have the long tube and just ordered the telescoping new one. Will have to put the project on hold for a bit.

You can get relative values with the default calibration (not the "Default" device, you'll want to add your SW1 to the app). You can also get pretty close by setting the with-weight calibration value (Object #1) to zero. Then, when calibrating, measure completely empty in place of measuring the rod with weight.

 

[Shroud]

You can get relative values with the default calibration (not the "Default" device, you'll want to add your SW1 to the app). You can also get pretty close by setting the with-weight calibration value (Object #1) to zero. Then, when calibrating, measure completely empty in place of measuring the rod with weight.

Thanks, for the quick service and response. I will have to look at the app since I don't understand what you are saying

 

[Shroud]

You can get relative values with the default calibration (not the "Default" device, you'll want to add your SW1 to the app). You can also get pretty close by setting the with-weight calibration value (Object #1) to zero. Then, when calibrating, measure completely empty in place of measuring the rod with weight.

Ok, I got this assembled and using the default calibration one racquet was 450sw and the other was 440sw. I will see how it goes when the calibration rod shows up since these are just relative values. Would it be safe to add about 3g at 12pm for the 440sw stick?

Thanks for the help

 

[Shroud]

You can get relative values with the default calibration (not the "Default" device, you'll want to add your SW1 to the app). You can also get pretty close by setting the with-weight calibration value (Object #1) to zero. Then, when calibrating, measure completely empty in place of measuring the rod with weight.

Ok, so I got the calibration rod and though i found the calibration confusing I think I calibrated it. The extended reading though was 10 points lower than printed 280-290. Anyhow when I measured it came our 437sw and 448sw respectively which is pretty much what the default calibration gave. Anyhow is there a way to know if the calibration is accurate? I can't seem to clear the measurements to start over. Or do i need to?

That said I think those numbers are accurate.

 

[bfroxen]

After calibration, you should be able to measure the calibration rod and get values very close (certainly within 1 kg·cm²) to the values on the label. This assumes that you entered the label values into the app, as it was a replacement rod.

The calibration process “tells” the app how quickly objects of two known swingweights will oscillate, so after, they should match.

There’s no need to clear measurements. The calibration checks and calculation only consider the three latest measurement groups.

 

[Shroud]

After calibration, you should be able to measure the calibration rod and get values very close (certainly within 1 kg·cm²) to the values on the label. This assumes that you entered the label values into the app, as it was a replacement rod.

The calibration process “tells” the app how quickly objects of two known swingweights will oscillate, so after, they should match.

There’s no need to clear measurements. The calibration checks and calculation only consider the three latest measurement groups.

I think I need to do the calibration again but the extended measurement is off by 12. Will try to start over.

 

[Shroud]

After calibration, you should be able to measure the calibration rod and get values very close (certainly within 1 kg·cm²) to the values on the label. This assumes that you entered the label values into the app, as it was a replacement rod.

The calibration process “tells” the app how quickly objects of two known swingweights will oscillate, so after, they should match.

There’s no need to clear measurements. The calibration checks and calculation only consider the three latest measurement groups.

i don't think I am doing it right. Measurements are all over the map. The calibration rod measures 8 for a listed value of 7.6. When extended I was getting 233 for a listed value of 220. Now i am getting 268-269 for the extended rod. Measurements with racquets had a 51 point variation from the low of 396 to the high of 447 with an average of 417. The measurements were higher on ones where the racquet didn't "bang" the side when starting. Also in the app it has an option for left or right but what is the orientation? Looking at the sticker or looking from the butt cap end?

The racquets would drag on the floor so I have the machine up on a yoga block so it doesn't drag. Would that affect things?

Help

 

[bfroxen]

You should release with the cradle rotated clockwise when viewed from above. The stops are asymmetric, so if you release from the wrong side, the cradle will bang into the opposite side (as you mentioned). This is addressed in the videos and written guide. In case you didn't notice, there is a playlist of videos embedded at the top of the Getting Started page of the guide.

Your calibration rod has values of 7.6 and 292.3, so I'm not sure where 220 comes from. It's important to release the cradle consistently to get repeatable measurements. See the tips & tricks video for a short bit on releasing the cradle (

). Once you're able to get repeatable measurements, then re-calibrate and measure your racquets again.

If the yoga block is stable, it could work. The SW1 should be placed on a stable, elevated surface (table, desk, counter, etc.) so that the racquet can swing in free air.

 

[Shroud]

You should release with the cradle rotated clockwise when viewed from above. The stops are asymmetric, so if you release from the wrong side, the cradle will bang into the opposite side (as you mentioned). This is addressed in the videos and written guide. In case you didn't notice, there is a playlist of videos embedded at the top of the Getting Started page of the guide.

Your calibration rod has values of 7.6 and 292.3, so I'm not sure where 220 comes from. It's important to release the cradle consistently to get repeatable measurements. See the tips & tricks video for a short bit on releasing the cradle (

). Once you're able to get repeatable measurements, then re-calibrate and measure your racquets again.

If the yoga block is stable, it could work. The SW1 should be placed on a stable, elevated surface (table, desk, counter, etc.) so that the racquet can swing in free air.

Thanks again for the help. The 220 number came from the tool itself but in the cradle it was turned so I saw 220 then 7.6. Its CO2-2220 and I just saw the 220. Looking correctly its 292.3.

Sadly I could never get it to read 292. I got consistent 272 readings with the mean being 272.47 over 10 readings. Could it be possible that the number is 272 instead of 292? Or do I need to keep playing around? If so what can I do differently?

I measured the racquets and got consistent readings of 418 and 426 respectively with 10 samples each. The counter clockwise tip helped! Those readings jive with the delta of the racquets before I got the new rod.

Thanks again.

 

[Shroud]

OK, I added lead to the lower sw racquet and now it measures 426 with the differences between the racquets being 0.49 which is acceptable for me. Thanks for all the help.

Oh, The SW1 is great and seems pretty accurate with the position of the tube string dampener affecting the readings.

 

[bfroxen]

Thanks again for the help. The 220 number came from the tool itself but in the cradle it was turned so I saw 220 then 7.6. Its CO2-2220 and I just saw the 220. Looking correctly its 292.3.

Sadly I could never get it to read 292. I got consistent 272 readings with the mean being 272.47 over 10 readings. Could it be possible that the number is 272 instead of 292? Or do I need to keep playing around? If so what can I do differently?

I measured the racquets and got consistent readings of 418 and 426 respectively with 10 samples each. The counter clockwise tip helped! Those readings jive with the delta of the racquets before I got the new rod.

Thanks again.

After calibration, measurements of the rod should match the "Object #1" and "Object #2" values from the Calibrate page. That's what calibration does; it makes those values match. When you tap the "Calibrate" button, the calibration results below the button will update. What are those values for you?

There are a few things to check:

1. Is the tare button active? It's filled blue when active and unfilled when inactive. When it's activated, it makes the last measurement the new zero point, so subsequent measurements will be lower by that amount.
2. Do the "Object #1" and "Object #2" values match the label on the rod?
3. Is/was the calibration rod fully-collapsed and fully-extended? It's about 8" long collapsed and 29" long extended.

 

[sureshs]

I used 2 scales and the head weight and the tip weight are identical except for the .1g. I can live with that

Doesn't it make a huge difference to a player at your level?

 

[Shroud]

Doesn't it make a huge difference to a player at your level?

nope

 

[Shroud]

After calibration, measurements of the rod should match the "Object #1" and "Object #2" values from the Calibrate page. That's what calibration does; it makes those values match. When you tap the "Calibrate" button, the calibration results below the button will update. What are those values for you?

There are a few things to check:

1. Is the tare button active? It's filled blue when active and unfilled when inactive. When it's activated, it makes the last measurement the new zero point, so subsequent measurements will be lower by that amount.
2. Do the "Object #1" and "Object #2" values match the label on the rod?
3. Is/was the calibration rod fully-collapsed and fully-extended? It's about 8" long collapsed and 29" long extended.

I guess the whole calibration process is not something I understand. I just entered it manually what it was reading:

1. Yes
2. No, I could never get the readings to match what was printed, especially for object 2
3. Yes it was fully extended with 4 sections showing.

Guess I need to watch the vid again.

 

[Shroud]

After calibration, measurements of the rod should match the "Object #1" and "Object #2" values from the Calibrate page. That's what calibration does; it makes those values match. When you tap the "Calibrate" button, the calibration results below the button will update. What are those values for you?

There are a few things to check:

1. Is the tare button active? It's filled blue when active and unfilled when inactive. When it's activated, it makes the last measurement the new zero point, so subsequent measurements will be lower by that amount.
2. Do the "Object #1" and "Object #2" values match the label on the rod?
3. Is/was the calibration rod fully-collapsed and fully-extended? It's about 8" long collapsed and 29" long extended.

Sorry, I don't think this product is for me. I can't even get it calibrated. Leveled it on a board, and here is the last of 3 failed efforts to calibrate

Help

 

[bfroxen]

I guess the whole calibration process is not something I understand. I just entered it manually what it was reading:

1. Yes
2. No, I could never get the readings to match what was printed, especially for object 2
3. Yes it was fully extended with 4 sections showing.

Guess I need to watch the vid again.

For the replacement calibration rod that I sent you, Object #1 should be 7.6, and Object #2 should be 292.3. Those are the values printed on the label. You don't change these as part of the calibration process. Normally, you never change them, but you needed to change them once for the replacement rod.

The tare button should NOT be active. It's only needed for the pickleball adapters, and some people like to use it for the twistweight adapter.

1. Tap the Tare button to deactivate (should be unfilled).
2. Update Object #1 to 7.6 and save.
3. Update Object #2 to 292.3 and save.
4. Create an empty measurement group.
5. Take one measurement of the collapsed rod.
6. Create a second measurement group.
7. Take two measurements of the extended rod.
8. Create a third measurement group.
9. Take one measurement of the collapsed rod.
10. Verify that the measurement group checks are satisfied. (If not please post screenshots of the Measure and Calibrate tabs. You may need a couple screenshots of the the Calibrate tab to get the calibration results below the Calibrate button.)
11. Tap the Calibrate button.
12. Check the calibration results below the Calibrate button. The spring constant should be in the 220s, and the Apparatus MoI should be between 5 and 12. (If not post screenshots.)
13. Re-measure the calibration rod. It should measure 8 (maybe 7) and 292 (maybe 293).

 

[Shroud]

For the replacement calibration rod that I sent you, Object #1 should be 7.6, and Object #2 should be 292.3. Those are the values printed on the label. You don't change these as part of the calibration process. Normally, you never change them, but you needed to change them once for the replacement rod.

The tare button should NOT be active. It's only needed for the pickleball adapters, and some people like to use it for the twistweight adapter.

1. Tap the Tare button to deactivate (should be unfilled).
2. Update Object #1 to 7.6 and save.
3. Update Object #2 to 292.3 and save.
4. Create an empty measurement group.
5. Take one measurement of the collapsed rod.
6. Create a second measurement group.
7. Take two measurements of the extended rod.
8. Create a third measurement group.
9. Take one measurement of the collapsed rod.
10. Verify that the measurement group checks are satisfied. (If not please post screenshots of the Measure and Calibrate tabs. You may need a couple screenshots of the the Calibrate tab to get the calibration results below the Calibrate button.)
11. Tap the Calibrate button.
12. Check the calibration results below the Calibrate button. The spring constant should be in the 220s, and the Apparatus MoI should be between 5 and 12. (If not post screenshots.)
13. Re-measure the calibration rod. It should measure 8 (maybe 7) and 292 (maybe 293).

Thanks for all the help! I am getting closer. Though the spring constant was 216

Can I use this or do I need to do it again? Thanks!!

 

[bfroxen]

Thanks for all the help! I am getting closer. Though the spring constant was 216

Can I use this or do I need to do it again? Thanks!!

That's a bit lower than I'm used to seeing, but it could be OK. If you get the expected values when measuring the calibration rod, then it's good.

 

[Shroud]

That's a bit lower than I'm used to seeing, but it could be OK. If you get the expected values when measuring the calibration rod, then it's good.

Thanks! I got 7 and 291 when I measured after calibration. Is that OK?

 

[bfroxen]

Thanks! I got 7 and 291 when I measured after calibration. Is that OK?

It's close, but you should be able to do better. You may need to work on releasing the cradle more consistently. A fan blowing directly on the device will hurt repeatability. When I measure the extended rod five times in a row, the standard error of the mean is usually less than ±0.05 (or ±0.01 at most for the collapsed rod). That's the number displayed after the mean when you have three or more measurements in a group. See what you're getting, and work to get it below ±0.10. When you have that dialed in, calibrate again and check.

 

[Shroud]

It's close, but you should be able to do better. You may need to work on releasing the cradle more consistently. A fan blowing directly on the device will hurt repeatability. When I measure the extended rod five times in a row, the standard error of the mean is usually less than ±0.05 (or ±0.01 at most for the collapsed rod). That's the number displayed after the mean when you have three or more measurements in a group. See what you're getting, and work to get it below ±0.10. When you have that dialed in, calibrate again and check.

At this point I am just embarrassing myself. Calibrated again once I got to the 0.10 mark and then measured extended and its now 304 and I erased it and again its 304, not 292. Sorry I will try again but I don't seem to be able to get this to be accurate.

 

[Shroud]

It's close, but you should be able to do better. You may need to work on releasing the cradle more consistently. A fan blowing directly on the device will hurt repeatability. When I measure the extended rod five times in a row, the standard error of the mean is usually less than ±0.05 (or ±0.01 at most for the collapsed rod). That's the number displayed after the mean when you have three or more measurements in a group. See what you're getting, and work to get it below ±0.10. When you have that dialed in, calibrate again and check.

Ok I tried again and recalibrated. Its pretty good now:

Measured some racquets and they are close so I just need to add a bit of lead to the smaller sw one:

Thanks so much for all your help!

 

[bfroxen]

Thanks so much for all your help!

Looks good. You're welcome.