How does this swing weight machine work

[Nickc]

https://www.ebay.co.uk/itm/144963126022

 

Table at end shows specific reading on the digital weighing scale for a given swing weight. How does this work with clubs of overall different weights.

Edited March 25, 2023 by Nickc

[Stuart_G]

1 hour ago, Nickc said:

https://www.ebay.co.uk/itm/144963126022

 

Table at end shows specific reading on the digital weighing scale for a given swing weight. How does this work with clubs of overall different weights.

 

Swing weight is a measure of a moment force about a particular fulcrum point (14" from the butt end of the club).   As long as that is what is being measured, it will work for clubs of any weight.

 

I didn't read the fine print - but I'd guess that the only difference between that and a more "normal" swing weight scale is that you have to measure and find the fulcrum point before placing the club on the scale.  While a more traditional swing weight scale will basically do that for you.

 

[Nickc]

Thanks. My confusion is that for example the table shows a reading of 605 grams on the digital scale to be D1 but my clubs don't even weigh that much (and reading does not include the weight of the equipment on the scale as scale zeroed before club put in place).

Edited March 25, 2023 by Nickc

[ChaosTheory]

Poke around Dave Tutelman’s website.  This page talks about the gram numbers for swing weight.

 

http://www.tutelman.com/golf/measure/digitalSwingweightScale1.php#use

[ChaosTheory]

The eBay seller’s gram numbers seem high.  Maybe they include the weight of the arm.  I have a digital sw scale once sold by golfsmith.  The scale itself was programmed to do the conversion to swing weight for the user.  That scale died, so I substituted a plain digital scale.

 

 I “tare” the scale with the arm resting on it, and then set the club onto the scale.  So my gram readings correspond with Tutelman’s numbers.  I have a chart somewhere…

Edited March 25, 2023 by Snowman9000

[Stuart_G]

36 minutes ago, Snowman9000 said:

Poke around Dave Tutelman’s website.  This page talks about the gram numbers for swing weight.

 

http://www.tutelman.com/golf/measure/digitalSwingweightScale1.php#use

 

Yes the scale is an actual fulcrum and the force of club leveraging the fulcrum is what's measured - not just the static weight of the club.

 

29 minutes ago, Snowman9000 said:

His numbers seem high.  Maybe they include the weight of the arm.

 

Or maybe just taken at a different distance from the fulcrum axis?

Edited March 25, 2023 by Stuart_G

[ChaosTheory]

11 minutes ago, Stuart_G said:

 

Or maybe just taken at a different distance from the fulcrum axis?

Yes.  It’s too early, my brain hasn’t warmed up yet.  😑

[AzRoger]

I have the SW scale referenced above and it seems to work well, very repeatable, just need a good digital scale that accurately measures grams. Since I purchased it Swingw.com has come out with an XL version, ~$10 more than the V3 but probably worth it IMO, no need to measure and mark 14" down from the grip on every club being measured for SW.

[AzRoger]

3 hours ago, Nickc said:

Thanks. My confusion is that for example the table shows a reading of 605 grams on the digital scale to be D1 but my clubs don't even weigh that much (and reading does not include the weight of the equipment on the scale as scale zeroed before club put in place).

As mentioned above you're not measuring the total weight of the club with this SW scale, just the weight of the clubhead end from the 14" balance point.

Edited March 25, 2023 by AzRoger

[Stuart_G]

2 hours ago, Snowman9000 said:

Yes.  It’s too early, my brain hasn’t warmed up yet.  😑

 

Never happens to me 😆

[joostin]

All right here we go... had to make a diagram.  It just comes down to a simple torque/moment calculation - same thing done by online calculators and my Excel calculator+.

 

The gram scale measures the weight exerted by the swingweight scale's arm and club when supported at a 14" fulcrum.  We know the club's moment from a 14" fulcrum corresponds to a swingweight.  We (or scale designer) also know the scale arm's weight exerted at its distance from the fulcrum.  The only thing we need is the total weight exerted on the gram scale to correlate to the swingweight.  Looks and calculates like this:

It says torque at the 14" fulcrum = 0.  Total weight seen by the gram scale * distance of the weighing point to the fulcrum = Scale arm weight * arm's CG from the fulcrum + club weight * club's CG from the fulcrum.  We just need W1 to get a corresponding swingweight. 

 

[AlohaPineapple]

I have this scale and find it super convenient, previously was using the excel method but slight differences in measuring the balance point created variance.   The scale comes with a table where the gram weights displayed convert to a swing weight.