Hx calibration

[TrgBK]

Hi Kuokuo,
during calibration, what HX value should I use? If i set the HX to 20 and the load cell reading is 24 or 25, what value should I set on the Hx? Thanks
Trg

[206cc]

Just enter the value from your external tension gauge.

If you measure 24–25, then enter 24–25.
(For a 20kg load cell, it is usually around 17–19 before calibration.)

[TrgBK]

Hi Kuo, Do you mind sharing what the HX calibration algorithm works? Thanks

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On Sun, Apr 19, 2026 at 7:04 PM Kuo ***@***.***> wrote: Just enter the value from your external tension gauge. If you measure 24–25, then enter 24–25. (For a 20kg load cell, it is usually around 17–19 before calibration.) — Reply to this email directly, view it on GitHub <#60?email_source=notifications&email_token=BUKUJZ4I5Y3O53OIYN65KCT4WSXCNA5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNRWGIZDGNJWUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVRTG633UMVZF6Y3MNFRWW#discussioncomment-16622356>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BUKUJZZITFWUCHZY36OQPU34WSXCNAVCNFSM6AAAAACX6LAOS2VHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTMNRSGIZTKNQ> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[206cc]

The HX calibration is not a complicated algorithm.

The HX711 raw value is first zeroed by subtracting the zero-load value HX711_V0.

Then the result is converted into grams using the HX711_CAL coefficient:

Tension(g) = (HX711 raw value - HX711_V0) / 100 * (HX711_CAL / 20)

So HX711_CAL is basically a scaling factor used to convert the HX711 raw reading into the actual tension value.

During calibration, I use an external tension gauge as the reference.
If the machine display does not match the external gauge, the HX711_CAL value is adjusted until both values are close.

For a 20 kg load cell, the calibrated HX value is usually around 18.

[TrgBK]

Thanks for the explanation.

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On Wed, Jun 10, 2026 at 7:03 PM Kuo ***@***.***> wrote: The HX calibration is not a complicated algorithm. The HX711 raw value is first zeroed by subtracting the zero-load value HX711_V0. Then the result is converted into grams using the HX711_CAL coefficient: Tension(g) = (HX711 raw value - HX711_V0) / 100 * (HX711_CAL / 20) So HX711_CAL is basically a scaling factor used to convert the HX711 raw reading into the actual tension value. During calibration, I use an external tension gauge as the reference. If the machine display does not match the external gauge, the HX711_CAL value is adjusted until both values are close. For a 20 kg load cell, the calibrated HX value is usually around 18. — Reply to this email directly, view it on GitHub <#60?email_source=notifications&email_token=BUKUJZ6BKFVD553EP7GVTNL47E6B3A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZSGQ4TSMRZUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVRTG633UMVZF6Y3MNFRWW#discussioncomment-17249929>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BUKUJZ7UE3DNNJCJY2BJCGT47E6B3AVCNFSNUABHKJSXA33TNF2G64TZHM3DQNJUGMYDSNZRHNCGS43DOVZXG2LPNY5TSOJQHE2TON5BOYBA> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/BUKUJZ22D4J67PLUT2HIS2D47E6B3A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZSGQ4TSMRZUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVJTG633UMVZF62LPOM> and Android <https://github.com/notifications/mobile/android/BUKUJZ5F7HITDS3JLVEPHBT47E6B3A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZSGQ4TSMRZUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVZTG633UMVZF6YLOMRZG62LE>. Download it today! You are receiving this because you authored the thread.Message ID: ***@***.***>

[TrgBK]

Hi Kuo, Need your advice. I was using fixed Base clamp to string my badminton racket. Some how I always feel that the two centre mail vertical strings poundage are always lower than I targeted. Is there a way to verify the string poundage? And I observed the clamp relaxed quite a bit when I released it. Thanks Thia

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On Thu, Jun 11, 2026 at 4:08 PM Terang Thia ***@***.***> wrote: Thanks for the explanation. On Wed, Jun 10, 2026 at 7:03 PM Kuo ***@***.***> wrote: > The HX calibration is not a complicated algorithm. > > The HX711 raw value is first zeroed by subtracting the zero-load value > HX711_V0. > > Then the result is converted into grams using the HX711_CAL coefficient: > > Tension(g) = (HX711 raw value - HX711_V0) / 100 * (HX711_CAL / 20) > > So HX711_CAL is basically a scaling factor used to convert the HX711 raw > reading into the actual tension value. > > During calibration, I use an external tension gauge as the reference. > If the machine display does not match the external gauge, the HX711_CAL > value is adjusted until both values are close. > > For a 20 kg load cell, the calibrated HX value is usually around 18. > > — > Reply to this email directly, view it on GitHub > <#60?email_source=notifications&email_token=BUKUJZ6BKFVD553EP7GVTNL47E6B3A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZSGQ4TSMRZUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVRTG633UMVZF6Y3MNFRWW#discussioncomment-17249929>, > or unsubscribe > <https://github.com/notifications/unsubscribe-auth/BUKUJZ7UE3DNNJCJY2BJCGT47E6B3AVCNFSNUABHKJSXA33TNF2G64TZHM3DQNJUGMYDSNZRHNCGS43DOVZXG2LPNY5TSOJQHE2TON5BOYBA> > . > Triage notifications, keep track of coding agent tasks and review pull > requests on the go with GitHub Mobile for iOS > <https://github.com/notifications/mobile/ios/BUKUJZ22D4J67PLUT2HIS2D47E6B3A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZSGQ4TSMRZUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVJTG633UMVZF62LPOM> > and Android > <https://github.com/notifications/mobile/android/BUKUJZ5F7HITDS3JLVEPHBT47E6B3A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZSGQ4TSMRZUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVZTG633UMVZF6YLOMRZG62LE>. > Download it today! > You are receiving this because you authored the thread.Message ID: > ***@***.***> >

[206cc]

1. You can use a rotational string tension tester to measure the relative tension of each string. Keep in mind that it measures relative tension, not the absolute stringing tension. Please refer to this video:
   https://youtu.be/xYqu03XBzFU

2. Yes, the center two main strings usually have slightly lower tension. This is not a problem with the tension head. My solution is to increase the tension of the first two center mains by about 2 lb. However, 2 lb is not an absolute value—it depends on the stiffness of your stringing machine and your stringing technique, so you may need to adjust it accordingly.

[TrgBK]

Thanks for the tip!

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On Tue, Jul 28, 2026 at 7:56 AM Kuo ***@***.***> wrote: 1. You can use a rotational string tension tester to measure the relative tension of each string. Keep in mind that it measures relative tension, not the absolute stringing tension. Please refer to this video: https://youtu.be/xYqu03XBzFU 2. Yes, the center two main strings usually have slightly lower tension. This is not a problem with the tension head. My solution is to increase the tension of the first two center mains by about 2 lb. However, 2 lb is not an absolute value—it depends on the stiffness of your stringing machine and your stringing technique, so you may need to adjust it accordingly. — Reply to this email directly, view it on GitHub <#60?email_source=notifications&email_token=BUKUJZ7DN26H63XWOFLKULL5G7T33A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZYGA2DQOJRUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVRTG633UMVZF6Y3MNFRWW#discussioncomment-17804891>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BUKUJZ2I5EREOGTBJP2OWET5G7T33AVCNFSNUABHKJSXA33TNF2G64TZHM3DQNJUGMYDSNZRHNCGS43DOVZXG2LPNY5TSOJQHE2TON5BOYBA> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/BUKUJZ5CO6YXE2HPMDIPTV35G7T33A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZYGA2DQOJRUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVJTG633UMVZF62LPOM> and Android <https://github.com/notifications/mobile/android/BUKUJZ26A6222M7IVMPSJUT5G7T33A5CNFSNUABIM5UWIORPF5TWS5BNNB2WEL2ENFZWG5LTONUW63SDN5WW2ZLOOQXTCNZYGA2DQOJRUZZGKYLTN5XKMYLVORUG64VFMV3GK3TUVZTG633UMVZF6YLOMRZG62LE>. Download it today! You are receiving this because you authored the thread.Message ID: ***@***.***>