Lockout Machine Calibration

[UQ_Student]

I've got a spring-scale calibrator that I'm using to calibrate my lockout machine.

When tensioning <= 50 pounds, the calibrator reads the same as the set tension. However, when checking > 50 pounds, the calibrator reads >=5 pounds less e.g. 55 pounds gives a reading of 50, 60 -> 52, 70->55.

Is this normal? I'm new to lockout machines having just bought the machine new last week.

The tension adjustment screw seems to make little difference. Also, I'm using Yonex poly on both ends of the calibrator.

 

[Rabbit]

Sounds like you have a problem with your tension head.

 

[esgee48]

What you are seeing is not normal.
When you set up the machine, did you remove all the pieces that prevents the tension head from being damaged while it is shipped?
These are the readings at lock out? or a few seconds after lock out?
I would keep checking with multiple pulls at each tension to ensure that you are not reading something that is stretchy. Or use the thickest string you have on both ends.

If all else fails, contact Spinfire Support. The machine is new, so they have to help you.

edit: In case you are not doing this, make sure that you are pulling the scale calibrator straight when checking tension. Do not pull vertically and horizontally as this can lead to low readings.

 

[Irvin]

My guess is your have a calibrator or method issue.

 

[Karma Tennis]

So, the higher the pulled tension, the greater the gap between the set tension and the calibration reading.

That suggests the string is stretching and losing tension quickly.

When testing a LO, use the stiffest pieces of string you can find. Aramid if possible. Thickest Gauge. And preferably pieces that are well used.

The method I use is to have two lengths of string on each side of the Scale. Make sure all string is properly secured to the Scale, tension head, and clamp.

When testing, tension the string quickly (IE Crank the winder at a quick consistent pace) and Read off the scale as soon as the LO brake engages.

Also consider using a different scale ... I use a scale with a digital readout and that works fine. I test the machine at 30lbs and 60lbs using four lengths of well used Volkl Cyclone 16 gauge.

 

[UQ_Student]

So, the higher the pulled tension, the greater the gap between the set tension and the calibration reading.

That suggests the string is stretching and losing tension quickly.

When testing a LO, use the stiffest pieces of string you can find. Aramid if possible. Thickest Gauge. And preferably pieces that are well used.

The method I use is to have two lengths of string on each side of the Scale. Make sure all string is properly secured to the Scale, tension head, and clamp.

When testing, tension the string quickly (IE Crank the winder at a quick consistent pace) and Read off the scale as soon as the LO brake engages.

Also consider using a different scale ... I use a scale with a digital readout and that works fine. I test the machine at 30lbs and 60lbs using four lengths of well used Volkl Cyclone 16 gauge.

So the problem was that the poly on the clamp was slipping ever so slightly before the machine locks out when pulling with high tension.

I found out because I had a look at the clamp and the diamond coating was tinted RED! The string was poly tour fire so it was also super-slick.

For future readers who have the same issue, the problem was solved by cleaning and tightening the clamp.

 

[Karma Tennis]

For future readers who have the same issue, the problem was solved by cleaning and tightening the clamp.

Glad you figured it out. Yes, using a slick piece of string makes it difficult.

And you have learnt a good lesson about clean string clamps. Recommend you clean them thoroughly with pipe cleaners dipped in isopropyl alcohol after every TEN string jobs you do. Also clean the gripper plates on the Lockout Tension Head. That will keep the machine tip top.

 

[esgee48]

So Shakespeare was right; Much Ado About Nothing.
So a thicker string or Kevlar would have worked too.
Can we assume that the calibration was subsequently successful and that the patient will be allowed to live?
Enjoy your new machine.

 

[Irvin]

For future readers who have the same issue, the problem was solved by cleaning and tightening the clamp.

Slipping clamps can’t cause your problem, the clamp slipping will give you bad readings though. The reading you take should be at the instant your brake release lever trips. That’s the point when the ref tension is met. From that point on the tension in the string will drop from string relaxation or clamps slipping. If you’re reading 55 lbs with the ref tension set to 70 lbs your brake release will never trip. So (if your machine is adjusted properly) you met the 70 lbs, the lever tripped, and then you waited to make your reading.