Calibrating an Alpha Blu

Discussion in 'Stringing Techniques / Stringing Machines' started by NiteFly, Aug 19, 2008.

  1. NiteFly

    NiteFly Rookie

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    I finally received the Alpha blue I got from the auction site. The machine looks to be in good shape and is very sturdy. The clamps don't slip and the string gripper holds the string steady.

    I went to calibrate it tonight and I run out of tension screw before I reach the desired tension. I am using an Alpha tension calibrator. Does this mean that I need to replace a spring or something? It gets close, it shows 50lbs on the calibrator when I have the tension head set at 53. The higher I go, the more it is off though. It shows 70 lbs when I am set at 76. Any thoughts?

    I figure I can string like this, but it seems like I will have to check tension every time.
     
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  2. Mansewerz

    Mansewerz Legend

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    Alpha blu? Was this an earlier model?
     
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  3. Zhou

    Zhou Hall of Fame

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    [​IMG] Here is a picture of the machine. It is an earlier model of Alpha.
     
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  4. SW Stringer

    SW Stringer Semi-Pro

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    Take a bunch of readings that cover the range that you expect to use. For example: take readings every five pounds from 45 to 75 pounds - at least two at each setting. If you took two readings per setting you will have fourteen sets of data points, an x (machine reference tension) and a y (actual tension). Plug the numbers into a linear regression formula (Excel has one) and the program will spit out an equation of the form: y = m * x + b Use that equation to print out a chart that shows the machine reference tension vs actual tension from 45 to 75 pounds in one pound increments. Recallibrate and reprint a new chart as needed. (i.e. - every 50 racquets, every 3 months, and whenever you suspect the mechanism has shifted)
     
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  5. dancraig

    dancraig Hall of Fame

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    You might also want to check the accuracy of your calibrator. You can do this with barbell weights. They can be "calibrated" too.
     
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  6. william7gr

    william7gr Professional

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    It's a ratio. The machine isn't going to be off by three pounds when you set the tension to 10 but also it wont be off by three when you set it to 100.
     
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  7. NiteFly

    NiteFly Rookie

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    Makes sense. Thanks.
     
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  8. NiteFly

    NiteFly Rookie

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    This sounds like a great idea. Thanks. Is my tension head OK though? Would replacing any of the parts allow me to get to the correct tension in the calibration? I was reading through a Gamma manual and it had a little section on adjusting the tension brake after a lot of use. Could that be something I need to do on the Alpha?
     
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  9. Zhou

    Zhou Hall of Fame

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    I would give Mark a call at Alpha and ask him what he would recommend for you.
     
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  10. NiteFly

    NiteFly Rookie

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    I emailed him and he responded quickly. He sent me a pdf of the manual yesterday and he is mailing me a replacement tensioning adjustment screw today. As many on this board already know... you can't beat this customer service!

    Mark thinks the screw might be stripped and it definately looks worn in the middle.
     
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