Crank machine and tension calibration...

[MTZ]

I was calibrating my crank machine and noticed something weird, or maybe not. I use an electronic fishing scale to calibrate my machine, which provides me with accuracy to ounces. I noticed that when my crank locks out closer to left side of the crank arm, the tension reads lower than if the crank locks out closer to the right side of the crank arm. the difference is about 7-9% of the tension. Has anyone else noticed this and if so, is this normal or is something off with my machine.

TIA

 

[PaintTheLine]

On my Gamma X-ST using a spring loaded tension calibrator (also Gamma)
I get the same reading every time as long as I do a nice, slow,
controlled crank. I tried just giving it a quick crank and it's off by appx.
+2 or -1 lbs. Again if I do a controlled crank of appx. a 4 count until it locks out I get the same reading everytime (+/- 0 lbs). But it is a spring calibrator so I admit I could very well be off by .5 and possibly not notice.

Could it be the digital scale? It's surprising it could be off by up to 5 lbs from pull to pull.

Mat

 

[MTZ]

On my Gamma X-ST using a spring loaded tension calibrator (also Gamma)
I get the same reading every time as long as I do a nice, slow,
controlled crank. I tried just giving it a quick crank and it's off by appx.
+2 or -1 lbs. Again if I do a controlled crank of appx. a 4 count until it locks out I get the same reading everytime (+/- 0 lbs). But it is a spring calibrator so I admit I could very well be off by .5 and possibly not notice.

Could it be the digital scale? It's surprising it could be off by up to 5 lbs from pull to pull.

Mat

Thanks for checking it out for me.
I don't think it's the scale, cause it's consistent when I am consistent testing it, position when the crank locks out. I will try the controlled motion and let you know how that does. Thanks.

 

[Hal]

I have a similar issue with my Alpha crank machine. In my case, it seems to be different if it's closer or farther from the turn table, but maybe it was a left/right thing as you describe. I'll have to check it out.

 

[MTZ]

Tension...

I have a similar issue with my Alpha crank machine. In my case, it seems to be different if it's closer or farther from the turn table, but maybe it was a left/right thing as you describe. I'll have to check it out.

I think we are talking about the same thing. What I meant by the crank arm, probably not the right label, was the thingamajic that the tensioning device (tension head?) slides back and forth on. It Horizontal and has teeth, it has stops on either side so that the tension head doesnt fall (slide) off of it.

 

[Hal]

Yep, sounds like we have the same issue. Let me know if you find a solution. I'll do like wise.

 

[LttlElvis]

You can get different readings with a crank.

1.) The further your initial starting point is from the turntable, the more accurate the reading.
2.) Quicker lever motion will give a different reading from a slow steady motion.

You just have to get a system down to become consistant. Usually try to start the tensioning head at the same position on the track if possible. Also use a slow consistant motion when turning the lever.

Do the same when calibrating and stringing.

 

[MTZ]

You can get different readings with a crank.

1.) The further your initial starting point is from the turntable, the more accurate the reading.
2.) Quicker lever motion will give a different reading from a slow steady motion.

You just have to get a system down to become consistant. Usually try to start the tensioning head at the same position on the track if possible. Also use a slow consistant motion when turning the lever.

Do the same when calibrating and stringing.

Thanks.

 

[LttlElvis]

I did switch to a Wise Tension head solely for consistancy. Never had a problem with a crank. I know tensioning speed and tension head do make a difference (although it may be very small).

Once I switched to the Wise Tension head, I cannot tell a difference between my personal rackets.

 

[MTZ]

I did switch to a Wise Tension head solely for consistancy. Never had a problem with a crank. I know tensioning speed and tension head do make a difference (although it may be very small).

Once I switched to the Wise Tension head, I cannot tell a difference between my personal rackets.

I want to switch as well to the Wise, but just cant justify the additional cost.
Besides myself,I do about 2 racquets a week for other people. I wonder if there are any second hand electronic tension heads for sale.