Machine Calibration

SavvyStringer

Professional
Hey all,

I've been scrolling for a few days and not finding anything recent that I actually care to comment on so I thought I would start my own post with a question for you all.

How often do you check the calibration your machine? Things to include in response: Type of machine, and reasoning behind calibration frequency.

Personally, I string on a Baiardo. I check the calibration/calibrate once a month, every time I move the machine, or every time I power the machine down. Whichever comes first. My machine stays on 24/7 if I am not traveling to string a tournament or we are not having storms that have made the power go out. The only time I turn it off when I am going to be home is this time of year when we get almost daily evening storms that make the power flicker. Other than that, I usually only turn it off to move it or if I will be out of town longer than 3 days. Most often my checks and calibrations are monthly or after moving the machine. Mine tends to stay within a tenth of a kilo all the time and I rarely have to actually recalibrate the machine.
 

MaxSwing

New User
I have a drop weight machine that is only brought out when I need it (roughly once a week), I remove the weight every time I store it. So even if the tension is the same between racquets I am re-calibrating.

Ok ok so maybe not quite what you were after and mine is a little jokey. I do however plan on getting an electronic machine later this year (Tennis Man Deluxe LE v3 - once they are back in stock) and I would imagine I will calibrate it monthly the same as you. I might need to get a better calibration tool as mine is the standard Pros Pro analogue pull so 'detail' down to 1/10 of a kilo is not easy.
 

Herb

Semi-Pro
Pretty much the same as you. I check both Baiardo's monthly, or any time I move one. I leave my primary on all the time, but do not calibrate every time I power off. When I get real busy Jan-May I check twice a month.
 

10shoe

Professional
I thought about bringing up this topic as well because my machine is about a half pound out of calibration according to my Prince Digital Calibrator. I am stringing on a Toyo Zouki machine and there is no calibration procedure because Toyo Zouki insists the machine is self calibrating. When I check calibration there are some tensions that are pulling spot on, so at 35 lbs the machine and the calibration tool are in agreement. But at 50 lbs, I am pulling 49.5 lbs per the PDC.

There is a trimpot on the motherboard inside the tension head that I know can be used to adjust the calibration (shhhhhhhh, don't tell Toyo Zouki) but the adjustment calls for extremely delicate touch and I know from experience that if I turn the screw on the trimpot even the tiniest amount I will probably end up with the machine a full pound off in the other direction. So, I'm leaving it be.

I also have a Shimpo force gauge. I recently created an adapter so that I can use the steel cable from the PDC on the Shimpo. The Shimpo has two settings, one for peak tension and the other for (I dunno, average tension?). The Shimpo tells me things are even worse than the PDC, so I put it away and pretend it doesn't exist.

I also have a spring loaded calibrator which I bought for use with a Star 4 that sits here collecting dust. If anyone out there still uses a spring loaded calibrator, be aware that they can lose adjustment. To check if yours is bad, try turning the calibrated rod. If the reading changes while you are turning it, the lock nuts inside have unlocked and the device is no longer trustworthy.

Edit: I just remembered why I was thinking of starting a thread about calibration. I think it was a post by @Herb where he mentioned that college coaches were demanding to check the calibration of his machine with their own calibrators. That just left me shaking my head.
 
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kkm

Hall of Fame
I thought about bringing up this topic as well because my machine is about a half pound out of calibration according to my Prince Digital Calibrator. I am stringing on a Toyo Zouki machine and there is no calibration procedure because Toyo Zouki insists the machine is self calibrating. When I check calibration there are some tensions that are pulling spot on, so at 35 lbs the machine and the calibration tool are in agreement. But at 50 lbs, I am pulling 49.5 lbs per the PDC.

There is a trimpot on the motherboard inside the tension head that I know can be used to adjust the calibration (shhhhhhhh, don't tell Toyo Zouki) but the adjustment calls for extremely delicate touch and I know from experience that if I turn the screw on the trimpot even the tiniest amount I will probably end up with the machine a full pound off in the other direction. So, I'm leaving it be.

I also have a Shimpo force gauge. I recently created an adapter so that I can use the steel cable from the PDC on the Shimpo. The Shimpo has two settings, one for peak tension and the other for (I dunno, average tension?). The Shimpo tells me things are even worse than the PDC, so I put it away and pretend it doesn't exist.

I also have a spring loaded calibrator which I bought for use with a Star 4 that sits here collecting dust. If anyone out there still uses a spring loaded calibrator, be aware that they can lose adjustment. To check if yours is bad, try turning the calibrated rod. If the reading changes while you are turning it, the lock nuts inside have unlocked and the device is no longer trustworthy.

Edit: I just remembered why I was thinking of starting a thread about calibration. I think it was a post by @Herb where he mentioned that college coaches were demanding to check the calibration of his machine with their own calibrators. That just left me shaking my head.
Thanks for your thorough post. What are companies such as Toyo Zouki thinking when they say self-calibrating and don’t give the user any simple way to calibrate?
 

LOBALOT

Legend
So how close is close enough and what about variances when testing at the various tension levels i.e. 20, 30, 40, 50?

Would you say 50.5 is good for 50?

What if 40 said 37.88 as one reading but 50 said 52.3 just as an example (not actual readings)?

I mean I know one can logically assume an answer to these questions but just wondering if assumptions are correct in this instance?
 
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10shoe

Professional
Thanks for your thorough post. What are companies such as Toyo Zouki thinking when they say self-calibrating and don’t give the user any simple way to calibrate?

I don't know what they are thinking but I can tell you that at one point before Yonex bought them Toyo Zouki allowed folks like me with legacy equipment to send tension heads in for repair and I received back a tension head that was pulling 51.5 lbs when set at 50.
 
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tjanev

Rookie
ok, so i went to see how to calibrate the mt-400 tomcat. and there's no option!!. wtf. also no manuals or pdf's of the tomcat. tried other units' manuals and they have different tensioning machines. sheesh.
 

tjanev

Rookie
ok. Off topic. What is more important? Having an accurately calibrated machine or calibrating your machine so that you get an accurate number off of an ert-300. Most of the time i'm not getting the same numbers. I checked my tension on the machine, and its pretty accurate. Personally speaking, i have a feeling the ert's accuracy depends on a number of factors as not every racquet is the same. different materials and absorbing factors must influence the read out of the ert's piezo sensors. I use it mainly to read the before and after so i can see the drop in tension over time.
 

10shoe

Professional
I decided to calibrate my machine last night. I have recently noticed a drop in DT values on some of the racquets from repeat customers. So, on a racquet where I am expecting a DT of 37, I am getting 36. According to my Prince Digital Electronic Calibrator (DEC) with my ToyoZouki machine set at 50, it was pulling 49. So I crack open the case on the unit and turn the screw on the trimpot clockwise about one micron and it throws the calibration off to 52.5 lbs. The tiniest little turn the other way and the DEC is flickering between 49.5 and 50. Good enough.
 
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kkm

Hall of Fame
(n)I don't know what they are thinking but I can tell you that at one point before Yonex bought them Toyo Zouki allowed folks like me with legacy equipment to send tension heads in for repair and I received back a tension head that was pulling 51.5 lbs when set at 50.
Before you sent it in how much was it pulling when set at 50? 1.5 lb off isn’t too good.
 

kkm

Hall of Fame
I decided to calibrate my machine last night. I have recently noticed a drop in DT values on some of the racquets from repeat customers. So, on a racquet where I am expecting a DT of 37, I am getting 36. According to my Prince Digital Electronic Calibrator (DEC) with my ToyoZouki machine set at 50, it was pulling 49. So I crack open the case on the unit and turn the screw on the trimpot clockwise about one RCH and it throws the calibration off to 52.5 lbs. The tiniest little turn the other way and the DEC is flickering between 49.5 and 50. Good enough.
Between 49.5 and 50 is good enough. Did you check the calibration at any other tensions?
 

10shoe

Professional
Before you sent it in how much was it pulling when set at 50? 1.5 lb off isn’t too good.
It wasn't pulling at all and I was looking at owning a 90 lb paperweight. I am mucho grateful to the folks at Toyo Zouki for consenting to repair the tension head (they didn't have to) and was thrilled to have it working again. But I don't remember the machine ever being off calibration more than half a pound until I sent it in for repair.

Now that Toyo Zouki is owned by Yonex and they are refusing to work on any machine doesn't bear the name Yonex I have become fairly expert at repairing on my own. So I have completely disassembled this unit and replaced key components in the drive like the lead screw nut and the linear and flange bearings as well as the motor and a smattering of electronic parts.
 
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kkm

Hall of Fame
It wasn't pulling at all and I was looking at owning a 90 lb paperweight. I am mucho grateful to the folks at Toyo Zouki for consenting to repair the tension head (they didn't have to) and was thrilled to have it working again. But I don't remember the machine ever being off calibration more than half a pound until I sent it in for repair.

Now that Toyo Zouki is owned by Yonex and they are refusing to work on any machine doesn't bear the name Yonex I have become fairly expert at repairing on my own. So I have completely disassembled this unit and replaced key components in the drive like the lead screw nut and the linear and flange bearings as well as the motor and a smattering of electronic parts.
They won’t even be working on the older Yonex stringing machines much longer.(n)
 

SavvyStringer

Professional
So how close is close enough and what about variances when testing at the various tension levels i.e. 20, 30, 40, 50?

Would you say 50.5 is good for 50?

What if 40 said 37.88 as one reading but 50 said 52.3 just as an example (not actual readings)?

I mean I know one can logically assume an answer to these questions but just wondering if assumptions are correct in this instance?
I'm shooting for .1 lb of variance. So at 55 it could pull 54.9 or 55.1. Part of the Baiardo reclaibration does it at 10kg, 20kg, 30kg, 40kg. You just push the button while it's pulling and it flips that over to lbs and I adjust off that.
 
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