Gamma 5800 ELS calibration

F

FischProN1

New User
Hello, i've bought this machine but i've tested it with a gamma tension calibrator and this is the result:
5 Kg ok
10 Kg ok
15 kg =>14 Kg readed on display
20 Kg =>18 Kg readed on display
25 Kg =>23 Kg readed on display

I've readed on the manual that in this case i must contact gamma because this isn't an offset error.
GammaTech probably can help me! :grin:
Thanks
 
Are you using the spring-loaded type of tension scale? If so, your calibrator may be off. Have you tried using a digital scale?
 
@ Gamma Tech

Would you mind sending me an eMail how to calibrate, too?

eMail would be fsp @ gmx . com

TIA

Flix
 
Thanks a lot, Bret.

Results:

10kg ok
15kg ok
20kg ok
25kg / 24,6
28kg / 27,6
30kg / 29,6

So I suggest, it is not an offset error?
 
flix,
you need to adjust the tension curve, if it was off by .4kg at 10kg, 20kg, 30kg then the offset would need adjusted.
bret
 
Since this thread already exists, I will just post in here. Maybe @Gamma Tech is still around and can give some guidance.

I have a 5800 ELS (not even two yrs old), and I just got delivered one of these cheap luggage digital scales. I swaged a ferrule set onto a stainless steel cable to start testing the tension readings on my machine, and I'm a bit concerned. Using both the mains and the crosses display button, I'm consistently getting 2-to-2.5lbs lower luggage scale reading than that of the tension head. You can see my amateur setup below. Machine set at 53#, getting readings consistently of 50.9-to-51#.

I'm inclined to believe the scale is just cheap junk, but what are thoughts from others who have attempted this type of calibration method? Should I buy another digital scale to try and replicate the readings? Should I be concerned and attempt to re-calibrate the machine?

4M6WOQ0.jpg

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You string is dragging over that rubber pad on top of you standard which could be throwing off your reading a little. Try to hold you string with the clamps only turning the table 90 degrees so the string does not rest on the pad.
 
Good idea, I'll see if I can get that to work somehow. I would somehow need the clamp(s) though to hold the digital scale via the top ring.

The picture also shows the whole setup in a relaxed state, not pulling tension in that picture. The scale shows the consistent tension reading until I reset it. I'll have to see if the cable still rests on the turntable pad once I activate the tension head.
 
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chrisingrassia said:
Good idea, I'll see if I can get that to work somehow. I would somehow need the clamp(s) though to hold the digital scale via the top ring.
Click to expand...
I would use a tennis string on each end of the scale instead of the ring and green cable. I believe that model has a good enough brake to hold the turntable. Might be a good idea to back up the clamp with a starting clamp.
 
Irvin said:
I would use a tennis string on each end of the scale instead of the ring and green cable. I believe that model has a good enough brake to hold the turntable. Might be a good idea to back up the clamp with a starting clamp.
Click to expand...
Too late for that on this scale. But perhaps I could buy another scale (they're only like 7 bucks) and do the string method with that one.
 
chrisingrassia said:
Too late for that on this scale. But perhaps I could buy another scale (they're only like 7 bucks) and do the string method with that one.
Click to expand...
Why spend $7 just keep it the way it is and connect tennis string on each end too. Check to if it makes a difference. If it does by 2# it does and just know that before you UNcalibrate it.
 
There should not be any obstructions at all between the tension calibrator and the gripper on the tensioner. Try this….Rotate the turntable 90 degrees (perpendicular to the machine base) and lock it with the table brake. Move one of the base clamps into the center of the turntable and lock it. Get rid of the hooks on the scale and replace those with string. Use whatever string you have laying around that has as little stretch as possible. Clamp one end with a string clamp and pull tension on the other. There should be nothing touching the string or calibrator other than your string clamp at one end and the gripper at the other end. Make a few pulls just to tighten up the knots and get some of the stretch out of the string.

By the way….no fan of luggage/fish scales here.
 
Gamma Tech said:
There should not be any obstructions at all between the tension calibrator and the gripper on the tensioner. Try this….Rotate the turntable 90 degrees (perpendicular to the machine base) and lock it with the table brake. Move one of the base clamps into the center of the turntable and lock it. Get rid of the hooks on the scale and replace those with string. Use whatever string you have laying around that has as little stretch as possible. Clamp one end with a string clamp and pull tension on the other. There should be nothing touching the string or calibrator other than your string clamp at one end and the gripper at the other end. Make a few pulls just to tighten up the knots and get some of the stretch out of the string.

By the way….no fan of luggage/fish scales here.
Click to expand...

Questions to GammaTech. With high end Gamma machines :

1) Does the string angle make any difference. I mean the angle at which the string comes from racket to the tension head ?
2) What should be the expected accuracy of properly calibrated machine, is there any overshoot and how much tension loss triggers re-pull
3) Is re-pull any different from initial pull thinking of overshoot
4) Do string stretch properties affect overshoot ?
 
OccasionalStringer said:
Does the string angle make any difference. I mean the angle at which the string comes from racket to the tension head ?
Click to expand...
I assume this question relates to Print Ported rackets. If the turntable is locked to hold the string at the top of the port you're probably redction the frame-string friction and your tension inside the frame is higher that you will find in the lower half of the frame.
OccasionalStringer said:
What should be the expected accuracy of properly calibrated machine, is there any overshoot and how much tension loss triggers re-pull
Click to expand...
Tension is just a number. If the racket feels good at 55 that's the number you use. The SBS or DTis more what the player feels and that depends on other factors (string pattern, frame stiffness, and head size) than just reference tension.
 
Irvin said:
I assume this question relates to Print Ported rackets. If the turntable is locked to hold the string at the top of the port you're probably redction the frame-string friction and your tension inside the frame is higher that you will find in the lower half of the frame.
Click to expand...
Not necessarily. For example, my 5800ELS turntable is significantly higher than the diablo. In other words, the plane of the grommet holes is .5-.75" higher than that of the diablo and tension head, causing it to pull tension at an angle.
 
Irvin said:
I assume this question relates to Print Ported rackets. If the turntable is locked to hold the string at the top of the port you're probably redction the frame-string friction and your tension inside the frame is higher that you will find in the lower half of the frame.

Tension is just a number. If the racket feels good at 55 that's the number you use. The SBS or DTis more what the player feels and that depends on other factors (string pattern, frame stiffness, and head size) than just reference tension.
Click to expand...

My questions where not related to any specific racket. I'm just curious to know what to expect from Gamma machines regarding pure pull tension accuracy (whether or not it affects the end results that much)

But if there is a dependency on the angle it also means that in the calibration process you should have the same angle as having the racket in the cradle (to get as accurate calibration as possible, even it might have only a minor effect in SBS)

And yes, tension is just a number and there are several other factors affecting resulting SBS, including the stringer. But wouldn't that also imply that why to bother to calibrate at all.

Anyhow, I suppose that every stringer wants the machine pull as close to the desired tension as possible.
 
Questions to GammaTech. With high end Gamma machines :

1) Does the string angle make any difference. I mean the angle at which the string comes from racket to the tension head ?
2) What should be the expected accuracy of properly calibrated machine, is there any overshoot and how much tension loss triggers re-pull
3) Is re-pull any different from initial pull thinking of overshoot
4) Do string stretch properties affect overshoot ?


The best way to answer your question is….yes. Just about everything will have an influence on the accuracy of calibration, and pulling tension in general on any stringing machine. If all the moons are lined up perfectly you will always have a straight line from the calibrator to the gripper, and be on the same plane, and then to have the same conditions being exactly the same as when you are stringing the frame. In addition you would have the same string on the calibrator as what you are using to string the racquet with. The temperature would be the same and the humidity as well. Technically any of those attributes will have some effect on what happens when you pull tension on a string.

The difference in angel makes a difference in accuracy and could be around .5 pound depending on the type of string, angel, etc. However the roller guide on the gripper does help to offset the angel by creating a consistent entry into the gripper. The difference in re-pull from initial pull, overshoot and stretch properties can also vary by .5 pound.

There are so many attributes that are a bit out of our control when stringing. The best thing to do is, as many suggest, is to be as consistent as possible when checking calibration, calibrating, and most importantly when stringing.
 
I've always thought the angle of the string going to the Diablo should make a difference. Now you've heard it from a Mechanical Engineer very familiar with stringing machines. If I ever get a machine with an electronic brake the engages on every pull I would disengage it.
 
Yes, there are calibration instructions in the machine manual. The calibration process/instructions have changed over the years on the 5800. There are three versions depending on the age of the machine since the electronic controls have evolved. If you can not find the instructions or have any trouble doing it, let me know.
 
Gamma Tech said:
Questions to GammaTech. With high end Gamma machines :

1) Does the string angle make any difference. I mean the angle at which the string comes from racket to the tension head ?
2) What should be the expected accuracy of properly calibrated machine, is there any overshoot and how much tension loss triggers re-pull
3) Is re-pull any different from initial pull thinking of overshoot
4) Do string stretch properties affect overshoot ?


The best way to answer your question is….yes. Just about everything will have an influence on the accuracy of calibration, and pulling tension in general on any stringing machine. If all the moons are lined up perfectly you will always have a straight line from the calibrator to the gripper, and be on the same plane, and then to have the same conditions being exactly the same as when you are stringing the frame. In addition you would have the same string on the calibrator as what you are using to string the racquet with. The temperature would be the same and the humidity as well. Technically any of those attributes will have some effect on what happens when you pull tension on a string.

The difference in angel makes a difference in accuracy and could be around .5 pound depending on the type of string, angel, etc. However the roller guide on the gripper does help to offset the angel by creating a consistent entry into the gripper. The difference in re-pull from initial pull, overshoot and stretch properties can also vary by .5 pound.

There are so many attributes that are a bit out of our control when stringing. The best thing to do is, as many suggest, is to be as consistent as possible when checking calibration, calibrating, and most importantly when stringing.
Click to expand...


Well, one reason I asked this was to compare Gamma to my low end pro's pro v888 in this respect (from time to time I have been thinking to upgrade but I have already put Pince 6000 clamp bases and string clamps to the machine). Anyway, according to my measurements (with several digital scales and spring tension calibrators) v888 pull accuracy is decent (after some tuning) and for some reason unknown to me it has improved recently on it's own.

But there is a strong dependency on the string angle so that if I wrap the string around the diablo going first under then the tension head pulls at around 30% higher tension. This comes directly from the mechanical construction as the angle affects how the string tension stresses the load cell bridge. Some time ago there was a brief discussion about this in another thread where Irvin mentioned that according to his measurements with Star 5 it does not make any difference which way the string is wrapped around the diablo.

So based on your answer its the same with Gamma and you can wrap the string both ways around the diablo (only 0.5 pound difference)? Not that there is any reason to go first under the diablo but it would be just nice to know.
 
OccasionalStringer said:
Irvin mentioned that according to his measurements with Star 5 it does not make any difference which way the string is wrapped around the diablo.
Click to expand...
I did? I don't ever remember taking readings going backward around the Diablo. I would think though that it should not make a difference connected to a scale. Connected to a grommet in a frame it would create a greater bend angle and there more string to grommet friction resulting in a lower tension inside the frame.
OccasionalStringer said:
So based on your answer its the same with Gamma and you can wrap the string both ways around the diablo (only 0.5 pound difference)? Not that there is any reason to go first under the diablo but it would be just nice to know.
Click to expand...
I think John was talking about the angle where the string is not on a straight line through the gripper to the point where the string is connected whether that be on a scale or into a grommet. From the Diablo to that point it is always straight.
 
^^^Yes, you did. Can't remember the name off the thread but it was 1-2 years ago.

And yes, reading it again I think he talks about the line from diablo to gripper

Going under the diablo increases grommet angle but in v888 bigger effect is what happens inside the tension head. In short, in v888 the subassemly containing the diablo and the gripper pivots around an axle. When the tension head pulls this subassembly rotates due to string tension and thus the string creates rotational torque which further presses the load cell bridge assembly. Chanching the string angle changes also the length of the lever with which the string creates rotational torque. In v888 when going first under the diablo shortens this lever which means that the load cell is loaded less and this further means that the control electronics want's to pull harder to see the load cell signal value for the selected pull tension.
 
As far as whether I said it or not I'll have to take your word for it.
OccasionalStringer said:
And yes, reading it again I think he talks about the line from diablo to gripper
Click to expand...
Better read it again he said from the calibrator to the gripper. The calibrator is the scale not the Diablo.
Gamma Tech said:
If all the moons are lined up perfectly you will always have a straight line from the calibrator to the gripper
Click to expand...
That means it does bend horizontally at the Diablo. Going around the Diablo it must bend vertically. I'm also not sure the 5800 has a Diablo the owner's manual calls it a gripper drum and there is an gripper plates travel adjustment on the back of the gripper plates.
 
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^^^

The following is from the thread "Diablo use", post 53. October 2014. But actually it does not say if you measured the tension with a scale inside a frame with different diablo wrappings. Would be interesting to know if there is a difference in Star 5 (at least to me and only as a general knowledge of modern tension head cababilities, without any link to final outcome of a string job).

Irvin said:
Well I just tried that on my Star5, it does not matter if I go under, over, under and around, over and around, through a frame, or not. The output of the load cell (what it reads on the navigator - the Star5's display) remains the same.

Now that begs the question, how are you measuring the output of the load cell?
Click to expand...
 
Thanks for finding that. On a Star5 the output of the load cell (which controls tension cutoff) is what you see on the navigator. Therefore it stands to reason the number you see on the navigator should always be the same with the same reference tension. If you like I can connect an external gauge later to see if the pulling force changes at all but I don't see a reason for it as I always go around the Diablo clockwise even when I use a bridge.
 
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I think it would be interesting to see what the scale inside a frame on Star 5 shows when you go first under. I will later check this with my wise (it has a different construction to move the tension head with the threaded rod, I believe that Star 5 is chain driven) when I'm back home.

I think everybody goes clockwise around the diablo, but still.
 
I just bought a second digital luggage/fish scale tonight, should be here by Tuesday. This one is orange color though, so I'm sure it will give accurate tension readings now :cool:

I'll have to rummage through the 5800 manual though if it's still reading ~2# lower than the tension head.
 
Got my second luggage scale set up today. Still pulling 1.5# lower than the tension head setting. Tested it at 50#, 55#, 60# and 65#. So now what do you guys think?
 
You can check the accuracy of your luggage scale just by weighing a gallon of water. Should be 8.34#/gal at ~ room temp, 2 gal 16.68#....(google is your friend and don't forget to add the weight of the container) If your scale is not accurate, you know the offset. If the scale is accurate, then you know whether your e tensioner is calibrated correctly or not. 2 cents.
 
esgee48 said:
You can check the accuracy of your luggage scale just by weighing a gallon of water. Should be 8.34#/gal at ~ room temp, 2 gal 16.68#....(google is your friend and don't forget to add the weight of the container) If your scale is not accurate, you know the offset. If the scale is accurate, then you know whether your e tensioner is calibrated correctly or not. 2 cents.
Click to expand...
Will give it a shot, thanks! I did find the calibration method in the machine manual, so I can tinker with it later.
 
Yes, but if you don't have to touch the e tensioner, so much better. You may find that the scale is 1.5# light which means your e tensioner is right on. :)

FWIW, I use a digital luggage scale that I know is right since it was calibrated with 1-5 gallons of water. (Water went into yard at end of test.)

edit - 2 pints = 1 quart; 4 quarts = 1 gallon. Liquid measuring cup is all you need.
 
Any of the current Gamma clamps will fit into the base clamps on the 5800. The clamp with the widest gripper jaw is the Black metal composite clamp.
 
@Gamma Tech
I would really like to upgrade some items on my 5800ELS now that I just picked up a country club client.
Is it at all possible to buy separate towers with just a single turn knob instead of three separate like they have now? One knob to turn to make the arms open/close.

Also, what's the difference between the standard 5800ELS clamps and the black composites you mention above? Your website makes the black ones look like plastic.

Heck, how much just to buy a complete 9900 turntable only
9900_Highest_elevation_DSC9780-1.jpg
 
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So I've got a general question for everyone.
(I'm not going to start my own thread since I hate when people do that and could just ask a question in an existing thread).
My machine is a 5800ELS and I'm going to be updating the turntable. On the mounting arms, where the racquet touches, there's the V-shaped pads. I've seen some arms on different brand machines where instead of a V, it's more of an L-shaped pad, the L part is parallel to the ground. Do you guys think the V or L shaped pads are better?
 
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chrisingrassia said:
So I've got a general question for everyone.
(I'm not going to start my own thread since I hate when people do that and could just ask a question in an existing thread).
My machine is a 5800ELS and I'm going to be updating the turntable. On the mounting arms, where the racquet touches, there's the V-shaped pads. I've seen some arms on different brand machines where instead of a V, it's more of an L-shaped pad, the L part is parallel to the ground. Do you guys think the V or L shaped pads are better?
Click to expand...
Those are V or C supports and K supports. The V / C (as @jim e says) are much better and will eliminate a lot of blocked holes. When you have K supports the frame sits flat on the bottom of the support and the piece going up sometimes has a good chance if blocking holes especially stringing CAP grommets. You can get around the problem if you plan for the problem mounting the racket though.
 
I've not used a K support before but I liked the concept given that the tension head always pulls down on the string. Made sense to have a flat pad at that spot.
 
chrisingrassia said:
I've not used a K support before but I liked the concept given that the tension head always pulls down on the string. Made sense to have a flat pad at that spot.
Click to expand...
No matter what type supports you have with 360 rotation you allways pull down on the string.
 
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