Machine comparison

[Pleiades]

Several months ago, there was a thread that was attempting to compare hobby machines to the top line electronics. There were assertions that the hobby machines could produce near equal results with the top machines. I made a statement that said that there's a difference and it's measurable. I was challenged to produce figures. Well, I finally had some time to do just that. However, I didn't use hobby machines. I stacked my Sensor against my other 2 machines; another electronic and a crank type. Both are top notch having seen duty in a pro shop/specialty shop atmosphere. I did the test using my machines because I know how well cared for they are. No worry about calibration, dirty clamps, dirty tension head jaws, etc., etc.

I used a POG OS and strung it with Prince syngut/duraflex 17 gauge. Pretty much standard stuff. I used a simple one piece box pattern. I pulled the frame off of the machine the instant I tied off the last cross. Didn't mess with any string straightening. All was done to promote consistency.

The readings were done with an ERT300 and here's the results: The Sensor reading was 44. The electronic challenger was 42 and the crank machine was 40...as I expected. Again, these machines have all been in a high volume operation, so they are considered very good for their type. Why don't I name them? Good question. It makes no difference to the results, so I don't want the makers of the machines think I'm product bashing. I know people that work for both companies,so it's best left that way.

Yea, but you didn't string with a hobby machine. What for?! If machines with GOOD clamps, GOOD tensioning mechanisms and GOOD frame supports can't match the Sensor, why even bother with a hobby machine?

And for those of you with hobby machines, this is not bashing you or your machine. I'm making the point that there are reasons why you see Sensors/Star 5s/Technifibre machines in the stringing cabins of the top tournaments.

Take the test results with whatever grain of salt you wish. I know what I found to be true. I knew it before, but now there's numbers to go with it.

 

[gjoc]

I used a POG OS and strung it with Prince syngut/duraflex 17 gauge. Pretty much standard stuff. I used a simple one piece box pattern.

What reference tension did you use?

Any pre-stretch, manual or machine?

Pre-knot tension bumps, or no?

By “no worry about calibration,” did you mean that you didn’t worry whether or not they were calibrated, or that you weren’t worried because you knew that they were calibrated?

I would think that in a test like that, to try and draw those kinds of conclusions, the first thing that you would absolutely have to do, in order for the results to have any validity whatsoever, would be to confirm what tension was actually being pulled.

 

[Pleiades]

What reference tension did you use?

Any pre-stretch, manual or machine?

Pre-knot tension bumps, or no?

By “no worry about calibration,” did you mean that you didn’t worry whether or not they were calibrated, or that you weren’t worried because you knew that they were calibrated?

I would think that in a test like that, to try and draw those kinds of conclusions, the first thing that you would absolutely have to do, in order for the results to have any validity whatsoever, would be to confirm what tension was actually being pulled.

Sorry. 60lbs reference tension. I wasn't concerned with calibration, cleanliness, etc because they are my machines and are meticulously cared for. 8 lbs overtension on the tie-offs. No prestrectch.

Like I said, take the results however you like. I knew what the outcome would be from past experience. Like it or not, hobby machines are no match for top electronics.

 

[wally]

So here's a quation for you-----

Many of cannot afford or our business volumes do not justify a Sensor/Star 5/Technifibre stringer.

Some of us have taken higher end crank stringers and added an electronic tension head. How do you think this would stand up in a comparison with your Sensor????

I do agree from personal experience with the diference between the straight crank and my setup mentioned above. The crank at the same tension seems to be "softer" VS the constant pull electronic.

 

[barry]

So the point is none of your machines produced the desired 60 pound tension. How do you know which one of your machines is correct?

Seems to me 60 pounds tension should be independent of what machine it is pulled on. Are you saying a Klippermate 60 pounds is different than a Star 5? Since the crank machine measured 40, maybe you should add 4 to it to match the Star machine.

I think the ERT300 is a relative measure of tension, not much different than the spring based Gamma unit we have all used for years.

 

[SW Stringer]

Several months ago, there was a thread that was attempting to compare hobby machines to the top line electronics. There were assertions that the hobby machines could produce near equal results with the top machines. I made a statement that said that there's a difference and it's measurable. I was challenged to produce figures. Well, I finally had some time to do just that. However, I didn't use hobby machines. I stacked my Sensor against my other 2 machines; another electronic and a crank type. Both are top notch having seen duty in a pro shop/specialty shop atmosphere. I did the test using my machines because I know how well cared for they are. No worry about calibration, dirty clamps, dirty tension head jaws, etc., etc.

I used a POG OS and strung it with Prince syngut/duraflex 17 gauge. Pretty much standard stuff. I used a simple one piece box pattern. I pulled the frame off of the machine the instant I tied off the last cross. Didn't mess with any string straightening. All was done to promote consistency.

The readings were done with an ERT300 and here's the results: The Sensor reading was 44. The electronic challenger was 42 and the crank machine was 40...as I expected. Again, these machines have all been in a high volume operation, so they are considered very good for their type. Why don't I name them? Good question. It makes no difference to the results, so I don't want the makers of the machines think I'm product bashing. I know people that work for both companies,so it's best left that way.

Yea, but you didn't string with a hobby machine. What for?! If machines with GOOD clamps, GOOD tensioning mechanisms and GOOD frame supports can't match the Sensor, why even bother with a hobby machine?

And for those of you with hobby machines, this is not bashing you or your machine. I'm making the point that there are reasons why you see Sensors/Star 5s/Technifibre machines in the stringing cabins of the top tournaments.

Take the test results with whatever grain of salt you wish. I know what I found to be true. I knew it before, but now there's numbers to go with it.

Pleiades, thanks for posting the beginning of your experiment, or let's say test 1 of the experiment. Of course what you should know as well as anyone is that consistency is the name of the game. That's getting the same results day in, and day out, with whatever machine you have. So after having run test 2 through 10 on each machine with the same racquet, string, ref tension, barometric pressure, temperature, humidity, etc you should have enough data to run a statistical analysis. The machine that produces the smallest standard deviation (of DT values) is the best machine. I look forward to your results. Thanks again.

 

[volusiano]

At the minimum, you should have calibrated all 3 machines with a digital fish scale or something to confirm that they all pull at the exact same tension before you start, and you didn't do that. So your data is no good.

Especially if you're quoting only 5% deviation in ERT300 data between the Sensor and the electronic challenger, then you should have been a stickler to making sure that you start out with the same reference point for all 3 machines on this most important parameter. The fact that they're all in good working condition doesn't mean that they pull exactly the same tension, unless you calibrate them yourself with the same scale.

It's common to expect crank machines which don't provide true constant pull to under perform the electronic machines that do have true constant pull. 10% off on DT reading between the Sensor and the crank is not that bad. That's why string manufacturers recommend a 5-10% tension drop on constant pull machines if you want to match the stringbed stiffness with what you're used to on a crank machine. There's no surprise there.

I don't think people with crank machines claim that they're better than electronic machines. They only claim that they can produce a consistent string job like the electronic machines. So if you string twice with a crank machines and you get a reading of 40 DT both times, then that's a consistent string job. If you want to get a DT reading of 44 like what the Sensor gives, then just up the tension on the crank to make up for it until you get 44 DT.

 

[Nuke]

The readings were done with an ERT300 and here's the results: The Sensor reading was 44. The electronic challenger was 42 and the crank machine was 40.

Pleiades, I'm a hobby stringer, so forgive me if I'm naive here, but does the higher tension immediately after stringing absolutely indicate that the machine does a better job? I don't doubt that it's a superior machine, but couldn't you just increase the tension settings on the "lesser" machines to compensate, and then arrive at the exact same final tension on all three machines?

 

[abllee2198]

DT differences among calibrated machines.

I've also noticed DT differences when using the same type string at same tension in the same frame.

The differences you observe are due in part to (1) differences in peak pulled tension in each machine, to (2) differences in frame support among machines, and to (3) clamp drawback.

Some machines will slow before reaching reference and creep up to and hold reference others will overshoot reference resulting in a very short prestretch, then correct and hold at reference.

You need a special calibrater to measure peak pulled tension. I use a Japanese Shimpo calibrator which measures normal and peak pulled tensions.

The other differences are from rigidity of frame support and clamp drawback.

Point is, calibration is just part of the answer to differences among all machines.

A..Lee

 

[gjoc]

Sorry. 60lbs reference tension. I wasn't concerned with calibration, cleanliness, etc because they are my machines and are meticulously cared for. 8 lbs overtension on the tie-offs. No prestrectch.

Like I said, take the results however you like. I knew what the outcome would be from past experience. Like it or not, hobby machines are no match for top electronics.

Well, I still think you should have started each stringing by measuring the actual tension being pulled, but interesting info nonetheless--thanks for posting your results.

One thing though--can you confirm it was the OS (107) that you were stringing, not the mid (93)?

If it was 60 lbs, a DT of 44 is oddly high for the OS, but right on the money for the mid.

 

[Pleiades]

My machines are calibrated electonically. All were checked prior to the test. No, I'm not going to do additional tests...don't have the time. Yes, the machines pull 60lbs when set at 60lbs. The difference is more in the clamps and the mount than anything else. The Sensor has a massive turntable that is extremely rigid and with the clamp bases updated, IMHO, these are the best clamps in the industry.

Look, I knew the results would come out the way they did before I did the test. And the tests would continue to come out the same way. I know Albert's reputation. He touches on some very good information. And you'll notice he also mentions the clamps.

And as far as matching the Sensor by upping the tension, you can do that, but how will the clamps and the base react to the extra tension? Will there be more drawback? Will the turntable flex more?

Again, and for the last time, this little test was not done to bash machines. How many times have you read that it's the person running the controls, not the machine? Well, if the person running the controls on a Sensor or Star 5 also runs the controls on a lesser machine, the string job from the Babolat machine is going to be better.

And I'll say this for the last time; there's a reason why the stringing cabins of the top tournaments have top line electronics.

And with that, I bid you adieu.

 

[Steve Huff]

Albert Lee and Pleiades are correct. Some of you seem to be over emphasizing 1 point (the tensioning mechanism) in what makes a machine better. If all pull at an actual 60#, the one who's stringbed is nearest the reference (and actual tension pulled) has done a better job. If you have to increase the reference (actual) tension to increase tension, then you are compensating for 1 of the weaknesses in the machine (perhaps clamps, mounting system, etc). By increasing tension, you add more stress to the frame. People seem to miss this point when comparing crank machines to constant pull machines too. Constant pull machines average about a 10% tighter stringbed, not because they pull 10% more, but because they don't lose as much tension when the sting is clamped. A crank pulls, stops immediately, the string continues to relax, and you get a certain stringbed stiffness. The constant pull pulls, and keeps pulling as the string is relaxing, still never pulls more than the reference tension, and ends up tighter as it has taken up slack as the string relaxed--not because it pulled 10% more.

 

[volusiano]

I agree with all the points Steve Huff, Albert Lee and Plieades said. I'm not trying to defend crank machines. I don't even own a crank. I have a LaserFibre MS200DX, which is true constant pull.

So I understand fully what Steve Huff said about the crank's drawback because it stops pulling and lets the string relax. I also agree that increasing tension on the crank to make up for this weakness does not make the crank adequately comparable to the more expensive machines.

I also don't think anyone is arguing that electronic machines like the Sensor are not superior than crank machines. Most likely, it probably has superior mounting and clamp and tensioning systems due to its high end price. You get what you pay for.

What I would contend with, however, is using the DT reading as a yard stick to prove the superiority of one machine over another. I own an ERT300 myself, and I've tracked and taken many different readings over many different strings and string jobs over many different rackets that I own. To me, all the DT reading means is the end result of the desired stringbed stiffness. You can arrive at the desired DT many different ways, one of which is just to increase the tension.

I'm not sure by saying that the Babolat Sensor gives a DT reading of 44 while another electronic machine gives a DT reading of 42 and finally the crank gives a DT reading of 40 proves that the Sensor is the best machine. Instead, the knowledge that a machine with a better design and better clamp and mount and tensioning system like the Sensor is proof that it's the superior machine. But not its DT reading of 44.

 

[SW Stringer]

Exscusez moi your majesties! It is proper etiquette when serving tripe to the commoners to apply liberal amounts of grey poupon, thus making the dish of Franco-merde that much more palatable. That secret refrigerated compartment in the back of all Babolat machines is yet another reason why they are clearly superior - why it keeps your poupon fresh and ready to use. I too must bid adieu since I must retire to the throne room to refill empty grey poupon jars,as you see, zee orders, zey just keep coming in!

 

[gjoc]

I'm not sure by saying that the Babolat Sensor gives a DT reading of 44 while another electronic machine gives a DT reading of 42 and finally the crank gives a DT reading of 40 proves that the Sensor is the best machine. Instead, the knowledge that a machine with a better design and better clamp and mount and tensioning system like the Sensor is proof that it's the superior machine. But not its DT reading of 44.

To me, his DT readings of 44 and 40 for the Sensor and the crank, respectively, only proves that those two machines are actually equal in all respects except for the tension head, since his measured offset is exactly the 10% one would expect to see between the two types of tensioners (constant-pull and lockout) on the same machine.