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drop shot
03-15-2004, 10:07 PM
I have been looking at some of the lower end Laserfiber machines lately and they look pretty solid. Can anyone who has one shed some light as to the difference in their drop weight system compared to something like Gammas drop weights? Also Gaines and Steve Huff what are your opinions on the Laserfiber?

bcaz
03-15-2004, 10:59 PM
This is interesting. I have an MS200TT and I'm very happy with it. LaserFibre claims, and many other attest to the fact, that they have the only constant-pull drop-weight machines. I'm not an engineer. I talked to a stringer tonight and he woofed that it's just bogus marketing and that electronics (he was stringing on a Gamma w/electronic head at the time) were the only true constant-pull machines. I happen to believe the LaserFibre/Stringway claims, but I'd like to hear more.

Engineers out there (I know you're out there), speak up! FWIW, I'm getting good, consistent results with my stringing machine.

hangzhou
03-15-2004, 11:19 PM
As I mentioned before, according to laserfibre machines' mechanism, the pull force should be constant no matter where the arm resides. It should only be a function of drop weight location on the arm and not a function of arm angle. There might be small deviation if the string is not clamped correctly, or angle is way too big.

bcaz
03-15-2004, 11:35 PM
Thanks, Hangzhou -- can you explain how or why?

David Pavlich
03-15-2004, 11:48 PM
Not an engineer, but it would be interesting to place a calibrator on any drop weight and fool around with the drop arm angle to see what, if any, deviation there is.

Ok you drop weight guys. Let's see a scientific study on your machines. It would shed some light on a pervasive topic. I know I'd like to see it.

David

hangzhou
03-15-2004, 11:50 PM
It's tough without using picture. Here is the picture: http://www.stringway.com/dwm.htm (wrong link before, sorry).

For regular drop weight system, left side. F=WH/R=WLcos(A)/R. Assuming L is the distance from weight to center and A is the arm angle. So it will vary until A=90, then the tension will be the reference tension.

For Laserfibre machine, right side picture. F=WH/V=WLcos(A)/(Rcos(B)). Assuming L is the distance from weight to center, A is the arm angle, and B is angle for tension head to vertical reference line. It looks like same as regular drop weight system now. But cos(A)/cos(B) will be constant 1, if the tension head (the string clamping point to center) is perpendicular to the arm (A=B). so F=WL/R, always constant.

Very smart idea inside the mechanism... Make sense?

topspin
03-15-2004, 11:57 PM
A couple of posters here have tested the laserfibre ms200tt to see if the claims are true, so they tested the tension accuracy at almost every possible angle. The result was consistent and precise tensioning at every angle with a slight deviation if the arm is almost maxed out. This is consistent with what hangzou mentioned about the angle being too big.

So that's pretty good and it is true constant pull no matter what some guy who likes electronic stringers says. In fact, his electronic stringer is a lot more likely to lose calibration since the system relies on a series of complicated mechanical parts and software either of which is a lot more prone to failure than the earth's gravitational pull.

hangzhou
03-16-2004, 12:10 PM
Don't have enough time last night, so let me finish this topic up now regarding tension variance.

For regular drap weight machines, the tension will be different for different arm angle A. Let's say the reference tension is 60 lbs, for different arm angle A, you will have:

Angle A: 0 5 10 15 20
Tension: 60 59.77 59.08 57.95 56.38
Diff %: 0% 0.38% 1.5% 3.4% 6.1%

It's almost impossible to get arm angle to 0 all the time, and quite often it will end at more than 10 or 15 degree. So the tension will drop down at least 3% more, i.e. about 2 lbs. Plus other facts, the actual tension will be far less than 5% of reference tension.

More worse is every string will have different tension value if there is no slip on grommets. Take one extreme case, say one main is at 60 for actual tension, and the next main might have tension of 56 lbs if the arm angle is about 20 degree.

For laserfibre machine, the actual tension variance comes from the angle between string to horizon. As the arm angle being too big, that angle will go up and the tension variance will go up nonlinearly. But if the arm angle stays in within 30 to 40 degree, which is quite easy, then the variance is very small to neglect.

Gaines Hillix
03-16-2004, 04:43 PM
I've never owned a Laserfibre machine, so I can't speak from experience, but the feedback on these machines has been 99% positive over a several year period and Stringway has made little improvements over time, so you really can't go wrong with one of these, if you can afford one. Their resale value is excellent also. This is not to say that a machine like an Alpha Revo 4000 or Gamma Prog ST II won't do a good job for the money though.

bcaz
03-16-2004, 10:51 PM
hangzhou:

Thank you very much for your analysis. I have an advanced degree and actually minored in math in college, so I can understand your explanation. My intituition and experience with my own machine led me to the same conclusion, but you provided a solid explanation.

Tennis often draws analytical personalities. All you high school and college students out there, have you read this thread? Do you agree?

hangzhou
03-16-2004, 11:44 PM
Found interesting information over here: http://www.stringforum.net/mforum.php?show=stringway_m50&model=Stringway%20M5 0.

The key information is "Stringway admits to a 1.1lb difference between 20 degrees low and 20 degrees high", which I cann't prove since I don't have the machine yet. :-)

So the difference in theory is 3.82 lbs for regular drop weight and 1.1 lbs for laserfibre machine (6.1% or 1.8%) at 20 degrees of arm angle. If the angle goes down, then laserfibre machine will have much better result than regular drop weight machine.

I don't know the mechanism for crank machines, so I couldn't make decent analysis on them. Anyone has suggestions?

RacquetDoctor
03-17-2004, 04:05 PM
I haven't been posting much lately...but here is my two cents...I owned a ml100 with the stand for a bit over 2 years. Gaines is right on the resale...sold it for %80 of what I paid for it, the buyer got the remainder of the 10 year warranty. With regards to accuracy, the machine is spot on. If you measure the weight distance correctly, you'll have no issues. I looked at the link, and I don't believe it to be accurate. Maybe it is, but personal experience tells me no. I did lots of testing with the machine I had, and at a 30 degree angle, High or Low, the tension was the same. Bottom line, at the price point, I don't believe the machine can be beat.

Mark