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Anonymous
05-18-2004, 03:21 PM
What are the True Constant Pull machines?
Silent Partner DG and what else?

David Pavlich
05-19-2004, 12:16 PM
There's a bunch of them out there. You mentioned the DG and I have the Aria. Several of our posters converted their crank machines to CP electronics by purchasing a Wise tension head, which seems to be giving our fellow posters great service. The Wise head also leaves open the option of putting the lockout mechanism back on if something were to go wrong or the electricity went out.

Babolat Sensor, Sensor Expert, Star III, Star IV, several Technifibres, Prince 3000 and of course the good ole' drop weight machines and before Drak puts a knot on my head, the Laserfibre MS200DX.

Lotsa' stuff out there.

David

mr. stevo
05-20-2004, 12:10 AM
What are the True Constant Pull machines?
Silent Partner DG and what else?

so what's the difference between constant pull and TRUE constant pull? or are you refering to the same thing? i am confused. :?

Anonymous
05-20-2004, 03:53 AM
From what i understand....
constant pull pulls the string to the set tension
true constant pull pulls the string to the set tension then some more to compensate for string stretching. So in other words constant pull pulls the string and holds it leading to some loss in tension. True constant pull pulls the string and keeps pulling it so it is the tension you want.
DId i confuse you even more?

rich s
05-20-2004, 04:00 AM
you are confusing lock-out with constant pull.

constant pull is constant pull is constant pull... there is no "true" constant pull.

crank machines are lock-out.

all drop weights are constant pull and the microprocessor controlled electronic machines SP Aria, Babolat Star, etc are constant pull.

constant pull machines apply a continuous constant tension on the string whereas on lockouts the tension head trips at the desired tension but it does not continue to pull on the string so you will have a slight tension loss.

abllee2198
05-20-2004, 08:00 AM
You either are or your not. There are no degrees of constant pull, some are just better at it than others.

So to say it another way, if you're not lock out, then you must be constant pull or you string with an awl and dowel.

If you're pregnant, you could be locked out. Now everyone's confused. Hahahaha,

Have a great week guys this is so much fun!

A. Lee

Rabbit
05-20-2004, 08:59 AM
As I understand it, drop weights are not true constant pulls because they, like lockouts, don't maintain the same tension. A drop weight's tension is only accurate (LaserFibre excepted) if the arm is perfectly level. Therefore, if the string stretches and the arm goes past level, which it will, then tension is not accurate.

It really all boils down to what you get used to. I strung on a Tremont for the longest time and it was really a subpar machine. But, I got used to the string jobs.

I then got a drop weight which was a step up because it produced more consistent results than the Tremont. The dropweight I had was a table top Gamma. The dropweight that I used produced a consistent string job, but the string job overall felt softer than what I now use. I've been told that the reference tension is lower on drop weights, but I don't know how one would go about verifying that. The main problem I have with drop weights (or at least mine) was the clamps. If you buy a drop weight, make sure that you get fixed clamps. Flying clamps are terrible. To work, they have to have two strings, which means that some movement is inevitable. IMO, you lose more tension with bad clamps than anything else.

About 5 years ago, I moved up to a Prince Neos. It produces even more consistent results than anything I've ever used or has been used to string one of my frames. The argument about lock outs like the Neos holding a tension constant and the string elongating or stretching really don't hold water with me. I don't leave the string at tension for more than 5 seconds. If a string can elongate in 5 seconds, then so be it, but I have a hard time believing that it makes that much difference. The Neos also has one of the best set of clamps and mounting system around. The thing is built like a tank. If anything, I probably overbought my stringing machine.

Tension is a number, and that's all it is. What you're really concerned about is results. When I strung with my dropweight, I strung my rackets at 65 pounds as marked on the tension arm. When I moved to the Neos, my tension went down to 58 pounds to produce the same feel, with the same string.

What you're really concerned about is the result. Any quality machine will produce good results. How much does a quality machine cost? IMO, don't cut corners. If you do, you'll be disappointed.

I can personally vouch for the Prince Neos as a great machine. I have read/heard nothing but good things about LaserFibre machines as well. They claim to have a dropweight that doesn't have to have the arm level to maintain tension. Given that, it may be the best deal for the money. It also depends on what kind of stringing you're going to be doing. If you're stringing for yourself, then you can use a machine that doesn't have a lot of speed inherent in its design. But, if you're stringing for money, your best bet is a quality lock out machine since they are faster, and more consistent than drop weights. A buddy of mine who owns a proshop here locally has looked at Babolat machines and just can't justify the expense. I don't know enough about the higher end machines to make a judgement myself, but for most folks, a quality lock out machine will last a lifetime.

rich s
05-20-2004, 10:23 AM
Take a look at this thread:

http://tt.tennis-warehouse.com/viewtopic.php?t=6471&highlight=

If you set your reference tension to 60lb and you are off by 10 degrees (above or below horizontal) you are still pulling 59lb of tension. See the table below.


Degrees From Horizontal.....Percent of Reference Tension.....Resulting Tension (60 lb Ref)
1.............................................99.9 8%...................................59.99
2.............................................99.9 4%...................................59.96
3.............................................99.8 6%...................................59.92
4.............................................99.7 6%...................................59.85
5.............................................99.6 2%...................................59.77
6.............................................99.4 5%...................................59.67
7.............................................99.2 5%...................................59.55
8.............................................99.0 3%...................................59.42
9.............................................98.7 7%...................................59.26
10...........................................98.48 %...................................59.09
11...........................................98.16 %...................................58.90
12...........................................97.81 %...................................58.69
13...........................................97.44 %...................................58.46
14...........................................97.03 %...................................58.22
15...........................................96.59 %...................................57.96

A dropweight is about as true as a constant pull machine as exists. you don't need electricity, you don't need and fancy electronics

you will be accurate to +/- 1 lb of reference tension with the arm being off as much as +/- 10 deg from horizontal.

10 degrees equates to the arm being off horizontal by 3 inches up or 3 inches down assuming the arm is about 18" long.

!Tym
05-20-2004, 06:04 PM
Totally agree. The myth that dropweights aren't true constant pull unless they're a Laserfibre is true, but only to a degree that does not really warrant much of a discussion.

A plain Jane dropweight is accurate enough. To be honest, a pound here or there either way is truly inconsequential, remember the USRSA study which exposed just how truly UN-sensitive we are to string tension when given a "blind" test?

The real problem I've always had with dropweights is not that their tension is "wildly" inconsistent as is the myth, it's that they're nowhere as easy to use or as fast to use as the Laserfibre dropweight. I'm sorry but twisting a ratchet gets OLD fast, and if you string a lot can lead to blisters.

The main advantage of the Laserfibre is that the dropweight is always resting in a convenient "ready" position, and all it requires is that you slightly lift the dropweight up and insert the string. THAT is the ingenius part of it. The slight gain in accuracy is nice, but surely will not turn you into can't miss machine like Michael Chang on the court. Get real.

That said, as long as you're not stringing much and mostly just for yourself, a non Laserfibre dropweight is a great idea...but ONLY if you can get one with prosumer quality clamps and mounting a la the higher scale crank machines.

This is where dropweights skimp and you lose. Flying clamps, in particular, are the bane of all existence in terms of losing tension in my experience. You'll never get a truly tight string job with them, unless you bump the reference tension ridiculously high. As I recall, it seemed like I needed 10 or so pounds more tension to match the results of a constant pull machine with nice fixed clamps.

And after a certain, the point the fixed clamps just did not really seem capable of holding a higher tension.

This is ok, if you don't mind a softer string job; but I wouldn't recommend it if you're stringing for others.

David Pavlich
05-20-2004, 08:04 PM
Rabbit: As an experiment, set up your calibrator and set your tension head for 60 lbs. Crank it over and watch the calibrator for 5 seconds. It will move back ever so slightly. It's just a fact of life with a lockout machine. I did it with my Gamma and the result speaks for itself.

Having said that, the Neos is an excellent machine. I would be willing to be that more racquets have been strung on a Neos than any other single machine.

It's the operator that makes the stringbed consistent. Sure, the type of stringing machine makes life easier, but if the operator does things correctly and does it time after time, the finished product will be fine. You can string with a Sensor Expert and if you don't follow the proper procedure, the racquet will be strung incorrectly. Pretty simple.

David

Swan Song
05-21-2004, 08:24 AM
Hey, don't forget about the other Babolat series like the 2000, 3000?, 4000, 5000, and some of the early ones. The ones that I have mentioned are the ones with the rising head except the early ones. Obviously, no one can forget about Star III, and Star IV. Kudos to Dave for not forgetting to put down Star III, IV, and the Sensor series.

Koz
11-01-2006, 05:03 PM
I must say this is a very informational thread! That's why I'm bringing it back from the dead. I found the data posted by rich s very useful! I was actually able to put the stuff I'm learning in college (mechanical engineering) to use, and came up with the same values posted above.

That being said, I thought it might be interesting to add that with a ratcheting/cam style dropweight tensioner, after string elongation, you can adjust the lever arm to a MAXIMUM of 5 degrees off of horizontal*** without having to remove the string from the tensioner. In other words, on every pull, you should be able to get the lever arm horizontal, or up to 5 degrees off; and as shown above, even at 5 degrees, you're still for all intensive purposes, at the reference tension (99.6%!)


And like !Tym said, at that point, it's more or less up to your clamps. I bet it's much more likely for your clamps to slip or drawback and cause a bigger discrepency between actual and reference tension than your (ratcheting dropweight) tensioner would cause.

***note, this is based off of my personal Gamma ratcheting tensioner, which has 36 'clicks' in one revolution. Assuming uniform spacing inbetween the ratchet 'teeth', that's 10 degrees between teeth ('clicks'). If your arm ends up 10 to 6 degrees under horizontal, give it a click , now it's 0 to 4 degrees above horizontal. (3 degrees below horizontal gives same tension as 3 degrees above horizontal, etc). If your arm ends up 5 to 0 degrees below horizontal, might as well just leave it there, as at worst (5 degrees off), you're looking at a tension that's 99.6% of your reference tension. So if you were stringing at 100lbs, it would actually be 99.6lbs; and at a reference tension of 60, you'll get the number rich s posted, 59.77 lbs. Not too shabby!

kchau
11-01-2006, 05:33 PM
where do i get a laserfibre machine? and how much does the tabletop model cost? (with fixed clamps)

varuscelli
11-01-2006, 05:40 PM
where do i get a laserfibre machine? and how much does the tabletop model cost? (with fixed clamps)

There has been a TON of stuff written on LaserFibre machines in the last couple of weeks (on quality and availability). You might want to go over a few of those threads and read some of what's been posted.

But you could start with their site:

http://www.laserfibre.com/home.html

kchau
11-01-2006, 05:52 PM
There has been a TON of stuff written on LaserFibre machines in the last couple of weeks (on quality and availability). You might want to go over a few of those threads and read some of what's been posted.

But you could start with their site:

http://www.laserfibre.com/home.html

i found it, and they are quite expensive, very convienent though, essentially a babolat star tensioner without power :D

Steve Huff
11-01-2006, 08:33 PM
Rabbit, lockout machines are really nice machines, especially the Ektelon/Prince line. The Neos is actually their first machine not built in the US. But, the area I see a main advantage in constant pull is this. A constant pull (correctly calibrated) will yield about a 10% tighter stringbed than a lockout (correctly calibrated). While the number is purely arbitrary, for those people that string at very tight tensions, a constant pull machine puts less stress on the racket. Ex. if you play best with a racket that has an RDC stringbed stiffness of say 59, you might need to set a lockout machine at 66# to achieve that stringbed stiffness, but only 59# to get that same number on a constant pull machine. Studies done by the USRSA have shown that constant pull machines yield approx. 10% tighter stringbeds due to the continued pulling for a few seconds after the string is pulled at the set tension. So, where the CP machine pulls a steady 59# on the frame, the LO must pull a quick 66# and then allow the string to settle in at 59. So, if you're stringing a lot of rackets in the upper end of their tension range, I'd say you could apply less stress on the frame using the CP.

Rabbit
11-07-2006, 04:21 AM
Interesting stuff.

rod_b
11-07-2006, 06:20 AM
A question about tension loss when not pulling at a zero degree horizontal position...

Why is this only true for horizontal? I've seen many rackets where the mains change direction through the throat at great angles. Many times while pulling crosses, there is no straight line pull between far side hole, the near side hole and the tension head. Just wondering...

andrew_b
11-07-2006, 07:06 AM
A question about tension loss when not pulling at a zero degree horizontal position...

Why is this only true for horizontal? I've seen many rackets where the mains change direction through the throat at great angles. Many times while pulling crosses, there is no straight line pull between far side hole, the near side hole and the tension head. Just wondering...
I think they're talking about the weight arm being horizontal, not the string. The difference in tension is because the drop-weight machines are calibrated that the weight is pulling at the reference tension when the arm is level.

play well,
Andrew