is anybody aware of tests being done on the differences of stress being put on strings by different machine techniques of putting tension
on the string?

my hypothesis is that a constant pull will put a lot more stress on the string then a crank, can anybody verify this?

the whole idea of "tension" is the stress on the string.

I believe that a drop-weight gets a better resulting tension maintenance than a crank by allowing more of the weaker bonds to break under continued stress. You can see this on a constant pull system.

The crank on the other hand locks out immediately at the desired tension and many bonds are still breaking after the lock so there is considerably more initial tension loss.

I haven't personally tested this, but it seems logical-

From a theoretical point of view I do not see a significant difference between the systems if ! the same SBS is to be achieved.
Drop wheight and electronic constant pull will pull tension and both will compensate for the first seconds tension loss (stretch) in the string by keeping tension up. DW will compensate almos liear analog and electroic in little steps dwith step size depoending on complexity of the particular machine.
The crank will have to pull higher initial tension to get the same SBS as it will not compensate for initial tension loss unless you crank extremely slowly. How much higher is debatable many estimate with 10%. The string only sees tension applied within a certain time. As the crank would have to apply higher tension quickly I see almost more probability that it is harsher on the string compared to the constant pull systems.

I'll chime in my thoughts too.  I'm working under the assumption that you ultimately want the same string bed feel from the constant pull machine and the lock out machine.  If that's the case, we can pretty much forget about reference tension.  I'm also talking about electric constant pull machines and not drop weights since I haven't used a drop weight in about 25 years, so my area of knowledge doesn't cover them.

I tend to think that the constant pull machine will not be more stressful to the string.  In fact, I think in a lot of cases it will be less stressful.  My reasoning for this is that a lot of people on lock out machines really pull the lever on the crank machines very very quickly for speed's sake.  I think this "fast pull" can put more strain on a string than  the more smooth pull of a constant pull machine. Also, many constant pull machines have diablo barrels which can help lessen pressure to the strings in the tension head string grippers.  I'm not aware of many lockout machines that utilize a diablo barrel.

As for the effect of the constant pull of the tension head prior to clamping off, I think its pretty minimal as compared to the lockout machine.  Even though the lockout machine is no longer pulling once it achieves the desired tension, its still maintaining the tension on the string, that will be resulting in the same string bed feel.

I'm no scientist, so maybe I'm wrong though.  Would like to hear from others about this.

martin wrote on Nov 6^th, 2010, 12:47pm:

The diablo allows the string to enter the tension jaws at the same angulation each time, and also takes away some of the tension on the string as it enters the tension clamps so it is gentler on the string. Also with some softer strings like nat. gut, if you need to pull a string for a second time for any reason, you can wrap the string around a second time, so a different string section will be in the tension jaws at the same place.It makes it easier on the string.

Your 1st statement above, does not make sense unless the neos you are referring to has an electronic unit on it like a Wise, as the neos were lock outs not constant pulls like you stated.

Hi Albert, another little known benefit of the diablo is when stringing with poly/aramid fibre that has a very low amount of stretch. This can cause some electronic machines to fail to release the string from the jaws after a pull as there is not enough slack. Wrapping the poly around the diablo an extra one or two times creates more stretch throughout the added length and allows the tensioned string to be released. I LOVE diablos! Liam
Nothing to do with this post .. freezing to death in a cold corridor at a $42.5 challenger in Loughborough, first racket in this morning was a BADMINTON  racket for one of the staff, 22lbs and using the diablo of course my lovely new Gamma 5800 Els. Here with Jackie Vaughan and her Star 4 and she says "Hi" to everyone.

concerning neos, i meant to write crank (certainly not constant pull)

thanks for info on diablo, very interesting

i am prediciting eventual "retro" flashback where some very trendy hipsters want there raq's strung on crank