Some stringers only pull every second string and believe there are no losses from doing so. This myth persists quite stubbornly. So, I set up a small test. As a ‘reference,’ I always strung with 9 kg, once with constant pull and once with 15% prestretch.
Constant Pull means: The string is always pulled at 9 kg. If the string yields, the machine automatically readjusts to maintain that tension.
Prestretch means: The string is briefly pulled with more than 9 kg (in this case, with 15% more, so 10.4 kg), then released to 9 kg, and then continuously pulled at 9 kg, just like with Constant Pull.
Overview of the test:
| Constant Pull | Loss | Prestretch | Loss | |
|---|---|---|---|---|
| Single pull on mains | 8,92 kg | 0,9% | x | x |
| Double pull on mains | 7,54 kg | 16,2 % | 8,68 kg | 3,6 % |
| Single pull on crosses | 8,40 kg | 6,7 % | 9,02 kg | 0 % |
| Double pull on crosses | 4,60 kg | 48,9 % | 5,68 kg | 36,9 % |
Control test:
During the control test, the string was pulled with 9 kg. Due to a little deflection (the string has a small angle in the direction) the 9 kg are not quite reached. However, the 80 grams are negligible and if the string yields, it is automatically readjusted.
Double Pull on Mains with Constant Pull:
Attempted to pull two strings with constant pull on the mains. Pulled with 9 kg constant pull, 7.54 kg was measured on the other side.
Double Pull on Mains with Pre-stretch:
Attempted to pull two strings with pre-stretch on the mains. Pulled 9 kg with pre-stretch (15% -> 10.4 kg), and 8.68 kg was measured on the other side.
Single Pull on Crosses with Constant Pull:
An attempt was made to tension one string with constant pull on the cross strings. With constant pull, 9 kg was pulled, and 8.40 kg was measured on the other side.
Single Pull on Crosses with Pre-stretch:
An attempt was made to tension one string with pre-stretch on the cross strings. With pre-stretch (15% -> 10.4 kg), 9 kg was pulled, and 9.02 kg was measured on the other side.
Double Pull on Crosses with Constant Pull:
An attempt was made to tension two strings with constant pull on the cross strings. With constant pull, 9 kg was pulled, and 4.60 kg was measured on the other string.
Double Pull on Cross Strings with Pre-stretch:
Attempting a double pull on two cross strings with prestretch. With prestretch (15% → 10.4 kg), 9 kg was pulled, and 5.68 kg was measured on the other side.
