Maybe the answer is already somewhere in the forum but I can't find it! In the yonex stringing instructions, they said to start tensionning with the down crosses and finishing with the ones at the top of the head. But my stringer always begin with the center crosses and then do 2 up, 2 down... etc... He says that doing like this, the frame is less stressed. IMHO i would agree with my stringer, but I also can't imagine yonex giving bad instructions.. What do you think about that? Thanks
To each of their own I guess. I learned to string bottom up so I have always done that. Never had any problems.
I actually agree with your stringer but... keep in mind that since you don't have a starting knot to tension against that you're going to lose some tension on both the top and bottom finishing knot. By starting with a starting knot and tensioning bottom to top or top to bottom, you'll only lose tension from one finishing knot.
This "50/50" pattern is more common in tennis, and IME it definitely gives the most even possible stress. As druss says, though, having two tie-offs, rather than a tie-off and tie-on will lead to a bit more tension loss at both ends. Also, SH told us, it does take slightly longer (and requires a bit more prep). If I have a particularly high tension (>30, usually) to do I will just back off a bit for the top five or six crosses; my top two crosses are usually limited to 28, then adding a pound every two crosses until I get to the required tension. I've never (yet) had a frame break.
Most definitely - done properly it puts the racket at no more risk than any other method, and the freshest, tightest string is up near at the top half of the bed (where you want it).
Yes, I have always gone op down. Like you say as you go further down the racket the string can get straggly at high tensions, I can't imagine the results if it was like that at the top, where you hit it more.
When starting the crosses - either from top to bottom or bottom to top - is it acceptable [safe] to tension / pull the first cross against your starting knot or does the first cross need to be clamped. I am not a stringer, but I am keen to learn. I am hoping to buy my first machine very soon.
Yes, you can tension the first cross against the starting knot, but the problem with most electronic tensioners AFAIK is that the tension head is strong enough to break the knot if you tension directly on the first cross. What most stringers do is to pull the first cross by hand then tension the second cross using the tension head and clamp on the second tensioned cross. Note that if you are stringing with a flying clamp, you will also have to tension on the second cross string from the starting knot as you need to clamp on two tensioned strings for the clamp to work.
When I string, most time I do go from the middle, and I try to over come the extra tension loss (for the knots) with 3 extra lbs for the last cross tension.
My practice is to add 10% on the main tie off. String cross 10% higher tension than main. Start tension the 2nd cross from the throat. If the cross is less or equal to the Yonex recommended range, add 10% on top of the cross tension on the last cross before tie off. This is my practice and I find it works well for Klippermate M140 and Wilson Baraido. Why 2nd cross? Because the starting knot usually slip into the grommet if not big enough.