DAVE: You're right, torque is insignificant at impact with a driver, but interestingly it can be a little more with a big heavy putterhead and a very soft tip shaft, but generally only if you have a heel shafted 400-500g putter head which thus puts the CG well away from the shaft centerline. Interesting contrast there by the way between a driver and a belly/long putter. Driver = very light head compared to the belly/long putter, yet much higher downswing speed vs the putter. The only place that torque really plays a part with the possible dispersion result with the driver is on the downswing, ie if you have a torsionally flexible shaft with a very fast and forceful downswing, the CG of the driver being well away from the shaft centerline can cause the head to twist before impact. But on the putter, this won't happen because the downswing speed is so much less than with the driver, even if the shaft is torsionally flexible. Then at impact as you stated the ball is gone from the driver too fast and what we have all seen on freeze frames from high speed cameras is twisty/ripply shaft movement that happens AFTER the ball is gone. But on a 400-500g putter head, if the head is heel shafted AND the putter shaft is very tip/torsionally flexible at the same time, you really can get a little bit of flex/torque response movement of the head such that it can contribute to some tiny bit of off-line result. And remember too that the driver has a little more advantage in this from it horizontal face bulge as opposed to the putter faces being dead flat. But anyway this is one other little reason for making long/belly putter heads with the shaft bore close to the center (CG). In that case you can pretty much scratch off any effect of the shaft contributing to the off-line result of the putt, and then restrict the effect of the too flexible long putter shaft to a matter of feel - ie the golfer either likes or hates that flippy feel at the bottom of the stroke. Most hate it so best to make the long putter shafts more tip half stiff.
Tom W -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Dave Tutelman Sent: Saturday, December 21, 2002 9:10 AM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: RE: ShopTalk: belly putter At 08:49 AM 12/21/02 -0700, tom wishon wrote: >Having just designed some individually special shafts for both long and >belly putters... Torque would only be a problem if the tip stiffness were >also too flexible for a couple of reasons first, many of the belly or long >putter styles have the shaft bore fairly close to the center of the >blade. Therefore, a reasonably on-center contact with the putter face >would not elicit much of any impact generate torque response in the shaft. Tom, Maybe I'm confused, but I don't see this as a factor in any event, even with a heel-shafted putter. Here's my reasoning: * The ball is in contact with the clubface for less than a millisecond. * For that short a duration, any impact-related twist is resisted almost exclusively by the moment of inertia of the head. The shaft torque is so small compared to inertial forces that it doesn't come into play at all. I know both points above are true for a full swing. Why would they not be true for a putter as well? Cheers! DaveT
