DevotedGolfer.tv

Bob Vokey, Titleist Interview at the PGA Merchandise Show, Orlando, Florida 2012

The Devoted Golfer video editorial team attended the PGA Merchandise show with video gear and a list of interview appointments.  Mark Maness, PGA Class A Pro and Director of instruction at the Golden Bear Golf Center in Carrollton Texas discussed the new wedges with Bob Vokey.  This is a sneak preview of this interview.  It will release soon on devotedgolfer.tv with the other interviews that were recorded at the show.

This is a study of the radial properties of 6 shafts.  It is a supplement to the golf shaft alignment video. I discussed bow vs spine in that video, and mentioned that the two did not necessarily align with each other. But the example used in the video very closely aligned with one of the FLO’s. In this larger study of 6 shafts, there are examples showing more clearly the point that was made in the video.

The charts below show the effectiveness of the Three Point bearing tool, often referred to as a spine tool and a tip weight laser tool in locating the radial stiffness high and low points of a driver shaft.  The tip laser device, often refered to as Flat Line Oscillation FLO or Vertical Oscillation Plane VOP was an effective tool for finding the stiff and weak planes of the shaft.  This can be accomplished by the club maker by FLOing the shaft in a CPM device and noting the CPM of the shaft at each of the two FLO planes.  The stiff and weak planes are easily identified.

The bearing based Spine tool is not a reliable device for identifing the stiff and weak planes of a shaft.

This study was inspried by the writing of my friend, Dave Tutelman.  This link is his article on the subject, http://www.tutelman.com/golf/shafts/allAboutSpines.php

Four properties were measured as follows:

Stiffness

The stiffnes of the shaft as measured every 10 degrees.  The shaft was clamped at the butt end, the tip was deflected 1″, the load cell was set to zero.  The shaft was then deflected 5″.  This method measures the stiffness of the material without any affect from any bowing or curvature in the shaft.  The readings are shown as the blue line.  The readings were smoothed to eliminate measurement ‘noise’.

Vertical Oscilation

A weighted laser tip was attached to the shaft.  The shaft was deflected 3″ and released.  The laser trace was recorded in a 5 second timed exposure.  The shaft was rotated until a stable plane of oscillation was found.  The photo of the trace is shown to the right of the shaft.  The shaft was then turned 90 degrees and the second stable plane was located.  The solid red line shows the stable plane of the shaft closest to the stiff side of the shaft.  The dashed red line, the stable plane that was on the softer side of the shaft.

Bow

Using a three point bending tool the bow of the shaft was located.  This tool is a pair of bearings in a tube.  The shaft is inserted into the ID of the bearings and a third bearing is used to deflect the shaft.  The shaft turns to the bowed side to minimize the stress of the loading force.  The Bow is shown as a Yellow line.

Tip Deflection

The shaft was inserted into a machining chuck which can be rotated.  Two pieces of card stock were bent 90 degrees and set against each side of the tip.  The shaft was rotated.  The cardstock was pushed away from the shaft as the tip moved during the rotation.  The points of maximum deflection to the right and left were noted and indicated by the black line.

I have used a FlightScope 3D doppler radar launch monitor for the last 5 years. This year I upgraded to the X2 model when it releases. The electronics have been upgraded. The accuracy improved and the unit is easier to setup. I discuss many of the changes with David Nel, technical support guru for FlightScope.

Golf Shaft Flexural Rigidity – EI Profiling

Young’s modulus is a measure of the stiffness of an elastic material.  It is often used to determine the strength of a beam.  Shaft stiffness varies along the length of the shaft.  Using Young’s modulus, the ratio of stress to strain, a shaft can be measured at different points along its length.  This has come to be known as shaft profiling.  When the values are expressed per Young’s modulus, this is called EI Profiling.  Other databases, using different methods to measure stiffness, are also used for the same purpose.  A fitter uses knowledge of the flexural profile of shafts to quickly find a shaft that fits a golfers swing. (more…)

Shaft alignment has been debated by club makers for a long time.  A esoteric language evolved with terms like type 1, 2 & 3, N1, N2, NBP.  My experience and my understanding of the 8 page article, http://www.tutelman.com/golf/shafts/allAboutSpines.php written by my friend, Dave Tutelman is the basis of this video.  There is a lot of misinformation about shaft spines.  Most of which is a based on so called spine finders.  These three point deflection devices show an apparent tendency of a shaft to snap to a particular plane.  This video show exactly what they measure and goes on to truly measure the radial profile of a shaft.

The tour vans are at PGA events on Monday and leave on Wednesday afternoon.  This year at the HP Byron Nelson Championship in Dallas, I went to some of the tour vans with Leith Anderson, owner of California Golf Technology in Palo Alto Califronia and a professional cameraman.  We got to spend time with Barry Lyda, a tour fitter for Callaway and had a great discussion about Callaway products, players and Barry’s experiences during the 20 some years he has been on tour.