Shaft length should be a function of your wrist to floor measurement. If your current shafts are 1.5 inches longer than standard (there is not really a true standard), then you must be rather tall or have an unusually long wrist to floor measurement.
For the sake of setting the bar, many will consider a standard length 7-iron to be 37″. The shafts of iron clubs above and below that 7 iron can be changed in 1/2″ increments. Most often graphite shafts are cut 1/2″ longer than steel in order to maintain the club’s swing-weight, as graphite shafts are normally much lighter than steel shafts. You could cut the graphite shafts to the same length as steel, but you would need to add weight to the club head to normalize the swing-weight.
While it depends on one’s ball striking ability, generally the longer a shaft the less the average golfer will hit the ball in the center of the clubface, especially on long irons or woods/drivers. Conversely, a longer shaft, on an on center hit, will produce more distance, as the increased shaft length will produce greater club head speed (basic physics).
What set of hybrid club heads are you looking to make into a set? The weight of the individual club heads, as well as the weight of your shafts, will have a significant role in how long the shaft should be. If you do not have that data, an accurate scale, or a swing-weight scale, then you can build a set quite easily, but your clubheads could turn out very inconsistent in their measurements, and that could affect your game.
I would ask you what is your current index (handicap)? If you do not have one, what do you shoot for 18 holes on average? How many yards do you hit your 7-iron and your driver?
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