|Today’s tip takes a look at bore types and how to trim shafts accordingly.
As you look at a shaft’s trimming instructions and see a trim note that
references bore type, trimming must be adjusted accordingly to maintain
the flex profile of that particular shaft. Remember, if there is no reference
to a trim note related to bore type, do not add to the shaft trimming.
Here’s a look at how to understand shaft trimming and how it is related
to bore type:
Initially we must define what is meant by though bore, blind bore, M1
and M2 related to metal wood tip trimming. A through bore (also spelled
thru-bore) shaft is one that penetrates through the bottom of the club.
You can see the where the shaft exits of the head; or at least ends at
the sole of the club. A blind bore is one in which the shaft bottoms out
1/2″ from the groundline. An M2 bottoms out at 1″; an M1 bottoms
out 1 1/2″ from the groundline.
Our catalog defines all of our models as to bore type. But what if you
are working with a non-Hireko head? How is bore type determined? It’s
really very simple. Take a shaft and measure its length. Let’s say it
measures 45″ for example. Put the shaft in the hosel of the club
into which it will be installed. Measure the length of the club with this
shaft test fitted into it. If it is 45 1/2″, it is a blind bore.
A measurement of 46″ indicates an M2; a measure of 46 1/2″ shows
that the head is an M1. That’s all there is to it. Then simply follow
the trimming instructions found in the catalog for proper shaft trimming.
But what if the measure is not exactly as stated above? Let’s say you
get 46 1/4″. Simply adjust the trimming accordingly. This measure
is between an M1 and M2. You can look at the M1 trimming and then trim
1/4″ less than the instructions specify or you can look at the club
as an M2 and trim 1/4″ more. It’s that easy!
When shafting irons, you can somewhat follow the same rule. The standard
bottom of bore to groundline in irons is 1″. Adjustments can be made
if this measure is different than the 1″ standard. If the measure
is less than 1″, you will trim less off the shaft; equal to how much
less than 1″ the measure is. If the measure is more than 1″,
you will trim that much more from the shaft than the trimming instructions
Hopefully this tip will help to clarify tip trimming measurements. Remember,
any time that you have questions, feel free to call us at 800-367-8912
or 800-321-4833 or check us out on the Forums at www.hirekogolf.com; we’ll
be happy to be of help!
by Jeff Summitt
Hireko Technical Director