How I fit for heft
I have found a way to fit a golfer for heft across a set. (Normally, it
set of irons, and I'll describe it this way. But, if judiciously done,
the process could be extended across the whole set.) The process here
does not assume that the clubs will be MOI-matched or
swingweight matched; the result may be either -- or neither. But it
will give a good heft fit for that golfer, across the set.
The process applies only to clubs whose major intended use is full
swings. Most golfers use their sand wedge and lob wedge mostly or only
finesse shots around the green, partial swings and punches. Those clubs
need to be heft-fit separately, based on their primary use. You should
not expect them to be an extended match of the rest of the set.
In the description below, I assume a swingweight scale as the "heft
meter" in your shop. But the process works just as well with an MOI
pendulum or MOI spring. In neither case am I assuming that the match
will be an MOI match or a swingweight match; everything just works out
for the best.
- Decide on the clubs that will be included in the match.
this will be full-swing irons, or perhaps include the hybrids if the
shafts are about the same length, weight, and balance as the iron set
likewise for the grips. If
not, see the end of this section for tips on how to deal with it. For
the rest of this discussion, I will assume the set is irons, from the
PW to the 4-iron.
a pair of clubs corresponding to the extremes of the set,
whose components are similar to the target set. In our example set, the
extremes would be the 4i and the PW. (If the target set is already
built, and you are just re-weighting them, that is ideal for testing.)
It is important to have grips on the test clubs similar to the grips
for the target set as well.
- Take those two clubs, the golfer, and a roll of lead tape
measuring site. It is a lot better if it is a real grass site; driving
tend to mask the effect of fat hits, and avoiding fat hits are
definitely part of the iron fitting process.
- Have the golfer hit the shortest club (in this case the
adjust the heft with lead tape on the back of the clubhead or around
the hosel. Adjust until the fit is best. For irons, I do
about maximizing distance. My indication of a good fit is
reliability: the most consistency in distance and direction, and the
fewest percentage of bad hits. (If your test subject is a good golfer,
that will probably be his/her figure of merit as well. If you can't
convince the golfer not to obsess over maximum distance, the process
still works with distance as the figure of merit.)
you have the right lead tape on the shortest club, leave it
there and repeat step #4 for the longest club (in this case the
4-iron). You may want to switch back and forth between the clubs a few
times, to make sure that hitting each club does not reduce the
reliability of the other club. Golfers have some "swing memory", and
on-the-course performance has to avoid single-club swing memory.
- Take the two clubs back to the shop, with the ideal lead
still on them. Measure the swingweight (or MOI, if that is your
instrument of choice).
- Take a piece of graph paper, and make a plot like the one
the values you measured! The graph below is for my measurements.
red dots are the fitted clubs' measured
length and heft (swingweight or MOI). Draw a straight line
red dots. Now locate the other clubs on the line, according to their
lengths; for instance, the 5-iron in this set will be 38.5", so put the
blue 5i dot where the curve meets the 38.5" gridline.
- The graph now gives the fitted swingweight of each club in
set. A few things to note, so you can understand the full flexibility
of this process:
When I build the set, I match them without grips. They build to about
10 swingweight points higher than the gripped clubs, and they match one
another better when done. If I have the opportunity to measure the
red-dot clubs (the extremes that I measured) without the grips, then
those measurements go on the graph.
- If your instrument measures MOI instead of swingweight,
plot is in MOI and the graph gives the fitted MOI of each club in the
- The curve shown happens to be an MOI-matched set, and it
be MOI-matched if you build to those swingweights. (How do I know?
Because the swingweight
slope is 1.3
points per inch.)
- If the 4i and PW had been fitted to the same swingweight,
the line would be horizontal and the golfer would be properly fitted to
a swingweight match.
- Finally, remember this is your
slope! If you (or this golfer) fits something other than a
swingweight or MOI
match, the process will discover the fact and give the proper match.
The process assumes that the shafts and the grips are similar in weight
balance across all the clubs being matched. If this is not the case,
you need to alter the process in a rather complicated way -- more
complicated than I am willing to do myself. For instance, if the irons
have 85g shafts, the fairway woods 80g shafts, and the driver a 65g
shaft, I would use this process to match the irons and fairways, but
fit the driver separately.
Now we know how to estimate heft before the fact, and measure it
after the fact. But a clubmaker is often faced with an important
aspect: altering the MOI or swingweight when a design that's good for
other purposes -- particularly length -- gives the wrong heft.
Let's say you have picked the components you need,
is just wrong. You can't go to a heavier/lighter shaft or clubhead; the
reason might be as simple as you're starting with an already completed
(or store-bought) club. What do you do to increase or decrease the
From the definition of swingweight, we can increase it by adding weight
14" from the butt or subtracting weight less than 14" from the butt. Let
me strongly recommend against the latter; any swingweight
achieved near the butt is bogus, and is not reflected in a
heavier-swinging club. There may be other uses
for butt weight
for some golfers, but swingweight adjustment is not one of them.
If you're considering heft in terms of MOI, you won't suffer any such
confusion; weight at the butt has no effect.
So we'll have to add weight to increase the heft. In
to minimize the total weight gain for a particular swingweight or MOI
add it as far as we can from the pivot, at the clubhead. How do we do
Whether we're adding weight in a port, in the shaft tip, or taping it
the clubhead, we should bear in mind the amount of material we'll need
to apply. Consider the table below:
- The best way is inside the clubhead, if that's physically
woods and metalwoods either have weight ports or at least have room for
you to make one. A few irons also have them (including some models from
Golfsmith and most from Tom Wishon). If your
club has a weight port, you can increase the swingweight with lead or
powder, or shot) and epoxy or "mouse glue" to hold it in place.
If your wood doesn't have a weight port, you can make one.
of making a weight port is slightly different for woods and metalwoods.
With woods, you just have to remove the soleplate and you can do the
woodworking to hollow out an area and fill it with lead and epoxy. Then
replace the soleplate. (Check a repair book for the ins and outs of
and replacing soleplates.)
With metalwoods, drill
a hole in the
bottom of the hosel (or just remove the hosel plug if it's removable).
Put a "paste" of lead or tungsten powder mixed with epoxy or mouse glue
into the hole.
Then replace the hosel plug. A couple of details:
can use just the "Part A" of two-part epoxy. That way,
there is no working-time problem. The "paste" stays sticky and viscous
forever, so the fact that it isn't a hardened bond shouldn't hurt. The
down side is that, left in a car trunk or garage, the past might flow
to the lowest point. The up side is that it won't ever break loose and
rattle, as a cured epoxy might.
- When you drill the hole, use a 1/4" bit. The hole will
enough to leave a shoulder to seat the shaft, yet big enough to fit a
plastic drinking straw -- my preferred tool to insert the weighted
- If you have to make a new hosel plug, you can do so by
it out of plastic -- like the polyethylene top of a coffee can. My tool
of choice for the punch is the sharpened tip of a steel shaft of the
right diameter. Sharpen it with your 20° coning countersink. Then
use a [not sharpened] shaft tip to seat the plastic disc in the hosel.
- If your clubhead doesn't have a weight port and you can't
one, add the weight with lead tape on the clubhead itself.
the best place to put the tape is somewhere that doesn't greatly affect
the placement of the CG of the head. Note that this implies adding tape
on two diametrically opposite sides of the clubhead, with the CG on the
line connecting them. If you can do this at the heel and toe of the
you'll also be increasing the peripheral weighting, thus making the
But, in truth, the position of the tape won't make too
The tape will seldom be as much as 10 grams, so neither the moment of
nor the CG can be much affected by it. (It takes a lot of tape to get
10 grams; the tape I use is a half-gram per inch, and that's pretty
I have heard a number of people complain that they don't
because it's "ugly". The best I can do here is to point out relevant
- "Beauty is as beauty does." (William Shakespeare, poet.)
- "Form follows function." (Louis Sullivan, architect.)
- "When you hit the ball, you'll forget what it looks
(John Solheim of Karsten Golf,
describing his incredibly ugly Ping Zing.)
- Some still are convinced by the "ugly" argument, and
at the tip of the shaft inside the hosel. There are two ways of
This is okay, as long as you
don't add too much weight there. Weight at the shaft tip will move the
CG of the clubhead (and thus the "sweet spot" of the club) upward and
the heel. This is undesirable, but the move is negligible as long as
don't put more than about 10 grams there.
- Ready-made tip weights, that are epoxied into the shaft
when the shaft is installed in the head. These are available in lead,
brass, and tungsten.
- Heavy powder (lead or tungsten) added down the shaft of
already-assembled club, and secured near the tip with a cork. (Of
course, you'll have to remove the grip to add the powder and cork.)
A more serious problem with this approach is the danger of
the shaft tip. This could result from:
These failure modes are much more common in graphite shafts than steel.
As Murphy's law would predict, shaft-tip weights for graphite shafts
thicker flanges and are longer, leading to more shaft vulnerability. So
- The flange on the bottom of ready-made shaft-tip
forces the shaft
to "bottom out" short of the bottom of the bore. That means there is
supported tip in the hosel. Most weight designs limit this to about
but some steal more bore from the shaft. "Short-shafting" is the most
cause of graphite shaft breakage.
- The second leading cause of graphite shaft failure is
epoxy "plug" inside
the shaft, that rises to or above the top of the hosel. If you epoxy
weight in place inside the shaft, it becomes such a plug. So get a
that isn't a tight fit inside the shaft, and don't epoxy it to the
but rather inside the hosel, or just epoxy the flange to the tip of the
you are using powder and a cork instead of epoxying in a tip weight,
the cork or column of compressed powder may have the same effect as an
- I have seen some advocate drilling holes in the stainless
clubhead, and filling the holes with lead. I don't mean a weight port
the inside of a hollow clubhead, but rather a replacement of stainless
steel with lead.
This is pretty ineffective, because the gains of
trivial. Stainless steel weighs 8 grams per cc, and lead 11 grams per
That means that for every cc replaced, you gain only 3 grams (a little
over one swingweight point). Just for reference purposes, a 1cc hole is
made by a 3/8" drill bit 1/2" deep. That's pretty severe surgery for
iron heads, and you only get three extra grams out of it.
|50-50 Solder (Pb,Sn)
|Wood's metal (Pb,Bi)
While epoxying is a technology familiar to every clubmaker, we
automatically be scared off by the thought of melting lead. It's easier
than you think, and gives a much higher-density weight. You can melt it
with your shaft-removal torch, and drip it into a mold of
some sort -- or directly into the cavity, if possible. Solder, which is
still heavier than a lead/epoxy paste, can be easily melted with an
electric soldering iron.
It is probably worth noting that lead, absorbed repeatedly over long
periods of time, is toxic. If you weight clubs with lead powder or by
melting lead once or twice a year, this is no big deal. But, if you are
a professional clubmaker who does this all the time, you need to treat
lead as a hazardous material.
From the definition, we decrease swingweight by subtracting weight more
than 14" from the butt or adding weight less than 14" from the butt. As
noted above, swingweight modification at the butt, while it does affect
both the calculated and measured swingweight, does nothing for the
of the club in any constructive way. It doesn't affect the MOI -- the
real, physics-based measure of heft -- nor does it show any effect in
computer simulations. Heavy grips and butt weights affect the
swingweight, but not the underlying heft factors.
There may be other
uses for butt weight
for some golfers, but swingweight adjustment is not one of them.
So the only ways to decrease heft usefully are to reduce the
shaft weight or length, or the clubhead weight. Consider:
- Shaft weight is controllable, at some expense. Lightweight
shafts offer a way to reduce swingweight. Weights range from the
weight steel shafts, at 120-130 grams, to lightweight graphite, at
grams. There are even super-light shafts in the 50-gram range. That's a
range of over ten swingweight points. But as the weight goes
down the price goes up, especially if you want to keep torque constant.
Moreover, it takes about three times the weight savings in the shaft to
equal the swingweight impact of saving weight in the clubhead.
- Clubhead weight is a lot harder to control. The total
of head weights is less than
10 grams, or five swingweight points, and the vast majority
of component heads lie in a 3-gram range. (That's a 5-iron between 253
and 256 grams, and the rest of the irons on a 7-gram interval.)
One way of reducing head weight is grinding it off. I've
a grinding cylinder in a Dremel Moto-Tool, removing as much as 7 grams
of steel. The best way is to remove material from the inner wall of the
cavity-back, since the cavity walls are not structurally important. But
have plenty of abrasive disks handy; you'll wear them out fast on the
hard stainless steel used in most golf clubs. And don't try this trick
on forged clubs, unless you're going to have them re-chromed
length can be reduced but, as we saw in the previous
if a shorter club and a more upright lie can be tolerated. For every
degree of lie that
shaft is more upright, it can be a half inch shorter or three
points lighter. Of course, you will still need to make sure the new,
shorter length is still appropriate to the golfer. Then you must do a
dynamic lie test
to fine-tune the lie. After all, changing the length and lie changes
the swing plane, so it may change the swing enough to knock off the
OK, so you've decided what length club you need to build.
From a completely different set of considerations,
what swingweight it needs to be. (We'll use swingweight for this
example, because it's a little harder than MOI.)
All that remains now is to choose a compatible set
from the catalog and build the clubs. Right? Well, maybe. Let's look at
a challenging example of design to a simultaneous specification of
I'll focus on the case of long clubs, because that's
most frequently found a challenge in designing to both the right length
and swingweight. Consider the problem of designing a set of irons for
son, who is very tall and requires clubs 1.5" over a nominal men's set.
However, I don't want to give him anything that swings heavy. From
experience, I know he does best with a D-1 or so.
We'll work the problem for a 5-iron; I advise
starting with a
middle iron, because the solution that works for that club usually can
be applied equally well to the longer and shorter irons. (This
isn't as applicable when working with woods because most bags don't
a lot of them, and the driver is frequently designed quite differently
from the others.)
|Start with a "standard" sort of
(say an Acer)
|True Temper Dynamic
for men's 5I
|Gives a swingweight
of . . . . .
No surprise that "standard" components will give a "standard"
But, when we add 1.5 inches to the length, the
to D-9. (Check with the sensitivity tables; 6 swingweight points per
times 1.5 inches is 9 points.) To get to D-1, we have to do things to
by about 8 points. Let's look at the different ways we could
This is the first approach that comes to mind, because weight at the
is a very strong determinant of swingweight. (If we were trying to
swingweight instead of decreasing it, adding weight to the clubhead is the
time-honored way of doing it.)
Unfortunately, there isn't too much available in this
Golfsmith heads are down to 253 grams for the
5-iron, but I know nothing on the market any lighter.
Looking at the swingweight tables for cross-sensitivity, we
saving 3 grams of head weight saves 2 swingweight points. We'd be down
to D-7. Let's do it!
We've saved all we can at the
saving a gram really buys
something. It takes 10 grams in the shaft to save a swingweight point.
We're trying to get from D-7 to D-1, so we will need to save 60 grams.
That means we need a 68-gram shaft (60 grams less than the "standard"
128g from the table).
Can we find shafts that
irons? Well, they will be graphite, not steel, at that weight. And
looking in the catalogs, we find they are
available. But shafts
that light tend to have a flex
profile and torquethat
are better suited to slower-swinging seniors and women, not a
tall, strong athlete. An iron shaft that would fit my son for the other
shaft specs (other than weight) will be 10-15 grams heavier, in the
78-83g range -- and there are a lot of choices there. So let's get
something in that range, and resign ourselves to needing to still find
an extra swingweight point or a bit more. (This was originally written
in the 1990s. By 2013, it is not all that hard to find a decent
graphite shaft for irons at or under 70g. They cost a little more, but
you're still way ahead compared with brand name off-the-shelf clubs.)
It should be noted here
that, while most steel
shafts have a centered balance point, almost all graphite shafts have a
balance point 3/4" to 1.5" higher than the middle of the shaft. That
will reduce the swingweight further. For instance, raising the balance
point by 1" on an 80g gram shaft will reduce the effective moment of
the shaft by 80 gram-inches. Remembering that 50 gram-inches is one
swingweight point, we may have achieved our target swingweight already.
In fact, we probably want
to try the club out
in this configuration. In many cases, a slightly higher swingweight
than the one that gives optimum golf shots with give good golf shots --
and more more reliably. (That's experience more than theory.)
But suppose our testing
shows that we really
need to reduce the clubs by another point plus...
We can't save any more swingweight by reducing weight, but maybe we can
reduce the length. Yeah, I know we said 1.5" long but....
A lot of tall players learned their swing before they got a
of clubs built for their height. Those that did tend to have a rather
swing plane. That means we already should have been thinking about an
lie for them, but now we have additional motive. Remember that each
of lie is worth 1/2".
Let's try it! We only need to reduce the club's swingweight by 1-1.5
points, which means reducing the length about 1/4 inch. That is only a
half degree more upright. We know we are going to measure and set the
lie angle dynamically after the clubs are finished. If a half degree
error on the lie angle matters to you, then you can count on having to
bend some of the clubs to match the golfer anyway. So the swing plane
change due to 1/4" of length reduction is probably not going to change
the amount of bending to get the clubs' lie angles right.
A more important consideration is whether the shorter, more upright
club is good for the golfer. You can only find that out by having him
hit balls. The choices at this point are:
Frankly, the latter will usually be better in the long term, but only
trying it out can tell which to do. In fact, both designs are very
close at that point -- much closer than you'll ever
be able to
fit this golfer with off-the-rack clubs.
- The clubs are good at the target swingweight and 1/4"
than designed, with lie adjusted for the slightly more upright swing
- Go with the target length and one swingweight point heavy.
may sound foolish and even
patronizing to say that. When I wrote it, I felt like McDonalds lawyers
must have felt after the lawsuit. "OK, let's print in large letters on
all our coffee cups, 'HOT! DO NOT POUR IN YOUR LAP!'" But I actually
got email from someone who went through the measurements.... then used
my graph instead of making his own based on his [very different]
modified June 30, 2017