How to Match Shafts - 2

Dave Tutelman -- December 16, 2005

Use of the Spreadsheet

If you have Excel on your computer and have not downloaded the spreadsheet yet, here is another link to it:

matching.xls

Protect it!

One of the first things you should do is make the spreadsheet file read-only. This will protect it from things you might do that would damage it, like writing data into a formula cell. If you do that and the file is written over, then the damage will be done to your permanent copy. But if the file on the disk is read-only, then you can't overwrite it -- not even by accident. You can simply close what you have done without saving it, and open the undamaged spreadsheet again.

Rulers, units, and the spreadsheet

The basic spreadsheet gives estimated tip trim in decimal inches, like 1.65 inches. Your ruler probably doesn't present measurements that way. Most of the rulers you buy in a US store will have inches to some power-of-two fraction (usually sixteenths). It may also have a millimeter scale on it. There are three ways you could deal with it:

Learn to live with it.
Change the spreadsheet to give sixteenths of an inch.
Change the spreadsheet to give millimeters.

Actually, all three are practical. Here's how to do each.

Live with it

This is what I have been doing up to the time of this writing. I just know from memory the decimal equivalents of eighths of an inch, and I interpolate from there. For instance, I know offhand that .625" is 5/8 of an inch. So, if the spreadsheet tells me to start at 1.65 inches, I know that's just a tiny shade over 1-5/8".

Below is a table for reference purposes.

Decimal	`.125`	`.25`	`.375`	`.50`	`.625`	`.75`	`.875`
Fraction	`1/8`	`1/4`	`3/8`	`1/2`	`5/8`	`3/4`	`7/8`

You undoubtedly already know the quarters and halves off the top of your head. As a clubmaker, you probably already know that 3/8" = .375", because you ream iron hosels to that diameter. You also probably know that 5/8" = .625", because it's just slightly larger than the butt of most shafts. So there's only two more numbers you would have to memorize. But, if you have to memorize more than three numbers you didn't know already, this approach is the wrong one for you.

Sixteenths

You can change the spreadsheet to read in sixteenths of an inch. That matches the ruler you are likely to have. Before you do this, be aware that Excel's fractions capability is not very sophisticated. It will give you just sixteenths. For instance, it will not say 1/4, but rather 4/16. If you want to live with this, here's how to convert the spreadsheet:

Select (highlight) the numeric cells in the "Est Trim" column.
Right-click over the highlighted selection, which will bring up the pop-up menu shown.
Select "Format Cells" from the menu.

Now you should have the Format Cells dialog box on your screen.

Pick the "Number" tab on the Format Cells dialog box.
Select "Fraction" from Category.
Select "As sixteenths" from Type.
Click "OK".

You have changed the output readings to sixteenths of an inch, as shown. Look how the numbers have changed in form but not in value. For instance, the cell that was 2.86 before is now
2 14/16 (which is the same as 2 7/8). If you can read this more easily than decimal, then this is for you. If not, consider the next option: millimeters.

If you change your spreadsheet for sixteenths, you probably ought to save it as matching_16.xls, and protect it by making it read-only. Bring up that protected spreadsheet as your working copy.

Millimeters

It is easy to find rulers that measure in millimeters or centimeters, and you certainly can't estimate the tip trim any closer than a millimeter. If you feel like working in millimeters, the spreadsheet can be made to do that, as follows:

In the lower left corner of the spreadsheet is a light green cell containing the word "inches". It indicates the units of measure for the estimated trim. Change it to "mm" by selecting that entry from the drop-down list.

That will change the units of measure to millimeters for the estimated trim column. For instance, the cell that was 2.86 inches is now 72.57 millimeters. Of course, you will treat it as 72mm.

If you use millimeters for your tip trimming, then you have to remember one other thing. When you extend the tip 2 inches to get the TTS, you won't have an inch ruler there to help. But 2" is almost exactly 50mm, a nice round number. So just extend the tip 50mm.

If you change your spreadsheet for millimeters, you probably ought to save it as matching_mm.xls, and protect it by making it read-only. Bring up that protected spreadsheet as your working copy.

Overwriting a target load

If you have made the disk copy of your spreadsheet "read only", then it is protected from any permanent corruption. So now you can make changes in the working copy that you otherwise shouldn't -- and you can't damage your saved copy. And some of those changes can occasionally be useful. For instance you can treat wedges differently from the other clubs in tip-trim; see the example below.

Before you do any of this, let me remind you again... Be sure to make your saved copy of the spreadsheet read-only to protect it.

Example: Special treatment of wedges

Many people don't like the wedges to continue in the same progression as the other clubs. That is, the other clubs have something like a half-inch per club of tip trim, but you may want less of an interval. For instance, my approach for my own clubs is to make the shafts for all the wedges the same length and flex as my nine-iron.

You can deal with this on the spreadsheet by entering explicit values for the target load. This will override the way the spreadsheet normally works, incrementing the target load for each club. (This overwrites some of the spreadsheet's formulas, which is another reason you should make your copy of the spreadsheet read-only.)

In the example shown, all the wedge target loads have been written in with the same values as the 9-iron. The result is a set of estimated trim recommendations to give that target load with the shafts as chosen.

Matching a set of woods

Matching a set of woods has a number of differences from matching a set of irons, in ways that make it difficult to use the spreadsheet we've already looked at. Here are a few:

You don't have a constant length increment. Unlike irons at a half-inch spacing, woods tend to be more irregular lengths.
You probably aren't using the same model shaft in all clubs.
Since you have chosen specific shaft models for specific clubs, it would be inappropriate to sort them. You already know which shafts go in which clubs.
Since the shafts may be different models, they are likely to have different tip-trim sensitivities.

So the spreadsheet has another page to cover these differences. Select the tab labeled "Woods", and let's look at the changes in how we use the spreadsheet to match woods.

In the example shown, we are going to make a matched set of four woods from three different models of shaft:

A driver using an MCC "Orange Crush" shaft, R-Flex.
A 3-wood using a Mercury Performance, S-Flex. We're using a high-launch shaft for this club, to make sure we can get it up from the fairway.
A 5-wood and 7-wood using the True Temper EI-70... just because the customer really wants it. Note that we assigned these two shafts so the one with the stiffer raw flex goes in the shorter club.

Here are the steps to matching the clubs. They are similar to matching irons, so the descriptions and explanations will be brief:

Enter the descriptions of the clubs in the brown area.
Set the beam length of your NF4. Normally this will be 38" for woods.
For each shaft, measure the raw load with the tip solidly against the tip stop, and enter it in the proper yellow box in the "Raw Load..." column.
While you have each shaft in the NF4, extend the tip 2" and measure the load again. Enter it in the proper yellow box in the "Load with Tip..." column.
Enter a Target Load in the blue column for each club. Here's how I came up with numbers for the design example:

I decided to use a target load increment of 0.2Kg per inch of club length. The reasoning is pretty similar to that for the irons.
I started with 3.50 as the target load for the driver. You will soon know from experience what load corresponds with what performance.
Knowing the length of each club, I multiplied the club-to-club difference in length by the target load increment of 0.2 in order to come up with the target load difference.
For instance, between the driver and 3-wood there is a 2-inch difference in length. 2 inches times 0.2Kg/inch is 0.4Kg. So we have to make the 3-wood 0.4Kg stiffer than the driver -- hence its target load is 3.90.

You can now read the estimated tip trim in inches from the spreadsheet. Note that, if you changed inches to mm on the first page of the spreadsheet, it affects this page as well.
Use the estimated tip trim as you did for the irons. Place the shaft in the NF4 with the tip extended by the estimated tip trim, and check to see that the load is the target load. If it is not, move the shaft and measure again. Repeat until you have the target load.
Mark and trim the shaft.

If you are hand-calculating instead of using the spreadsheet, the formula is basically the same is it was for the irons. But, since you already have two measurements for each shaft, you don't have to explicitly calculate the TTS. Here is the formula:

Trim = 2*(TargetLoad - RawLoad) / (Load2inches - RawLoad)

Here are a few additional things to note about matching woods:

The example has a smooth variation of 0.2Kg per inch for Target Load. But that works only if each of the clubheads has roughly the same distance from the bottom of the bore to the ground. If the clubs differ markedly in this regard, the trim should be adjusted accordingly. That is, the higher the bottom of bore to ground measurement (often referred to as BBGM), the more you should trim the tip to maintain the same overall stiffness.
The Est Trim column has funny entries for the rows where you didn't fill in any shaft data. The spreadsheet was deliberately made with more rows than you are likely to use. Empty rows will cause the calculation to divide by zero, so Excel is complaining. But that does not hurt the answers in the valid rows.

Last modified by DaveT - 12/18/2005