Don’t use lead tape!
That will increase the weight and lower the frequency. Use Aluminium foil, or
a piece of white electricians tape.
Another thing that is
very important is to make sure the clamped end stays still. A small vice that
is not securely bolted to a solid bench, that shakes as the club is twanged,
will also reduce the frequency. It effectively is saying the shaft is not
clamped at the point it enters the clamp, but “back a bit”, where a “bit”
depends on how close to motionless the vice is. Note that mounting it on
a lightweight table that also shakes, will lower the readings
too.
Bruce
-----Original
Message-----
From:
[EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Royce Engler
Sent: Wednesday, February 05, 2003 9:50
PM
To:
[EMAIL PROTECTED]
Subject: RE: ShopTalk: Frequency meters
and deflection boards
I've had
a Brunswick freq analyzer for several years...one of the early things I
learned was the effect of clamping on frequency. When I bought it, I
also bought a calibration shaft, and it turns out that what you actually do to
calibrate the machine is change the clamping location. Sooooo as
it turns out, the correct clamp length for my **system** (and I'll elaborate
on that a little more in a minute) turns out to be about
4".
I
mentioned the clamping "system"....here's what that includes: The base
of the machine has a v shaped slot that the grip is clamped into (you have to
measure shafts with grips on them...I have a whole drawer full of split
grips). The shaft is clamped by a plate with one end resting on the
base, and the other has a v-shaped slot that matches the one on the
base. The clamping force is applied by a screw type mechanism with a
slip arrangement that allows the handle to slip when it reaches a certain
torque (I have no idea what that quantity is, but the instructions say to turn
it until you get three clicks. This is similar to the clamp knobs on the
Golfsmith FA.
One day
I noticed that the clamp arrangement was squeaking, and like any good
engineer, I took it apart and greased it. Lo and behold, suddenly my
frequencies jumped. I "recalibrated" and found that I needed to shorten
the clamping length to get the same frequency. What had happened was
that by lubricating the clamp, I enabled it to get tighter before the torque
limiters started slipping, thus the clamp pressure had increased, resulting in
an increase in measured frequency.
Enter
the PCS Equalizer...The way the Equalizer works is that it measures a shaft
against an arbitrary standard and assigns a frequency to it. You then
measure the frequency of that shaft in your machine, and compare the measured
frequency with the standard frequency to get a conversion factor. That
conversion factor then generates a set of curves similar to the FM precision
curves, but calibrated to your freq analyzer, clamping system, and
all. Soooo.....
The
bottom line is that if I wanted to, I could make a shaft read in a wide range
of frequencies, all of which would be correct for the configuration of
clamping length, pressure, and grip. The key is to get a good comparison
standard and try to be as consistent as possible in how you clamp the
shaft.
Having
said that, I do notice that sometimes the electronics get fooled by a dark
colored shaft. I noticed that sometimes a black graphite shaft would
read quite a bit lower than others. What I figured out was that the
electric eye that counts the times the shaft goes by it couldn't always "see"
the shaft and missed counts, which leads to a lower indicated frequency.
Solution is to keep some strips of lead tape handy and wrap the shaft where it
is in the path of the sensor. Also helps to have a good strong light
behind you pointing toward the sensor. Steel shafts reflect light
better, so they don't seem to suffer from the problem.
Sorry
for the long note, but hopefully it is useful to
someone.
-----Original
Message-----
From:
[EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
[EMAIL PROTECTED]
Sent: Tuesday, February 04, 2003 11:13
PM
To:
[EMAIL PROTECTED]
Subject: Re: ShopTalk: Frequency meters
and deflection boards
Dave
You are correct. That was a very good test. It opened my
eyes. The clamping mechanism is more important than the electronic side
because it is where all the variable seems to lie. The electronics are
pretty well governed by design and components used while the clamping
mechanism as well as the bench and its stability are where most of the
deviations seem to lie between machines. I for one liked your home made unit
because yours broke the CPMs down to less than one. I would like to have one
that breaks it down to tenths which I think is overkill but that is just me.
Charlie B
