Park tensiometer... Lubrication reduces readings by 20%

On Mar 24, 10:05 am, "Phil, Non-Squid" <[email hidden]>

Quoted message said:

If you're certain, why not just turn the adjustment screw until your 129
measures 128kgf again?

That's the issue... I don't know which is correct. if the unit comes
unlubricated (seems to be the case with mine at least), and is
calibrated with significant stiction (maybe... maybe not... they don't
calibrate each device) then that would be an ok approach. But if they
calibrate them with stiction that can be easily removed with a little
lube, then I think their method is flawed. Stiction is not something
you want in a tensiometer anyway.

Ron Ruff said:

Basically that is it. I got the idea yesterday to lube (Dupont Teflon
lube) my 4 month old Park gauge yesterday, because I figured "what
could it hurt?". A spoke that previously measured 129kg (2 days ago)
now measures 105kg. A spoke that measured 102kg now measures 80kg.
Both are without tires, in case you were wondering.

Lubrication is probably a good thing, since if there is stiction in
the device that will reduce the consistency of the readings. My
question is... which one is likely to be correct? If they are
"calibrated" to include the stiction, then my readings are too low
now. A ~20% change is *not* small.

If you're certain, why not just turn the adjustment screw until your 129
measures 128kgf again? Check again with the 102 and if it matches then you
should be good. Now you just have to keep it lubed.
--
Phil

Ron Ruff said:

Basically that is it. I got the idea yesterday to lube (Dupont Teflon
lube) my 4 month old Park gauge yesterday, because I figured "what
could it hurt?". A spoke that previously measured 129kg (2 days ago)
now measures 105kg. A spoke that measured 102kg now measures 80kg.
Both are without tires, in case you were wondering.

Lubrication is probably a good thing, since if there is stiction in
the device that will reduce the consistency of the readings. My
question is... which one is likely to be correct? If they are
"calibrated" to include the stiction, then my readings are too low
now. A ~20% change is *not* small.

they're calibrated dry, so they should be used dry. we can all easily
point out that reducing friction is a good thing in theory, but in
reality, this is a $60 device and it's a question of how it was
calibrated. got to be consistent if you want to measure absolutes.
relatives too for that matter.

i say stay dry.

jim beam said:

Ron Ruff said:

Basically that is it. I got the idea yesterday to lube (Dupont Teflon
lube) my 4 month old Park gauge yesterday, because I figured "what
could it hurt?". A spoke that previously measured 129kg (2 days ago)
now measures 105kg. A spoke that measured 102kg now measures 80kg.
Both are without tires, in case you were wondering.

Lubrication is probably a good thing, since if there is stiction in
the device that will reduce the consistency of the readings. My
question is... which one is likely to be correct? If they are
"calibrated" to include the stiction, then my readings are too low
now. A ~20% change is *not* small.

they're calibrated dry, so they should be used dry. we can all easily
point out that reducing friction is a good thing in theory, but in
reality, this is a $60 device and it's a question of how it was
calibrated. got to be consistent if you want to measure absolutes.
relatives too for that matter.

i say stay dry.

How dry? Finger/nipple grease and lube will invariably find its way onto
the meter. Does this mean it needs to be degreased before each use?

--
Phil

It hardly seems that stiction will be so predictable and smooth that it can
be included in the calibration of a measuring instrument. Ever heard of
"slip-stick?" Once the surfaces begin to slide, they come to a new resting
place, and start to build up unreleased force again. At the other extreme
from the tensiometer we have earthquake faults.

On Mar 24, 2:04 pm, "Leo Lichtman" <[email hidden]>

Quoted message said:

It hardly seems that stiction will be so predictable and smooth that it can
be included in the calibration of a measuring instrument.

That's what I was thinking... you'd want stiction to be out of the
picture entirely, or at least reduced to a negligible level. If I can
reduce the readings by 20% by adding a little lube, then it isn't hard
to imagine a little corrosion or dirt adding more than 20% to the
original stiction.

Does everyone elses make a scraping noise as it is opened and closed?
I thought lubrication would get rid of that but it didn't seem to
help. It is coming from the pointer which has two washers (nylon?) on
either side. Oddly, one of the washers actually rubs on the scale...
the scribed marks in the aluminum plate. That doesn't seem like a very
good design. Anyway, the scrapng sounds like metal on metal, but I
don't see any metal on metal contact.

Hang a 100Kg weight off a spoke and you can calibrate it.

"Ron Ruff" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Basically that is it. I got the idea yesterday to lube (Dupont Teflon
lube) my 4 month old Park gauge yesterday, because I figured "what
could it hurt?". A spoke that previously measured 129kg (2 days ago)
now measures 105kg. A spoke that measured 102kg now measures 80kg.
Both are without tires, in case you were wondering.

Lubrication is probably a good thing, since if there is stiction in
the device that will reduce the consistency of the readings. My
question is... which one is likely to be correct? If they are
"calibrated" to include the stiction, then my readings are too low
now. A ~20% change is *not* small.

Ron Ruff said:

good design. Anyway, the scrapng sounds like metal on metal, but I
don't see any metal on metal contact.

Correction... the two metal arms *are* rubbing on each other. That is
the greatest source of noise.

Ron Ruff said:

Ron Ruff said:

good design. Anyway, the scrapng sounds like metal on metal, but I
don't see any metal on metal contact.

Correction... the two metal arms *are* rubbing on each other. That is
the greatest source of noise.

There is no rubbing between the two metal arms on my TM-1. The only
points of contact between the black arm and the blue arm are along the
tension "scale", isolated plastic washers, and the the pivot point
itself (on the pivot pin). But no rubbing contact.

Perhaps your example is damaged in some way?

Nick Payne said:

Hang a 100Kg weight off a spoke and you can calibrate it.

"Ron Ruff" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Basically that is it. I got the idea yesterday to lube (Dupont Teflon
lube) my 4 month old Park gauge yesterday, because I figured "what
could it hurt?". A spoke that previously measured 129kg (2 days ago)
now measures 105kg. A spoke that measured 102kg now measures 80kg.
Both are without tires, in case you were wondering.

Lubrication is probably a good thing, since if there is stiction in
the device that will reduce the consistency of the readings. My
question is... which one is likely to be correct? If they are
"calibrated" to include the stiction, then my readings are too low
now. A ~20% change is *not* small.

That's a large person.

--
Phil

Phil said:

jim beam said:

Ron Ruff said:

Basically that is it. I got the idea yesterday to lube (Dupont Teflon
lube) my 4 month old Park gauge yesterday, because I figured "what
could it hurt?". A spoke that previously measured 129kg (2 days ago)
now measures 105kg. A spoke that measured 102kg now measures 80kg.
Both are without tires, in case you were wondering.

Lubrication is probably a good thing, since if there is stiction in
the device that will reduce the consistency of the readings. My
question is... which one is likely to be correct? If they are
"calibrated" to include the stiction, then my readings are too low
now. A ~20% change is *not* small.

they're calibrated dry, so they should be used dry. we can all easily
point out that reducing friction is a good thing in theory, but in
reality, this is a $60 device and it's a question of how it was
calibrated. got to be consistent if you want to measure absolutes.
relatives too for that matter.

i say stay dry.

How dry? Finger/nipple grease and lube will invariably find its way onto
the meter. Does this mean it needs to be degreased before each use?

you're not going to get finger grease into that anvil shoulder easily.
greasy spokes are another matter, but again, i can't imagine why you'd
be using lube that far up a spoke.

just wipe with a clean dry cloth. and the spoke.

Ozark Bicycle said:

There is no rubbing between the two metal arms on my TM-1. The only
points of contact between the black arm and the blue arm are along the
tension "scale", isolated plastic washers, and the the pivot point
itself (on the pivot pin). But no rubbing contact.

Slop in the pivot allows the black arm to contact the blue arm when
the scale is at about 20. It doesn't seem to cause a lot of friction,
though... I think most of that is coming from washers rubbing on the
scale. It's been like this since I bought it. It hasn't been dropped
or anything.

Ron Ruff said:

On Mar 24, 5:46 pm, "Ozark Bicycle"

Quoted message said:

There is no rubbing between the two metal arms on my TM-1. The only
points of contact between the black arm and the blue arm are along the
tension "scale", isolated plastic washers, and the the pivot point
itself (on the pivot pin). But no rubbing contact.

Slop in the pivot allows the black arm to contact the blue arm when
the scale is at about 20.

FWIW, it seems there is more slop in the pivot on your example than on
mine; there is always a visible gap on my example, even if I apply a
bit of pressure to bring the arms 'together'.

Quoted message said:

It doesn't seem to cause a lot of friction,
though... I think most of that is coming from washers rubbing on the
scale. It's been like this since I bought it. It hasn't been dropped
or anything.

hey ron...we have three of these tensiometers at the shop and two
started to creak.....

it was easy...to see that it was coming from the area where the spring
coils around a post.

one of the tensiometers was lubricated with just a hint of tri flow
(it's really runny so no need for a whole drop)..

the other was lubricated with phil's oil which i think was a mistake
as it took it's sweet time to get down to where the coil onctacted the
post....and because of that...a bit more lubricant was used....

now the one that had the tri flow is reading about 10% below and the
one with the phils is reading about 20% below.....

i know this because before doing anything to these two...i checked the
same spoke several times....the reading was dead on with each
tensiometer......

i then checked the tension with the DT Tensio and then compared what
the park ones read AFTER being lubricated against the Tensio
readings.....as you'd guess...the park ones were off....

it's not a bad tensiometer, the park, but i need to call park tomorrow
and see what the deal is.....

Ron Ruff said:

Basically that is it. I got the idea yesterday to lube (Dupont Teflon
lube) my 4 month old Park gauge yesterday, because I figured "what
could it hurt?". A spoke that previously measured 129kg (2 days ago)
now measures 105kg. A spoke that measured 102kg now measures 80kg.
Both are without tires, in case you were wondering.

Lubrication is probably a good thing, since if there is stiction in
the device that will reduce the consistency of the readings. My
question is... which one is likely to be correct? If they are
"calibrated" to include the stiction, then my readings are too low
now. A ~20% change is *not* small.

sal bass said:

i then checked the tension with the DT Tensio and then compared what
the park ones read AFTER being lubricated against the Tensio
readings.....as you'd guess...the park ones were off....

Thanks... that is what I was wondering about. I lubed that pivot area,
as well as the place where the spring arm slides, and also the
pointer. So I guess the gauge was more accurate "dry"... but it still
seems like a bad idea to have a tensiometer with so much stiction.
Plus, the arms on mine are scraping against each other...

Quoted message said:

it's not a bad tensiometer, the park, but i need to call park tomorrow
and see what the deal is.....

Me too. But they'll be surprised to get two calls about this in one
day...

Ozark Bicycle said:

FWIW, it seems there is more slop in the pivot on your example than on
mine; there is always a visible gap on my example, even if I apply a
bit of pressure to bring the arms 'together'.

A little further investigation showed that the bolt that holds the
pivot together was loose... and it automatically loosens when the arms
are closed and opened a couple of times. Hopefully a little loctite
will fix that.

I had to back off the spring adjustment screw a lot (almost all the
way) to get the same readings I was getting before. Park obviously
plans on it having a lot of stiction.

Ron Ruff said:

Ozark Bicycle said:

FWIW, it seems there is more slop in the pivot on your example than on
mine; there is always a visible gap on my example, even if I apply a
bit of pressure to bring the arms 'together'.

A little further investigation showed that the bolt that holds the
pivot together was loose... and it automatically loosens when the arms
are closed and opened a couple of times. Hopefully a little loctite
will fix that.

My example, purchased ~4 years ago, has been opened and closed
thousands of times, yet the pivot has never loosened. I wonder if QC
has gone downhill or if you just got a bad example. Perhaps they
"forgot" the Loctite (?).

Quoted message said:

I had to back off the spring adjustment screw a lot (almost all the
way) to get the same readings I was getting before. Park obviously
plans on it having a lot of stiction.

Earlier, you posted that the arms were rubbing together; if the TM-1
were "calibrated" in that condition at the factory, "a lot of
stiction" is an understatement.

Ozark Bicycle said:

Earlier, you posted that the arms were rubbing together; if the TM-1
were "calibrated" in that condition at the factory, "a lot of
stiction" is an understatement.

The rubbing of the arms doesn't seem to make much difference. Also I'm
measuring aero spokes in the 15-16 range, and contact doesn't occur
until a little after that.

I spoke to Calvin at Park today. He mentioned that some sort of
cleaning solvent might be used to bring the unit back into "spec", but
I replied that I'd rather keep it lubricated. He said they would
calibrate it for free. He agreed that a little locktite on the bolt
would solve the loose pivot problem.

On 25 Mar 2007 22:23:25 -0700, "sal bass" <[email hidden]>

Quoted message said:

now the one that had the tri flow is reading about 10% below and the
one with the phils is reading about 20% below.....

i know this because before doing anything to these two...i checked the
same spoke several times....the reading was dead on with each
tensiometer......

i then checked the tension with the DT Tensio and then compared what
the park ones read AFTER being lubricated against the Tensio
readings.....as you'd guess...the park ones were off....

How did the pre-lube Park readings compare to the DT readings?

Pat

Email address works as is.