tap dimensions/c-record cranksets (pics tomorrow)....



S

sal bass

Guest
ok...i've got two c-record cranksets.....both in VERY good condition.
less than 100 miles i'd bet.

i've got three sets of taps......park 9/16ths X 20......eldi 9/16ths
X20.....and var 9/16ths X 20.....

i've got two sets of pedals....decent platforms from mks and a set of
shimano pd-m959s......


let me be very clear here and mention that the threads on the spindles
and the cranks are SPOTLESS. there isn't even a hit of grease or grime
or anything on or between the threads.....i'm meticulous when it comes
to cleaning things. wiping is for asses.

so.....i try to thread each pedal into the proper arm. i can turn the
mks and shimano spindles about three whole turns and then it gets
really tight. i'm not one to force things for fear of damaging the
threads.....so i back them out....i try threading them in from the
backside of each arm and they thread in like butter......so i figure
that the first few threads might be damaged....



so...and here's the weird part.......i take the three sets of taps
(each are about a year old but none has seen more than about 10
uses)......




the var first.....on each arm....i can't even get the tap to penetrate
the face of the crank arm.....can't even do that....and if i can't do
that.....i can't get a hold of some threads.....

BUT.....with the vars from the backside of each arm...i can get about
two whole turns....and then....it's like i'm using a tap that's tapered
cause the tap won't budge....again....i'm not forcing anything....




next the eldi.....same thing....can't even get them IN the hole to try
to catch some threads.....

BUT.....from the backside of the arm....same thing...i can get two
whole turns on each.....




last the park.....front the front i was able to get three whole turns
then a lot of friction.....

so i decided to tap the arms from the backside.....a bunch of
effortless turns and at the end...the tap meets some resistance but
passes right through pulling up only a fine bit of aluminum....the bits
were about 1/10th the size of a piece of glitter....really fine....



so i think it's odd that neither the var or the eldi could even get
started from the front...............BUT from the back....i couldn't
get more than two whole turns and then just a harsh hault after those
two whole turns.........


but just to be sure....i tried to pass the else set and the var set
through the front and back of the arms AFTER passing the park
through......

same thing.....i couldn't get EITHER the var or the eldi to get past
the face of the arm.....and from the back side.....not but two hole
turns and i coudl easily feel that the tap would start gouging up
chunks of aluminum from the arm........





so...i thought 9/16ths X 20 was 9/16ths X 20 no matter what tap was
used?

the taps weren't trashed or in poor condition.....neither were the
cranks or the spindles.......

anyone have any idea as to why the eldi and var wouldn't even allow me
more than two whole turns from the backside of the arms (even AFTER
passing the park taps through the arm) and none from the front?


pics will be posted tomorrow.......
 
A

A Muzi

Guest
sal bass wrote:
> ok...i've got two c-record cranksets.....both in VERY good condition.
> less than 100 miles i'd bet.
> i've got three sets of taps......park 9/16ths X 20......eldi 9/16ths
> X20.....and var 9/16ths X 20.....

-snip-
> so.....i try to thread each pedal into the proper arm. i can turn the
> mks and shimano spindles about three whole turns and then it gets
> really tight. i'm not one to force things for fear of damaging the
> threads.....so i back them out....i try threading them in from the
> backside of each arm and they thread in like butter......so i figure
> that the first few threads might be damaged....
> so...and here's the weird part.......i take the three sets of taps
> (each are about a year old but none has seen more than about 10
> uses)......
> the var first.....on each arm....i can't even get the tap to penetrate
> the face of the crank arm.....can't even do that....and if i can't do
> that.....i can't get a hold of some threads.....
> BUT.....with the vars from the backside of each arm...i can get about
> two whole turns....and then....it's like i'm using a tap that's tapered
> cause the tap won't budge....again....i'm not forcing anything....
> next the eldi.....same thing....can't even get them IN the hole to try
> to catch some threads.....
> BUT.....from the backside of the arm....same thing...i can get two
> whole turns on each.....
> last the park.....front the front i was able to get three whole turns
> then a lot of friction.....
>
> so i decided to tap the arms from the backside.....a bunch of
> effortless turns and at the end...the tap meets some resistance but
> passes right through pulling up only a fine bit of aluminum....the bits
> were about 1/10th the size of a piece of glitter....really fine....

-snip-
> same thing.....i couldn't get EITHER the var or the eldi to get past
> the face of the arm.....and from the back side.....not but two hole
> turns and i coudl easily feel that the tap would start gouging up
> chunks of aluminum from the arm........

-snip-

Manufacturing tolerances.
We recently discussed Campagnolo's poor allowance for chrome depth on
the 1037a pedals of the seventies. Their cranks also start out loose at
the beginning of a run and end up tight just before tool change just
like everyone else.

The Eldi taps are generally accepted as the industry standard. Although
we own some Park in 1/2" we're Eldi for pedal taps here and no
complaints. (Campagnolo pedal taps were not included in the small or
the large case, and cost more than even I could justify)

Just curious - if you grab a dead left side crank from the garbage at a
local LBS, does the Eldi tap remove material _after_ the Park tap? (Left
arms fail commonly at the spindle and should be free for the asking)

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
 
Q

Qui si parla Campagnolo

Guest
sal bass wrote:
> ok...i've got two c-record cranksets.....both in VERY good condition.
> less than 100 miles i'd bet.
>
> i've got three sets of taps......park 9/16ths X 20......eldi 9/16ths
> X20.....and var 9/16ths X 20.....
>
> i've got two sets of pedals....decent platforms from mks and a set of
> shimano pd-m959s......
>
>
> let me be very clear here and mention that the threads on the spindles
> and the cranks are SPOTLESS. there isn't even a hit of grease or grime
> or anything on or between the threads.....i'm meticulous when it comes
> to cleaning things. wiping is for asses.
>
> so.....i try to thread each pedal into the proper arm. i can turn the
> mks and shimano spindles about three whole turns and then it gets
> really tight. i'm not one to force things for fear of damaging the
> threads.....so i back them out....i try threading them in from the
> backside of each arm and they thread in like butter......so i figure
> that the first few threads might be damaged....
>
>
>
> so...and here's the weird part.......i take the three sets of taps
> (each are about a year old but none has seen more than about 10
> uses)......
>
>
>
>
> the var first.....on each arm....i can't even get the tap to penetrate
> the face of the crank arm.....can't even do that....and if i can't do
> that.....i can't get a hold of some threads.....
>
> BUT.....with the vars from the backside of each arm...i can get about
> two whole turns....and then....it's like i'm using a tap that's tapered
> cause the tap won't budge....again....i'm not forcing anything....
>
>
>
>
> next the eldi.....same thing....can't even get them IN the hole to try
> to catch some threads.....
>
> BUT.....from the backside of the arm....same thing...i can get two
> whole turns on each.....
>
>
>
>
> last the park.....front the front i was able to get three whole turns
> then a lot of friction.....
>
> so i decided to tap the arms from the backside.....a bunch of
> effortless turns and at the end...the tap meets some resistance but
> passes right through pulling up only a fine bit of aluminum....the bits
> were about 1/10th the size of a piece of glitter....really fine....
>
>
>
> so i think it's odd that neither the var or the eldi could even get
> started from the front...............BUT from the back....i couldn't
> get more than two whole turns and then just a harsh hault after those
> two whole turns.........
>
>
> but just to be sure....i tried to pass the else set and the var set
> through the front and back of the arms AFTER passing the park
> through......
>
> same thing.....i couldn't get EITHER the var or the eldi to get past
> the face of the arm.....and from the back side.....not but two hole
> turns and i coudl easily feel that the tap would start gouging up
> chunks of aluminum from the arm........
>
>
>
>
>
> so...i thought 9/16ths X 20 was 9/16ths X 20 no matter what tap was
> used?
>
> the taps weren't trashed or in poor condition.....neither were the
> cranks or the spindles.......
>
> anyone have any idea as to why the eldi and var wouldn't even allow me
> more than two whole turns from the backside of the arms (even AFTER
> passing the park taps through the arm) and none from the front?
>
>
> pics will be posted tomorrow.......


Nope but what you have seen is common, both in terms of needing to tap
the crank arms for the pedals mentioned and sometimes having to tap
from the back side.
Not unusual at all, the same thing I had to do with both of my C-Record
cranks for SP pedals.
 
S

sal bass

Guest
i figured there were tolerance issues......but even passing the park
straight through the arms...the eldi would not even catch one
thread......so my real question is about the taps.....


the eldi removes a lot of material after the park tap has gone
through.....






A Muzi wrote:
> sal bass wrote:
> > ok...i've got two c-record cranksets.....both in VERY good condition.
> > less than 100 miles i'd bet.
> > i've got three sets of taps......park 9/16ths X 20......eldi 9/16ths
> > X20.....and var 9/16ths X 20.....

> -snip-
> > so.....i try to thread each pedal into the proper arm. i can turn the
> > mks and shimano spindles about three whole turns and then it gets
> > really tight. i'm not one to force things for fear of damaging the
> > threads.....so i back them out....i try threading them in from the
> > backside of each arm and they thread in like butter......so i figure
> > that the first few threads might be damaged....
> > so...and here's the weird part.......i take the three sets of taps
> > (each are about a year old but none has seen more than about 10
> > uses)......
> > the var first.....on each arm....i can't even get the tap to penetrate
> > the face of the crank arm.....can't even do that....and if i can't do
> > that.....i can't get a hold of some threads.....
> > BUT.....with the vars from the backside of each arm...i can get about
> > two whole turns....and then....it's like i'm using a tap that's tapered
> > cause the tap won't budge....again....i'm not forcing anything....
> > next the eldi.....same thing....can't even get them IN the hole to try
> > to catch some threads.....
> > BUT.....from the backside of the arm....same thing...i can get two
> > whole turns on each.....
> > last the park.....front the front i was able to get three whole turns
> > then a lot of friction.....
> >
> > so i decided to tap the arms from the backside.....a bunch of
> > effortless turns and at the end...the tap meets some resistance but
> > passes right through pulling up only a fine bit of aluminum....the bits
> > were about 1/10th the size of a piece of glitter....really fine....

> -snip-
> > same thing.....i couldn't get EITHER the var or the eldi to get past
> > the face of the arm.....and from the back side.....not but two hole
> > turns and i coudl easily feel that the tap would start gouging up
> > chunks of aluminum from the arm........

> -snip-
>
> Manufacturing tolerances.
> We recently discussed Campagnolo's poor allowance for chrome depth on
> the 1037a pedals of the seventies. Their cranks also start out loose at
> the beginning of a run and end up tight just before tool change just
> like everyone else.
>
> The Eldi taps are generally accepted as the industry standard. Although
> we own some Park in 1/2" we're Eldi for pedal taps here and no
> complaints. (Campagnolo pedal taps were not included in the small or
> the large case, and cost more than even I could justify)
>
> Just curious - if you grab a dead left side crank from the garbage at a
> local LBS, does the Eldi tap remove material _after_ the Park tap? (Left
> arms fail commonly at the spindle and should be free for the asking)
>
> --
> Andrew Muzi
> www.yellowjersey.org
> Open every day since 1 April, 1971
 
S

sal bass

Guest
but don;t you think it's odd that after tapping witht eh park...the
eldi would not even start from the front side and only a turn or two
from the back?

the taps are labeled the same.....





Qui si parla Campagnolo wrote:
> sal bass wrote:
> > ok...i've got two c-record cranksets.....both in VERY good condition.
> > less than 100 miles i'd bet.
> >
> > i've got three sets of taps......park 9/16ths X 20......eldi 9/16ths
> > X20.....and var 9/16ths X 20.....
> >
> > i've got two sets of pedals....decent platforms from mks and a set of
> > shimano pd-m959s......
> >
> >
> > let me be very clear here and mention that the threads on the spindles
> > and the cranks are SPOTLESS. there isn't even a hit of grease or grime
> > or anything on or between the threads.....i'm meticulous when it comes
> > to cleaning things. wiping is for asses.
> >
> > so.....i try to thread each pedal into the proper arm. i can turn the
> > mks and shimano spindles about three whole turns and then it gets
> > really tight. i'm not one to force things for fear of damaging the
> > threads.....so i back them out....i try threading them in from the
> > backside of each arm and they thread in like butter......so i figure
> > that the first few threads might be damaged....
> >
> >
> >
> > so...and here's the weird part.......i take the three sets of taps
> > (each are about a year old but none has seen more than about 10
> > uses)......
> >
> >
> >
> >
> > the var first.....on each arm....i can't even get the tap to penetrate
> > the face of the crank arm.....can't even do that....and if i can't do
> > that.....i can't get a hold of some threads.....
> >
> > BUT.....with the vars from the backside of each arm...i can get about
> > two whole turns....and then....it's like i'm using a tap that's tapered
> > cause the tap won't budge....again....i'm not forcing anything....
> >
> >
> >
> >
> > next the eldi.....same thing....can't even get them IN the hole to try
> > to catch some threads.....
> >
> > BUT.....from the backside of the arm....same thing...i can get two
> > whole turns on each.....
> >
> >
> >
> >
> > last the park.....front the front i was able to get three whole turns
> > then a lot of friction.....
> >
> > so i decided to tap the arms from the backside.....a bunch of
> > effortless turns and at the end...the tap meets some resistance but
> > passes right through pulling up only a fine bit of aluminum....the bits
> > were about 1/10th the size of a piece of glitter....really fine....
> >
> >
> >
> > so i think it's odd that neither the var or the eldi could even get
> > started from the front...............BUT from the back....i couldn't
> > get more than two whole turns and then just a harsh hault after those
> > two whole turns.........
> >
> >
> > but just to be sure....i tried to pass the else set and the var set
> > through the front and back of the arms AFTER passing the park
> > through......
> >
> > same thing.....i couldn't get EITHER the var or the eldi to get past
> > the face of the arm.....and from the back side.....not but two hole
> > turns and i coudl easily feel that the tap would start gouging up
> > chunks of aluminum from the arm........
> >
> >
> >
> >
> >
> > so...i thought 9/16ths X 20 was 9/16ths X 20 no matter what tap was
> > used?
> >
> > the taps weren't trashed or in poor condition.....neither were the
> > cranks or the spindles.......
> >
> > anyone have any idea as to why the eldi and var wouldn't even allow me
> > more than two whole turns from the backside of the arms (even AFTER
> > passing the park taps through the arm) and none from the front?
> >
> >
> > pics will be posted tomorrow.......

>
> Nope but what you have seen is common, both in terms of needing to tap
> the crank arms for the pedals mentioned and sometimes having to tap
> from the back side.
> Not unusual at all, the same thing I had to do with both of my C-Record
> cranks for SP pedals.
 
S

sal bass

Guest
here are the pics.........


the taps.....

http://i15.photobucket.com/albums/a386/ipodusersmustdie/misc77001.jpg





the threads BEFORE being tapped......

http://i15.photobucket.com/albums/a386/ipodusersmustdie/misc77007.jpg




park tap from the back...took of little if any material.....

http://i15.photobucket.com/albums/a386/ipodusersmustdie/misc77008.jpg




park tap from the front....after passing the park tap through the
back.....it passed through the front without a problem....

http://i15.photobucket.com/albums/a386/ipodusersmustdie/misc77009.jpg



this is the eldi from the back AFTER the park had been passed
through........about two whole turns on each arm was about all i could
get and i KNEW that if i kept turning it.....i'd feel it pull up lots
of aluminum.....it won't budge from this point.....

http://i15.photobucket.com/albums/a386/ipodusersmustdie/misc77011.jpg





this is the eldi tap from the front AFTER the park tap had been passed
through.......couldn't even get it started.....

http://i15.photobucket.com/albums/a386/ipodusersmustdie/misc77010.jpg
 
A

A Muzi

Guest
>> sal bass wrote:
>>> ok...i've got two c-record cranksets.....both in VERY good condition.
>>> less than 100 miles i'd bet.
>>> i've got three sets of taps......park 9/16ths X 20......eldi 9/16ths
>>> X20.....and var 9/16ths X 20.....
>>> i've got two sets of pedals....decent platforms from mks and a set of
>>> shimano pd-m959s......

-snip-
>>> the var first.....on each arm....i can't even get the tap to penetrate
>>> the face of the crank arm.....can't even do that....and if i can't do
>>> that.....i can't get a hold of some threads.....
>>> BUT.....with the vars from the backside of each arm...i can get about
>>> two whole turns....and then....it's like i'm using a tap that's tapered
>>> cause the tap won't budge....again....i'm not forcing anything....
>>> next the eldi.....same thing....can't even get them IN the hole to try
>>> to catch some threads.....
>>> BUT.....from the backside of the arm....same thing...i can get two
>>> whole turns on each.....
>>> last the park.....front the front i was able to get three whole turns
>>> then a lot of friction.....

-snip-
>>> same thing.....i couldn't get EITHER the var or the eldi to get past
>>> the face of the arm.....and from the back side.....not but two hole
>>> turns and i coudl easily feel that the tap would start gouging up
>>> chunks of aluminum from the arm........
>>> so...i thought 9/16ths X 20 was 9/16ths X 20 no matter what tap was
>>> used?
>>> the taps weren't trashed or in poor condition.....neither were the
>>> cranks or the spindles.......
>>> anyone have any idea as to why the eldi and var wouldn't even allow me
>>> more than two whole turns from the backside of the arms (even AFTER
>>> passing the park taps through the arm) and none from the front?
>>> pics will be posted tomorrow.......


> Qui si parla Campagnolo wrote:
>> Nope but what you have seen is common, both in terms of needing to tap
>> the crank arms for the pedals mentioned and sometimes having to tap
>> from the back side.
>> Not unusual at all, the same thing I had to do with both of my C-Record
>> cranks for SP pedals.



sal bass wrote:
> but don;t you think it's odd that after tapping witht eh park...the
> eldi would not even start from the front side and only a turn or two
> from the back?
>
> the taps are labeled the same.....


As I wrote Eldi are generally accepted as the industry standard.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
 
S

sergio

Guest
sal bass wrote:
> here are the pics.........


Pardon me, and be sure I don't intend to be offensive at all.
Do you lubricate at all?

Sergio
Pisa
 
C

* * Chas

Guest
"sal bass" <[email protected]> wrote in message
news:[email protected]
> ok...i've got two c-record cranksets.....both in VERY good condition.
> less than 100 miles i'd bet.
>
> i've got three sets of taps......park 9/16ths X 20......eldi 9/16ths
> X20.....and var 9/16ths X 20.....
>
> i've got two sets of pedals....decent platforms from mks and a set of
> shimano pd-m959s......
>
> let me be very clear here and mention that the threads on the spindles
> and the cranks are SPOTLESS. there isn't even a hit of grease or grime
> or anything on or between the threads.....i'm meticulous when it comes
> to cleaning things. wiping is for asses.
>
> so.....i try to thread each pedal into the proper arm. i can turn the
> mks and shimano spindles about three whole turns and then it gets
> really tight. i'm not one to force things for fear of damaging the
> threads.....so i back them out....i try threading them in from the
> backside of each arm and they thread in like butter......so i figure
> that the first few threads might be damaged....
>
> so...and here's the weird part.......i take the three sets of taps
> (each are about a year old but none has seen more than about 10
> uses)......
>
> the var first.....on each arm....i can't even get the tap to penetrate
> the face of the crank arm.....can't even do that....and if i can't do
> that.....i can't get a hold of some threads.....
>
> BUT.....with the vars from the backside of each arm...i can get about
> two whole turns....and then....it's like i'm using a tap that's tapered
> cause the tap won't budge....again....i'm not forcing anything....
>
> next the eldi.....same thing....can't even get them IN the hole to try
> to catch some threads.....
>
> BUT.....from the backside of the arm....same thing...i can get two
> whole turns on each.....
>
> last the park.....front the front i was able to get three whole turns
> then a lot of friction.....
>
> so i decided to tap the arms from the backside.....a bunch of
> effortless turns and at the end...the tap meets some resistance but
> passes right through pulling up only a fine bit of aluminum....the bits
> were about 1/10th the size of a piece of glitter....really fine....
>
> so i think it's odd that neither the var or the eldi could even get
> started from the front...............BUT from the back....i couldn't
> get more than two whole turns and then just a harsh hault after those
> two whole turns.........
>
> but just to be sure....i tried to pass the else set and the var set
> through the front and back of the arms AFTER passing the park
> through......
>
> same thing.....i couldn't get EITHER the var or the eldi to get past
> the face of the arm.....and from the back side.....not but two hole
> turns and i coudl easily feel that the tap would start gouging up
> chunks of aluminum from the arm........


> so...i thought 9/16ths X 20 was 9/16ths X 20 no matter what tap was
> used?
>
> the taps weren't trashed or in poor condition.....neither were the
> cranks or the spindles.......
>
> anyone have any idea as to why the eldi and var wouldn't even allow me
> more than two whole turns from the backside of the arms (even AFTER
> passing the park taps through the arm) and none from the front?
>
> pics will be posted tomorrow.......
>


There are size tolerances for most threaded fasteners like nuts, bolts and
machine screws which allow a certain amount of slop for ease of assembly
and disassembly.

Stud type fasteners on the other hand have interference fits that are
designed so that they wont come loose under normal use.

Pedal threads are similar to studs. They are not meant to be frequently
installed or removed.

The nominal size for a standard 9/16-20 H5 tap would be .562 +.002 to
..0025. but there are a lot of other factors involved.

An interference fit would use a tapped hole size .001 to .002 smaller than
nominal, a fastener .001 to .002 larger than nominal or both depending on
design requirements.

This web site explains some of the issues involved with tap sizes without
getting overly technical. Read the part from Tap Size down :

http://www.natool.com/engdata/data10.php

Most of the pedal taps I've seen over the years have been pretty poor
quality when compared to taps used in manufacturing. They are generally
made of carbon steel instead of high speed steel and they are cut taps
rather than precision ground taps. That is the threads are machined into
the taps with another tool rather than being made on a precision tap
grinding machine.

One explanation for why the taps may go into the crank arm from one side
and not the other is something called "thread drunkenness". That's were
the thread pitch is off slightly.

Instead of being 20 TPI (Threads Per Inch) the threads on the tap or in
the part may be 20.5 or 19.5 TPI or something similar. This is caused by a
poorly made tap or worn out tapping equipment.

The threaded fastener may start in easy and get harder to turn the further
it goes in. Also the holes in the cranks may have been tapped from the
backside to begin with so that's why the taps start easier from the back
side.

Another cause could be an "egg shaped" hole. The original tapped hole is
wallowed out near the beginning due to worn out tapping equipment, a dull
tap used during manufacturing or poor Fixturing that allows the part to
move around while being tapped (or all of the above).

The last thing is that the threads on pedals are not very accurate. They
are cut or rolled into the pedal spindles before they're hardened by heat
treatment. During heat treatment, the threads can change a considerable
amount.

I always check the threads on a new set of pedals to make sure that there
aren't any burrs that might damage the crank arms. I've seen top quality
pedals with defective threads but that's something that you don't hear
about very often because the person installing them usually just forces
them into the cranks.

Except for certain components most bicycles are not precision machines.
Crank arms aren't designed for frequent pedal changes. The pedal threads
in aluminum cranks are designed for an interference fit so the pedals
don't loosen and wear out the threads prematurely.

HTH,

Chas.
 
C

* * Chas

Guest
"sergio" <[email protected]> wrote in message
news:[email protected]
>
> sal bass wrote:
> > here are the pics.........

>
> Pardon me, and be sure I don't intend to be offensive at all.
> Do you lubricate at all?
>
> Sergio
> Pisa
>


Good point. Aluminum galls on to tools very easily. A light oil is the
minimum required, special tapping fluids are better.

Chas.
 
Q

Qui si parla Campagnolo

Guest
sal bass wrote:
> i figured there were tolerance issues......but even passing the park
> straight through the arms...the eldi would not even catch one
> thread......so my real question is about the taps.....
>
>
> the eldi removes a lot of material after the park tap has gone
> through.....


Like cranks and pedals and taps, there are good ones and great ones.
Eldi are great but how they are cut at the very end and how they 'grab'
the crank threads, and the condition and cut of the pedal threads,
etc...as I mentioned, running a tap from the opposite direction is not
uncommon.
>
>
>
>
>
>
> A Muzi wrote:
> > sal bass wrote:
> > > ok...i've got two c-record cranksets.....both in VERY good condition.
> > > less than 100 miles i'd bet.
> > > i've got three sets of taps......park 9/16ths X 20......eldi 9/16ths
> > > X20.....and var 9/16ths X 20.....

> > -snip-
> > > so.....i try to thread each pedal into the proper arm. i can turn the
> > > mks and shimano spindles about three whole turns and then it gets
> > > really tight. i'm not one to force things for fear of damaging the
> > > threads.....so i back them out....i try threading them in from the
> > > backside of each arm and they thread in like butter......so i figure
> > > that the first few threads might be damaged....
> > > so...and here's the weird part.......i take the three sets of taps
> > > (each are about a year old but none has seen more than about 10
> > > uses)......
> > > the var first.....on each arm....i can't even get the tap to penetrate
> > > the face of the crank arm.....can't even do that....and if i can't do
> > > that.....i can't get a hold of some threads.....
> > > BUT.....with the vars from the backside of each arm...i can get about
> > > two whole turns....and then....it's like i'm using a tap that's tapered
> > > cause the tap won't budge....again....i'm not forcing anything....
> > > next the eldi.....same thing....can't even get them IN the hole to try
> > > to catch some threads.....
> > > BUT.....from the backside of the arm....same thing...i can get two
> > > whole turns on each.....
> > > last the park.....front the front i was able to get three whole turns
> > > then a lot of friction.....
> > >
> > > so i decided to tap the arms from the backside.....a bunch of
> > > effortless turns and at the end...the tap meets some resistance but
> > > passes right through pulling up only a fine bit of aluminum....the bits
> > > were about 1/10th the size of a piece of glitter....really fine....

> > -snip-
> > > same thing.....i couldn't get EITHER the var or the eldi to get past
> > > the face of the arm.....and from the back side.....not but two hole
> > > turns and i coudl easily feel that the tap would start gouging up
> > > chunks of aluminum from the arm........

> > -snip-
> >
> > Manufacturing tolerances.
> > We recently discussed Campagnolo's poor allowance for chrome depth on
> > the 1037a pedals of the seventies. Their cranks also start out loose at
> > the beginning of a run and end up tight just before tool change just
> > like everyone else.
> >
> > The Eldi taps are generally accepted as the industry standard. Although
> > we own some Park in 1/2" we're Eldi for pedal taps here and no
> > complaints. (Campagnolo pedal taps were not included in the small or
> > the large case, and cost more than even I could justify)
> >
> > Just curious - if you grab a dead left side crank from the garbage at a
> > local LBS, does the Eldi tap remove material _after_ the Park tap? (Left
> > arms fail commonly at the spindle and should be free for the asking)
> >
> > --
> > Andrew Muzi
> > www.yellowjersey.org
> > Open every day since 1 April, 1971
 
S

sal bass

Guest
no no.....i get it.....but yeah....they did have tons of cutting fluid
on them.....i posted the pictures with them dry just to show a bit more
detail......and show that these taps were old or beat up and that the
cranks were junk either.....





sergio wrote:
> sal bass wrote:
> > here are the pics.........

>
> Pardon me, and be sure I don't intend to be offensive at all.
> Do you lubricate at all?
>
> Sergio
> Pisa
 
A

A Muzi

Guest
> "sal bass" <[email protected]> wrote in message
> news:[email protected]
>> ok...i've got two c-record cranksets.....both in VERY good condition.
>> less than 100 miles i'd bet.
>> i've got three sets of taps......park 9/16ths X 20......eldi 9/16ths
>> X20.....and var 9/16ths X 20.....
>> i've got two sets of pedals....decent platforms from mks and a set of
>> shimano pd-m959s......

_snip-
>> so.....i try to thread each pedal into the proper arm. i can turn the
>> mks and shimano spindles about three whole turns and then it gets
>> really tight. i'm not one to force things for fear of damaging the
>> threads.....so i back them out....i try threading them in from the
>> backside of each arm and they thread in like butter......so i figure
>> that the first few threads might be damaged....

-snip-
>> two whole turns....and then....it's like i'm using a tap that's tapered
>> cause the tap won't budge....again....i'm not forcing anything....
>> next the eldi.....same thing....can't even get them IN the hole to try
>> to catch some threads.....
>> BUT.....from the backside of the arm....same thing...i can get two
>> whole turns on each.....

-snip-
>> so i think it's odd that neither the var or the eldi could even get
>> started from the front...............BUT from the back....i couldn't
>> get more than two whole turns and then just a harsh hault after those
>> two whole turns.........

-snip-
>> same thing.....i couldn't get EITHER the var or the eldi to get past
>> the face of the arm.....and from the back side.....not but two hole
>> turns and i coudl easily feel that the tap would start gouging up
>> chunks of aluminum from the arm........
>> so...i thought 9/16ths X 20 was 9/16ths X 20 no matter what tap was
>> used?

-snip-

**chas wrote
> There are size tolerances for most threaded fasteners like nuts, bolts and
> machine screws which allow a certain amount of slop for ease of assembly
> and disassembly.
>
> Stud type fasteners on the other hand have interference fits that are
> designed so that they wont come loose under normal use.
>
> Pedal threads are similar to studs. They are not meant to be frequently
> installed or removed.
>
> The nominal size for a standard 9/16-20 H5 tap would be .562 +.002 to
> .0025. but there are a lot of other factors involved.
>
> An interference fit would use a tapped hole size .001 to .002 smaller than
> nominal, a fastener .001 to .002 larger than nominal or both depending on
> design requirements.
>
> This web site explains some of the issues involved with tap sizes without
> getting overly technical. Read the part from Tap Size down :
>
> http://www.natool.com/engdata/data10.php
>
> Most of the pedal taps I've seen over the years have been pretty poor
> quality when compared to taps used in manufacturing. They are generally
> made of carbon steel instead of high speed steel and they are cut taps
> rather than precision ground taps. That is the threads are machined into
> the taps with another tool rather than being made on a precision tap
> grinding machine.
>
> One explanation for why the taps may go into the crank arm from one side
> and not the other is something called "thread drunkenness". That's were
> the thread pitch is off slightly.
>
> Instead of being 20 TPI (Threads Per Inch) the threads on the tap or in
> the part may be 20.5 or 19.5 TPI or something similar. This is caused by a
> poorly made tap or worn out tapping equipment.
>
> The threaded fastener may start in easy and get harder to turn the further
> it goes in. Also the holes in the cranks may have been tapped from the
> backside to begin with so that's why the taps start easier from the back
> side.
>
> Another cause could be an "egg shaped" hole. The original tapped hole is
> wallowed out near the beginning due to worn out tapping equipment, a dull
> tap used during manufacturing or poor Fixturing that allows the part to
> move around while being tapped (or all of the above).
>
> The last thing is that the threads on pedals are not very accurate. They
> are cut or rolled into the pedal spindles before they're hardened by heat
> treatment. During heat treatment, the threads can change a considerable
> amount.
>
> I always check the threads on a new set of pedals to make sure that there
> aren't any burrs that might damage the crank arms. I've seen top quality
> pedals with defective threads but that's something that you don't hear
> about very often because the person installing them usually just forces
> them into the cranks.
>
> Except for certain components most bicycles are not precision machines.
> Crank arms aren't designed for frequent pedal changes. The pedal threads
> in aluminum cranks are designed for an interference fit so the pedals
> don't loosen and wear out the threads prematurely.


Although I think you're bordering on overstating the case, all the
points you make apply here. Campagnolo Record cranks are not junk but
yes, bicycle parts are not held to aerospace prototype levels of fit either.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
 
C

* * Chas

Guest
"A Muzi" <[email protected]> wrote in message
news:[email protected]
> > "sal bass" <[email protected]> wrote in message
> > news:[email protected]

<snip>
> > The last thing is that the threads on pedals are not very accurate.

They
> > are cut or rolled into the pedal spindles before they're hardened by

heat
> > treatment. During heat treatment, the threads can change a

considerable
> > amount.
> >
> > I always check the threads on a new set of pedals to make sure that

there
> > aren't any burrs that might damage the crank arms. I've seen top

quality
> > pedals with defective threads but that's something that you don't hear
> > about very often because the person installing them usually just

forces
> > them into the cranks.
> >
> > Except for certain components most bicycles are not precision

machines.
> > Crank arms aren't designed for frequent pedal changes. The pedal

threads
> > in aluminum cranks are designed for an interference fit so the pedals
> > don't loosen and wear out the threads prematurely.

>
> Although I think you're bordering on overstating the case, all the
> points you make apply here. Campagnolo Record cranks are not junk but
> yes, bicycle parts are not held to aerospace prototype levels of fit

either.
>
> --
> Andrew Muzi


Andy,

Ya, it was overkill but I tried to give the OP possible reasons why he was
having problems with his pedals.

I wasn't inferring that the cranks were junk. I've seen poor quality
threads on pedals even Campys. Any burr on the pedal threads can make them
hard to screw in plus damage the threads in the crank.

Chas.