crank cotter press usage


Michael Wilson
 

I have one of Mark Stonich' Bikesmith Design cotter pin presses.  Is there a technique to avoid bending the threaded shaft of stubborn cotter pins?  

I also need to invent a method of using the tool on the cotter pins with bent shafts.  I prefer not to revert to the hammer and punch method on drilled out pins.  My hammer aim never was good and is getting worse.  Maybe shortening the punch so the press can push on it instead of the hammer.


chris witt
 

have you tried pre-stressing the pin with the press, while running it thru a cycle or 2 of heating & cooling. you don't have to heat it enuf to endanger the metallurgy of the press, the pin, the spindle or the crank. just make it expand & contract a few times.

On 11/6/2021 8:08 AM, Michael Wilson wrote:
I have one of Mark Stonich' Bikesmith Design cotter pin presses.  Is there a technique to avoid bending the threaded shaft of stubborn cotter pins?


James Kearney <jkengineturner@...>
 

Soak in PB Blaster. I use a large blacksmith post vise with a socket on the top part of the pin. A 3 foot handle on the vise cranks a whole lot of pressure on the pin. Never failed yet. It helps to have an extra pair of hands to get the bike up into the vise jaws. Go visit your local smith!

On Nov 6, 2021, at 11:39 AM, chris witt <ctwitt@...> wrote:

have you tried pre-stressing the pin with the press, while running it thru a cycle or 2 of heating & cooling. you don't have to heat it enuf to endanger the metallurgy of the press, the pin, the spindle or the crank. just make it expand & contract a few times.

On 11/6/2021 8:08 AM, Michael Wilson wrote:
I have one of Mark Stonich' Bikesmith Design cotter pin presses. Is there a technique to avoid bending the threaded shaft of stubborn cotter pins?




Eric E.
 

I had the same problem. However, I did use a penetrant to try to loosen the cotter. Ultimately, the cotter still bent to the point I had to resort to a drill. I ended up drilling to just through the depth of the crank arm, and using a pin punch to drive the cotter pin out since the sides of the pin could now collapse. It turned out that the pin had been incorrectly installed (or was the wrong size/shape), and had been appatently driven in with a sledgehammer. Even if the press would have gotten the pin out, the pin would not have been salvageable. 


Michael Wilson
 

How do you prevent threaded post bending with the vise technique?

My main takeaway is that I am less competent than other people at these tasks.  And yes I have a lot of other evidence in that direction.  I was about 3x slower than a friend while I worked on one side of a race car project and he worked on the other.

I have not tried heat/cool.  That would require a heat skill that I do not seem to possess.  I have had little success with PB Blaster in any other case.  I have had some success with Marvel Mystery Oil in freeing up parts that are supposed to move with respect to each other.

I am new to the press technique and have not yet figured out how much I can turn the handle before the pin bends.  Some cotters just push out, and others just bend, at what seems to be the same load and rust/clean of the cotter/crank interface.  For example an old Peugeut UO-8 looked very clean everywhere, but the threaded ends just bent.  But my winter bike for salt and ice conditions, assembled maybe 20 years ago and then put away uncleaned 17 years ago had one side just push out with zero issues.

I have successfully removed every cotter I needed to remove, but more often than I liked it required a lot of drill and hammer and punch.  I have a tube setup to act as an anvil so the hammer load was not going through the bearings (which is what I did when I was 20).  But that is a lot of work.

Maybe PB Blaster and heat/cool as the default method before applying a lot of pressure is the plan.  Avoiding setting fire to the grease in the bearing will be another challenge of the heat/cool method.  Especially interesting if you have one of those plastic sleeves in the bottom bracket to keep the dirt that falls down the seat tube with an open-top seat post from contaminating the bearings.  Melting or burning that would be sub-optimal.


James Kearney <jkengineturner@...>
 

Just lucky here I guess. I have had success with Blaster but use your own that you like. A machinist vise has parallel jaws so the force should just push it out. So far never had to drill and don’t want too!


On Nov 7, 2021, at 12:51 PM, Michael Wilson <mtwils@...> wrote:


How do you prevent threaded post bending with the vise technique?

My main takeaway is that I am less competent than other people at these tasks.  And yes I have a lot of other evidence in that direction.  I was about 3x slower than a friend while I worked on one side of a race car project and he worked on the other.

I have not tried heat/cool.  That would require a heat skill that I do not seem to possess.  I have had little success with PB Blaster in any other case.  I have had some success with Marvel Mystery Oil in freeing up parts that are supposed to move with respect to each other.

I am new to the press technique and have not yet figured out how much I can turn the handle before the pin bends.  Some cotters just push out, and others just bend, at what seems to be the same load and rust/clean of the cotter/crank interface.  For example an old Peugeut UO-8 looked very clean everywhere, but the threaded ends just bent.  But my winter bike for salt and ice conditions, assembled maybe 20 years ago and then put away uncleaned 17 years ago had one side just push out with zero issues.

I have successfully removed every cotter I needed to remove, but more often than I liked it required a lot of drill and hammer and punch.  I have a tube setup to act as an anvil so the hammer load was not going through the bearings (which is what I did when I was 20).  But that is a lot of work.

Maybe PB Blaster and heat/cool as the default method before applying a lot of pressure is the plan.  Avoiding setting fire to the grease in the bearing will be another challenge of the heat/cool method.  Especially interesting if you have one of those plastic sleeves in the bottom bracket to keep the dirt that falls down the seat tube with an open-top seat post from contaminating the bearings.  Melting or burning that would be sub-optimal.


Thomas
 

The best way I know of to get these out is to make sure they are put in correctly in the first place  ...   
   Sorry, that is not really helpful when it is already in and you want it out, but  ...
Whenever you do put a cotter pin in, make sure it is made of appropriate grade of metal, is the correct size, both the axle and pin are smooth and clean and all holes in the crank are even, smooth, in-line (not "wallowed out"), sized correctly in their bore ...   etc., including held in appropriate 180* to the other crank...    This will help when it comes time for removal of pins  ...

perhaps elementary to you, but perhaps worth mentioning     ;-}

noMadic  Thomas

On 11/7/21 9:51 AM, Michael Wilson wrote:
How do you prevent threaded post bending with the vise technique?


Mark Stonich
 

Mike,
How old is your press?
At first I just copied the throat dimensions of the discontinued Park Tool press. But I did go to a larger, stainless bolt.

After a few years I realized that, since the threaded stem isn’t centered on the cotter, using the press at right angles to the crank arm meant the stem often couldn’t be perfectly centered on the cupped bolt. Still worked as good as the Park. (Maybe a little better as the stainless is slipperier)

So I redesigned it with a deeper throat, so it can be used parallel to the arm. This allows the bolt to center on the stem. 




Mark Stonich
Bikesmith Design and Fabrication LLC
5349 Elliot Ave
Minneapolis MN USA
Ph. +1 (612) 710-9593


James Kearney <jkengineturner@...>
 

Much better design then the Park I think and easier to use then a large smithing post vise.


On Nov 7, 2021, at 7:45 PM, Mark Stonich <bikesmithdesign@...> wrote:


Mike,
How old is your press?
At first I just copied the throat dimensions of the discontinued Park Tool press. But I did go to a larger, stainless bolt.

After a few years I realized that, since the threaded stem isn’t centered on the cotter, using the press at right angles to the crank arm meant the stem often couldn’t be perfectly centered on the cupped bolt. Still worked as good as the Park. (Maybe a little better as the stainless is slipperier)

So I redesigned it with a deeper throat, so it can be used parallel to the arm. This allows the bolt to center on the stem. 




Mark Stonich
Bikesmith Design and Fabrication LLC
5349 Elliot Ave
Minneapolis MN USA
Ph. +1 (612) 710-9593

<Park.jpeg>
<dimensions-9-24-2011.jpeg>
<cp-dimensions.jpeg>
<new_press_on_raleigh.jpeg>
<~ cotter instructions.pdf>


Michael Wilson
 

It is a new one.  As a side note, looking at the tool and one of my one-piece (as opposed to swaged) 3-arm Stronglight cranks, I am going to need to bevel the outside edges so they do not sit on the fillet curve between the crank and the spider.

I think it is not using the tool parallel to the arm.  I thought of that after my last post and before reading this.  I had not recognized that perpendicular to the arm can put a bending moment on the pin.  Nor recognized that perpendicular to the arm on a right side crank may leave the tool bolt not quite centered on the cotter pin.

Now to invent a method of removing the bent cotters without a hammer.

And maybe remember to read instructions, even if the usage appears to be obvious.