Left crank coming loose

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NATURAL ANKLING
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Re: Left crank coming loose

Postby NATURAL ANKLING » 6 Sep 2016, 9:57pm

Hi,
Not marking out blue die................
https://en.wikipedia.org/wiki/Engineer%27s_blue

"Engineer's blue is a highly pigmented paste used to assist in the mating of two or more components.

Joseph Whitworth popularized the first practical method of making accurate flat surfaces, during the 1830s, by using engineer's blue and scraping techniques on three trial surfaces. Prior to his scraping technique, the same three plate method was employed using polishing techniques, giving less accurate results. This improvement led to an explosion of development of precision instruments using these flat surface generation techniques as a basis for further construction of precise shapes.

Engineer's blue is prepared by mixing Prussian blue with a non-drying oily material (for example, grease). The coloured oil is rubbed onto a reference surface, and the workpiece is then rubbed against the coloured reference; the transfer (by contact) of the pigment indicates the position of high spots on the workpiece.[1] This method has been used to test the flatness of surfaces and the trueness of a bearing assembly.

When Prussian blue is mixed with methylated spirits it forms a quick drying stain which is known as marking blue or layout dye. This stain is used in the marking out operation in metalworking. Both the "marking out" blue, and the "scraping blue" may be referred to as engineer's blue, which can lead to substantial confusion.

The engineer may be told to "blue it up" when using this piece of equipment.

Prussian blue is widely used by tool makers when the core and cavity of a mould is matched during final assembly. It is also used in other tooling applications—especially during assembly—such as stamping tools and pressure die casting tools. A thin coating of Prussian blue is applied (usually with a paint brush) on the "insert"—regardless of the shape or contour—of the mould or tool before the matching is done with the mating part. If the Prussian blue (generally called as just "blue") appears evenly on the mating area, it is considered—by the tool makers—as "good matching" and thus expecting a good final product from the tool. Usually no tool would be transferred to testing or production without "blue matching", a term generally used by the tool makers in Asia. In other words, Prussian blue is considered as an integral part of precision tool making.

In the US, the terms machinist's blue, scraping blue, or simply bluing are used instead of engineer's blue."
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fastpedaller
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Re: Left crank coming loose

Postby fastpedaller » 6 Sep 2016, 10:17pm

One thing worth mentioning (please correct me if I'm wrong) is that one crank and the BB axle need to be marked with a paint pen before removal so they go back in the same position if the same parts are being re-used. The other crank's position will of course be known once the first one is replaced! :wink:

Keezx
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Re: Left crank coming loose

Postby Keezx » 6 Sep 2016, 10:33pm

I've never done that in 40 years...think it's pure theory.

Brucey
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Re: Left crank coming loose

Postby Brucey » 7 Sep 2016, 9:32am

re engineer's blue; a modern short cut for this is to simply use a marker pen inside the crank taper. If the axle is light coloured, you can use the marker pen on that instead/as well, but if it is dark coloured, it is usually difficult to see what is going on.

A light coating of spray paint is sometimes OK for this job too, but many leave a film that is too thick, and/or that flakes off in lumps.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Annoying Twit
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Re: Left crank coming loose

Postby Annoying Twit » 9 Sep 2016, 10:13am

Returning from the general discussion to the specifics of my bike: so far, so good.

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mjr
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Re: Left crank coming loose

Postby mjr » 9 Sep 2016, 10:46am

Annoying Twit wrote:Returning from the general discussion to the specifics of my bike: so far, so good.

What did you torque it to (4 kg m?) and have you retightened yet? Any greasing? Any other tips? :)
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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Annoying Twit
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Re: Left crank coming loose

Postby Annoying Twit » 9 Sep 2016, 1:19pm

mjr wrote:
Annoying Twit wrote:Returning from the general discussion to the specifics of my bike: so far, so good.

What did you torque it to (4 Kg m?) and have you retightened yet? Any greasing? Any other tips? :)


I don't have a torque wrench. I tightened it 'pretty tight'. I didn't grease it, though the bolt has had some threadlock on it in the past and this seems to make it a slightly tighter fit than it was originally, even though I removed what I could.

I'm not skilled enough to give tips. Please read the much more informative discussion in this thread.

EDIT: BTW: I have now read of quite a few cases of people who have bought the wrong type of 'square/diamond' taper crank. It seems quite a common error for the unwary.

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mjr
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Re: Left crank coming loose

Postby mjr » 9 Sep 2016, 4:28pm

Annoying Twit wrote:I'm not skilled enough to give tips. Please read the much more informative discussion in this thread.

Sorry for being unclear: I was trying to ask if you'd used any of the other tips given above by various people.
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
All the above is CC-By-SA and no other implied copyright license to Cycle magazine.

Annoying Twit
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Re: Left crank coming loose

Postby Annoying Twit » 9 Sep 2016, 4:37pm

mjr wrote:Sorry for being unclear: I was trying to ask if you'd used any of the other tips given above by various people.


Not really. I just did it. The one tip I applied was Brucie's advice not to use thread lock on the bolt as the crank may settle after a while of use and need tightening again. If I thread locked it when I put the crank on, then it may lock the bolt in the wrong place. Other than that, I just bunged it on and gave it a good tightening.

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NATURAL ANKLING
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Re: Left crank coming loose

Postby NATURAL ANKLING » 12 Sep 2016, 11:22pm

Hi,
Well never say never :oops:
Had a creak on the left pedal area, got much worse next ride :(
Ah crank bolt loose, crummy cartridge BB and retaining locking sleeve was loose too.

Skip trainer with steel crank arms. Not sure how many miles its covered, cant remember when I put it on but say 1000 miles ago.
Whacked it back together and will keep an eye on the bolts....................

Never used steel square socket cranks before, the rubbish finish on the socket won't help.
Attachments
SDC12724_a.jpg
Crummy socket face with circular machine marks in centre.
SDC12718_a.jpg
SDC12712_a.jpg
Priority Is Still 500K In 24......Cant Move On Till Then..............Stay Focused Guys And Keep Sharp.....
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9494arnold
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Re: Left crank coming loose

Postby 9494arnold » 14 Sep 2016, 9:02am

I hesitated before posting this, I have actually had the end come off a quality (TA or Stronglight but the Old School ones with the Polished bearing Surfaces) axle as a result (possibly) of overtightening. Nothing serious, didn't fall off (more luck than anything) but had to wait for an hour or so for International Rescue.
I use a Torque Wrench now but I used to used the bolt, do it pretty tight and then back it off and re tighten it, just seemed the right thing to do. Mind how you go.

9494arnold
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Re: Left crank coming loose

Postby 9494arnold » 14 Sep 2016, 9:05am

PS Assemble Dry (no grease) or you stand a good chance of having a creaky crank :(

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NATURAL ANKLING
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Re: Left crank coming loose

Postby NATURAL ANKLING » 14 Sep 2016, 11:59am

Hi,
9494arnold wrote:PS Assemble Dry (no grease) or you stand a good chance of having a creaky crank :(


I might of misunderstood what you said, if its dry it might creak if it moves?
My cranks are unbranded (no markings whatsoever and plastic covered) and I did not give it a thought that the socket was so poorly made when I originally put it on.
Priority Is Still 500K In 24......Cant Move On Till Then..............Stay Focused Guys And Keep Sharp.....
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9494arnold
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Re: Left crank coming loose

Postby 9494arnold » 14 Sep 2016, 3:16pm

Convention is to put cranks on "Dry" (not lubricated) or you may induce a creak,not sure why but |I've cured a couple by dissasemly and a thorough lean and dry re assembly. Suppose a creak would indicate some movement.

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NATURAL ANKLING
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Re: Left crank coming loose

Postby NATURAL ANKLING » 14 Sep 2016, 5:58pm

Hi,
Although I have never thought that much of it (I don't work and paid to look at bikes all day like some) I am not whipping cranks on and off every day unless I can help it, so marking the arm position on the spindle with tipex probably has merit.
Priority Is Still 500K In 24......Cant Move On Till Then..............Stay Focused Guys And Keep Sharp.....
You'll Find Me At The Top Of a hill...............Somewhere


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