The nuts and bolts

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Dieseldame
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The nuts and bolts

Post by Dieseldame »

I am looking for some general principles about tightening nuts and bolts without torque specifications. What "rules of thumb" do you use for tightening with the following considerations....

Washers - copper, flat, locking
Type of contact (metal to metal, gasket, RTV..etc)
Size of bolt / nut
Material differences (aluminum, steel, cast etc)
Duty (banjo fitting, gear casing, alternator mount, etc)

Thanks!

DD
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Madzng
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Re: The nuts and bolts

Post by Madzng »

The link below will not answer all of your questions, but may answer some.

I am sure that I have more information, its just finding it....

http://www.bossard.com/index.cfm?app_ca ... =text_file
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Dieseldame
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Re: The nuts and bolts

Post by Dieseldame »

Thanks for the referral, but I wasn't able to open the link. It was trying to open a "cfm" file rather than a pdf for some reason. Have you successfully opened this?

I would also mention that I did some looking around and didn't find much on the topic so thought maybe folks could share their experience and personal guidelines on the topic!

DD
Pacific Barbarian
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Re: The nuts and bolts

Post by Pacific Barbarian »

This is not an easy one. All I can comment is that this is where your experience as a Marine Engineer should guide you through.

Proper knowledge of materials, being aware of your own capabilities.

Carefull not to overtighten, loctite can be used to ensure it doesnt come loose.

Proper anealing of copper washers, even brand new ones, before installing.

Always choose the correct tools for the job.

If you are uncertain, well actually, read the manual BEFORE the job is undertaken :lol:
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Dieseldame
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Re: The nuts and bolts

Post by Dieseldame »

Thanks Barbie...can I call you that?

My experience has taught me that squishy feeling just before the cap comes off, followed by that squishy feeling in my stomach - the manual does not always give a guideline. I work on smaller engines sometimes and its tricky to get them to the right tightness and easy to twist them off...I like the loctite idea - I will add this to my gear bag.

Did not know that you are supposed to anneal even new copper washers..why is that?

DD
Pacific Barbarian
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Re: The nuts and bolts

Post by Pacific Barbarian »

It is good practice to anneal new copper washers. They come out a lot softer, which is what you want to form a compression seal. Perform a small test yourself. Take two brand new copper washers, anneal the one, then test with a sharp object like a scriber, or perform a simple bend test. See which one is softer :mrgreen: Copper work hardens and I suspect somewhere during the fabrication process it work hardens.
Big Pete
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Re: The nuts and bolts

Post by Big Pete »

Copper age hardens as well as work hardens.

For anyone out there who doesn't know, support the washer on a pice of wire or similar, gently heat to cherry red, (experience as an Engineer again, don't melt it!) and quickly dunk it in cold watergen to lock the crystaline lattice of copper molecules in place.

The opposite of alloy steels which would be made harder by this process.

This is also why it is bad practice to "quench" a recently welded piece of steel with water. It is always much better to allow welded components to cool as slowly as possible, so that stresses are not locked into the weld which can cause stress corrossion and fatigue problems.
In large scale welding workshops the work pieces are slowly heated in a furnace before welding then slowly cooled in a furnace to relieve the stresses.

BP
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