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fasteners, lock washers are bad.


motocat12

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25 minutes ago, Pauly said:

Loc-Tite and torque wrenches. 

All Daymn Day!

Says the guy that looked down at his front MC reservoir 1/2 through his stint and saw it dangling next to the mount.:facepalm:

Edited by TimTheAzn
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Not too sure about some of that "engineer" list. Kinda strange.

Aerospace has it's own rules. The list of rules was long (Two big manuals full of rules and requirements). We didn't use common lock washers. We did sometimes use inside or outside star washers, in electronics, for grounding. We used a lot of safety wire. We used self locking nuts, especially self locking nutplates that rivet into place on sheet metal. No one puts threads in shear, that's a failure waiting to happen. A minimum of 4 threads in bearing required, 6 to 8 preferred. We never ever put a bolt (some types of bolts are ok), nut or lock washer against a part without a plain washer in-between. Plain washers are punched out of sheet metal, and have a sharp side vs a rounded side; put the rounded side against your part and the sharp side up in the air. (edit: Backwards! sharp side goes down, and the rounded side goes under the bolt or machine screw to prevent contact at the radius under the head and trying to break it.) The torque from the bolt side isn't the same as the nut side, if it's a through bolt with a nut, torque the nut. Torque requirements are strict, and doesn't include "torquing to yield" or " turn it an extra 90 degrees". Hardware of all types is never re-used more than 4 times, and then it's replaced with new. It slowly deforms to failure. Zero cadmium plate, we used zinc plate. All steel hardware was zinc plated. Certain metals never contact each other, it generates di-electric corrosion. The common error is stainless steel and aluminum in contact. Titanium and aluminum in contact is a disaster. I don't remember using chromed hardware anywhere.

That's a few of the highlights.

Note: Japanese motorcycles use a different type of Phillips (JIS). Striping (cam-out) is common, when using SAE phillips tools. There's special JIS screwdrivers and bits for them. I don't always use them, but I've got them. You can find them on Amazon, or motorcycle tool websites. Or replace them all with socket head cap screws.

Read aircraft hardware: https://www.flight-mechanic.com/category/aircraft-materials-processes-and-hardware/

Edited by ReconRat
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I tried to safety wire my front sprocket nut and it came off.  Safety wire isn't that safe.  Yamaha had a recall because of the nut backing off on the 2nd gen R6.  They wanted mechanics to use a splined washer  that you bend over the nut.  Along with  retaining compound.  which is for thread less assemblies.  That shit doesn't come off without a press or puller.  

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On 6/30/2019 at 9:25 AM, ReconRat said:

Plain washers are punched out of sheet metal, and have a sharp side vs a rounded side; put the rounded side against your part and the sharp side up in the air.

Plain washers and special countersunk washers should go rounded side towards the head of the bolt.  Most bolts in aviation have a small radius between the head and the shank.  The rounded edge of the washer gives room for that radius and helps prevent nicks/damage from causing a stress crack in that area and causing bolt failure.

national-aerospace-standard-nas-1587-12c_2.jpg

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On 7/6/2019 at 7:16 PM, vf1000ride said:

Plain washers and special countersunk washers should go rounded side towards the head of the bolt.  Most bolts in aviation have a small radius between the head and the shank.  The rounded edge of the washer gives room for that radius and helps prevent nicks/damage from causing a stress crack in that area and causing bolt failure.

national-aerospace-standard-nas-1587-12c_2.jpg

That's true. Maybe I got that backwards. Now I'll have to look it up. I do remember using those special beveled washers for special bolts.

edit: Yup, sharp side should be down. Rounded side always against bolt or machine screw radius. Keeping the bolt from breaking is more important than the surface below the washer.

Edited by ReconRat
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On 6/30/2019 at 8:57 PM, Pauly said:

Nordlock washers are pretty dope, too. 

This. Split washers are useless, yet engineers keep using them because reasons. AvE did some experiments on his channel and showed that split lock washers dont augment the breaking torque of a bolt at all. It's just another item on the BOM.

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