Nuts, bolts and washers. Help please.

[facthunter]

Trouble with a complex washer like that it has to be HARD and be subject to just breaking.   Nev

[onetrack]

Anerobic adhesives are the best thing ever invented for stopping nuts from coming undone. I didn't see Nordlock testing their lockwasher against Loctite thread lock.

[Garfly]

12 hours ago, onetrack said:

Anerobic adhesives are the best thing ever invented for stopping nuts from coming undone. I didn't see Nordlock testing their lockwasher against Loctite thread lock.

 

Yes, strangely, Loctite is not included in their testing but I notice that, in this full official version of the promo,

adhesives - and locking wire - do, at least, warrant a mention (at 02: 45)

 

 

 

 

 

Anyway, that other (truncated) posting of the video  https://www.youtube.com/watch?v=kx-DyuIcGGc 

has a Comments thread about Loctite, which I found interesting (albeit, as an interested spectator only, regarding aero-mechanics  ;- )

 

 

Jerry Cann

4 days ago

I was working on aircraft when Loctite put their pitch to use that product on fasteners in the aero industry. I went to a seminar on their products which were superior to many types of securing nuts including cotter pins. There was only two types of locktite back them, red for permanent lock and blue for threadlock. I would have liked to see how loctite compares to Nord-lock both in performance and price

 

 

 

 

 

Edited April 7, 2023 by Garfly

[facthunter]

Anytime you undo a nordlock you are going to have some metal shavings.  It wouldn't be cheap to make either and adds weight and distance. Nev

[old man emu]

I thought that there were two main uses for a washer:

1: To spread the Force (pressure) created by the tightening nut over a wider area of the surface of the material being fastened together. Pressure = Force per unit area. Penny washers on wood or regular washers against aluminium.

2: To act as a sacrificial protector between two surfaces where there was relative movement, e.g a nut and bolt combination used as an axle for a control surface hinge.

 

There is are, of course the two types of star washers, of which the Nordlock seems to be a fancy (ie expensive) variety. And nylon washers which inhibit electrolysis between a steel fastener and aluminium sheet.

 

Glad no one picked up the grammatical error 

[Ian]

Not sure if it's been mentioned however one of the key benefits of wired or pinned crown nuts is that they can be verified as "locked". Far more difficult with locktite or similar.

[Garfly]

Yes, good point Ian.   I've heard somewhere that a drawback of locking wire is that it can allow that first little bit of loosened clamp load.

So maybe loctite, nordlock AND lock wire for critical bolts??

[onetrack]

2 hours ago, Ian said:

Not sure if it's been mentioned however one of the key benefits of wired or pinned crown nuts is that they can be verified as "locked". Far more difficult with locktite or similar.

With critical assembly, it's easy enough to tighten to specs using loctite, then mark the fastener with a paint-type marker, to verify tightening and locking.

[facthunter]

The "usual" spring washer is subject to failure. Lock tabs aren't a bad idea.  The yellow paint is often to assure the machine has not been tampered with in  some competitions. Nev

[facthunter]

A lot of stuff these days has no locking at all. That's in locations where the torque is pretty high . Head bolts are never locked. Main bearing caps frequently not locked. Some rocker adjusters are a high friction bolt that requires no locking. Special low angle thread and hollow bolt. Often it just gives you a warm and fuzzy feeling inside and does little else. What locks the lock tab screw? Nothing Nev

[rgmwa]

Paint or powder coating under washers can result in torqued bolts losing tension over time which you can't check easily if Loctite has been used on the nuts or bolt threads. For example on engine mounting bolts. 

[facthunter]

Those parts/areas should be masked.   Nev

[old man emu]

6 hours ago, Ian said:

Not sure if it's been mentioned however one of the key benefits of wired or pinned crown nuts is that they can be verified as "locked". Far more difficult with Loctite or similar.

To my mind, that is a secondary, but useful, effect of wiring or pinning a castellated nut. If you have a look where fasteners with a hole in the shank are used they do not usually perform a clamping function. They are usually used for keeping things in place where there is movement, like control surface hinges, or for keeping axle nuts firm against the wheel bearing, but not clamping it against the hub. So there is an allowance for the nut to move in and out for a fraction of the circumference of the shank and a cotter pin prevents the untorqued nut from unwinding itself. Its hard to get the correct torque on a nut while at the same time getting the hole in the shank to line up with a slot in the castellated nut.

 

However, that doesn't apply to bolts with holes in the head of the bolt. These are used where two items are being clamped together and no movement is permitted between the two. In that case, the nut is torqued into place before the head of the bolt is lockwired in such a way as to prevent it unwinding from the nut. 

 

Sorry that these are sideways. I can't get them to stay rotated the correct way.

  

 

[Jabiru7252]

There's also the ambihelical nut. It's strange because you undo it to tighten it.

[facthunter]

It's the nut holding the controls you need to pay attention to.   Nev