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Re: NASA: Split Lock Washers Are "Useless"!

 

On 12/29/22 15:55, Jeff Green wrote:
To the moderator, can you please kill and delete all of this thread?
but... this last was the good part! I've done lots of thinking about split lock washers over my years...

The malicious ex girlfriend with nut/bolt knowledge is a plotline worthy of TV writer upgrading in the "true crime" category!
--
John Griessen
Re: NASA: Split Lock Washers Are "Useless"!

 

Microdyne bought most of our hardware from Accurate Screw Machine. We used internal toothed lock washers in our products, except for a couple connectors that came with custom hardware. Those received a drop of breakable Loctite. This was issued with the expiration date clearly marked, so I got a lot of partial bottles for my own use to keep it out of the toxic waste stream.They were pulled from the production floor within a month of the expiration date, along with worn solder sponges and anything else that was questionable. We tested the calibration on the soldering irons and the conductivity of antistatic mats? every 90 days, as well.

On Sat, Dec 31, 2022 at 5:30 PM Jim Allyn - N7JA <jim@...> wrote:
On Thu, Dec 29, 2022 at 08:17 PM, Jeff Green wrote:
Guys I didn't mean to start the flame war of the 21st century
Generally speaking, nobody ever does mean to start a flame war, but they start anyway.? They seem to be unpredictable.? I appreciate the information you posted, and I'm sure others here do as well.? If some want to argue about it, not much to be done about that.? Somebody once told me the most useful skill one can learn is to shrug one's shoulders, perhaps mutter "oh well" under one's breath, and move on.? I haven't mastered the skill yet, but those few times I have managed to do it, it does seem to be a very useful skill.? On NASA's advice, I will rethink my past usage of split washers.

Re: NASA: Split Lock Washers Are "Useless"!

 

On Thu, Dec 29, 2022 at 08:17 PM, Jeff Green wrote:
Guys I didn't mean to start the flame war of the 21st century
Generally speaking, nobody ever does mean to start a flame war, but they start anyway.? They seem to be unpredictable.? I appreciate the information you posted, and I'm sure others here do as well.? If some want to argue about it, not much to be done about that.? Somebody once told me the most useful skill one can learn is to shrug one's shoulders, perhaps mutter "oh well" under one's breath, and move on.? I haven't mastered the skill yet, but those few times I have managed to do it, it does seem to be a very useful skill.? On NASA's advice, I will rethink my past usage of split washers.
Re: NASA: Split Lock Washers Are "Useless"!

 

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I ordered both off of ebay. My son likes to work on performance cars as his hobby.

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Good information is hard to come by.

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Ross

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From: [email protected] <[email protected]> On Behalf Of Jeff Green
Sent: Saturday, December 31, 2022 7:10 AM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] NASA: Split Lock Washers Are "Useless"!

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I've ordered both books, should be here Wednesday next.
Too add fuel to the fire:
Re: NASA: Split Lock Washers Are "Useless"!

 

Prof. Lee's recommendation of this book is spot on. Carroll Smith's book makes the whole subject fun and more rigorous at the same time. What is not to like?

Anthony
Re: NASA: Split Lock Washers Are "Useless"!

 

This has been an interesting sidebar topic but only relevant if we take our equipment to the field.

I find the Aircraft Spruce catalog a good reference for hardware used in high vibration and temperature extreme environments. There is their page on hardware nuts:

<>

Another good source are marine catalogs. Here is an example from a West Marine catalog:

<.

Keep in mind nylon stop nuts may not be usable in extremely high temperatures but I doubt if our equipment is used at these temperatures.

Mike N2MS
Re: NASA: Split Lock Washers Are "Useless"!

 

Jeff

i don't see the significance of lockwashers on agricultural equipment that can suffer great vibration with the subject of test equipment which is nearly always used under very different conditions. Sometimes thread drift throws up interesting stuff but agricultural? running repairs is a very long way from test equipment design and construction.

Regards and HNY

Alan G8LCO
Re: NASA: Split Lock Washers Are "Useless"!

 

Interesting topic!

So what does NASA use to bolt two surface together, anyone knows?
Re: NASA: Split Lock Washers Are "Useless"!

 

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Those are links to the tables of contents for the two books, not to the whole books.

-- Tom
-- 
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070
On 12/29/2022 20:17, Jeff Green wrote:

Guys I didn't mean to start the flame war of the 21st century, I thought most people herein build "stuff" and might benefit from learning what we've been doing "wrong" all of our lives.

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Engineer to Win, and The Nuts, Bolts, Fasteners, and Plumbing Handbook, by Caroll Smith are both on the SAE.ORG webpage for free.


I'm guessing this means they are freely available to anyone who is interested.

Engineer to Win:


The Nuts, Bolts, Fasteners, and Plumbing Handbook:

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Re: NASA: Split Lock Washers Are "Useless"!

 

If you really want to understand fasteners, fastener engineering, and the practical applications thereof from the perspective of a non mechanical engineer, there are two books to own: Engineer to Win, and The Nuts, Bolts, Fasteners, and Plumbing Handbook, both by Caroll Smith. He presents the material with a minimum of BS and a maximum of practical knowledge of working in both the aerospace and auto racing industries. Unless you’re going to be a PE or work at NASA, there is little more you will ever need to know.

On Dec 29, 2022, at 21:54, Neil Smith G4DBN <neil@...> wrote:

?I use Nord-Lock washers for antenna rotator fixings at height and for fixings where critical safety issues exist and I need high strength threaded fasteners. Otherwise I use tab washers, wiring and Aerotight nuts where I don't need extreme strength or where there are heat cycles and vibration and the fasteners need to be stainless. I like the aesthetic of Aerotight nuts.
Neil


On 29 Dec 2022, at 23:59, Mikek <amdx@...> wrote:

?Many will find this testing of different nut locking styles interesting, even though it is put on by a company producing the 'best' solution.
Re: NASA: Split Lock Washers Are "Useless"!

 

I use Nord-Lock washers for antenna rotator fixings at height and for fixings where critical safety issues exist and I need high strength threaded fasteners. Otherwise I use tab washers, wiring and Aerotight nuts where I don't need extreme strength or where there are heat cycles and vibration and the fasteners need to be stainless. I like the aesthetic of Aerotight nuts.
Neil

On 29 Dec 2022, at 23:59, Mikek <amdx@...> wrote:

?Many will find this testing of different nut locking styles interesting, even though it is put on by a company producing the 'best' solution.
Re: NASA: Split Lock Washers Are "Useless"!

 

Many will find this testing of different nut locking styles interesting, even though it is put on by a company producing the 'best' solution.
https://www.youtube.com/watch?v=IKwWu2w1gGk
???? Mikek
Re: NASA: Split Lock Washers Are "Useless"!

 

On 12/29/22 17:55, Jeff Green wrote:
To the moderator, can you please kill and delete all of this thread?
You can always mute the topic if you don't want to see it. No, I'm not deleting it.

Vince - K8ZW.
--
Michigan VHF Corporation -- nobucks dot net

K8ZW -
Etsy Shop:

Re: NASA: Split Lock Washers Are "Useless"!

 

On Thu, Dec 29, 2022 at 02:55:17PM -0800, Jeff Green wrote:
To the moderator, can you please kill and delete all of this thread?
Just a reminder, this is a mailing list with a sort of functional web interface.
It is not a web forum.

Once you post something it's out there in a zillion mailboxes (well, at least
a couple thousand).

Paul

--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@... | Unix/Linux - We don't do windows
Re: NASA: Split Lock Washers Are "Useless"!

 

There has.

Take a look at Nord-Lock wedge lock washer



The one downside is that they are a little bit harder to install; its possible to install them incorrectly. They consist of 2 parts, and the orientation of the parts relative to each other is critical. This adds assembly time and cost.

Greg
Re: NASA: Split Lock Washers Are "Useless"!

 

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Yes. Amazing ignorance of bolted joints.? The torque on the screw should have been far higher than the flattening torque.
Paul G8AQA

On 29/12/2022 19:53, Chuck Moore via groups.io wrote:

Interesting on the softer metal observation when using split washers.

When I landed in a shop designing receivers in 1979, the lead in mechanical design
was adamant we stack a flat washer under the split lock washer. The flat washer
was placed against the aluminum surface of the case or module with the split washer
placed between the flat washer and head of the machine screw. We used Stainless
Steel hardware (316, not L or H) as the radios were sold to differing branches of the
military and government.

I questioned the lead designer once about how the split washer worked to minimize
loosening due to mechanical shock as when tightened down, unless carefully torqued
the split washer simply flattened and why the flat washer did not simply slip. His
explanation was that the split washer was not designed to cut into the metal but hold
tension on the screw once torqued. He also contended that the stainless and aluminum
would interface resisted slippage.? As he held a masters degree and was a registered
PE I never pushed the matter.

As far as I know none of our customers complained about hardware loosening and
many of the radios were installed in airborne platforms.

Re: NASA: Split Lock Washers Are "Useless"!

 

You'd think that after 150 years, something better would have been invented. John Grover would turn in his grave if he had not used his washers.

Wikipedia says:
"John William Grover?(20 April 1836 – 23 August 1892), was an early??consulting civil engineer responsible for several notable buildings in London and railway lines in?,?,??and?. He was the inventor of the?."

On Thu, 29 Dec 2022 at 19:53, Chuck Moore via <wd4hxg=[email protected]> wrote:
Interesting on the softer metal observation when using split washers.

When I landed in a shop designing receivers in 1979, the lead in mechanical design
was adamant we stack a flat washer under the split lock washer. The flat washer
was placed against the aluminum surface of the case or module with the split washer
placed between the flat washer and head of the machine screw. We used Stainless
Steel hardware (316, not L or H) as the radios were sold to differing branches of the
military and government.

I questioned the lead designer once about how the split washer worked to minimize
loosening due to mechanical shock as when tightened down, unless carefully torqued
the split washer simply flattened and why the flat washer did not simply slip. His
explanation was that the split washer was not designed to cut into the metal but hold
tension on the screw once torqued. He also contended that the stainless and aluminum
would interface resisted slippage.? As he held a masters degree and was a registered
PE I never pushed the matter.

As far as I know none of our customers complained about hardware loosening and
many of the radios were installed in airborne platforms.

Re: NASA: Split Lock Washers Are "Useless"!

 

Interesting on the softer metal observation when using split washers.

When I landed in a shop designing receivers in 1979, the lead in mechanical design
was adamant we stack a flat washer under the split lock washer. The flat washer
was placed against the aluminum surface of the case or module with the split washer
placed between the flat washer and head of the machine screw. We used Stainless
Steel hardware (316, not L or H) as the radios were sold to differing branches of the
military and government.

I questioned the lead designer once about how the split washer worked to minimize
loosening due to mechanical shock as when tightened down, unless carefully torqued
the split washer simply flattened and why the flat washer did not simply slip. His
explanation was that the split washer was not designed to cut into the metal but hold
tension on the screw once torqued. He also contended that the stainless and aluminum
would interface resisted slippage.? As he held a masters degree and was a registered
PE I never pushed the matter.

As far as I know none of our customers complained about hardware loosening and
many of the radios were installed in airborne platforms.
Re: NASA: Split Lock Washers Are "Useless"!

 

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Just a brief comment, you also have to take into account the hardness of the mating surfaces and fasteners when you connect. Split lock washers will work fine with an aluminum or softer metal than your lock washer. (ie. grade 5 stud in aluminum, grade 5 or grade 8 lock washer, grade 5 or harder). The grade 8 nut will be less effective than the grade 5. The grade 8 lock washer will dig into the other surfaces slightly and be slightly more springy than the grade 5.
Don Bitters
Re: NASA: Split Lock Washers Are "Useless"!

 

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Most lock-washers come into action after the joint has failed.

Some star washers are used to make sure of a good electrical connection by digging into both surfaces. This might be a valid use.

The other big mistake people almost always make is to put a thin locknut over the normal thickness nut.? As you tighten the "locknut" it takes the load off the normal nut so the load is now taken by the thin nut!? Always fit the thin nut first.

Likewise split-pins only come into action when the joint has already failed. The can however stop the nut falling into other works until the vibration has worked through the split-pin or the bolt has failed due to fatigue.? Look at what is used on engine con rods.

Paul G8AQA

On 29/12/2022 13:09, Jeff Green wrote:

Let me know if this is too far off topic and I will delete it.

Strictly speaking this isn't about precision, but it is something many EEs don't fully understand. Even master mechanics, and those trained in aircraft maintenance?often don't get it.

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But I bet many here build their own equipment and most will use split lock washers...

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I know HP did in a lot of their test equipment.

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We ran into this on a piece of farm equipment. A critical bolt/nut kept coming undone and locktight wasn't a good choice because the area has oil drip on it during normal operation.

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------------------------------

NASA: Split Lock Washers Are "Useless"!

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Roger Bogrash

Published Aug 30, 2019

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"I know we have a problem with loosening but I don't understand why...we use split lock washers everywhere".

This is not the first time I've had this conversation with an engineer, customer or even an experienced distributor. Engineers know a lot especially in their field but they don't always understand everything when it comes to fasteners - so when a bolted joint comes loose and they are using a DIN, ASTM or other standard "locking fastener" they scratch their heads.

I get it, its effectively a spring and pushes against both the nut and/or bolt and the work surface or flat washer placed on the work surface. The force it exerts on the work part(s), the axial load and the sharp edges of the cuts in the washer, that will surely prevent loosening - well, not really.

So often I talk to engineers and explain that there are many factors that contribute to loosening, and until that conversation the logic is - lets just throw on something that is called a lock washer and let it do exactly that, be a washer that provides locking. Well, there's your problem -?they don't work! Don't take my word for it, here is NASA concluding they do not help prevent loosening and they have known about this for decades!?

“The typical helical spring washer … serves as a spring while the bolt is being tightened.?However, the washer is normally flat by the time the bolt is fully torqued. At this time it is?equivalent to a solid flat washer, and its locking ability is nonexistent.In summary, a?lockwasher of this type is useless for locking.”

??-?

NASA, these are the brilliant minds that send people into outer space. They put the lives of astronauts on the line and the futures of their families into darkness if things go wrong - because if something goes wrong, it really goes wrong BIG. It would make sense that they would invest time and money into making sure that every nut, bolt and washer is up to spec and does what it is supposed to do because they simply cannot afford an accident or a maybe.

Yes they are cheap but how does that help solve a problem if they don't work? There are a lot of locking fasteners out there; lock washers, lock nuts, thread lockers, pins, welds and others - how do you choose something that works for you and how do you know it will work in solving your problem?

First off, please do not use split lock washers to prevent loosening - don't.

The next step is to do your own research, understand the pros and cons of each option. There is no perfect solution, some locking fasteners work in some applications but not in others - for example you would want to avoid serrated washers in areas with extensive and repeated impact shock or substantial settling in the work part(s) or surface, but they might be fine for no or low vibration applications without impact shock or settling.

Talk to the company you are considering and of course they will tell you the benefits but, always try to understand the downsides or limits of each option - when is this option NOT suitable or when will it NOT work. This simple piece of advice most companies do not follow is a major reason split-lock washers are sold in in enormous quantities to end users that simply don't know any better.

Parameters to keep in mind when choosing a locking fastener are:

  • Maintenance: Will this require a lot of regular replacement or repeated re-torquing. Is this a locking fastener that is known to come loose over time or has it been tested to stay secure even under vibration?
  • Time: How long will this product last? How long does the installation/disassembly take?
  • Effectiveness and Performance: Will it actually work in YOUR application? Will it work in the specific type of vibration you are dealing with and do you know what the different types of vibration are? Does the guy selling you fasteners know?
  • Cause Of The Problem(s): Do you fully understand what is causing loosening in your joint and what result actually matters to you? Are you speaking with someone that can answer that?

Split lock washers are a discussion I've had many times, yet it never seems to go away. I have seen them used just about everywhere, I've found them coming loose in the gym, on bridges, tractors, mining equipment the list goes on. With time they will hopefully be used less and less, but in the meantime - be cautious.

If you found the above helpful, feel free to share it and leave a like or comment to let me know. To be notified of future articles, you are welcome to follow me and if you have questions or need input relating to this topic, feel free to contact me.

Written by Roger Bogrash, Director of Business Development @??Locking Fasteners

-----------------

The NASA report on fasteners can be found at:

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I doubt if most of us have to worry about nuts and bolts loosening due to vibration, but you never know.

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We solved our problem with a nut with a an internal nylon insert and replace the nut every time it is removed.

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