Slocumotion
Member
And in general, other than shakeproof and large diameter load spreaders , what are they actually doing?
Flat washer under shakeproof -what does that achieve?
- Thread starter Slocumotion
- Start date
pvb
Well-known member
A flat washer under a shakeproof washer effectively negates the point of fitting a shakeproof.
Lon nan Gruagach
Active member
Thats what I think. But all BBC rack mount equipment is secured with flat washer under shakeproof.
Plum
Well-known member
Unless you are fastening a non metalic/compressible component or bolting through a slotted hole there is no benefit from a flat washer and if then the bolt is tightened correctly there is no benefit from a shakeproof washer. If you take apart a modern car/engine you it will be rare to find any washers at all in these types of joints. Bolting plastic type materials is different .
Www.solocoastalsailing.co.uk
Www.solocoastalsailing.co.uk
<152587>
...
This thread just about sums up the engineering knowledge on here. Nixt, zilch, none, aucun. And the shameful part is that you all purport to advise on subjects to novices.
Lon nan Gruagach
Active member
Are you going to provide some useful information or just slag everyone off, even if some of the posts are open question about what had been presented as best practice by very qualified engineers?
<152587>
...
Because it is specified by engineers who know their subject.
Lon nan Gruagach
Active member
Good. So, to maybe answer the OP, Why?
What benefit does flat under shakeproof washer provide?
<152587>
...
You come over as an experienced engineer, as such you shouldn't need me to educate you. Lets hear it from you. Judging from your post #3 you aint got a clue. Subject closed.
Lon nan Gruagach
Active member
Yes, I am experienced. Experienced enough to know that I don't know everything. In cases where I don't know, I happily use methods and systems designed by those that do. Every once in a while I see a casual opportunity to find out. This appeared to be one of those.
As far as you are concerned it seems I was wrong.
So, on this particular subject I'll carry on implementing what is specified.
CLB
Well-known member
Ok, but what about the rest of us? You have an opportunity to educate those that are interested and not experienced.
Richard10002
Well-known member
Your contribution only serves to add to the lack of knowledge you suggest... Why are you here?
lw395
Well-known member
A spring washer keeps the bolt under tension, even if the joint moves, the bolt stretches a little, temperature etc.
So the nut is much less likely to come undone.
The flat washer has a bigger radius than the spring washer, so has more friction against the base material than it does against the spring washer. It's unlikely to rotate. It's there to avoid damaging softer metal base material usually, or to spread the load, or to provide a regular surface for the shakeproof washer to work on. E.g. if the surface of the base part is not machined.
So the nut is much less likely to come undone.
The flat washer has a bigger radius than the spring washer, so has more friction against the base material than it does against the spring washer. It's unlikely to rotate. It's there to avoid damaging softer metal base material usually, or to spread the load, or to provide a regular surface for the shakeproof washer to work on. E.g. if the surface of the base part is not machined.
reeac
Well-known member
My observation is that the ends of the spring washer dig in slightly so giving some locking although the compressive compliance does also tend to maintain the compression in the event that something stetches a bit. I don't know about modern car engines ...haven't rebuilt one since 1982 although that one's still running well.
pagoda
Active member
+1
Modern car nuts often have a built in flange (AKA flat washer) to spread the load on the base material. The nuts also are frequently self locking (use once versions)
paulajayne
Active member
Question was shake proof washer not spring.
A flat washer under a shake proof negates the advantage of a shake proof.
So it is poor engineering to fit like this.
macd
Active member
That neatly sums up your contribution to the sum of knowledge. Anything else?
greeny
Well-known member
The flat washer has a bigger radius than the spring washer, so has more friction against the base material than it does against the spring washer. It's unlikely to rotate. It's there to avoid damaging softer metal base material usually, or to spread the load, or to provide a regular surface for the shakeproof washer to work on. E.g. if the surface of the base part is not machined.[/QUOTE]
I'll hang my hat on this being the reason. Fine if the base material is soft plastic or irregular surface there's good reason for the larger flat washer. Too often I've seen them fitted in circumstances where i would not consider them advantageous and may even increase the likelihood of the fastening becoming loose.
I'll now brace myself for the broadside from "third engines" when he tells us the real reason. hehe.
I'll hang my hat on this being the reason. Fine if the base material is soft plastic or irregular surface there's good reason for the larger flat washer. Too often I've seen them fitted in circumstances where i would not consider them advantageous and may even increase the likelihood of the fastening becoming loose.
I'll now brace myself for the broadside from "third engines" when he tells us the real reason. hehe.
D
Deleted member 36384
Guest
What’s a shake proof washer? There are many types and some are used with washers, some not. RFI.
Go to www.dropsonline.org and download reliable securing. Spring washers are shit.
Go to www.dropsonline.org and download reliable securing. Spring washers are shit.
Last edited by a moderator:
lw395
Well-known member
There are many sorts of 'shakeproof' washer and many engineering problems.
There are times when proper engineers who know what they are doing, specify a flat washer with some sort of shakeproof under the nut.
Many types of serrated shakeproof washers are made of spring steel and work as diaphragm springs.
If you've ever had trouble getting a product through qualification, including vibration testing, you'd know that some things are counter-intuitive.
