Spherical Washers

[Mike Walsh]

Hello

I'm working through some machine issues using spherical washers, and there is some interest in the required orientation for the washer set.

Machine documentation shows that the nut should go on the flat surface of the convex part, and the flat surface of the concave part should go against the clamping surface (machine).

Can anyone help me understand if there is a reason for said orientation or does it not matter?

appreciate any help anyone can offer.

Thanks!
Mike Walsh

[arborist]

I do not know the answer to your question, but was interested to find that for DIN standard items, the concave part is conical (a 120 degree countersink) rather than spherical.

https://www.kipp.com/gb/en/Products/Ope ... ition.html

I think I have seen nuts where the convex spherical seat is part of the nut itself rather than a separate item. In that case, you would have no option with regards to orientation.

[Bill Shields]

the assumption (from my learning) is they are installed that way on the off chance that the nut may be smaller than the OD of the washer...

and that NOBODY would be stupid enough to put the washer down on a surface too small to support the OD....

[Rick]

download.png (13.34 KiB) Viewed 82 times

If you look at the assembly above you will see that the bolt is constrained from rocking in the lower machine element. In this case a nut on the end of the bolt or if the lower machine element it tapped either assembly method will prevent the bolt from rocking. The bolt is perpendicular to the lower machine element and should not rock or be put in a bending load. The pivot point for the spherical washer is up near the top of the bolt head in the picture, so the concave half of the washer is what pivots to handle the "un-parallel" top surface. The concave half of the washer has a larger thru hole to clear the bolt diameter as it pivots. The top convex section doesn't pivot due to it is constrained by the bolt head in this case or nut depending on how the assembly is designed. The thru hole of the convex half will be a closer fit to the bolt diameter since it doesn't pivot.
Hope this makes sense

[arborist]

The concave half of the washer has a larger thru hole to clear the bolt diameter as it pivots.

Please could you give a source for the diagram you show and check the figures in any accompanying table of dimensions.

On the Kipp page above, the bore of both concave and convex is denoted D1, and is identical.

[Rick]

Sorry for the confusion, I went back and took another look. It seems that ones for smaller bolt sizes have same ID and larger bolt sizes have different ID's. All the ones I have used are like my description, never payed attention to the smaller ones. If the angle (non parallel surfaces) is small it really shouldn't matter about orientation if there is enough clearance between the bolt and ID so as not to bind up.

The main concept/point I was trying to make is that its the half that is against the angled machine surface that's going to shift, that's the one that the bolt to ID clearance needs to be verified to not bind up on the bolt.

The diagram I just got off of the internet. The ones McMaster Carr sells in the link below have the same ID for under 1" bolts and different IDs for above 1" bolts

https://www.mcmaster.com/products/washe ... spherical/