Lock Washers, Internal and External

[idy]

Lock washers seem to help keep pots and jacks tight and in place. Best practices for inside/outside teeth? Seems like either works...

[Ice-9]

I prefer inside as outside looks bad and can damage paintwork. Inside is good for biting into an unpainted (on the inside) enclosure and creating a good grounding point.

[davent]

Inside teeth as outside teeth sometimes end up with nothing to bite into on a pot, jack or switch, there's a narrow shoulder between the part body and the threads.
dave

[PRR]

https://www.engineersedge.com/wwwboard/posts/18149.html
'....internal versus external it is application dependent. Usually an external is used for plastic materials to spread the locking load and engagement "cuts" over a wider area.
'With the external one, the screw head has to be as large as the washer and that is not always desirable or possible. Often the internal one can present a better "look" as it is nice and round, smooth and flat from an outside view.
'With the internal one the clearance hole for the screw has to be quite tight in the base material otherwise there is good locking to the screw but poor locking to the base material. This is what lead to the internal/external type Kelly pointed out. The external locks to the plastic, the internal to the screw head.'
---------------
https://en.wikipedia.org/wiki/Washer_(hardware)#Spring_and_locking_washers
'The internal style has the serrations along the inner edge of the washer, which makes them more aesthetically pleasing. The external style has the serrations around the outer edge, which provides better holding power, because of the greater circumference. The combination style has serrations about both edges, for maximum holding power.'
--------------
https://www.garagejournal.com/forum/showthread.php?t=149672
'Well the internal one looks better when fastened together, they also have less digging in surface area. The external ones have more grip area but they can be "unsightly" when in use with the little tentacles sticking out.'
but
'Toothed (both internal and external) are designed for electrical conductivity, not for locking purposes. Typically found on ground screws, though can be used on any type of terminals that have screws or nuts.'
'There is no difference in either washer. They are equally worthless.'
--------------
https://forum.digikey.com/t/types-of-lock-washers-and-their-uses/930
'Internal Tooth- Internal tooth have teeth on the inner dimension of the washer and the outside of the washer is smooth. They are made for fasteners who have a smaller head. When the head is fastened into the hole the internal teeth will help grab the surface, while at the same time resisting against the force of the washer being compressed.
'External Tooth- External tooth have teeth on the outer dimension of the washer so that they can actually bite into the surface that it is put on, and the inside is still a cylindrical hole. They are designed for fasteners who have a bigger head. When the head is fastened into the hole the external teeth will help grab the surface, while at the same time resisting against the force of the washer being compressed.'
--------------
http://www.boltscience.com/pages/vibloose.htm

[thermionix]

Internal tooth, inside the enclosure.  I use them whenever I can, sometimes there isn't enough room though.

[idy]

I was pretty clear about "inside the enclosure." Thanks. I have noticed the issue of a "shoulder" on the pots. Pots and Jacks would act like "large headed" fasteners I guess.

[amptramp]

For jacks, the long frame style has a mounting screw so nothing can rotate.



Maybe not the choice for a 1590A but this is still a usable idea for anything larger.  This one is made by Switchcraft.

For pots, there is often an anti-rotation tab that can be used to relieve the stress on the mounting lockwasher and the internally toothed one would be sufficient for most purposes.

[davent]

For jacks, the long frame style has a mounting screw so nothing can rotate.



Maybe not the choice for a 1590A but this is still a usable idea for anything larger.  This one is made by Switchcraft.

For pots, there is often an anti-rotation tab that can be used to relieve the stress on the mounting lockwasher and the internally toothed one would be sufficient for most purposes.

... but you better hurry, Mouser only has sixteen in stock and none on order.

https://ca.mouser.com/ProductDetail/Switchcraft/MT332BX?qs=sGAEpiMZZMv0W4pxf2HiV5%2F%252bkl46h%2F2G65ibJBgvXcA%3D

dave