General > General Technical Chat
Solder dots around mounting hole - what are they for?
wraper:
--- Quote from: thm_w on October 26, 2023, 09:17:37 pm ---They work better than a plain washer, that NASA quote is a bit deceiving. They still don't work that well though (skip to 1:40)
--- End quote ---
Initially it lost tension almost as fast as with plain washer, it's only total loss of tension that took a bit more time. So it does not prevent unscrewing any better than plain washer, it just delays total failure.
Someone:
--- Quote from: VK3DRB on October 26, 2023, 09:53:25 pm ---It is a safety requirement in Australia that earthed chassis terminals have a nyloc nut securing the earth wire to the chassis and NO star washer between the lug and the chassis.
--- End quote ---
Citation of that requirement? Doesnt seem to appear in the usual suspects.
thm_w:
--- Quote from: wraper on October 26, 2023, 11:34:03 pm ---
--- Quote from: thm_w on October 26, 2023, 09:17:37 pm ---They work better than a plain washer, that NASA quote is a bit deceiving. They still don't work that well though (skip to 1:40)
--- End quote ---
Initially it lost tension almost as fast as with plain washer, it's only total loss of tension that took a bit more time. So it does not prevent unscrewing any better than plain washer, it just delays total failure.
--- End quote ---
Delaying failure means its better than a plain washer... Everything in the test other than the nordlock delayed failure, including the nyloc.
Of course this test was optimized to some level of vibration, and in other scenarios you won't have as much as this test, and the split washer may survive while a plain washer would fail.
nctnico:
IMHO the Nord-lock video is doctored. Just look at a car and how many bolts are put into the engine block alone without a washer and they won't run lose when torqued (and some bolts do not require a lot of torque; like 40Nm to 60Nm ) to spec. It is just a matter of good engineering. What kind of worried me on my previous car where the 6x M6 bolts holding the crank shaft pulley in place while needing like 40Nm of torque on each bolt. They never ran lose though.
thm_w:
Its an official test: DIN 65151, the bolt is hit directly with shear load vibration. They show initial preload is 75Kn, I guess that is M12 bolt? then it would be 180Nm of tightening torque.
If you have a setup with enough clamping force to prevent sliding movement, the bolt shouldn't easily loosen: https://www.boltscience.com/pages/vibloose.htm
In the case of your crank shaft pulley, I assume its balanced well, and the forces are opposing each other, that the shear load on those bolts is minimal. But yeah, not all automotive fasteners will have loctite or washers at all, surprising to me too.
Here is another example:
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