UHMW Block / Bolt / Washer Q

[flydjd]

Hi all,

I did a quick search but no joy....

With ref to the external step installation each 6A/7A/9A step kit comes with a AN3-25A bolt to pass through the UHMW block and Wd-657.
Washers are supplied (AN960-10's) but the drawings do not show any washers used with the bolts.
My understanding is that it is good practice to use washers as a bearing surface for the bolt head and nut.

My UHMW blocks are the correct width (2.375 " according to the drawings dated 6-16-92) but the supplied washers will not allow the necessary 1 to 2 threads of the AN3-25A bolt protruding from the nut.

A single AN960-10L washer under the nut would give 1 thread protrusion for this particular bolt.

Is this an acceptable solution ? (I would prefer to avoid ordering a couple of longer bolts ! )
Do UHMW blocks need washers at all ? - as the surface seems to allow rotation without damage unlike metal to metal.
As an aside do bolt and nut torque values change according to the material being clamped or only according to the bolt/nut type ?

[az_gila]

...is sort of soft, I prefer washers at both ends.

I just put a very shallow counter bore in at one end so that the bolt length would be correct.