Subject: Re: Washers-when to use and when not

From: Buddy Randolph <[email-masked]>
Date: Wed, 03 Jul 1996 10:10:15 -0400

Bernielama wrote:
> 
> This may seem like a dumb question... <snip>

Threaded fasteners are in fact "machines" that consume a lot of 
engineering effort in critical applications, and your questions are 
certainly not dumb.

> Is there a "proper" situation to use a
> washer? <snip>

Flat washers are used to distribute the load over a greater surface 
area and/or to help protect the part finish from a bolt head or nut.

> <snip>...a bolt is used to
> fasten a piece of sheet metal to a  piece of steel tubing which has a hole
> drilled through a flattened end. Does it matter which side the nut is on...<snip>...
> and should I use a washer on the
> "nut side", the "bolt side", or both sides?...<snip>...does it matter whether I apply torque to the nut or the bolt...?

First the second question: it's better to hold the bolt and turn the 
nut, because bolts generally offer more resistance due to additional 
friction where they touch the part.  There's also the wind-up of the 
bolt as it responds to the torque, but I believe this is the same 
regardless of which is turned (comments, anyone?).  Given that the nut 
is turned a washer under the nut would help keep the nut corners from 
scarring the part during turning, thus reducing the resistance due to 
this interference (assuming the flat washer spinning against the part 
offers less).  A washer under the bolt head would do the same but 
might not be desired with heavy stock and a proper hole size, because 
the bolthead corners would help hold the bolt in place as they dug in 
and didn't turn.  This leads to the first question: heavy pieces that 
can take this bolt-head pressure and don't need a washer to distribute 
the load are often placed directly against the bolt head, with lighter 
stock protected from scarring and tearout by the washer under the nut.  
Haven't mentioned lock washers, etc. but that's for another post.  
Hope this helps.   --Buddy

---

From: [email-masked] (Bernielama)
Date: 3 Jul 1996 00:38:37 -0400

This may seem like a dumb question but I haven't found a definitive answer
in the FAQ for this newsgroup: Is there a "proper" situation to use a
washer? Is there ever a situation when one should not use a washer?

Here's a hypothetical: There is a typical "joint" where a bolt is used to
fasten a piece of sheet metal to a  piece of steel tubing which has a hole
drilled through a flattened end. Does it matter which side the nut is on
(touching the sheet metal or the tubing?) and should I use a washer on the
"nut side", the "bolt side", or both sides? Or am I just contemplating a
silly question and it really doesn't matter at all.

Also, does it matter whether I apply torque to the nut or the bolt (via a
wrench/rachet/etc)?