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bolts & washers
bodger - 26/4/07 at 02:22 PM

When is it considered good engineering practice to put a washer under the bolt head & when should you leave it off ?


Bluemoon - 26/4/07 at 02:24 PM

You should use one on the bolt/nut that is to be turned durring tightening.

Dan

[Edited on 26/4/07 by Bluemoon]


locoboy - 26/4/07 at 02:28 PM

Is that simply to stop the turning bit wearing away the thing your clamping with the nut/bolt?

I put them on the bit im tightening but only because it stops my socket or spanner taking the paint off the thing im clamping..........is that good enough engineering practice for you


Bluemoon - 26/4/07 at 02:34 PM

No sure locoboy I guess it's to ensure that the coefficent of friction is the same/predictable so you can torque them up correctly? Anyhow this method also stops the paint comming off as you say!

Dan


gazza285 - 26/4/07 at 02:39 PM

Make sure that the washers are the right way round too. They usually go under the nut as it is the nut that should be turned. If you turn the bolt then you risk thread damage is it is binding anywhere. Unless it is a blind hole, then it depends on what you are tightening and how accurately you want the bolt torque to be as washers can lead to false torque readings.

Simple eh?


Mal - 26/4/07 at 03:05 PM

I agree with the previous comments if a bolt is clamping rigid metal parts, but washers also serve to spread load when clamping weaker or deformable materials, such as sheet aluminium, GRP, other plastics or wood.

Mal


designer - 26/4/07 at 03:06 PM

Unless the bolts have special heads - always use a washer.


BenB - 26/4/07 at 03:22 PM

Put them under both, only turn the nut not the washer...

Belt and braces


02GF74 - 26/4/07 at 03:39 PM

quote:
Originally posted by designer
Unless the bolts have special heads - always use a washer.


hmmm, crossflow engines cyclinder head bolts don't have washers nor do the heads look special ????


Bluemoon - 26/4/07 at 04:40 PM

As is maybe but ford will have don repeated tests to find the correct torque setting for this combination of head/bolt...


ScotJebus - 26/4/07 at 05:38 PM

since they are proberly strech bolts a washer would mess with the strecheness? id say use washers to spread the load protect what is being scrwed into and so that they look nicer!