Washer bore sizes

[Parlo]

Does anyone know why there is clearance in the bore of a washer? There is nothing worse than the washer not concentric with the screw head on assembly.

 

[mmcmdl]

The bolt wouldn't go thru the washer if there were no clearance .

 

[Parlo]

The bolt wouldn't go thru the washer if there were no clearance .

I meant that there is an unneccessary amount of clearance. Even if the hole was dead size, bolts are under nominal anyway.

 

[DAT510]

Standard Metric Flat Washer Dimensions Sizes Chart

amesweb.info

 

[Parlo]

Standard Metric Flat Washer Dimensions Sizes Chart

amesweb.info

Thanks, you can see that the M12 for example has 1mm to 1.27mm unneccessary clearance. To me that is far too much.

 

[mmcmdl]

You can always make your own own custom washers if needed if the lack of concentricity is an issue .

 

[Parlo]

I just don't see the need for so much clearance, there must be a reason.

 

[RJSakowski]

I will usually go one screw size smaller for a closer fit.

 

[Parlo]

I will usually go one screw size smaller for a closer fit.

Good idea, unfortunately it does not work in metric.

 

[DAT510]

I actually believe the larger clearance you are referring to, may be for the Bolt head to Washer interface vs Nut to Washer interface. Proper bolts are radiused at the head to shaft junction. Those radius are called out by standards. Since it's not a 90 degree corner, clearance will be needed allow the bolt head to properly seat flat against the washer vs hanging up on the radius.

Given it would double the sizes, if there were washers for the bolt head and different washers for the nut end, my guess is they went with the "larger" size for both.