wrench flats dimension question 2

[USAeng]

example:
machinist handbook shows max width across flats of nut... pick a 13/16 (.8125) nut and you have wrench opening of .818-.826. So I would call out wrench flats to be about .810 which is approx 13/16 which would have +-.005 on our part so wrench would fit ok... that's what I would do right now with my interpretation of the book...

is this a good way to do it? say if I pick a 5/32 wrench flat... then there is less between the max width of nut and minimum wrench opening --> so the handbook shows 5/32 nut to have a corresponding .158-.163 wrench opening. I would pick .151 +-.005 for wrench flats.... but this is much greater difference in comparison.... so maybe in this case one should pick .156 +.000-.005 for the flats?

thoughts? any general rules of thumb or maybe just a chart? if there is no chart or general rules- I was just going to make my own for every standard size. Thank you

 

[MintJulep]

Why not just use the dimensional limits for standard nuts?

 

[USAeng]

I thought about it... but wouldnt that create a possibility of coming up short since our tolerances are +-.005 for three decimal dimensions.... say 13/16 we come up at .8125 and we go with .813 then we end up .818 which is the low side of the tolerance for a box wrench according to the handbook... or on the smaller side for the 5/32 flat we go with .156 as the flat dimension and so our machinist makes it .161 which is .003 over the minimum wrench opening.

So should one simply make every wrench flat dimension equal to the max nut dimension given in the handbook and have +.000 -.005? That would seem to work, but what makes sense?

 

[hydtools]

Use min/max dimensions rather than the single dimension with your +-.005.

Ted

 

[MintJulep]

but wouldnt that create a possibility of coming up short since our tolerances are +-.005 for three decimal dimensions

What relationship to your "default" title block tolerances have to the functionality of nut and wrench dimensions? Apparently none.

Tolerances should be determined by functional requirements, not whatever happens to be in the standard title block.

what makes sense?

Using the established dimensional limits for nuts that are known to work just fine with wrenches.

 

[USAeng]

shoot... I was thinking about it just using the wrench opening table. I should have been using the nut/bolt tables and looked at width across flats. Thank you