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Obtaining Old Reference - Torque Capacity Hex Features

Obtaining Old Reference - Torque Capacity Hex Features

Obtaining Old Reference - Torque Capacity Hex Features

thread404-200026: Hex torque strength

Can anyone tell me how to get a copy of the old:
CASE, G.S. "Stresses on bolts-nut dimensions-wrench design, Mechanical Engineering, Sept 1927, pp919-925.

I would like to see if there is any additional treatment of the geometry fit factor CH in the torque equation


Believe it or not, we use hex features, in range of 7-16 inches width across flats, to torque drive large horizontal process vessel agitators, and it works remarkably (almost unbelievably) well.  However, I am trying to make some quantiative sense out of the design evolution.  Prior to finding this relation, we had been using only exotic (and perhaps useless) non-linear ANSYS analysis.


RE: Obtaining Old Reference - Torque Capacity Hex Features

If a local library archive does not have the volume you are looking for, the best and easiest is to request the article from the Linda Hall Library:


I have used their document service a number of times. IT IS GREAT.  They have access to A LOT of technical/scientific "stuff".  I recall that their usual turnaround time is only 48 hours for a document to scan and email, but you can get it even quicker for an additional cost.

RE: Obtaining Old Reference - Torque Capacity Hex Features

I wrote the post showing that article.  I got my copy from the University of Michigan library.  I think the Linda Hall library should have it and that would be my first call if I were you.

RE: Obtaining Old Reference - Torque Capacity Hex Features

Thanks guys...good info to have.

CoryPad:  Before I launch into aquisition mode, do you remember if the article had any additional details that would be useful to purpose, or did it just baldly state equation?

Thanks again

RE: Obtaining Old Reference - Torque Capacity Hex Features

Checkout the HK Technical manual for the capacity of the alloy hex screw s and then checkout the capacity of the driver at the Bondhus site.  Note the difference in key capacities.
A hex key will never strip out an alloy screw.  The most probable cause of failure will be the the hex key will cam out and if you can keep the key engaged it will twist or break. A point to remember is that the hex key becomes ineffective as a wrench at fastener strength levels starting around 180,000 psi.  





RE: Obtaining Old Reference - Torque Capacity Hex Features


I have that article in a moving box somewhere (changed employers after I posted that), so I don't have it handy to look at.  I seem to recall it had more than the equation - it had actual data and an empirical fit.  The cost should be ≤ 30 USD, so it should be worth the effort, regardless.

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