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Effective Threaded Hole Depth

Effective Threaded Hole Depth

Effective Threaded Hole Depth

(OP)
Is here a quick reference to effective threaded (tapped) hole depth? I realize this may be dependant on the grade of bolt used, pitch etc. Just looking for a quick reference or formula that may give some understanding.

Thanks!

RE: Effective Threaded Hole Depth

Hi Fairway

I very often use thread depth = 1.5 X bolt dia
usually for steels, as you say if it was a soft material
it may be 3 or 4 times bolt dia.

regards

desertfox

RE: Effective Threaded Hole Depth

As DF says 1.5 X bolt dia is rough rule of thumb for non critical (or whatever phrase covers it) threaded holes.

Sometimes expressed as 1 to 2 X diameter of bolt.

However, this is reall rule of thumb stuff.

KENAT, probably the least qualified checker you'll ever meet...

RE: Effective Threaded Hole Depth

(OP)
Thanks team. I always new the "rule of thumb, just looking for simple way or reference to validate it.

Thanks again!

RE: Effective Threaded Hole Depth

fairway,

Another opinion:  I always use the 2X bolt diameter that my CAD program (Solidworks) defaults to.  The 1.5X rule of thumb is based on the typical strength of threads and is a bolt engagement rule, not a tap depth rule.  Going to 2X usually means I can find a standard length bolt that gets at least 1.5x engagement in the hole.   

Timelord

RE: Effective Threaded Hole Depth

Good point Timlord, it's the engagement that's important.  The hole length just needs to be deep enough to accomodate this allowing for tolerances.

I always work back from my fastener & material thickness to work out my hole dept then normally round up to the next 'round' number and make it a "min full thread" call out.

As to validating it, I believe there have been threads (no pun intended) about that before, if not on this forum then maybe forum725: Welding, Bonding & Fastener engineering.  As I recall it my old stress man used to talk about the first few threads taking most of the load...

KENAT, probably the least qualified checker you'll ever meet...

RE: Effective Threaded Hole Depth

Hi Timelord

I read effective thread as meaning thread engagement.

Regards

desertfox

RE: Effective Threaded Hole Depth

As a machinist, keep in mind that regular taps have a tapered start, and need room at the bottom of the hole for chips. You don't want the tap bottoming out, you might break it. A bottom tap will finish off a hole deeper, but it's another step, and bottom taps dull quicker, and are even more sensitive to bottoming out.

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