Home Depot 1/4" Lag Screw

[JoeSpareBedroom]

That really depends on how they're run by the individual owners. The one I use is pretty remarkable.

[JoeSpareBedroom]

I have tried it. It's a non-event.

How far out of your way would you be willing to drive, in order to avoid having to turn your steering wheel in certain ways because of the way a parking lot was designed?

[The Ranger]

Are you kidding?! Wait for warmer weather? Spawn's one of them-thar polar b'ahrs. She loves the Pacific in winter.

The Ranger

[dpb]

The point is to have a larger pilot-hole in softer woods than hardwood to minimize the effort of installation but to ensure a full bite which can be marginal if use a full root diameter for pilot, particularly in softwoods that tend often to "crumble".

No claim made (at least by me) that there's any _precise_ ratio other than the aforementioned bigger/smaller based on the material.

I'd still wager there is some information at US FPL but I've not taken time to search for it.

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[notbob]

Hmmm....

Seems like it would be the opposite, the softer wood requiring a smaller pilot hole for more compression in surrounding wood to "ensure" a solid bite in a wood that tends to "crumble".

nb

[J. Clarke]

It's in "Wood As An Engineering Material", Page 7-11. What they say is:

"For low-density softwoods, such as the cedars and white pines, 40% to 70% of the shank diameter; for Douglas-fir and Southern Pine, 60% to 75%; and for dense hardwoods, such as oaks, 65% to 85%. The smaller percentage in each range applies to lag screws of the smaller diameters and the larger percentage to lag screws of larger diameters."

[Jon Danniken]

Excellent reference, J. Thank you for posting that, it is very much appreciated!

The lag bolt which snapped off had an average shank diameter of 0.182". Sixty percent of this value is 0.1092, while seventy five percent of this value is 0.1365, which puts a pilot bit of 1/8" right in the middle.

Jon

[JoeSpareBedroom]

Your usual vehicle is a long van?

[dpb]

Mea culpa...yes, that was inadvertent swap of the intent I didn't catch... :( sorry.

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[dpb]

...

Indeed...thanks for saving me the effort... :)

Now if I just hadn't made the swap of sense in the relative sizes... :(

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[Tom Watson]

What do you mean by "shank diameter"?

Machinery's Handbook lists the "body" or "shoulder" diameter of a 1/4" lag bolt as between .237" and .260". This is the area that is not threaded.

The "root diameter" is listed as .173". This is the diameter of the remaining cylinder after the threads are formed.

(American National Standard Square Lag Screws - ANSI/ASME B18.2.1-1996)

Regards,

Tom Watson

[Jon Danniken]

Thanks Tom, I should have said the root diameter.

Jon

[Leon]

I wonder if that material was written in modern years or 30 plus. I see lag screw failures galore.

[Leon]

BUT Jon,,,,,, While it is a kewl reference that agrees with what you were using as a pilot hole, how did that work out for you?

The information could be out dated for readily available fasteners today. If might be a new publication using old data.

[Jon Danniken]

It works out great, Leon, once I purchased lag bolts that weren't from the bulk bin at Home Depot. The bolts are currently holding up a home-made welded bracket, which in turn is holding up my bathroom sink.

The sink itself weighs maybe 20 or 30 pounds, so I tested the bracket by holding myself up with it, and it didn't budge.

Jon

[J. Clarke]

The numbers are based on maximizing holding power, not making a crap fastener survive being driven. They state the assumptions, which are 35,000 PSI yield and 77,000 PSI UTS, slightly higher than required for a Grade 1 bolt.

[J. Clarke]

Are you saying that the properties of wood have changed so radically in the last 30 years that lag screws hold differently in them now? Because the recommendations are not about allowing you to use crap screws without breaking them while driving, they are about sticking wood together so it stays stuck.

[Robert Bonomi]

Quite obviously, HD customers that don't know better.

[Robert Bonomi]

That depends on the store. I've got a couple of _very_good_ hardware stores that happen to be part of the ACE co-op nearby. And a first class one that joined up with TruValue. They've got people that -know- what they're talking about, _and_ carry a lot of stuff that is not the Ace/TruValue house label.

[krw]

KeithW and krw are the same person. Well, as much as anyone at home and work can be the same. ;-)

Too easy.