Lags vs. Timberloks [RE-wrenches]

[mlafferty at universalenergies.com]

Jeff C Wrote:

> My carpenter buddy says I should try TimberlokR 
fasteners instead of lags.  Anyone have any 
experience with them?

Supposedly they do not need predrilling, 
supposedly have 725 lbs/in pullout strength are 
lubricated for driving with low rpm drill are way 
cheaper - have black epoxy coating.

All:

I have been through the Engineering Evaluation Process, including
physical testing of a couple hundred pieces, with similar or perhaps the
same fasteners as related to mounting applications.

The "Pullout" is indeed strong.  They drive very well generally... At
least for the beginning thread portions.  They are a "hardened" as
opposed to "malleable" product.  

The weekness is in the "Sheer Strength".  Heads snap off.  It is a royal
pain when you have a headless shank sticking up above your intended
stopping point!  Especially in a tight spot!  

They are designed for Wood to Wood connections.  They have a very narrow
shank cross-section. Their design is such that they bury the head into
the "top piece".  One characteristic of this app that makes this
acceptable and seldom "snaps the head off", is that the wood is soft
enough (generally intended for timber or deck attachments) to allow them
to do so.  When driving into seasoned wood, like those trusses and
rafters we are attaching to, the "snap ratio" goes, well, through the
roof!  

Another difficulty encountered was "twisting out the side" and knots.
Due to their narrow shank the heat builds rapidly as you drive it into a
seasoned piece of wood.  This reduces some of the temper and they
"curve" in a curly-grained piece of wood. The exposed shank is unheated
at this point so it wants to "move over" or bend on you as you drive it.
This caused either a Stop-and-try-to-get-it-back-out or a Snap in most
cases.

The Engineering didn't calc satisfactorily when looking at the Metal to
Metal Sheer factor, either, by the way.

As a note, when I first looked at them, my initial observation was that
the skinny shank and small diameter of the built-in washerhead, wouldn't
"fill up" the pre-drilled holes in a mounting foot.  This would create a
potential for "sliding around" if the fastener was either not totally
tight or as the roof changed due to thermodynamics.  They required
stacking of two different washer sizes in order to adequately cover and
secure a 3/8" hole, but still didn't address the "slipping" factor
associated with the foot hole to shank diameter difference.

I personally believe that they are an excellent product for their
intended purpose, but not that "Oh, Boy!  I found my Dream Bolt!" for
bolting Glass to Roofs!

Two Cents!

Matt Lafferty
Universal Energies Institute
mlafferty at universalenergies.com
(916) 422-9772
(916) 628-7694 Cell
(916) 914-2247 Fax
www.universalenergies.com

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