There are four main styles of
available in a variety of sizes and finishes:
These fittings are very versatile and are designed to be inserted through
a hole and secured on the back side with the provided nut. Regular eye
bolts have a working load limit which should be taken into consideration
when used for lifting or supporting an overhead load. They are designed
for straight line loading only, and can bend and break if loaded at
Shoulder eye bolts have a supporting shoulder that allows them to be
loaded at slight angles, if properly installed. These fittings are very
versatile and are designed to be inserted through a hole and secured on
the back side with the provided nut. Its working load limit should be
taken into consideration when used for lifting or supporting an overhead
Lag eye bolts have threads designed to screw into wood. They don’t have
a working load limit because their strength is dependent on the species
and condition of the wood it is screwed into. For example: A lag eye
bolt will hold more load when screwed into a new oak board, compared to
an old pine fence post.
Machinery eye bolts are often used to screw into pieces of equipment to
serve as a lifting point. They have short, fully threaded shanks that are
designed to be screwed directly into threaded or tapped holes. These
fittings have a shoulder allowing for lifting at slight angles, and a
listed working load limit.
The size designation for eye bolts are common across all types.
This is a ½” x 6" shoulder eye bolt and a ½” x 6" Stainless steel lag eye
The ½” measurement references the diameter of the shank.
The 6” measurement refers to the length of the shank.
The larger the diameter of the shank, the larger the working load limit. A
longer shank length allows you to go through thicker objects. The threaded
portion varies for each eye bolt, so visit our website if you need more
detailed dimensions of our eye bolts.
Strength and Durability from Manufacturing
An indicator for how strong or durable an eye bolt will be is the way it is
manufactured. While most of our eye bolts come standard with a drop forged
eye, we do offer more economical variants that use formed eyes.
Drop forged or cast eyes are recommended for critical applications.
We offer our eye bolts in stainless steel, hot dipped galvanized steel, and
is the most
corrosion resistant and has the best-looking finish.
Oftentimes, loads are applied to eye bolts at an angle and for these types
of applications shoulder eye bolts should only be used.
Loading at an angle can alter the working load limit of the eye bolt.
It is important to note that all eye bolts are designed for loading with the
axis at the center of the eye. They should never be loaded perpendicular to
that axis because they are likely to bend and break.
Working Load Limit Effects due to Angular Loading
The degree of angle of your load can have a big effect on the working load
limit of the eye bolt.
This cable is at 0 degrees. At 0 to 5 degrees, the eye bolt is rated at 100
percent of its working load limit. In this case, the catalog working load
limit of this 3/8th inch eye bolt is 1,550 pounds.
At 15 degrees, the working load limit is reduced by 20% and the effective
working load limit of the eye bolt becomes 1240 pounds, which is 80% of the
original rated capacity.
30 degrees makes for 65% of the original rated capacity.
45 degrees makes for 30% of the original rated capacity.
90 degrees makes for 25 % of the original rated capacity. The 75% reduction
in capacity makes the effective working load limit only 388 lbs.
Because of the effect that angles have on eye bolts and working load limits,
we recommend using swivel hoist rings as an alternative choice. The
advantage to them over eye bolts is that they maintain 100 percent of the
working load limit at any angle from 0 to 90 degrees.
First, determine thickness of what the eye bolt will be going through.
Then, choose an eye bolt with a shank long enough so that the threads
protrude on the back side and allow the nut to be tightened properly.
If the unthreaded portion of the shank protrudes below the bottom surface
and does not allow the nut to be tightened, you can use washers to fill the
space of the unthreaded portion of the shank.
Machinery eye bolts are primarily intended to be installed into tapped
holes. The eye bolts are threaded to UNC standard and the hole needs to be
tapped accordingly to ensure the shoulder will be firmly seated against the
object to be lifted.
When drilling and tapping the hole for the eye bolt, the hole depth should
be the length of the shank plus one half the diameter of the shank.
As mentioned earlier, eye bolts are to be used so that loads are applied
about the axis of the eye.
When installing machinery eye bolts it may be necessary to add washers to
shim the eye bolt to achieve the correct alignment.
We will illustrate this by attaching 4 machinery eye bolts to each corner of
this lifting box. Note that all the eye bolts are NOT “in line.”
To correct this, we are going to add washers as needed to get the eye bolts
into the “in line” position as shown here.
General Safety Precautions
When selecting an eye bolt, it is necessary to know the load that will be
applied to the eye bolt. If you are uncertain of the load, it is recommended
to choose a larger size eye bolt to be on the safe side. Always take into
consideration the working load limit of the object to which you are
fastening the eye bolt to as this will effect the working load limit of your
entire rigging assembly.
Always inspect eye bolts before use.
Never use an eye bolt that shoes signs of wear or damage.
Always be sure threads on shank and receiving holes are clean.
Never machine, grind, or cut eye bolt.
Never rig or reeve a sling or cable from one eye bolt to the other as shown
We hope this video has helped you with the selection and installation of
eye bolts for your rigging assembly. If you have any further questions,
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