Faster fastening

Faster fastening

When it comes to concrete, consider whether you need to make a hole at all.

A pin set with a powder-actuated tool (PAT) can be the least expensive way to fasten materials to concrete.

“You must consider the makeup of the base material and the power of the load on the fastener to decide if a pin installed with a powder-actuated tool can work. Engineering drawings can specify if these can be used,” says Rob Obodzinski, senior product specialist at ITW Ramset Redhead.

In all areas, remember that operators must be licensed to install PAT fasteners.

If your need is speed
“If your need is speed, then PAT is the way to go as long as the base material is strong enough and the driven pin can support the load’s requirements,” says Obodzinski.

PAT-driven pins can support a variety of loads. “But if the fastened load is very heavy or the base material is made of concrete block or masonry-type material, a mechanical or adhesive anchor may be a better choice,” he says.

To select the correct pin for the job, he suggests users conduct a punch test where you take the selected pin and hit it into the base material with a hammer.

“If the concrete shatters like tile or glass, then the base material is too brittle to shoot; if it flattens the point of the pin, then the concrete is too hard to shoot; if the pin drives in like you are putting it through drywall, the base material is too soft and not conducive to powder-actuated fastening. But if the pin makes a slight indentation into the base material, then the material is safe for this type of fastening,” he says.

Once you’ve identified the pin for the job, Obodzinski suggests you start with the lightest (least powerful) load and make a test shot. The pin should penetrate the base material fully, but not deform or pass through the track or other material being fastened.

“PAT-driven pins can save time. But if your base material can’t withstand the driving force or must support thousands of pounds of load, drilling a hole and using mechanical or adhesive anchors is your best option,” he says.

Consider mechanical anchors
Mechanical anchors provide greater load-carrying capacity than PAT-driven pins. They come in many styles that can be matched to meet the installation’s requirements.

A wedge anchor is a common anchor type that works by pulling a stud up around the anchor’s clip as it tightens.

Self-tapping screws are another popular anchor type. The screw’s threads interlock with the concrete as it threads into the hole. Still other drive-in pins rely on friction with the hole sides to stay in place.

“As with all anchors, hole size is very important,” Obodzinski says. Many self-tapping screws come with a bit in the box to help assure workers use the correct bit size.

Whether you are drilling a hole for a mechanical or adhesive anchor, use the drill’s depth gauge. It prevents drilling too deep, which wastes time and wears bits. If you are using adhesive anchors it reduces the amount of material needed to fill the hole.

With adhesive anchors, it’s especially important to clean the hole. “Once the hole is drilled, blow out the hole, then use a brush to remove of the residue. This is a step that is often overlooked, but it can affect how the mechanical or adhesive anchor adheres with the hole,” he says.

Mechanical anchors have an advantage over adhesive anchors: When installed properly, they can support full loads immediately. Adhesive anchors take minutes, hours and sometimes days to set up depending on the formulation and the ambient temperature.

Check the spec
Manufacturers have a variety of adhesives that can meet anchoring specifications. Often, project engineers will identify specific mechanical or adhesive anchor types. If you wish to use another product, many fastener suppliers have submittal packages you can use to prove equivalency to the engineers.

“Work with your distributor salesperson to select the best fastener for your job,” he says. A wide variety of formulations offer the same or better holding capacity but can streamline installation to reduce labor costs.

With the wide range of adhesives across several manufacturers, Obodzinski cautions users to look at all the components needed to apply adhesives. “The injection tool, the adhesive cartridge and the nozzle work as a system. In some cases, parts and cartridges are interchangeable across types and even brands. But selecting one type may lock you into an expensive system that increases your costs without saving you time or improving quality.”

If the base material is a masonry wall or other hollow structure, Obodzinski says workers may accidentally blow through the inner wall of the block. When this happens, the base material doesn’t have enough strength to adequately support the load.

To remedy this, he suggests using an umbrella insert that flares out like a molly bolt to spread the fastener’s force across a wider surface area. This allows the adhesive and the anchor to bond better with the masonry for high load-carrying capacity.

“However, the anchor system is only as strong as the weakest part of the block, so you may not have increased the strength at all if the block is too badly damaged,” Obodzinski concludes.

Concrete drilling tips

There are several tips you can use to make drilling in concrete easier. Patrick Kearl shares some tips that Relton, Inc. offers worker drilling their way through concrete:
• While drilling, clear the hole by withdrawing the bit. This is very important in soft concrete.
• If you must drill overhead, use a smaller tool (SDS+ or hammer-drill) rather than a larger rotary hammer (SDS-max or spline-drive). Smaller drills are easier to handle.
• When drilling holes that are 3/4" diameter orlarger, use a core bit. It drills only the outside circumference of the hole vs. solid bits that must remove all of the material to make a hole.
• Keep a rebar cutter and 1/2" drill handy in case you hit rebar. Use the rebar cutter to cut through the rebar, then continue drilling with the carbide concrete bit.
• Keep carbide inserts (cutting edges) sharp. Carbide cutting edges can be resharpened.
• Keep the drill/hammer drill in top shape.
• Use the drill’s depth guide. The correct hole depth means less adhesive needed to fill the hole, less drill bit wear and less time on the job.
• Always check to make sure the drill is in forward, not reverse, speed.
• Pay attention to the drill speed. Turning a bit too fast can burn up the bit, cause braze failure or prematurely dull the bit.
• Use a direct-fit bit instead of an adapter (Quik-Lok or A or B Taper). Adapters lose energy, reducing cutting efficiency.
• Use the shortest bit possible. Don’t start a 48" hole with a 48" bit or drill a 6" hole with a 36" bit.

Safety tips
• Always wear the appropriate personal protective equipment.
• Watch for shock dangers such as standing water, improperly grounded tools and accidental drilling through live conduit or boxes.
• Do not lean on the bit or drill off-axis. It could break the bit, which could cause the operator to fall and be injured.
• When working overhead, use the right ladder and fall protection for the job.
• Do not hammer-drill through rebar. The bit can bind or break and could injure the operator.
• Never drill deeper than the flutes on the bit. The flutes help the dust exit the hole and if it can’t escape it could bind in the hole. A binding bit can suddenly jerk and turn, injuring the operator.
• Do not drill or operate heavy machinery while intoxicated.

Published in the March/April 2001 issue of Contractor Tools and Supplies magazine.