A kitchen makeover is at the top of the wish lists of many homeowners. More and more homeowners are working to create their dream kitchens by collaborating with experts and learning to do things themselves.
One of the most popular kitchen improvements is the installation of high-end countertops. Beautiful, functional granite and marble counters can elevate an entire kitchen. To attach a marble countertop to cabinets, a special, secure fastener is called for. For this job, many countertop installers use a machine screw anchor.
Machine Screw Anchors
Machine screw anchors are installed using a setting tool that expands the anchor in the base material. Once set, a bolt can be threaded and unthreaded as needed. The threads of the anchor are national coarse threads, so any fastener with national coarse threads can be threaded into them.
Working with Machine Screw Anchors
1. Use the correct tools
A hammer drill with a carbide-tipped bit must be used to create the correct hole.
The hammer drill must be set in the hammer and rotation mode. A straight rotation drill will not produce the hole tolerance required for the machine screw anchor.
The carbide tipped bit must meet ANSI standards. ANSI standards will ensure the correct tolerance between the diameter of the hole and the diameter of the anchor.
The diameter of the hole to be drilled is equal to the outside diameter of the anchor. The chart below shows which hole size is needed for each anchor diameter size:
Diameter Machine Screw Anchor
Diameter of Carbide Bit
2. Create the right kind of hole
The depth of the hole should be drilled to at least length of the anchor being installed. The length of the anchor is the minimum embedment depth for the anchor—but in most cases, embedding the anchor deeper will result in better holding values.
Consistent and correct hole depth can be achieved by using the depth gauge provided with the hammer drill. If a depth gauge is not available, simply wrap the bit at the desired embedment depth. If the hammer drill being used has a keyless chuck, the bit must be in the most retracted position when setting the depth gauge or taping the bit.
Carefully drill the hole
3. Carefully clean the hole
Clean the hole of all debris and dust before the anchor is installed. A wire brush that is the same diameter as the hole should be used in an up and down, turning motions. Then the hole should be vacuumed. Repeating this process will ensure that the hole is ready for the screw anchor to be installed. Compressed air can also be used, although it may create too much dust in the air to be used in some situations.
4. Finish the machine screw anchor installation
Hold the anchor body with its open end opposite to the cone-shaped, threaded section. Insert the anchor into the hole. Push or lightly tap with a hammer until the anchor body is flush with the surface.
Insert the corresponding setting tool into the anchor until the lip of the setting tool meets the lip of the anchor. With a hammer, strike the setting tool, which pushes the anchor body over the cone-shaped threaded part until fully set.
The anchor is now set in the base material and the fixture cannot be attached by inserting the bolt for the particular application. Do not over torque the bolt during installation. This may cause the anchor to spin in the hole creating a situation where the anchor could lose some or all of its holding strength.
Tips & Tricks
Each diameter of machine screw anchors has a unique setting tool that must be used. The designated diameter of the screw anchor is equal to the designated diameter of the setting tool that must be used. A 5/16” anchor requires the use of a 5/16” setting tool.