Many people are frustrated by breaking lag screws, such as the 3" screws used to mount overhead storage racks in their garage. The heads of the screws twist off leaving the threaded part stuck in the wood. Here are some suggestions for how to prevent this frustration.
The ideas here may be relevant to just about any use of longer lag screws, however my expertise comes from mounting ceiling brackets for overhead garage storage racks. These shelves depend on 2" penetration into the stud. These shelves come with 3" screws as they have to clear the sheet rock and thickness of the mounting bracket.
The first thing to do to avoid breaking lag screws is to predrill the hole. For 15/16" wide lag bolts, I use a 3/16" bit and drill down to the entire length of the lag screw. If you drill only part way down you will get heavy resistance when driving the screw. Some people choose to drill another hole inside that with a 15/16" bit, only to the depth of the unthreaded part of the lag screw. Also keep in mind that wood is a natural product, so there is a chance you will strike a knot in the wood. These areas do not to receive screws as well. The may force you to move your mounting hardware.
Secondly work with an impact driver to drive the screws. The job can be laborious using a socket wrench. A good rechargeable drill with the adapter for sockets will carry out the task. Though certainly the simplest solution is to use an impact driver. I've found that I must use two hands and stand squarely behind the drill to be able to run them in successfully using a cordless drill. But when I take advantage of an impact driver, I'm able to install the anchoring screws with just one hand plus I don't need to line up myself behind the screw. This is especially convenient whenever I am using a ladder and might need to reach out to the screw.
Next drive the screws only until the head contacts the surface. Do not tighten down the screws after that. They don't need to be over tightened. Over tightening often leads to twisting off the heads. A broken off screw can be especially problematic because you may not be able to relocate the mounting bracket in order to drill a new hole and put in a new screw.
To make it easier to turn the screw, apply wax or soap to the threads. Since soap is known to cause rusty threads with time, it's better to use wax. Add a small candle to your toolbox. You can usually skip this step if you're using a power tool.This tip is more relevant for those using a socket wrench.
If you're dealing with poor quality screws, think about making a visit to the hardware store for better quality screws. The material and grade of lag screws are marked on the head. No marks means the Grade 2 and has the lowest tensile strength. Three radial lines means grade 5, a medium carbon steel that's quenched and tempered. This grade ought to install successfully and not have frequent breaks. The final and strongest rating is Grade 8 with six radial lines on the head.
Stainless steel lag screws don't follow the same standards for marking the heads. They are usually stamped with something on the head anyway, to keep them from being confused with low-quality Grade 2 screws. They are also non-magnetic. Stainless steel lag screws have similar tensile strength as Grade 5, but are more prone to bending.
My last bit of advice to avoid breaking lag screws is to not reuse screws. A lag screw becomes stressed by driving into the wood. This means it's weakened and is more likely to break if reused compared to a new screw. Do not force a screw down by running it back and forth into the wood, either. A previously used screws may also have a small imperceptible amount of bend in it, which cause extra resistance when you try to drive it into the wood.
The ideas here may be relevant to just about any use of longer lag screws, however my expertise comes from mounting ceiling brackets for overhead garage storage racks. These shelves depend on 2" penetration into the stud. These shelves come with 3" screws as they have to clear the sheet rock and thickness of the mounting bracket.
The first thing to do to avoid breaking lag screws is to predrill the hole. For 15/16" wide lag bolts, I use a 3/16" bit and drill down to the entire length of the lag screw. If you drill only part way down you will get heavy resistance when driving the screw. Some people choose to drill another hole inside that with a 15/16" bit, only to the depth of the unthreaded part of the lag screw. Also keep in mind that wood is a natural product, so there is a chance you will strike a knot in the wood. These areas do not to receive screws as well. The may force you to move your mounting hardware.
Secondly work with an impact driver to drive the screws. The job can be laborious using a socket wrench. A good rechargeable drill with the adapter for sockets will carry out the task. Though certainly the simplest solution is to use an impact driver. I've found that I must use two hands and stand squarely behind the drill to be able to run them in successfully using a cordless drill. But when I take advantage of an impact driver, I'm able to install the anchoring screws with just one hand plus I don't need to line up myself behind the screw. This is especially convenient whenever I am using a ladder and might need to reach out to the screw.
Next drive the screws only until the head contacts the surface. Do not tighten down the screws after that. They don't need to be over tightened. Over tightening often leads to twisting off the heads. A broken off screw can be especially problematic because you may not be able to relocate the mounting bracket in order to drill a new hole and put in a new screw.
To make it easier to turn the screw, apply wax or soap to the threads. Since soap is known to cause rusty threads with time, it's better to use wax. Add a small candle to your toolbox. You can usually skip this step if you're using a power tool.This tip is more relevant for those using a socket wrench.
If you're dealing with poor quality screws, think about making a visit to the hardware store for better quality screws. The material and grade of lag screws are marked on the head. No marks means the Grade 2 and has the lowest tensile strength. Three radial lines means grade 5, a medium carbon steel that's quenched and tempered. This grade ought to install successfully and not have frequent breaks. The final and strongest rating is Grade 8 with six radial lines on the head.
Stainless steel lag screws don't follow the same standards for marking the heads. They are usually stamped with something on the head anyway, to keep them from being confused with low-quality Grade 2 screws. They are also non-magnetic. Stainless steel lag screws have similar tensile strength as Grade 5, but are more prone to bending.
My last bit of advice to avoid breaking lag screws is to not reuse screws. A lag screw becomes stressed by driving into the wood. This means it's weakened and is more likely to break if reused compared to a new screw. Do not force a screw down by running it back and forth into the wood, either. A previously used screws may also have a small imperceptible amount of bend in it, which cause extra resistance when you try to drive it into the wood.
About the Author:
Read more articles by Joseph Kraehenbuehl about attaching a shelf to your garage ceiling and other ways to organize your garage.
No comments:
Post a Comment