Ask twenty do-it-yourselfers how important pre-drilling is, chances are you’ll get at least ten different answers.
So, is pre-drilling necessary or just an added step almost never needed? That depends on many factors.
You need to pre-drill if:
You are using green wood. If the piece of wood you are drilling is heavy for it’s size, it is likely green, or young, wood OR
You are using treated wood. Treated wood is usually used for outdoor structures or decks OR
You are using hardwood. Birch, cherry, mahogany, maple, oak, poplar, rosewood, teak and walnut are all hardwoods OR
Your final hole will be larger than 3/8” OR
The wood you are using has been stored in humidity greater than 20% for more than 24 hours before drilling OR
You want to pre-drill.
You do not need to pre-drill if:
You are using dry wood that has not been pressure or chemically treated AND
You are using softwood like pine, cedar or redwood AND
The final hole will be smaller than 3/8” AND
The wood has been stored in dry conditions for more than 24 hours AND
You don’t want to.
If you don’t pre-drill treated or green wood, it will likely split when it dries.
Hardwood typically takes years to completely dry so you should always pre-drill hardwood, since it’s possible it still has drying to do.
Holes larger than 3/8” can put undo stress on wood. If you pre–drill these holes before inserting a screw or nail, most of the wood will be removed from the hole before nail or screw is inserted, reducing stress.
Always pre-drill with a bit slightly smaller than the final hole.
If the final hole will be 3/4” or larger, pre-drill in increments of 1/4?. Example: pre-drill with 1/4” bit, then 1/2? bit, then 5/8” or 11/16” bit.
Using a drill to fashion shelves can help your project last longer and retain it’s shape longer and better than shelves that are made with a hammer and nails.
The reason for this is that screws put in using a drill with the proper bit won’t pull away as the shelves are bumped and used like a standard nail will, the ridges on the screw simply provide sturdier hold. Once you have chosen the material for your shelves, and have the plans in hand. The next task at hand is to find the correct drill bit for the project.
Types of bits for the job. There are several types of drill bits to accomplish the job at hand, the one you chose would be dependent on the material the shelves are made of. For example, if the project is to be made from a relatively thin plastic, or soft wood you can use a twist bit. This general purpose bit works well for many simple shelves or shelves that come in the form of a kit.
A brad point bit is advantageous for wood shelving. In addition the bit head has special brads (high spots) that are good for accuracy and precision. An auger bit might be useful for speed in boring into wood. A general all purpose drill bit for shelf making is the adjustable wood bit. This practical tool is adjustable for hole size with a blade that will adjust from 3/4″ to 3″. Other types of bits that are available for an assortment of shelving materials include; glass and tile bits, a step bit, and a drill saw bit for wood or metal in particular in unusual contours.
Carefully measuring where you want the screws placed before you drill will save you a lot of aggravation. When you have found exactly where you want the screws to go mark the spot with a marker. It can be helpful if you pre-drill using a smaller headed bit, before inserting the screw. This predrilled hole will help insure that the screw goes in easily and straight. Taking the time to choice the right drill bit, measure their placement and pre-drilling will ensure your shelving retains their beauty for years to come.
Works fine with wood, polywood, fiberglass, etc. Cuts are clean and easy to do. Bits are all marked with the sizes.
The set is not high quality made, some of the center points don’t extend far enough, greater attention could have been paid to the sharpening finishes. Holes for 3/8″ hex shanks are too big, the four smallest bits fit well.
Don’t expect it will last for a long time in everyday use, but for occasional these are good for your workshop.