Ultimate Pilot Hole Guide – Method | Depth | Drillbit Size

Perfect drilling is a combination of many factors. Pilot holes are one of them. Drilling a pilot hole will take additional time, but it will lead to the most successful and safe drilling process; whatever material such as wood, brick, steel, stone and any you use, the pilot hole is essential for successful drilling methods. When you drill a pilot hole, you should know why do you do it properly.

Normally we drill pilot holes for safe, accurate, efficient, low force and speed drilling processes. Pilot holes are used to drive screws into woods and further drill with more diameter drill bits in metal and woods.

When you drill a pilot hole, you should pay attention to many sectors for safety, accuracy and efficiency. So let’s keep reading on until the end the proper guide for the drill pilot hole.

Why You Should Use A Pilot Hole for Metal and Wood

Pilot hole, predrilled hole, and advanced borehole are the same terms for the same hole which is drilled on the material before starting the complete drilling process or driving the screws.

The pilot hole is really important in many ways, such as safety, accuracy, low force, and speed drilling and driving screws are them. These are common for both metal and wood

Safety

Safety is the most important thing when we are working. Whatever task we do, we must prioritise safety. When you are drilling on a hard and polished surface such as tile or metal, your drill bit can be move here and there due to the soft surface. So you will not be able to point the drill bit in the exact place. This really affects the accuracy. When we drill a soft surface with the more diameter drill bit, we will not point to the exact place due to slipperiness.

Read More About – How to Use a Drill? Step by Step Guide!

Accuracy

When we drill on a slippery surface, we will not be able to point the drill bit correctly. This has mostly happened in the hard drilling process. But if there is any punch or small drilled hole, this will make it easier. Sometimes you will need to angle drilling in such materials. Can you do it? You can’t. The drill bit will slip, and it moves away, So you need a predrilled hole for the angle drilling also.

Low Force

Drilling for is really important. Force is considering the thrust. We need to thrust the drills for drilling inside. If we have sharp drill bits, we can do this easily. Thrust force is varied with the material type and amount of the material that needs to be cut and removed. When there are a few amounts of material, we have to thrust less. The pilot hole will remove the amount of material, and this will lead to low thrust and power.

Calculate The Drilling Power – Drilling Horsepower Calculator

Drilling Speed

When we start drilling, we have to start slowly from the beginning until we tap (punch) the point. But if there is a predrilled hole, we can start speed drilling as soon as possible we start drilling on it. Speed drilling will finish the work quickly.

When we dive in-depth into this topic, we can apply all these facts when we drill materials such as wood, metal, concrete, stone, bricks etc.

Drive Screws

Drive screws are essential for many carpentry works. Using a driver, we can do it easily. Most screws do not need a pre-drilled hole. These can be drilled into the wood directly. But when you work on the edge, the wood can be damaged when you drill without the predrilled hole. When we drive the screws, the material will be compressed and moved away from the hole. When this has happened edge, it will be cracked on the lease material side. So it is a really serious problem.

You can avoid this by only making the pilot holes.

Pilot Hole Size For Wood and Steel

Pilot hole size for wood as below.

Screw SizeDrill Bit Size for
Soft Wood
Drill Bit Size For
Hard Wood
#01/641/32
#11/321/32
#21/323/64
#33/641/16
#43/641/16
#51/165/64
#61/165/64
#71/163/32
#85/643/32
#95/647/64
#103/327/64
#113/321/8
#127/641/8
#147/649/64
#169/645/32
#189/643/16
#2011/6413/64
#243/167/32
Pilot Hole Size for Softwood and Hardwood

Soft Woods

Pine, Cedar, Redwood, Spruce, Douglas fir

Hard Wood

Oak, Maple, Hickory, Walnut, Cherry

The pilot hole size for steel is as below.

How to Drill a Pilot Hole in Wood and Metal?

Drilling the Pilot hole will need few steps. You can follow these steps to make the pilot hole in the wood and metals.

Step 01 – Select the drill bit.

Select the drill bit according to the diameter of the screw. You can check it with your screw size and select the appropriate drill bit sizes in inches using the above table. And also, for the metals, you can follow the same step. This guide will help you to select the drill bit sizes in inches and mm

American Screw Sizes Table – Check here

Read More About – 13 Types of Drill Bits for Wood: You Should Know!

Step 02 – Locate the point

The drilling location should be marked with a clear sign. You can use ink to mark the place. You can punch the exact point using the puncher.

Step 03 – Apply the cutting oils.

If you drill a pilot hole in the metals, you should apply the lubricants in order to reduce the drill bit by overheating and improving the cutting speed.

Step 04 – Start drilling.

You can start drilling slowly at the beginning and then increase the drilling speed as it needs. Do not start high-speed drilling. The drill bit will move here and there due to the high-speed drilling, and it will not tap the exact place correctly.

Read More About – Top 08 Drill Bit Problems and Solutions

Step 05 – Clean the hole

After you drill the pilot hole, you should clean the hole. If you use to drive screws through the pilot hole, it will need to apply more force. But if you drill that hole again, you do not need to clean it additionally.

Pilot Hole Depth for Metal

The average depth of the pilot hole for metal is 2-3 times the used drill bits diameter for the drilling pilot holes. For the screws, you must use recommended pilot hole depth according to the nominal diameter of the metal.

In most cases, screw pilot holes are not prepared in metals. If there is a special design or case screws, pilot holes can be created in the metal.

Pilot Hole Depth for the Wood

For the drilling pilot hole, you can use the least depth for the pilot hole, and if you use the pilot hole for the screw driving, you should maintain the below depth for the optimum result.

Screw SizeScrew LengthHole Depth
#21/2″1/4″
#35/8″1/4″
#43/4″3/8″
#53/4″3/8″
#61 1/2″3/8″
#71 1/2″3/8″
#82″1/2″
#92 1/4″3/4″
#102 1/4″3/4″
#122 1/2″3/4″
#142 3/4″1″
Pilot hole depth for screw length and hole depth

What Will Happen When a Pilot Hole is More Depth and More Diameter?

When the pilot hole is deeper than its recommended depth it will not tight well with inner materials. The screw will be loosened and it can’t hold more force. You can pull it out easily.

The pilot hole should not too wide or deeper. When it is wider and deeper it will not contact with the screw

How to Drill Pilot Hole without Drill Bit?

You can drill a pilot hole without a drill bit easily. You just need to use any type of nail without its head, or any small steel bar with one end in a chisel shape can use as a pilot drill bit for the wood. For the metals, you can use a puncher for that.

All these methods will create a small hole as the drill bit can hold tightly without moving here and there for the drilling purpose.

But for the screw drilling, you should have an equal diameter nail or steel bar for the screw-driving pilot hole preparation. If the hole is not enough for the shank diameter, the wood will be cracked easily. This can happen easily when you work on edges.

Conclusion

Pilot holes are really important for screw driving as well as drilling holes. Whatever material you use, you should use prepare the pilot hole for a safe, accurate, efficient and speed drilling process. For that, you should follow these steps.

Related Topics