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The Complete Guide to Drilling Through Metal
Drilling is a crucial process in metalworking. If you want to cut pieces with accuracy and success, you need to be able to handle your drill effectively. Whether you’re a seasoned metalworker or just starting out in the trade, it’s essential to know the ins and outs of the metal drilling process. Gather some pro tips and brush up on best practices with this complete guide to drilling through metal safely, accurately, and successfully.
Always Wear Proper PPE
Before you do anything in your workshop, you need to gear up with the right protective equipment. Never cut metal without safety glasses to protect your eyes from metal chips and other flying debris. It’s also essential to wear gloves. Choose a durable pair that can withstand scratches from rough metal edges, but make sure your gloves aren’t so thick that you lose dexterity.
Long sleeves are also a good idea for protecting your arms. Just be sure to avoid baggy sleeves that can get caught in tools and workpieces. Long hair can also get caught, so tie your hair back to keep it out of the way and out of your face.
Secure Your Workpiece
If your workpiece is loose, it will start to move around when you drill. In a best-case scenario, the piece will shift and vibrate, throwing off your drill and creating sloppy, inaccurate cuts. In a worst-case scenario, though, the loose metal is a serious safety hazard for you and anyone working around you.
Make sure you secure your workpiece before you start drilling. Never hold a workpiece in your hand, even if it’s small; you can lose your grip or end up cutting yourself with the piece or the tool. Instead, clamp the piece to your work surface to hold it securely in place. If you’re drilling into thin sheet metal, smooth it out and sandwich it between two pieces of wood to make sure it stays flat and secure as you work.
Mark and Dimple Your Metal
Dimpling your metal before you drill is a key step to ensure accuracy and precision as you work. It also helps steady your drill bit, preventing awkward angles as you drill your hole. Measure where you want your hole to be and mark it lightly with a pen or pencil. Next, you want to create a dimple—a tiny dip in the metal that will help keep your drill bit in place once you start working. Use a center punch or a nail and tap it lightly with a hammer to create your dent.
Choose the Right Drill Bit
If you want to make clean, accurate cuts without wasting a lot of time and energy, you need the right drill bit. Pay attention to both material and style as you select your bit.
For material, it’s important to match your drill bit to the type of metal you’re working with. High-speed steel bits are a common and versatile choice that work well with softer metals like aluminum, copper, and brass. However, they wear down quickly if you try to use them on harder metals. For tougher or more abrasive metals—like cast iron, stainless steel, and titanium—you want to use a carbide or high-speed cobalt drill bit.
The length and flute of your drill bit are also important. Always look for the shortest bit that can make your cut, because longer bits are more prone to breaking—especially if you don’t need their full length to drill your hole. As for flute types, a parabolic flute design offers a cleaner cut and smoother finish for softer metals, while a standard flute gives you better control when working with harder metals.
Use Cutting Fluids
It’s always a good idea to use cutting fluids when you drill. Whether you use a coolant to reduce heat buildup or a lubricant to improve your cut and wash away chips as you work, cutting fluids are a critical part of drilling clean, accurate holes.
To choose the right cutting fluid for your application, consider the material you’re working with. Softer metals tend to require less lubrication because they don’t produce as much friction with your drill bit, but they do create more metal chips as you drill. For this reason, you want to prioritize fluids that help wash away chips. Harder metals, on the other hand, call for fluids with high lubrication to prevent overheating as you cut.
Start Slow
No matter what you’re drilling, always start with a slow rotation speed for your bit. Some metals—like stainless steel or hardened steel—require a slower drilling speed. However, it’s important to start slow even when you’re working with softer metals. A slower rotation speed prevents unnecessary friction and gives you more control as you start creating your hole. If you need to, you can increase the rotation speed once you’ve started the hole.
Start Small
It’s also a good idea to keep your holes small to begin with, even if you need to make a larger hole. Starting small gives you more precision and control as you make your initial cut. It also prevents you from accidentally drilling the hole too big and ruining the piece.
You can always enlarge the hole later on either with a different drill bit or a boring bar. Alternatively, you can invest in a step bit to make a wide range of hole sizes with a single bit.
Create a Smooth, Neat Finish
Once you have the right shape and length for your hole, the final step in this guide to drilling through metal is to create a smooth finish. Drills often create rough cuts that you need to neaten and polish before the piece is complete.
There are several different finishing methods you can use depending on the results you want. Deburring tools grind away any burrs lingering in and around the hole, creating a smooth, neat finish. You can also use a reaming tool to smooth out the hole, improve tolerance, and even change the shape to create a tapered hole.
Find Drilling Solutions at TMT Toolbox
When you combine your drilling knowledge with high-quality metalworking tools, you can make sure every project is a success. TMT Toolbox offers an incredible variety of drill bits for cutting steel and other metals. Visit our website today to explore our vast online inventory or contact our team to find the specific product you need for your next project.
