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How to Drill Metal

Drilling metal typically is not too difficult if you set up properly to do so.

Some would call it a very tricky operation. With a few precautions, you too can be an expert at drilling metal items.

The first thing to consider is, “What is it that I actually want to accomplish?” Drilling metal requires the right tooling – often simply called a “drill bit”, proper hole and location measurements and a good amount of patience during the set-up process. Do it right the first time because there’s always time to do it right the second time, eh?

Things we suggest you always have handy (and use!) might be:

  • Safety Glasses
  • A Hand Drill, Drill Press, Bridgeport or Similar Mill, etc.
  • Tooling or “Drill Bits”
  • Cutting or Drilling Coolant / Fluid
  • Information – See the following CHART for some idea of the speed you should be running (RPM) when using HSS (High Speed Steel) tooling

Basic Drilling Guidelines or Instructions

    1. Always secure the piece that you want to drill. Use a proper vise or a clamp so it can not slip, spin, lift up, etc. If you are using a simple hand drill, you will need both of your hands to keep the drill steady.
    2. Measure exactly where you need to drill and mark it so you can see it. Bonus Tip: Our favorite method for marking a hole is to use a punch or something similar. This allows the “drill bit” to find the location more easily.
    3. If you need to find the center point on a part, measure your length and mark the half way point on all four sides of the piece. Draw a straight line across the center from top to bottom and then do the same from side to side. Your center point is where the two lines intersect. See our tip in step #2 for marking the center point.
    4. If drilling by hand, hold the drill steady and drill slowly. It is very important that the drill not slip. If the drill slips, you can cause damage, drill in the wrong location or even injure yourself or others.
    5. With a hard to drill metal like stainless steel, you need to make sure there is plenty of coolant. Drilling at the proper RPM rate or even slower is a necessity. Bonus Tip: Pushing relatively hard once the drill has started into the work piece can sometimes be helpful. It causes the “drill bit” to cut a larger and deeper chip which keeps the cutting surface of the tool in cool material rather than right at the surface where heat was generated on the previous rotation. Typically, this is useful on automated machinery and not as important when hand drilling.
    6. Generally, slower RPM rates mean better results when time is not an issue. If your cycle time is critical, then work with a tooling supplier to determine the optimal speed and feed rate for your actual material and tooling. We often suggest test drilling on a drill press or milling machine to help determine this prior to purchasing a self feed production drilling machine.
    7. Choose the right drill bit for the job. If there is any question about whether it is the correct tooling, you should contact a professional tool dealer or machinist who can help you.
    8. A cone “drill bit”, step “drill bit” or graduated style tool is sometimes useful for soft metal projects. It is designed to cut various sized holes in thin sheet metals typically but can be used on some other products with success. Typically, these tools are not professional grade though so special order tooling may be necessary if this is part of your plan.The transition or cone can be smooth or it can have graduated steps on it. Sometimes you can use one of these to cut a whole range of sizes of holes. Simply drill to the diameter you wish and save the time and cost of switching out tooling. AutoDrill Production drills can be adjusted to repeat the same depth of drilling to an accuracy of 0.001″ to 0.003″ on average and are easily adjusted by the end user to lock in this depth for maximum efficiency and repeatability.Bonus Tip: If you lack horsepower on your machine and you can’t use a cone or step drill to manage the drilling load, start with a smaller size tool. Gradually increase the size until you get the dimension you are looking for.Bonus Tip:When using a multiple drill spindle head, you can often stagger the tooling lengths to minimize the horsepower requirements. AutoDrill even manufactures custom gang drill / multi-drill heads with different length spindles if necessary.
    9. Get better tooling for more difficult jobs and harder materials. High-speed steel (HSS) drill bits are often coated with a special aluminum nitride layer and are good for most metals. Avoid using them without coolant and proper speed and feed rates on aluminum as the metal debris or chips tend to become stuck or “welded” to the tooling. This can often make clean hole drilling impossible. It can increase the burr on the top or bottom of a part, create an over sized hole, create poor hole quality, etc.There are cheap imitations out there. If you need a real tool, we suggest going to a tooling distributor rather than a local hardware store, etc. Here are two massive online sources for tooling: McMaster-Carr and MSC Direct (…There are others, but this will get you started in the right direction.)
    10. There are higher quality tools made such as Cobalt, TiN, Carbide or even Diamond. Keep in mind that some tooling simply is not made for smaller drilling machines. Micro vibrations caused by a lighter weight machine (i.e. not 10,000 lbs for example!) can cause the most expensive and durable tooling in the world to prematurely dull because the vibrations destroy the cutting edge.
    11. Take your time to do the job safely and cleanly. If you do not use caution when drilling metals, you may end up with holes that are out of round, and there is no fixing that problem. As we have said before, there may not be time to do it right the first time according to the pressures and deadlines… But there always seems to be time to do it right the second time. Just do it right the first time, every time!
    12. Bonus Tip: When working in the shop, chaos is your enemy. Act like a surgeon. When you take a tool out and use it, replace it immediately after finishing the job. Many people have been injured and many jobs have been ruined because someone thought they could clean up at the end of the day or at the end of the job.
    13. Beware of metal bits, chips and curls flying or spinning around. Always wear safety glasses and any other safety equipment when drilling metals.
    14. If you are the one setting up a manually triggered production drill, consider ordering a Two Hand Anti-TieDown (THAD) start button assembly. This forces the end user to press two buttons at the same exact time in order to start the drill. This can help eliminate injuries in your shop or in your customer’s shop! Do you really want your customer filing a lawsuit against you for not properly protecting their employee? It may not be right, but the legal system unfortunately allows them to do it so prepare now.

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