How to Drill, Cut and Tap Stainless Steel
Monday, October 11, 2021
While many of our stainless steel products come pre-drilled and cut, there are some circumstances where you may need to do additional work onsite, or post-installation. With the right tools and know-how however, working with stainless steel can be effortless. Whether you’re drilling, tapping or cutting stainless steel, the general sentiment is the same: start slowly, and keep an eye on the temperature.
It's important to keep in mind that working with stainless steel can be dangerous if the proper safety precautions are not taken. It is best to wear protective eyewear, earware and gloves when working with metal to help prevent accidents, injury or splinters. Metalwork should also not be done on hot, dry days as it a potential fire hazzard.
DRILLING STAINLESS STEEL
When working with stainless steel, it is best to use a sharp, high speed drill bit (often referred to HSS drill bits). These can be purchased at any hardware store, and are the most commonly used drill bits for metal applications due to their inexpensiveness and durability. It is important to note that drill bits intended for woodwork cannot be used on stainless steel, as they are often softer than the steel itself. Smaller drill bits can also be challenging to work with as they are more prone to bending/breaking under pressure.
Once you have sourced the correct drill bit, it’s time to start drilling! Set your drill/drill press to the slowest speed (or as slow as the trigger will allow) and apply as much pressure as possible to the drill bit.
In addition to pressure and speed, temperature is also a vital variable to consider when drilling stainless steel. In an industrial setting lubricant/coolant is applied continuously to the tip of the drill while working with stainless steel. While this mightn’t be achievable in a DIY setting, it’s still important to keep your steel as cool as possible. This can be done by intermittently stopping work, dripping small amounts of oil onto your drill bit and hole.Cutting oil will work best for this, however motor oil (or even wd-40!) can be used in a pinch. Stopping work will also help stop heat building, and give the stainless steel time to cool.
TAPPING STAINLESS STEEL
Before deciding to tap stainless steel, it’s important to consider the thickness of the steel being used; 3mm or thicker is ideal. Rivet nuts and nuts/washers can be used in situations where your stainless steel is too thin to tap.
Start off by drilling a hole in your stainless steel by following the steps outlined above. Once you have drilled a suitable sized hole, insert the tip of the tap to ensure the fit is correct. Before beginning tapping, apply a liberal amount of tapping oil to the bit (again, WD-40 or motor oil can be used if none is available). The more evenly the oil is applied, the easier you will find this process.
Unlike when you are drilling, it is best not to apply too much pressure when tapping stainless, as this can result in an uneven thread, or broken drill bits. Slowly guide your tap/bit through the predrilled hole, ensuring you hold your tool steady and straight. This process should be much easier than the initial drilling as less material is being removed.
CUTTING STAINLESS STEEL
There are many different ways to cut stainless steel, however when working with steel tube it is easiest to use a circular saw or angle grinder as opposed to tin snips or power shears.
Before you begin cutting your stainless steel, ensure that you have fitted a metal cutting blade (preferably diamond) to either your circular saw or angle grinder. Blades designed for cutting metal are much harder, and more durable than those used in woodwork. Attempting to cut steel with the wrong blade will result in it being dulled.
Before making your first cut, allow your circular saw/angle grinder to reach full RPM. When using a circular saw, work slowly, and continuously. Conversely, when using an angle grinder, it is best not to attempt the cut in a single pass as this could cause the steel to overheat and discolour.
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