This can be even more helpful when you are using a more rigid machine where you will take deeper cuts per pass. No matter what material you cut, on most hobby-grade CNC machines, when you wish to cut deeper than 1/8″, you usually will take multiple shallow passes, and the up-cut design of the bit will help keep the channel clean from dust and chips. This is very important, especially when cutting hard materials, like aluminum, deeper than 1/8″ where you run the risk of recutting chips, which can ruin the finish, cause chatter, or break the bit. One of the biggest advantages of the up-cut bit, is the ability to rapidly evacuate chips out of the area that the bit is cutting.

You will find a much larger selection and for many size end mills, you will find both up-cut and down-cut versions. Understanding this, I would consider shopping online, either from the place where you bought your CNC machine, or from a large end mill retailer. While these stores may be convenient, they do not offer the best selection of cutter types, especially for the CNC router. The main reason I mention this though, is because a lot of people use a big box store such as The Home Depot or Lowes as a source to get their bits for the CNC. A lot of applications in a CNC router can use a standard router bit (which is designed for a handheld router), but there are some where this is not possible (or recommended), such as bits that have bearings connected to the end – these you would not normally use in a CNC router. Second, understand that there are differences between what we call a “router bit” and an “end mill”. I used to take for granted that this was a known fact, but I do get a lot of questions from people on this since the spiral directions are actually opposite from one another and they assume you have to reverse direction of the bit rotation.

So when we talk about an up-cut or down-cut, we are addressing the way the flute and cut pattern is machined into the bit and not the direction that the bit spins. Two Considerations With These Bitsįirst off, this article will take into consideration that most CNC routers will run with the spindle, or router, in the clockwise direction. In this post I will discuss the differences between Up-Cut and Down-Cut router bits and when you should use each. A greater number of flutes reduces chip load and produces a much finer finishWhat types of End Mills are available?End cut types:Centre cutting end mills have one or more cutting edges at the tip to allow the user to plunge, drill or ramp into a cut.Non-Centre cutting end mills have peripheral teeth that allow the user to side cut or contour an external surface.Shank TypesEnd mills with a plain shank are used with a collet style holder and are the most common shank typeEnd mills with a Weldon shank have one or two flats with set screws in the holder that tighten on the flanks of flats to hold the mill to prevent it from rotatingTypical applications of End MillsEnd mills are used for profile milling, face milling, tracer milling, semi-finishing and finishing.It’s bad enough that there are literally tens of thousands of end mills and router bits that you can use on your CNC router, but then you have different variations of each as well. End Mills have cutting edges on the end and sides of the shank enabling them to cut in all directions.Why use an end mill?The end mill removes material by their movement within the milling machine or from the cutter's shape.The number of flutes (spirals on the end mill) give different results:2 flutes allow maximum space for chip ejection and are used for general milling operations3 flutes is an excellent choice for slotting, it has a larger cross-section and is used in general milling operations4, 5, 6 and 8 flutes can improve the surface finish if the feed rate remains the same. End Mills An end mill is a type of cutting tool that is used in milling applications.

02 end mill bits