The ‘chipload’ on a cutting tool is important because as material is removed it takes a little bit of heat along with it, and if the tool or the material starts to heat up then you’ll get poor cuts and bad edge finish, you may even burn or melt your material and dull your cutting tool. This is why fewer flutes are generally used on materials which can easily melt or weld themselves to the tool, such as plastics or aluminum.

Note: if you find any cutting tools being sold for dirt cheap, steer clear! When it comes to cheap bits you’ll find that the money you save ends up costing you in headaches from broken tools. If it’s your first time using a CNC router, expect to make mistakes while getting used to the Mill One. You’ll probably break/damage bits during the learning process, so consider holding off on buying the expensive ones until you’re more comfortable with your machine.

For more non-abrasive materials, coatings will only have an affect on the lifetime of the bit. However, for ultra-precision machining or when milling carbon fiber or hard metals, the wear resistance introduced by these coatings are worth their added cost.

Vmctoolslist pdf

One final deciding factor that needs to be accounted for is the hardness of the material. While it may be possible to cut away at aluminum with a 1mm end mill, we would certainly not recommend it because you’d surely end up with many end mills in the garbage. Instead, a tool should be chosen that you’re sure will be able to handle the stress of cutting the material you want to cut.

Learning how to tie a tool’s size and shape to its movement, rotation speed, material type, and material removal rate is nearly an art form. There are engineers whose job is knowing how to properly balance all these numbers and apply them based on part geometry, desired finish, and the total job cutting time. We at Sienci Labs are continuing to develop smarter algorithms so that this work can be done more autonomously through software. In the meantime, these more complicated cutting operations will be for you to explore as your learn more about what makes CNC routers tick.

Lastly, v-bits have a much more specialized usage in sign-making, PCB milling and other forms of engraving where a 2-dimensional pattern is cut into a material blank. You can vary the depth of cut of the v-bit to vary the width of the engraving. This means that for very fine lines, the Mill One will make very shallow cuts with the v-bit, and for wider lines, make deeper cuts.

When cutting material with a rotating bit, you can imagine that going too slow will dull or break the bit very quickly. For example, imagine trying to cut through a plank of wood with a saw except instead of moving the saw back and forth you’re just trying to push it directly through. Similarly, a bit that’s moving too fast can burn or melt the material that you’re cutting. Finding a happy medium between these two extremes is a balancing act between three main factors:

CNCmachinetoolslist pdf

Depending on if you’re looking to carve fine details, or just want to hog material out fast, choosing the right tool size is critical. For example, a smaller diameter tool can produce finer details but it limited to removing material slowly, otherwise it might break.

CNCturningtoolsname PDF

HSS usually combines with a variety of other alloys to have a high wear resistance and durability for cutting both soft and hard materials. Since HSS is softer than solid carbide it’s less likely to crack and instead wear out over time, so it’s limited to slower cutting speeds. HSS tools are also usually much cheaper than solid carbide tools and can be additionally improved if they come with a coating.

Tool tips can take on many shapes, with each tip designed to be used for a specific application. The three most common tip shapes are ballnose, flat end/fishtail,and v-bit/engraving.

Climb and Conventional cutting merely describe the way in which the cutter moves around the part in respect to its direction of rotation. In regards to a right-hand rotation spindle (the most common type), moving around a finished part counter-clockwise would be considered Conventional Cutting while a clockwise part path would be Climb Cutting. The terminology will be reversed if the spindle is of left-hand rotation or a pocket or hole is being cut out of the finished part.

With one of these tools in hand, you can start making cool and good-looking things on your Mill One without added complexity! Ensure that any cutting tool you end up using is installed as deeply as possible into the router, with a bare-minimum of 3/8” of the tool being inside the router for light cuts.

The following are a list of questions that are commonly asked during the setup or actual machining of plastics. The answers are general in nature, but should provide a starting point for further optimization of the cutting processes.

The solution to this is compression mills which spiral in both directions to ensure a smooth finish on both sides; however these bits are much rarer and come with a few of their own problems. You can also clamp a scrap piece of material either above (for upcut bits) or below (for downcut bits) the part that you wish to cut in order to reduce the amount of burring.

The second factor is typically a heat and material issue. It is not uncommon for a plunged hole to actually be smaller than the router bit that created it. This is a result of heat buildup and thermal expansion of the hole wall. It is particularly apparent in soft plastics and there are a number of solution methods that can be tried. Since heat buildup is the cause of the problem, the best methods of solution center around heat reduction. Slower spindle speeds, faster plunges, air blasts, or coolant will all reduce the effects of wall expansion. Peck or chipbreak drilling cycles can be a mixed bag depending on the cutter and the plastic. Sometimes they will eliminate the problem and other times they will exacerbate it.

Your tool must be harder than the material it is cutting. Thankfully, the materials that are used to make cutting tools are some of the toughest of the tough. The most commonly used materials are high speed steel (HSS) and solid carbide.

CNC cutting toolsname

Since there are so many different types and sizes of cutting tools, we’ve created a list below of just 3 different cutting tools that we strongly recommend to get started on your Mill One. We’ve created feed and speed tables for these tools for cutting in various materials so that you can copy/paste the values you need for your first projects. If you’re looking to get started with this recommended list, all of these tools can be found for purchase in our store!

CNCtool types images

On the other hand, solid carbide tools are very hard so they’ll stay sharp for longer and won’t wear as much at higher temperatures. Recently, carbide tools have become much cheaper and accessible for use in CNC routing, however it’s important to note that carbide cutting tools require much higher speeds in order to mill properly. This makes it a great candidate for cutting finishing passes, milling PCBs, and cutting materials that won’t easily burn or melt.

If you want to create anything on your machine, you’re going to need to learn some of the basics on cutting tools. These cutters are used by the Mill One’s router to carve away at materials in order to make the object you’re trying to create.

While Climb Cutting is the most prevalent method in metalworking and Conventional Cutting is the dominant method in woodworking, plastics routing is somewhere in between the two. There are usually significant differences between the finish on a Climb Cut part and a Conventional Cut part and the degree of difference can vary by plastic and cutter geometry.

This goes the other way too. If you find yourself looking at a price tag that’s half the cost of your machine then maybe you should consider upgrading to a new machine. The Mill One was built to be a simple learning platform, not the be-all and end-all of CNC machines ?

The other factors when considering Climb or Conventional Cutting is the aggressiveness of the cutter and part hold down. Climb Cutting is a much more aggressive means of cutting and can chatter or move small parts that are not fixtured well. In most cases soft chips that are difficult to extract from the cut are also more likely to weld to the climb cut side rather than the conventional cut side. The best method of approach for most new materials is to run sample parts with both methods of cutting at the same feeds and speeds and make the determination from there.

CNCturningtoolsname list

Most CNC cutting tools can be thought of like drill bits. However, not only can these cutting tools drill downward like drill bits, they can usually cut side-to-side as well. This enables the CNC router to cut away material in any fashion required to make your final 3D object.

Far and away the best method seems to be using the paper masking as a source for additional holding power. By precisely setting the depth of the cutter in relation to the spoilboard, many fabricators are able to cut completely through the plastic sheet without actually perforating the bottom masking sheet. This allows both universal and conventional vacuum system to act upon a large surface area and allows the added benefit of "single sheet on-single sheet off" loading and unloading.

The only rule of thumb that can be offered is that most soft plastics (HDPE, UHMW, Polypropylene, etc.) respond best to Conventional Cutting, while some harder materials (Acrylic, Polycarbonate, Nylon) can occasionally respond better to Climb Cutting. Typically Climb Cutting will only show an improved performance in the smaller diameters (less than 3/8"), but of course there are always exceptions.

Each of these factors must be suited to the properties of the material that you’re cutting; cutting through foam can happen much faster than cutting aluminum. We generalize these variables under the term ‘feeds and speeds’, and each cutting tool has a different set of ideal feeds and speeds.

End mills are typically used to mill most 2D parts and any 3D parts that do not have complex features, while ballnose mills excel at cutting 3D curves and contours to a smooth finish. Increasing the overlap between cutting passes for either of these tools will also boost their ability to produce a smoother surface finish.

The only drawback to this method is the difficulty in routing at a precise depth over multiple sections of the spoilboard without plunging through the paper masking. While the routers have enough positioning accuracy to repeatedly locate at the same depth, the spoilboards typically will have some bow or flex that can overcome the .010" thick paper zone. The standard solution is to fly-cut the board before use with a large diameter cutter to make it flat and parallel to the router head. There are dedicated cutters for this purpose but just about any large carbide tipped cutter will work for infrequent surfacing.

CNC toolslist

The flutes on the cutting tools are the cutting edges that remove material but also act as channels which move chips and dust away from the cut. Most tools have two or four flutes, but you can find tools with any number of flutes. When an cutting tool has less flutes, more material can be cut away per flute, per rotation. This means that fewer flutes will remove material faster, at the downside of making rougher cuts, meanwhile having more flutes increases the chance of a smoother surface finish.

While these problems are not unique to the machining of plastics, they can be much more difficult to solve than when confronted with them in metalworking or woodworking. Chip wrap is perhaps the most confounding problem, in that it does not always respond well to the standard peck or chipbreak drilling cycles that are available in the router controls. In the very soft and tough plastics such as polypropylene, it can take reducing the peck amounts to as little as .010" to prevent the long chip from curling around the plunging cutter. This can add significant cycle time and Z-axis wear over long runs. A better method is to program the router to ramp on entry for all transverse cuts and to helical ramp and interpolate for any holes that need to be made. This will prevent chip wrap and typically save cycle time. Crazing and "keyhole" slots typically require the same solution method.

If you’ve come looking for some tool recommendations, this is a list that we’ve put together for the slightly more experienced CNCer, or a beginner that’s ready to try something new (in your choice of either HSS or solid carbide):

Without the proper planning, you can expect many headaches along the way including broken tools, broken material, and an uneven or rough surface finish on your project. The following is more in-depth information on terminology and the theory behind how cutting tools are applied in a cutting job. A summary and some suggestions can be found at the bottom.

Creating a project with a nice surface finish on any CNC router usually comes with its difficulties. With the Mill One, we’ve continued applying our industry experience so that your chances of success when creating something awesome are as high as possible.

–Makezine- The Skinny on Endmills –CNC Cookbook- End Mill Guide –Guerrilla guide to CNC machining- Stocking up on End Mills –Tinker and Futz- A Guide to CNC Bits –CNC Zone- Router Bits and End Mills –Wikipedia- Milling Cutter –Shapeoko Wiki- End Mills –Hannibal Carbide Tool- Titanium Coatings

The first cause is explained above. As the cutter plunges, it has a tendency to "walk" and create a larger diameter hole than intended. This is another reason that interpolating the hole as opposed to plunging a hole is a better idea when using router cutters. Interpolated holes will exhibit improved diameter consistency versus plunged holes.

CNCtool type code

Crazing, or cracking of the material, is a result of the flat bottom cutter inducing too much stress into the part during the plunge. Ramping will ease the cutter in and prevent the bottom of the part from stress fracturing. If ramping is not an option, a higher spindle speed or slower feed rate can also reduce stress, but it sometimes shows a poor edge finish. Keyhole slots are the result of the router bit "walking" when it plunges. Drill bits have a sharp centering point and a cylindrical land around the outer diameter of the body that helps to keep them aligned in the cut. Router bits do not have any centering action and will aggressively try to move in a lateral direction. Because of this, the entry hole is often slightly larger than the bit diameter and it will be noticeable when the cut transitions from the plunging area to the routed slot. Once again, ramping will prevent any noticeable change in slot width throughout the entire cut.

Since v-bits can come in a variety of cutting angles, ensure that your bit has the right angle for your application. Usually larger (60 degree and 45 degree) v-bits are used for making signs and doing other detailing work whereas smaller angles (30 degree and lower) are used for PCB milling to achieve small trace paths.

Many fabricators will fly-cut before each shift or more often depending on humidity and warpage factors. Typically only .010" to .020" of an inch will need to be removed which will give significant life to a ¾" MDF universal spoilboard.

Carbide cutting tools have the ability to be covered in fancy coatings like TiN (titanium nitride), TiCN (titanium carbonitride), TiAlN (titanium aluminum nitride), and AlTiN (aluminum titanium nitride). All of these coatings can enhance the tool’s abilities by increasing its wear resistance, making it more thermally stable, lowering its coefficient of friction, or increasing its ductility.

The detail accuracy that you can produce with your machine is primarily determined by the cutting diameter of the tool, with the maximum depth determined by its length. Some of our go-to sizes include:

The spiral direction of the flutes will also have an impact on the surface finish of the material. Since the shaft on CNC routers always spins clockwise, if the flutes wrap in a counter-clockwise direction then the downward spiral will eject the material downward, meanwhile the opposite will eject them upward. The downside to both downcut and upcut bits is that they can cause ‘tearout’ (material splintering or burring) on either the bottom or the top of the material respectively.

There are cutting tools for every possible cutting application. Features such as tip shape, shank diameter, cutting diameter, tool length, flute count, helix direction and tool material can all vary from tool to tool. The material that you wish to cut, how fast you wish to cut it, and your desired surface finish will decide what features you want on the tool you end up using. Since there are a lot of variables, we’ll try to stick to the most commonly available cutting tools that you can use with your Mill One.