The posted g-code of the toolpath for the ShopSabre WinCNC controller is shown to the right of the illustration below. The tool cutter is shown at its approach position. Image courtesy of AirMotive Specialties, Inc. This rapid deceleration results in increased torque loads on the CNC machine. Feed Rate is important because it is directly related to virtually every aspect of NC machining from safety and productivity, to tool life, surface finish and part quality.Ĭonsider this. Suggested cut feed rates will vary depending on the type of material you are cutting i.
There is no reason to run at full speed though.Feed Rate is one of the most important factors to consider when implementing any CNC strategy. You will have more cutter speed which will make the tool cut easier and should provide a better finish. A good rule of thumb for RPM when using the HF is to keep the setting at 15, rpm or higher for cutting woods. It will give you the best finish results. Stepover is the same thing, it refers to the amount of overlap there is between passes. When you make one pass, you slightly overlap the previous pass to ensure that you are not leaving a small strip of grass uncut. If you think of stepover like mowing a lawn. The only exceptions to this would be for very light material like foam or Balsa wood. NOTE: As a general rule, you should not exceed the diameter of the tool as it can put undo stress on the machine, spindle and tool.
Depending on the wood you are cutting, you might be able to increase this. So you want to make note of this, especially if you intend to save the tool information as suggested below. For now, the best rule of thumb is to keep this at 10 or less.Ī 2 flute up spiral will have different settings than a 2 flute compression or down spiral. However if I use a Ramp of at least one inch, I can increase this. You can not plunge an end mill into material like you would a drill bit. Keep in mind that End Mills are meant to cut from the side whereas drills are meant to cut vertically. The stepper motors will have more torque at lower speeds and running at max speed can increase the changes that you lose steps during a job if, for instance, you run through a knot in the wood which will be harder to cut. So the time I cut that same material I can just choose that tool and these setting are optimized providing I am using the same tool with the same number of flutes. Then you would start the process all over with the new depth per cut. If it sounds effortless then you can increase the feed rate until you hear any signs of straining or chatter. I want to listen for chatter on the bit or straining on the spindle. To determine if you are spinning too fast, you can lower the RPM until you hear it bog a little and then increase it until there is no RPM sound variance while cutting. If it sounds like it is straining or chattering then increase the RPM. You will, over time, figure out the optimal settings for various materials that you use and you could name this tool for that material so you do not have to go through this process each time. You can also add on the type of material that this tool is for. I always use the format shown - type of tool diameter. In the Vectric programs, you will select a tool from the tool database. You will have different results depending on the spindle you are using, the number of flute in the bit and style of bit.
It is important to know these values so you do not set the software to exceed them - you can not force the machine to go any faster than it is capable of.Īlso, these values that I am giving below are just a starting point. There are speed and feed calculators on the market and online, but many times, they will over complicate the process, especially when you are working with wood.
Like with many things related to CNC, there is a lot of trial and error to find the optimal settings for your given machine, material and bit end mill that you are using.