How do I calculate the right cut settings for my bit?

The cut settings that can be adjusted in Easel are:

Feedrate - How fast the machine moves as it is cutting material
Plunge Rate - How fast the z-axis lowers into the material
Depth Per Pass - How much material is removed each pass
Spindle Speed (if available) - Revolutions per minute (RPMs) the spindle needs to spin

Plunge Type - Angle which the bit approaches the material

The bits in Easel’s Bit Selection menu come with default cut settings for bits we sell on our site. Whether you’re using one bit or performing a two-stage carve, these bits use cut settings we have tested at Inventables for your selected machine type and material type.

Feed rate override allows you to make adjustments to the machine’s speed once you’re carving, but this can help you get started.

The best place to get information about cut settings for a given bit is from the bit manufacturer. This is the quickest and easiest way to obtain this information for a bit.

However, it may not always be possible to obtain this information from your bit’s manufacturer. In this case, you can use the following equation:

Feed Rate = Spindle Speed * Chip Load * Number of flutes

You can manipulate this equation to calculate for unknown variables, if necessary.

For example: Chip Load = Feed Rate / (Spindle Speed * Number of Flutes)

Chipload will vary but for the most part between .003" and .005" are good inputs to use if you do not know your bits' chipload. Most milling bit manufacturers will have this listed in their product documentation. This is also a great resource on understanding milling bits: https://www.mscdirect.com/basicsof/end-mills

• ●  We have tested values starting with 16,000 RPMs as a starting point.
• ●  The plunge rate should be about 40% of the feedrate.
• ●  On the X-Carve Pro, we recommend starting with the diameter of the bit as the depth per pass. This can be adjusted depending on the bit.
• ●  On X-Carve and other non-Inventables machines, we recommend half the diameter of the bit depth per pass as a starting point.
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TIP: You should also consider the hardness of your material and the intricacy of your design. Remember cut settings are specific to the project, material, and bit combination. We highly recommend running tests before committing to cut settings on final projects.

Troubleshooting

If your cut settings are not optimal or calculated properly, you may see issues with your carves such as:

1. Bit gets stuck or the spindle stalls and causes offsets
2. Rough carves that require a lot of processing

3. Excessive wear on bits or bits breaking
4. Long carves

If the bit stalls, it could be partly due to the spindle torque/horsepower but this isn't necessarily an issue with X-Carve Pro. In general, you need to adjust cut settings accordingly. The bit can stall for a few other reasons:

1. impacted material
2. improper clamping
3. dull bits

If you are experiencing any of these issues, we would recommend starting by reducing the depth per pass first.

If you want to increase the depth per pass, you will need to reduce the feedrate by 25%-50% which is not necessarily optimal or makes sense at times. The ideal cut settings should produce chips, not dust.

You'll also need to ensure the bit is not removing more material than it can handle.

Our forum is an excellent place to learn more about calculating feeds and speeds for a specific bit and material pairing. It is also a helpful resource for specialty bit recommendations or suggestions about which bits to use for certain project types.