How to Prevent Hardwood Chipouts on Your CNC Router

How to Prevent Hardwood Chipouts on Your CNC Router

14th Feb 2023

How to Prevent Hardwood Chipouts on Your CNC Router

Do you have problems with hardwoods chipping out on your CNC router? If you do, here are some solutions to the issue.

It’s common, and we have encountered this many times, especially when routing 90-degree square corners. Chipout while cutting the perimeter to size on various hardwoods can be a major pain and cost you time, money, and plenty of scrapped wood.

We have come up with a process that is extremely effective and creates beautiful, clean cuts on solid wood glue ups.

Start by using either an upcut rougher or a downcut rougher. Whether you use an upcut or downcut are usually important depending on which edge requires a tear free edge, however, since we are only using the rougher to get us close to size, in this instance we are not too concerned with upcut or downcut. If your part hold down is lacking, use a downcut to help the forces work for you. The good thing about the roughing pattern on the cutting edge is that it breaks the chip up extremely fine, minimizing the risk of tearout or blow out at the corners. 

Toolpath Strategy

A good habit to get into is when you are creating your roughing toolpath is to leave 1/16” stock
on all sides, but at the corners, turn a radius that goes just slightly under the finish size. Since
the roughing pattern on the router bit minimizes the risk of chipout at the corners, going slightly undersized at the corners allows the next finishing tool to not cut at the corners. This minimizes the risk of chipout on the finish pass, where it is more prone to happening when using a sharp finishing bit.

Downcut 3 Flute Rougher

Use either an upcut or downcut slow helix finishing bit, depending on which edge you would like
to come out clean. Using a low helix spiral puts less strain on the edge since the cutting edge is
hitting more parallel to the edge as opposed to forcing the chips rapidly upward with a standard
helix tool, which can result in bad tearout. Low helix finishers are available in upcut or downcut.
With both roughers and finishers, it is always best to choose the largest diameter and shortest
length of cut needed to not sacrifice rigidity for the best possible cut quality, while also ensuring the tool holder and collet is in good shape.

To calculate the proper feed rate, use the chip load chart and formulas on our Speed and Feed Page.

Upcut 3 Flute Finisher
Here is a short video showing the toolpath in Fusion 360 Cam Software

Using this process will ensure that you’ll minimize hardwood chipout in your next project.

CleBitCo helps the Makers make, the Creators create, and the Doers do, and we can help you cut through it all - hardwoods, plywood, or softwoods. Plus, plastics like acrylics, polycarbonates, and polypropylene, and carving foam and rigid foam. With CleBitCo as your partner, you’ll be able to do more with your machines. Need some help with a project? Get in touch!