Useful tips for Fusion 360 CAM

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Fusion 360’s CAM workspace is so much more refined and mature in 2021, but many may still be doing things the long way or the hard way. Also, where limitations exist, there are workarounds!

New features in Fusion 360

Here’s an overview of newly added functionality in Fusion 360

  • CAM Templates allow you the ability to save operations as templates, so that operation parameters can be reused to create new tool paths.
  • Surfaces in CAM Toolpaths – Enabled surfaces as model input allowing surfaces to be taken into account when calculating tool paths eliminating the need to patch holes.
  • Enhanced CAM Simulation – Improved stock simulation with support for undercutting, multi-axis indexing (3+2) and collision detection have been improved

 

1. Understanding your tool capabilities

We may think that a tool is a tool and we just need to clear away unwanted material, so who cares if it’s fluted or spiral, but these can affect everything from finish to machine time. For example, fluted drill bits will have to ramp down into pockets whereas spiral bits can plunge safely. Depending on how many pockets you have, this can decrease your machine time significantly.

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The 2d Pocket operation allows for Helix cuts (essentially a circular cut that ramps down into a specified depth).
This is drastically slower than a Plunge straight into the wood – spiral bits are designed much like a drill bit,
allowing for a longer cutting edge

 

2. For high precision machining, always perform a roughing pass on edges before a finishing pass.

Sometimes, a finishing pass can end up ripping up corners that faced the cutting edge of the router bit. Adding your initial cut with a roughing pass allows you to chew through a bulk of the material quicker, while leaving the more important locations (such as the edges) to be finished with a slower passing and smaller bit for getting into and around tight locations. You can set up a roughing pass by simply setting the amount of Stock to Leave in the Passes section of your tooling feature:.tb_button {padding:1px;cursor:pointer;border-right: 1px solid #8b8b8b;border-left: 1px solid #FFF;border-bottom: 1px solid #fff;}.tb_button.hover {borer:2px outset #def; background-color: #f8f8f8 !important;}.ws_toolbar {z-index:100000} .ws_toolbar .ws_tb_btn {cursor:pointer;border:1px solid #555;padding:3px} .tb_highlight{background-color:yellow} .tb_hide {visibility:hidden} .ws_toolbar img {padding:2px;margin:0px}

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Radial Stock controls the amount of material to leave around the sides of the router bit, whereas
Axial Stock controls the amount of material to leave in Z-axis direction (ideally going straight down).

3. Know your machine and how it operates.

This will translate into how to not only setup your part prior to creating your cutting paths, but also creating the necessary G-Code. When setting up your part, it’s important to know how your CNC Router (or laser) handles X, Y, and Z coordinates. The Z-direction should always be perpendicular to your top face that you’ll be cutting from. You also need to pay attention to which side of the axis is positive and which is negative. By default, Fusion 360 shows the positive side with the arrow on your in-graphic triad.

If your parts Coordinate system doesn’t match up correctly to the CNC router, it can cause you a bit of a headache trying to figure out why the router bit is refusing to face the correct direction.

If your design requires a manual tool change, then it might be prudent to consider designing two separate G-Code Outputs. If your machine will automatically perform tool changes, you could probably skip this step. Some Router Machines will pause operations or offer a few seconds of time between a tool change to stop the Router and perform the bit change. Other machines (like the one I was using) will simply just ignore that pause and continue without warning, so be careful.

You can create separate G-code by simply selecting the operations you want first and let the job run to completion. This can be done from the browser tree or the operations tab in the post-process dialogue box.

You can also manually edit the G-code to enter m226 to pause at the end of the current cycle. This is an asynchronous stop and will pause the machine until human interaction is received (usually push start again when ready). This can be helpful if you want to pause the machine to do a manual change after the first operation.

4. If you’re unsure on the operation, pay attention to the Tooltips!

Typically this can be said of pretty much any tool or feature in an Autodesk Program, however they really went to the next level with the CAM operations. Beyond the actual CAM Feature Tooltips, they actually provide a tooltip for nearly every option within their features.

The little diagrams and explanations will appear if you hover over an operation or command for 2 sec. Sometimes, even the most experienced machinist gets overwhelmed with all the various ways to clear material. It is important to pay attention to the way the toolpath is generated. For example, 3D ramp and 3D contour but seem to do the same thing, but there are limitations and angles to consider when using the contour option and thus they may be suited to some jobs more than others.

And lastly, always play around and consider multiple approaches. Sometimes, changing a simple setting in your linking tab can change the outcome and machine time drastically.

In my next blog, I hope to show you a recent project I worked on making engravings on plywood and MDF, using a very basic and limited CNC router. Stay tuned!

 

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