What are undercuts?
Undercuts are features of a part where some material is hidden behind an overhanging geometry, making it impossible to machine with a standard tool from above. In milling, an undercut typically requires a special tool (like a T-slot cutter or lollipop/endmill) or a 5-axis approach to reach. Examples include a T-shaped slot, a dovetail groove, or any cavity where the top opening is smaller than the interior, leaving an overhanging lip. For CAM Assist, undercuts represent regions that cannot be machined with normal end mills in a purely 3-axis motion. However, CAM Assist does support undercuts by using operations like T-slot cutting if enabled and if you have appropriate tools. If the Undercuts option is on, CAM Assist will detect those features and generate toolpaths (with a tool like a keyseat cutter) to machine them . If off, it will ignore them, likely leaving that material.
Why is understanding undercuts in CAM Assist important?
Because if your part has undercuts and you don’t account for them, you’ll be left with leftover material that a normal strategy won’t remove (since the tool can’t get under the lip). Knowing what an undercut is ensures you use the right tool or strategy. CAM Assist giving an “Undercuts” feature means it can handle certain undercut scenarios automatically, which is great – normally those require manual programming or special CAM sequences. But you must provide the right tool (e.g., in the tool library, a T-slot cutter of the correct size). It also matters because not all undercuts are feasible even with that option – very complex ones might still be unmachinable without 5-axis. Recognizing an undercut in your design may influence your approach: maybe you choose to drill a relief hole or plan a secondary op. CAM Assist’s ability to do T-slot or undercut milling means it broadens the range of parts it can fully program. If you didn’t realize a feature was an undercut, you might be puzzled why CAM Assist left it; knowing what undercuts are ensures you either enable the feature or accept that it’s not doable in 3- axis. It’s crucial for parts like brackets with retaining grooves or parts with keyway slots, etc.
Where do I find / adjust the use of undercuts in CAM Assist?
How else could undercuts be known in CAM Assist?
- Reentrant features
- Overhangs in milling
- T-slot / keyseat / dovetail features
Related articles to undercuts
- What are tools in session? (ensuring the undercut tool is in your session to be used)
- What causes CAM Assist to not finish certain faces? (an undercut face might be left unfinished if undercuts weren’t enabled)
- What part file types are compatible (not directly related, just making sure geometry is represented
such that undercuts are recognized – e.g., proper solid model, not surfaces missing that confuse
detection)