Tips for Machining CNC Parts with Undercuts Feature

 

At Creatingway, we consider the machinability of varying features during part design. Some designs are notably easier to make than others when machining a part. An example of easy design parts with shallow cavities and large features. Hader designs like undercuts may present a challenge to our machining team. However, at Creatingway, we exploit the use of design alterations and specialized tools to make the task easier.

How To Correctly Machine Undercuts In CNC Parts

Undercut Machining

An undercut is a sunken feature in a part. Standard cutting tools, for example, end mils, cannot create undercuts. We need the help of specialized tools to make such features. It is because some surfaces of an undercut are inaccessible directly from overhead. The process of designing undercut parts is a challenging task. Also, such parts are hard to make thus incurring more costs, and machining specific undercuts standards us hard to achieve. Many undercuts exist where one workpiece part overhangs another. A gap thus exists that normal traditional tools cannot access. Such tools include three-axis mills and routers.

Undercut Machining Special Tools

Making simple undercuts needs tools like lollipop cutters and slot cutters. These special tools have unique shapes allowing them to make undercuts where traditional tools cannot. Both special tool cutters have a wider end tip and narrow shaft feature. A slot cutter has a flatter tip compared to the much rounder tip of the lollipop cutter. This makes the latter ideal for undercut machining curved shapes. Our machinist uses the distance between the shaft edge and outside tip to determine the overhanging distance cut for your machining CNC parts.

A Lollipop cutter is exceptionally useful for edge bearing and deburring a workpiece in the underside. It comes in a number of wrap angles, for instance, 220⁰ and 300⁰. Lollipop cutter possessing thinner necks can achieve large wrap angles thus creating a more spherical cutting end with more clearance. However, cutters possessing thicker necks have a smaller wrap angle thus providing less clearance but are notably more stable and rigid. The chance of tool breakage is thus lower.

One challenge facing the use of these special tools is that most CAM software lacks the algorithm needed to support them. A way around it is through the use of manual G-code or manual manipulation of the mill.

 

Unique Cuts in Undercut Machining

• Dovetail

A dovetail tool utilizes an angled blade to make an undercut. The resulting feature resembles a dove’s tail. It is trapezoid like with a narrow top and broad bottom. The cutting tool is available in the standard angles of 45⁰ and 60⁰. Other possible angles are in multiples of 10⁰ reaching up to 120⁰, however are less common.

• T-Slot

A t-slot tool comprises of a connected flat horizontal blade and a vertical shaft. This allows the tool to cut into a workpiece and also horizontally cut it in either direction. Thus the creation of a T-shaped undercut. The cutting tool is available in different width standards creating undercuts ranging from 3 mm to 35 mm in size.

• One-Sided Undercut

A one-sided undercut asymmetrically machines undercuts. It cuts sideways with the help of a special tool while making an extra cut protruding from the initial undercut. When designing an internal wall having a one-sided undercut, consider clearance. This will ensure the tool is working properly.

Undercut Machining Tips

• Partner with CNC Professionals

It is much easier to make the parts you need when you partner with a CNC professional machining company. The professional company usually has adequate expertise coupled with experience and the right tools to take care of even the trickiest of tasks. Whenever you are unsure of an undercut design, seek guidance from a professional to help out in optimizing design. This will ensure the highest quality in undercut standards and also lower error risk.

• Avoid Using Custom Tools

Custom tools take time to make and add costs to your project. Since they are only one-time-use tools, it is best to avoid them by designing standard dimension undercut features. We need a custom tool for a dovetail cut of 15⁰ since such a stool does not exist. However, for a standard 45⁰ cut, it makes the machining process easier.

• Avoid Undercuts If Possible

  

During the designing process of a part, wherever possible avoid undercuts. Undercuts are difficult to work with and require a special tool to make. It is thus much more cost-effective and efficient to not include them in a design. An instance of design not needing an undercut is designing a workpiece with tool space to make use of standard machining from the back. This avoids a difficult undercut from the front.

• Shallow Undercut Designs

The shallower the undercut design, the better. Most undercut cutting tools have a vertical shaft connecting to the blades. This limits the depth into which the tool can reach. Deeper designs may also compromise the stability of the cutting tool as the vertical shaft will be longer. It may result in increased tool vibrations lessening tool accuracy. Also, the tool may break. It is therefore important to create a design with depth accessible to most undercut machining tools. Contact Creatingway now for your CNC machining services.

 

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