9.15 Angle Milling
Micky R. Jennings
Angle millingis the process of creating an angled cut on a workpiece. This can be done in multiple different ways on a manual milling machine.
Holding the part in a vise at an angle is a good option for angle milling. This option is the quickest and can often be accomplished by using angle blocks. For added precision, dialing in the parts using trigonometry and a drop indicator is a popular method.
Smaller angular cuts, like chamfers, often utilize form cutters ground to the precise angle needed. For 45-degree angles that don’t need to be extremely accurate, the angled edges of a face mill work well.
Some angel milling methods are best for a larger work volume and are inefficient for smaller jobs. For instance, the machinist can adjust the milling head at one or more of the joints that attach the head to the ram to create angle cuts. This is a good option if there are many parts to be machined; however, if there are just a few parts, altering the milling head can be unnecessarily cumbersome.
Similarly, custom fixtures are a great option if high volumes of parts are to be cut at angles. A fixture can hold the part at a specific angle and allow for the angle to be milled on the part. This isn’t the best option for just a couple parts because a fixture will take extra time to design and machine.
Step by step process for milling an angle using angle blocks:
- Select an angle block that corresponds to the angled feature of the part.
- Load the part, along with the angle block, in the vise on parallels.
- Load an end mill or face mill into the milling machine. Generally, a tool that will accomplish the cut in one pass is best.
- Calculate the spindle speed and feed rate for the tool selected.
- Turn on the spindle and adjust the speed.
- Lock the quill.
- Gently touch the tool off to the prominent corner by raising the knee.
- Zero the knee.
- Calculate the amount to be removed from the part using right angle trigonometry.
- Remove the necessary material over multiple passes using face milling cuts.
- Turn off the spindle.
- Lower the knee.
- Clean and inspect the feature.
Step 1: Select an angle block that corresponds to the angled feature of the part.
Step 2: Load the part, along with the angle block, in the vise on parallels.
Step 2: Load the part, along with the angle block, in the vise on parallels.
Step by step process for milling an angle by dialing in the part at an angel in the vise:
- Load the part in the vise, one end on parallels, handled at the approximate angle of the required cut.
- Lightly tighten the vise.
- Attach a drop indicator to the head so that the indicator shaft is vertical.
- Calculate the amount of the vertical leg of the triangle associated with the angular cut. In the example shown, a 6-degree angle is to be cut. The operator can use whatever horizontal distance they like, but one that is an even number and easy to calculate is best. In this example, 1.000″ is used. The surface of the p