13 March 2018
13 March 2018,

Machinists are moving to CNC machines and they are taking their fly cutters with them. Smart move. Fly cutters remove large amounts of metal in a single pass. They are the perfect tool for machining large, flat surface areas.

cnc fly cutters by Sierra American

What is a Fly Cutter?

If you don’t know by now, a fly cutter is a rotary tool that use one or more single-point tools for plane surfacing. You insert the bit in the fly cutter and insert the fly cutter in your machine. You don’t need an additional arbor.  A normal fly cutter can be adjusted to cut up to a 2 inch (51 mm) diameter and is easily capable of taking a 0.01 inch (0.25 mm) deep cut in aluminum at this diameter.

use CNC fly cutter to machine heads and manifold intakes

Mercedes Benz head

Fly Cutter Applications

Fly cutters are all about the finish. For a mirror finish on metal, use a fly cutter. Got a head that needs to be completely smooth? That’s a job for the fly cutter. Is the bed on your machine slightly off? Use your fly cutter to level your bed. If a brush finish is fine, then you don’t need a fly cutter. But, if you want a flawless finish with no swirls or whirls you’ve got to use a fly cutter to finish in one pass. Only a low pressure tool like the fly cutter is up to the job.

Then, when your fly cutter is dull, just a little straight-forward grinding and you’re back in business. A fly cutter bit lasts forever. Grinding a fly cutter bit is easy. Just hand sharpen the edge or cutting tip.

Easy Does It

Feeds and speeds are slower with fly cutters, but that’s okay. You aren’t fly cutting to remove to an enormous depth, you are fly cutting for finish. That’s why slow and easy does it better. A thousand RPMs up to 2400 RPMs is the range depending on the bit.

Calculate the cutting speed for the tip of the tool and determine the RPM. Because fly cutters are single point tools, just use a feed rate similar to a lathe. Don’t forget to keep in mind the limitations of the material you are cutting and the material of your cutter.

Got fly cutter questions? Refer to our handy Fly Cutter FAQ.

American Made Fly Cutters

American machine shops love American made fly cutters. They love Sierra American Multi-Systems fly cutters.

  • Rigidity
  • Quality
  • Balanced
  • Large set screws
  • 5 year warranty

Be sure to ask for Sierra American fly cutters where you buy your tools. Don’t settle for less and don’t buy cheap, foreign imitations. The best quality for the best machinists.

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