23 July 2018
23 July 2018,

In the world of machining, usually faster is better. The faster you can mill a piece, the more pieces you can mill. The more pieces you mill the more money you can make. So, in the machine shop, the hare from the tortoise and the hare usually wins the race. Usually wins. But, when the job at hand is finishing, the fly cutter is the tortoise. And, when you want a superior finish, you want a tortoise. The fly cutter may be slow and steady, but it wins the race.

The face mill is a hare

The Face Mill versus the Fly Cutter

Whether you machine by CNC or manually, the face mill is the hare. Face mills need a big spindle with a lot of power to push them efficiently. That’s because face mills are large and hold many cutting surfaces. Use all that power to remove lots of material fast.

The fly cutter is a tortoise

The fly cutter is a tortoise. It generally sits on a small spindle. That small spindle doesn’t require a ton of power to turn it fast. So, fly cutters remove less material slower. But there is a benefit to that low horsepower. A single cutting surface that covers a larger area provides a better finish faster, even if the machine is running slower.

Say what?

use a fly cutter for a mirror like finish to metalSingle Pass Finish

Let’s start by all agreeing that the best finish possible comes from a single cutter. Multiple cutters leave multiple marks with each pass.

In order to get a face mill to act as one cutter you’ve got to invest in a face mill that allows you to individually adjust the height of each cutter (a very expensive option) or you’ve got to remove all the cutters except one (turning the face mill into a fly cutter). If you can’t control the height of the multiple cutters, you can’t control the chipload of each cutter. So, uniformity flys out the window. You’ve got to have uniformity for the best finish.

A face mill with multiple cutters adjusted to the same height or all cutters removed except for one still only covers a small area. That means multiple passes. Each pass leaves minute marks.

The best finish is made in a single pass to bypass those minute marks. So, even if the machine is running at a slower speed you are operating faster because you finish the part in one pass.

fly cutter set from Sierra AmericanThe American Fly Cutter for the American Machinist

Sierra American Multi-systems makes fly cutters right here in the United States. Every fly cutter that comes out of Sierra American is heat treated and balanced. They are ready to get to work for you.

When you get to work with Sierra American, you’ll appreciate the larger set screws. That means more stability and more rigidity. Music to your ears? Then listen up.

Ask for Sierra American by name where you buy your tools. If they don’t have it, ask them to order it. Why get ripped off by cheap foreign imitations, when you can have the real McCoy?

American manufacturing is coming back, and Sierra American is ready to support American machinists. So, get to work and work with Sierra American.

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