29 March 2017
29 March 2017,

You’ve got tool questions and we’ve got tool answers.  We get many questions about the fly cutter.  Here are some of the most common:

Which gives a better finish – a face mill or a fly cutter?  No question, the fly cutter wins hands down.  The fly cutter provides a single cutting surface.  If you use a fly cutter larger than the work area, you will get a clean finishing cut in a single pass.  Remember, the more passes you make the lower quality of the finish.  You can take all cutters off your face mill except one – but then all you have done is converted your face mill to a fly cutter.

Sierra American CNC fly cutters

    small fly cutter

Can you use a fly cutter on aluminum?  Yes, but you must use the right fly cutter.  Remember aluminum is soft.  You need something hard (like PCD) to make a good cut. 

How do you grind the bit?  Keep in mind the geometry of the cutter.  This means the end of the tool does the cutting.  Grind the rake into the end of the tool.  The bottom of the bit determines the surface smoothness.

What about feeds and speeds? Use your regular software to calculate your feeds and speeds.  Flycutters may run at lower RPMs, but your software knows for sure.  Always rely on your software for correct feeds and speeds. Way back in 2016 we advised you to rely on your software in this blog post

What about quick material removal?  If your goal is to quickly remove material, use the face mill first. You’ll get deeper cuts and faster chip removal.  Make a fly cutting final finish once youfly cutter have all your material removed.

Is tramming necessary?  Only if you want to do it right.  We get this question when someone is noticing a dip in the finish.  The problem isn’t the tool, it is the set-up.  Make sure everything is trammed and up to snuff before you make the first pass.

What makes a good fly cutter? The question is not only “what” but “who”.  The answer is Sierra American Multi-Systems.  Here’s why.

Large Diameter Fly Cutter

Sierra American makes using a fly cutter a breeze.  That’s because their large diameter sizes handle large cutters.  The larger the cutter, the fewer the passes.  The fewer the passes the finer the finish.

Stability and Balance

You need maximum stability and balance for finishing cuts.  That’s what you get from Sierra American.  Because their fly cutters are manufactured with larger 1/4-20 alloy set screws, you get better cutting blade stability.  Because they are balanced, you can run at the RPMs you need to get the finish you desire.

fly cutter setSave Time and Money

The Sierra American fly cutters uses larger 1/2” and 3/8” fly cutter bits. That means you make larger cuts. This makes the job go faster. In the shop, saving time equals saving money. You get more productivity.

Sierra American Multi-Systems makes fly cutters in the USA.  Each tool is backed by a 5 year warranty.  Demand quality and ask for Sierra American by name.  If your tool pusher doesn’t carry Sierra American, ask them to order it for you.

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