Chatter problems with feeds and speeds


I’ve been doing a lot of experimenting with my new PCNC1100, and learning to trust GWizard Calculator. While it seems to give reasonable results for a 6mm end mill, I’m having a very hard time with a 25.4 mm (1″) end mill or a 20 mm end mill.

I’m trying to cut an open pocket in an aluminum soft jaw, that will be 25 mm deep in Z and up to about 25 mm deep in Y. The aluminum is 6061 cold-drawn.

The 1″ tool is a 2-flute HSS uncoated with 3/4″ shank. The 20 mm tool is HSS TiCN with a 3/4″ shank.

At anything but the shallowest of side-step/cut width (< 0.5 mm), I get lots of chatter, especially with the larger tool. I don’t think I can go slow enough to cut the nearly 20 mm cut width the GWizard proposes, and certainly not at the proposed feed & speed. Similarly with the 20 mm tool, it’s proposing 15 mm width of cut. I can’t cut more than about 1 mm with the 20 mm tool.

So, what’s going on? I’ll try tonight with half the rated machine power, as Bob suggested, but I don’t think that’ll do any better.

Is there some factor I’m overlooking?

  • You must to post comments

Rick, chatter is a resonance phenomenon.  It can come about at virtually any time.  There are a lot of ways to change or minimize it covered in our Feeds and Speeds Tutorial chapter on chatter:

If the problem really is chatter, you should be able to minimize it with the techniques described there.

My suspicion is something else is at work though.  hen you say you get lots of chatter at virtually any cut depth for a full slot cut, that seems like some other problem must be at work.  The PCNC 1100 should have no problem doing a full slot that wide I wouldn’t think.  Why don’t you email me your feeds and speeds settings as a screen shot of G-Wizard and I will comment on them.  Send the email to


  • You must to post comments
Showing 1 result
Your Answer
Post as a guest by filling out the fields below or if you already have an account.
Show us your humanity*


Do you want to be a better CNC'er in 37 Seconds?

Get Better Tool Life, Surface Finish, and Material Removal Rates Fast.

It's that easy. You can install and get results in a matter of minutes.


Start Now, It's Free!



  GW Calculator

  GW Editor



  Deals and Steals

CNC Blog








     Feeds and Speeds

     G-Code Tutorial

     CNC Machining & Manufacturing

     DIY CNC Cookbook

     CNC Dictionary

CNC Projects


     Machinist's Search


     Online Groups


     Reference Data


     CNC Dictionary


     Tool Brands


     Hall of Fame

     Organization: Soon!





     Our History

     Privacy Policy

All material © 2017, CNCCookbook, Inc.

Pin It on Pinterest

Share This