Chatter- It’s Not the Machine

Everything has inherent vibration and harmonics.
Press the grip of an unstrung longbow to your ear and tap along the limb with the edge of a finger it rings in a rather surprising way with loads of harmonics.
Even the Earth itself rings after earthquakes.

Del

Understood, Del. The question in this post is whether or not the machine itself is the primary cause of the chatter, or is it the tool edge prep that CAUSES the CHATTER.

I agree that we can "find" harmonics in everything; The question here is to proximate cause - machine or tool edge.

Milo

But each machine (New or used) has its own frequency, and imo the only way to address it, is after it's brought online.

Having experienced this problem......... we had a number of issues that caused this......

• The machine design,
• The Poor Maintenance/Operation of the Machine (We had Fretting in one of the tool holders)
• Or the Tool

When I first started working around the machine tools Late 80's early 90's, I was really surprised that a different tool could cancel out some of the natural frequency 'chatter' out and the cut was acceptable.

Unfortunately at the time, it's trail and error to find the compatible cutting tool.......... Has this changed?

So how do you know that it was the machine and not the original tool...

Milo

Most of the time, You don't. Unless its more obvious such the fretting on the tool holder, end of lifetime bearing going out, ect....

It was at the shipyard, where allot of our contracts was with the navy (avenger class minesweeper) we had (2) two Shoda CNC routers... Not only did we use it for wood, but also for phenolics, FRP, most nonferrous metals..... We had restrictions on the use of coolant, so chip load was our major process to carry away heat. And the routers minimum rpm was 7500, had our own r&d worker order number to test the best process (rpm, feedrates, tooling) to get the best results. Again trial and error, but we documented everything and the material we were cutting/machining, (silicon/brone, copper/nickel, aluminum, to the phenolics). We worked with Shoda as well as our tooling suppliers for our more difficult process. Again, their expertise was let's try this.

The tooling salesmen knew not the blow smoke......, because we would take the bit right there and try it in front of them. And the salesman, would rather be straight with us, or we tell them we are not interested and don't call us, we'll call you.

Got to a point that Shoda used our capabilies as a selling point for their routers.