Waviness in the finish, what causes it and other questions.

[Edward]

Hi guys,

I had to enhance this picture to show the problem as it's actually quite faint. It's not just me, I have noticed it in many other people's finishes, usually when cutting thick pieces. In my case I was cutting (contouring) 15mm plate with an 8mm endmill and it only happens at the start of long pieces, i.e. when the milling machine bed is furthest from its centre, then it soon disappears along the line when the bed starts to travel closer to the centre. What can cause this waviness?



Second question. Cutting noises: do you have some video link where one can hear what "chatter" actually sounds like?

I have experienced what I think I would call "resonance", but maybe this is what you call "chatter". For example, when squaring the edge end of 40mm extrusion using a long 12mm endmill, you get this unbearable and continuous high pitch shrill noise that can sometimes be reduced a little by trying different motor revs, usually reducing revs, or increasing feed rate, I think. Similar noise sometimes when parting off on the lathe some distance away from the chuck.

So if this high frequency noise is what you call chatter, how does it differ from resonance?

Many thanks.

Edward