To Scott_Bob. Here is your last statement to Camminc.Originally Posted by Scott_bob
There you go again!
I did not say selecting the right RPM is a waste of time.
I just don't have to use your brand of dynamics to know what RPM to use. I use experience, and of course I refer to cutter mfgr's specs for the material I'm programming for, and I use Excel (spreadsheet) and it works great. I don't need a database to tell me what RPM to use.
What you did say was:
By the way, let me just say right here, that it is just down right goofy to think that the right RPM is all you need, to do HPM (High Performance Machining). Come on, a lot of us have many years of experience running CNC machines and I gotta say spindle speed is important don't get me wrong but, the effect on the features holding tolerance is not that great. Controlling chatter, oh yah, it's the biggest contributor. Our objective in using CNC machines is not to use them chatter free, but to make parts within specification, as fast as possible. Some day, I too will have to look at eliminating chatter; right now I don't have that problem. I guess that's because my spreadsheet does work, and I use the right RPM when I write the CNC programs.
Camminc’s reply: Here you go again, with the experience thing Scott_bob. Each machine has it’s own dynamic’s and each tool put into it makes those dynamics, which show up at the tool tip, which can be measured to create a stable cut. When you change the gage length of a tool, tool holder, over hang, type of tool, many other things, dynamics change, meaning a best stable cut changes from all these entities. So what I assume your saying is, you have all this knowledge and information in your mind from experience and or it is all in your spreadsheet? Sorry to say, I do not think you or any body is capable of it. Many times I have walked out into the shop and changed rpm of an operation from chosen parameters of programmers like your self to create a stable cut from an unstable cut, with the use of an impact test or audio or already collected data from a database. Over and over again it happens because programmers like yourself think the way you do. Please, don’t give yourself so much credit, it’s all in your mind. Cutter manufacture spec’s do not tell a programmer what rpm to run a cutter at, because they know it is a matter of dynamics on each machine tool. They might give maximum sfm for material, but to state a specific rpm is certainly not going to happen. Therefore, programmers pick an rpm, and if it is not a known dynamic rpm of a specific nomenclature of a tool in a specific machine, then it is a guess. No matter how you look at it. Chances are it might be right, but most of the time it is not. Telling people in this forum that your experience is better than all the research done at Universities like University of Florida, North Carolina State and many others around the country by professors and students all around the world, shows your lack your lack of consideration for other people’s points of view. Knowing what I know from being trained by experts in the field, it is an insult to all of us to hear this kind of thought. You discount expert events because of your belief’s, therefore discouraging all the readers of this forum from what you write to not believe anything but your way. People in this forum are here to find answers, not just your belief’s but all of us. I see it all the time, your ways of thinking about HSM are antiquated, outdated and misinformed. You have never experienced an impact test or audio chatter recognition, yet you give your opinion. You have no say so about them if you have no experience of them. Instead of discouraging it, why don’t you try and experience it, then make an opinion. That goes for a database also, talk with educated people about tracking information before you say something about a database that you know nothing about.