Re: Max & recommended shaft rpm
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Glen Linscheid
?Please roll with your own interpretations Herb, I agree that high HP and speeds are needed for production high volume machining, but often carbides and ceramics are the only way to cut some materials. I use carbides all the time both at carbide speeds and lower speeds for one off jobs, simply because my time is too valuable to waste grinding HSS and replacing a carbide insert puts you back within .001" normally of where you were when you swapped. I can't believe any experienced machinist doesn't understand relief angles to grind HSS, as there ARE times when HSS is the only way to do some jobs. ?Of course my own practice is to never use lighthouse style holders, and I'd agree, for those who do, it's probably not normally wise to use carbide, as most available carbide tools that would fit are the brased on type, and it's very hard to replace the tool with the precision one gets with QC toolposts and holders and carbide inserts. ?Threading with laydown inserts I find works better than HSS even at slow speeds, in fact other than CNC threading much manual threading is done at lower speeds with "In the white" color chips even with carbide. ?Granted we have hundreds of old carbide inserts in boxes with one or more new edges remaining, so it's not a matter of money for us. It does require more skills and/or experience to thread with carbides if the operator has trouble timing his exit. ?Having said all that let me say that if you are most comfortable using HSS it's all good, I'm not advocating one way or the other as much as saying there are ways to use carbide inserts that are better in my opinion even with a slow and wimpy old lathe at times. With respect, Glen On Wed, Jul 29, 2020 at 12:17 PM Herb Kephart <ebtm3@...> wrote:
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