John; BP was pushing the edge with the 4200 rpm top speed. When you look up bearing specs most consider 4000 rpm max continuous under load. If your head is truely that noisy then something else isn't right - cutting air that machine should just purr with the loudest noise being the motors fan.
My Hurco KM3P, a psydo BP type clone made in Spain by Kondia. Has a top speed of 4000 and 3600-400 is considered RED Zone as in the don't recommend long term use in these ranges. Like most in industry - if it isn't locked out - we are going to use it - and we had jobs we ran at 4000rpm from 7am till 10pm daily for weeks at a time. That spindle did not turn off or stop cutting the entire day. We used 2 operators at a time, each would unload a finished part and insert a freash one on there side of the machine table and the machine looped back a and forth being unloaded on one end while cutting at the other. Why did the Mfg limit the rpm - The mfg sure does not want to have a spindle failure within the warranty period. If your a really hard nose - you can get the terms added that the OEM will warrant the spindle for the duration of the lease. I have done this on several machines and in 2 cases it saved a small fortune. Now back in the 80's era when my machine was designed they used the vari-drive with a motor turning 1800 rpm. They used another small 3phase motor with a worm drive reduction to adjust the vari-drive speed (cranking the handle so to speak) and a special prox sensor to count the back gear teeth as a tach (much like Jon E. did but without the quad) Mine is surprising accurate and will land you within 7 rpm of the programed spindle speed cutting air. Once the speed is set it does not monitor speed variations under load. Since you allready have the VFD and encoder hooked up you could mount a stepper on standoffs to drive the speed adjustment wheel. Why do it this way - well, you stick with the existing motor running at its rated RPM so it is at its best for cooling, and power output. Now you could use the VFD to do minor "trim" adjustments with the feedback to compensate for load but we are talking about maybe +/- 5Hz My machine does what I call "nearly Rigid tapping". The tach senses the stop and reversal of the spindle by timing of the teeth and I use a very limited travel Bilz type tension/compression type holder ( I'm also running U200 tooling ). Most of the good BP head conversions that replace the vari-drive with a fixed ratio belt that I have seen bumped up the HP rating to a 5hp motor to have excess cooling and to make up for torque loss ect. when running at the far ends of the rpm ranges. ------------------------------------------------------------------------------ Introducing Performance Central, a new site from SourceForge and AppDynamics. Performance Central is your source for news, insights, analysis and resources for efficient Application Performance Management. Visit us today! http://pubads.g.doubleclick.net/gampad/clk?id=48897511&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
