On Monday 02 April 2018 10:23:33 Marius Liebenberg wrote: > Hi > I have had this piece of machine in the store for a long time. I think > it was used to decant fishing line to the smaller plastic reels. > I have a need for a small dedicated lathe that will onpy cut soft > materials like plastic and aluminium occasionally. > The spindle in the picture is what is currently fitted to the machine > and I would like to refurbish and use it. The question I have is what > RPM will I be able to run the spindle seeing that it uses these brass > bearings? > I am seeing an unusual lube distribution system in those bushings. Is there a lube pump and reservoir associated? Something that would assure a continuous flow of lube into the end grooves and thence lengthwise thru the groove I can see running lengthwise in the left half of each? With such a system running, and delivering a 1/2 cup of clean 0 to 5w oil a minute, I could see it spinning 30k revs. The rev limit would be how much heat the viscosity of the oil used was caused to be generated. Monitor with an IR thermometer. Personally, the oil will start to fail at around 300F, so seeing 150F on the bushing holder would make me slow it down.
If nothing of that sort of circulating lubricant exists, and its equipt with flip cap oilers, then some 30-50w oil to try and hold the hydrodynamic film, refreshed hourly might allow 2500 revs, depending on the load and any imbalance that might exist. Because the hydrodynamic forces are rpm dependent, there is of course a minimum speed that should be maintained when its carrying any lateral load. I get the impression that what little evidence of wear I see was caused by this minimum speed being violated, probably at startup and shutdown times. The small cross-section of the shaft will allow some flexure under load which may have overpowered the hydrodynamics, allowing some metal to metal contact, and that might have worn the bushings a bit bell-mouthed. With sharp tooling and copious coolant, it should do plastics and alu at decent cutting speeds just fine. Add the forced lube and 10k+ rpms should be doable. Watch it with an IR thermometer, and let it tell you when it needs forced lube. > ----------------------------- > Regards / Groete > > Marius D. Liebenberg > +27 82 698 3251 > +27 12 743 6064 -- Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
