On Thursday 02 March 2017 08:36:54 andy pugh wrote: > On 2 March 2017 at 03:08, Kurt Jacobson <kurtcjacob...@gmail.com> wrote: > > Since there has been a significant amount of discussion about the > > cheap MPGs I decided to take mine apart and find out how they work. > > I took a bunch of pictures during the disassembly, you can find them > > here: https://goo.gl/photos/w8fJaFLzzUsFzfmV7 > > Thanks for that. > > Looking at the design it looks like it ought to be pretty > coolant-proof, is that your impression? > > I have some on the front of my lathe apron, and so far have not used > coolant (mainly turning brass at the moment, so not necessary)
I haven't either, no coolant facility but coolant capability is on the 2nd page of my todo list. Fixing the hot countershaft bearings so I can spin faster than 750 revs is somewhat higher on the list. I suspect the shaft is scored a bit, so I'll push it out thru the porthole in the end of the base cabinet and order up a piece of A2 the right size & make a new one. The bronze bushings will be fun, or take the whole MaryAnn apart and have it reamed for a couple torrington needle cartridges that fit the shaft, trying to align the lube pinholes with the zerks. Which leads to a question as I bought one of those 1kw induction heaters, on fleabay. Should I warm up the area riding in the needle rollers? & if so, how hot & long for A2? Me obviously not an expert on this air hardening stuff. 10 minutes at 750 rpms in 2nd or 3rd gear belt slot, and both ends of it are north of 150F. Spindle bearings might be somewhere in the 90's F. in the same time frame so they're fine even if under a thou clearance & dragging slightly. With only a 1hp 3 phase motor, the drag from the countershaft has the motor slipping phase at 850 revs, regardless of belt position. Getting rid of that drag will make near 2k revs available but that might be limited by spindle bearing heat unless I shim a cap, or both, about a thou on one side only. Bronze spindle bearings, look brand new, as does the spindle bearing surface under the caps. Sweet! This lathe, I think, has been abused, but not heavily used. I think somewhere in the past, it fell over and drove the crossfeed screw thru the nut by landing on the compound, breaking and warping the compound castings to the point of just binning it. Someone "fixed" the crossfeed nut by tapping what was left for a helicoil insert, which was worn razor thin again while the screw looked, and maybe was, brand new. Backlash was above 80 thou when I unloaded it here. So I had to make a block riser on TLM to set the qctp on, and cnc it with all ball screws. Worst case backlash is now about 7 thou, and 5 of that is in the z thrust bearing I've yet to fine tune. Priorities... Thanks Andy. 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
