I want to thank everyone for your advice and encouragement on replacing my 5c lathe spindle bearings.
I was able to replace the bearings in the spindle. The spindle "locknut" was pressed on instead of threaded on. I had to build an aluminum collar with steel dowel pins that engaged on the bearing spacers (which had holes for this purpose) to press it apart. I could tell that coolant had entered the bearing housing by getting around the front labyrinth seal and is ultimately what had ruined the front bearing. Other than that I had to purchase a parts washer and cleaned the heck out of everything. I found a set screw hole on the front seal and have installed an air fitting in its place for air purge. That should reduce the chances of that type of failure occurring again. Packed the bearings with "high speed synthetic bearing grease." With a little warming all bearings installed smoothly like in the youtube video. It was a very nice to have that video as a reference and really helped with reassembly. I ran it in over a period of 2 days. Incrementally increasing RPMS and watching temperatures, keeping the spindle body itself under ~105 fahrenheit or comfortable to touch with hands, waiting for temperature to drop, then increasing speed by about 250 rpm. Now it will run cool at 3000rpm for an hour or so, getting up to about 90 degrees. I'm not sure what my rpm upper limit should be but that seems fairly fast. Obviously time will really tell but it has continued to run very smooth and quiet. After a test cut last night the parts are actually round now. Went from around .0005" out of round to at most .00005" out of round and surface finish seems much improved. Thanks again all! -Curtis On Wed, May 27, 2020 at 7:25 PM Curtis Dutton <curtd...@gmail.com> wrote: > Agreed. We will do the best we can and break in very slowly. I'll read up > on break in procedures and we have temp probes that we can use to watch it. > > Thanks all for the info! > > On Wed, May 27, 2020 at 3:20 PM Thaddeus Waldner <thadw...@gmail.com> > wrote: > >> I’ll chime in on the importance of a clean environment. They usually spec >> a ultra high purity grease for lubricant. >> >> They also usually have a fairly specific break-in routine. I.e a pair of >> temperature probes, one near each bearing, then run the spindle, starting >> at a slow speed. Gradually increase The speed to max over several hours, >> all the while keeping an eye on the temps. >> >> Definitely *don’t* spin it up right away to “see how it runs.” >> >> > On May 27, 2020, at 1:32 PM, Curtis Dutton <curtd...@gmail.com> wrote: >> > >> > Yes that youtube video seems to be very helpful. I've been watching it >> for >> > the last few days. >> > >> > Well we will give it a try then and see how it pans out. >> > >> > Thanks all >> > >> >> On Wed, May 27, 2020 at 2:03 PM Leonardo Marsaglia < >> ldmarsag...@gmail.com> >> >> wrote: >> >> >> >> I've never took apart the ones in the Mazak (Wich I asked for quotation >> >> once)but I disassembled other lathes that were similar and it's not >> that >> >> much of a pain. Surely you must make some tooling sometimes to get >> things >> >> done right but nothing else. >> >> >> >> 5.000 to 7.000 sounds about what they would charge for it. From what I >> >> remember the tricky part is to guarantee a free dust and grit assembly. >> >> They claimed to have a dust controlled environment much like a >> >> semiconductor factory but I suspect part of that is marketing. >> >> >> >> One common approach for big lathes is two double row roller bearings >> with a >> >> thrust bearing for the axial load. >> >> >> >> Leonardo Marsaglia >> >> >> >> El mié., 27 may. 2020 14:51, Jon Elson <el...@pico-systems.com> >> escribió: >> >> >> >>> On 05/27/2020 12:18 PM, Curtis Dutton wrote: >> >>>> So after finishing the retrofit of the old Miyano gang lathe the >> >> spindle >> >>>> bearings are shot. You can grab the spindle nose and push it side to >> >> side >> >>>> about .0005" to .001". The cut quality is also fairly bad. Just >> >> cutting a >> >>>> spring pass on an aluminum bar shows a lot of chatter like marks. >> >>>> >> >>>> I can also measure a .0005" to .001" axial play by pushing on the >> face >> >>> or >> >>>> the collet closer of the spindle. Not to mention there is roughness >> and >> >>>> fairly loud bearing noise while running. >> >>>> >> >>>> I expected this but I'm looking for someone that can refurbish it or >> >> any >> >>>> advice from others that have done this before. I haven't ever sent >> >>> anything >> >>>> out to be rebuilt so I'm ignorant on the process. >> >>>> One online quote I received was 4500 to 6500. Is that reasonable? >> Does >> >>>> anyone know of someone or have pointers? I'm not opposed to trying to >> >> do >> >>> it >> >>>> myself but I know it would be very challenging to get it right. I'm >> >> sure >> >>>> I'd need to order 2 sets of bearings... One for the first attempt and >> >> one >> >>>> to get it right! >> >>>> >> >>> Well, it may not be that tricky. It is probably just a pair >> >>> of angular contact precision ball bearings, >> >>> and may have some type of spacer to get the preload right. >> >>> Do you have any drawings of the >> >>> headstock? That might give some idea of how the spindle is >> >>> assembled. >> >>> >> >>> Jon >> >>> >> >>> >> >>> _______________________________________________ >> >>> Emc-users mailing list >> >>> Emc-users@lists.sourceforge.net >> >>> https://lists.sourceforge.net/lists/listinfo/emc-users >> >>> >> >> >> >> _______________________________________________ >> >> Emc-users mailing list >> >> Emc-users@lists.sourceforge.net >> >> https://lists.sourceforge.net/lists/listinfo/emc-users >> >> >> > >> > _______________________________________________ >> > Emc-users mailing list >> > Emc-users@lists.sourceforge.net >> > https://lists.sourceforge.net/lists/listinfo/emc-users >> >> >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
