Gene it is sitting fully submerged and that groove is on the top half of
the bearing so it should have a lot of oil on the bearing surface.
I dont need more than 1000 or 1500 RPM for the plastics.
------ Original Message ------
From: "Gene Heskett" <ghesk...@shentel.net>
To: emc-users@lists.sourceforge.net
Sent: 2018-04-02 17:33:21
Subject: Re: [Emc-users] What RPM
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>
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