Re: Beginner "should I buy this" questions


Clive Foster
 

Bob

I take your point about it being essential to maintain the head-stock
in a well lubricated state for long life.

However I don't think that any South-Bend head-stock can ever be well
lubricated when used for wood turning. The pesky fine dust gets
everywhere, even on systems with good external seals and the
South-Bend head-stock has no seals relying on dynamic surface tension
effects to keep the oil where its supposed to be. Can't see that it would
take very long before enough dust gets into the bearing, especially
the segmented type, to start yanking the oil out faster than the wick
can replenish it.

Big problem is that hard, fine finished steel on oil soaked cast iron will
run for a long time with less than marginal lubrication before serious
wear starts but once wear starts its pretty fast.

I'm none too sure that, although it can undoubtably work very well indeed,
a top feed and oiler mod is actually going to be an effective improvement.
Like many empirically developed systems the South-Bend wick feed
re-circulating system on segmented bearings is a good deal more
sophisticated in operation than it appears at first sight.
Or at least so I was told by a man with proven credentials as a
real expert in such matters who considered it both crafty and elegant.
I'd actually asked him about installing top feed oilers which seemed to
me much better to which his initial reply was "why go to all that trouble
to spoil the system and always get oil everywhere". Apparently top feed
onto the journal systems always have to leak down to work. Not
necessarily very much but, so I was told, sufficient to ensure that the
oil spreads properly over the bearing surface. Apparently fitting a spreader
groove or wick to the top minimises the leakage needed but also reduce
load capacity. Not that I've a clue whether or not such reduction is of any import.

Now lubrication is certainly not my area of expertise but where I really
am expert I have personal experience of how apparently simple things
can be a lot more sophisticated than they appear at first sight. I also
know that careful development allied to a feel for how things "want" to
go can extract much better performance from a superficially simple set
up than ought to be possible according to casual analysis.

One thing is for sure. In the absence of deliberate abuse and given a
modicum of care, benign neglect or better grade, the standard
South-Bend head-stock is very long lived and can be expected to
outlast the rest of the lathe.

Clive



Hi Chaps

I agree that woodturning and sand papering is bad - not only does it
leave the sand fragments all over the lathe but the wood just "pulls" all
the oil out of the bedways and the like. For a well lubricated spindle I
can't see that it would necessarily bring on the early demise of the main
headstock bearings.

HOWEVER if the lathe is always run at high speed
with INSUFFICIENT lubrication then this is where the problems start in
my opinion. My old 9" Model B was semi-seized in the main brg at the
front of the headstock. I managed to clean it up pretty well and then I
drilled and tapped the the top of the brg 1/8th BSP and fitted oilers that
drip a nice drop of fully synthetic oil into the brgs.. The holes thru to
the brg faces meet with a groove put in by hand... Works a treat.

Best wishes
Bonalybob
Bob Johnson BSc MSc NRA MIMechE CEng
DAMT Ltd
15 Bonaly Avenue
Edinburgh
Scotland EH13 0ET

Visit: www.damt.co.uk
Email: bj@... or bj@...
tel: +44(0) 131 441 4923 fax: +44(0) 131 441 4923
mobile: +44(0) 7745 801995

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