From: Robert Bastow <TeenutNOSPAM@hotmail.com>
Newsgroups: rec.crafts.metalworking
Subject: Re: Roller Bearing Loads?
Date: Wed, 11 Aug 1999 12:44:45 -0400

Tom,

I have no personal experience of the Holbrook but I have had a Smart & Browne
that was superb.

IMHO the Myford Super 7 has one of the best designed plain bearing headstocks
ever..considering its relatively low cost.

Interestingly, my recently aquired Deckel FP1 has the same arrangement on both
horizontal and vertical spindles.  It must be agreed that this is a machine on
which no expense was spared (By the manufacturer)

The Maximat Super II, is a very nice lathe...but cannot begin to pretend to be
in the same class as the Hardinge, Monarch, Holbrook, Rivett etc, class of
"Toolroom Lathes"

Right now the bearings are in good shape..but I find that, no matter how
carefully they are adjusted, I get "bearing chatter"..the characteristic spiral
marks of a roller bearing headstock..especially when high speed finishing softer
metals like Aluminum or copper.  Any attempt to adjust the bearings to a closer
running fit, results in over heating at high RPM.

I can put up with this for now..having bigger fish to fry at the present
moment.

However!!

The cost of replacement bearings, knowing Blue Ridge etc., will be frightening!
Yet I will have no guarantee that the performance will be any different.  As I
said earlier, the present bearings are in perfect condition.

Obviously the problem lies in the design and I CAN change that!!

This was what set my mind off in the direction of replacing (someday) the front
roller bearings on my Maximat with a properly designed, fully adjustable,
conical plain bearing. I plan to replace the inner race with a hardened steel
cone and the outer with a plain conical bearing.  I may go to a close grained
cast iron for this, rather than bronze..to give better load bearing capabilities
in the limited length available.

The rear bearing, currently a taper roller, will be replaced with an ABEC 7
angular contact, opposed pair.  The current lateral adjustment will then allow
the front bearing clearances to be set VERY finely.


Robert Bastow

Robert

tmartin@xtra.co.nz wrote:

> Well Robert,
>         What would you consider to be the "sans-pareil" of
>         plain-bearing headstock? Would Holbrook be amongst
>         the contenders?
> Tom
>
> Robert Bastow wrote:
>
> > Hi Tom,
> >
> > Provocative!  Moi?
> >
> > It takes a hellaciously precise, (read Expensive!!) rolling bearing to
> > equal the performance of a well designed taper bronze bearing (in the
> > hands of someone that knows how to adjust it properly.
> > 
> > The fact that your Monarch is one of the few machines so equiped does
> > nothing to sweeten my mood ;^)
> >
> > Robert
> >
> > tmartin@xtra.co.nz wrote:
> > >
> > > You are in a rather provocative mood, aren't you?
> > > Of course you will revert to a non-geared headstock in
> > > keeping with such "purist" designs won't you?
> > > As I own a Monarch, one of the first to eschew such
> > > pagan ideology, I will await with interest your reversion
> > > to the "Dark Ages" and the subsequent demise of the
> > > precision bearing industry as we know it! (LG)
> > >
> > > Tom
> > >
> > > Robert Bastow wrote:
> > > >
> > > > I am waiting for the Roller bearings in my Maximat Super II to
> > > > give up the ghost..So that I can figure out how to replace them
> > > > with tapered bronze bearings..Just like a "Proper"lathe!!
> > > >
> > > > Teenut
> > > >
> > > > mulligan@advinc.com wrote:
> > > > >
> > > > > In article <19990810084525.26640.00000024@ng-fq1.aol.com>,
> > > > >   geneleis@aol.com (GeneLeis) wrote:
> > > > >
> > > > > > ... so with big expensive stuff,...
> > > > > >  some serious thought goes into the mounting of these bearings.
> > > > >
> > > > > Or even the little stuff.  There was a reasonably long thread
> > > > > recently here about the tapered roller bearings in a milling
> > > > > machine spindle, and what would be the absolutely best way to
> > > > > set them up.
> > > > >
> > > > > Home shop stuff does not cost as much as the big boy's toys, but
> > > > > we sure care a lot about it!
> > > > >
> > > > > Jim

From: Robert Bastow <teenut@home.com>
Newsgroups: rec.crafts.metalworking
Subject: Re: SOUTH BEND ??
Date: Sat, 18 Sep 1999 00:30:52 GMT

"Gordis, Joshua" wrote:

> I have heard from some that the reason plain (bronze) bearings are superior
> to ball or roller bearings is that the latter can "read out" on the part,
> i.e. the infinitesimal "tick-tick" of balls traveling around ends up on the
> part.
>
> Personally, I have come to think this explanation as a lot of BS, and that
> if plain bearing were superior, than the Hardinge HLV would have them,
> rather than properly preloaded tapered roller bearings.

"Sometimes it is better to remain silent...!"

You should have stopped after your first paragraph, because you were dead right!

So far as the use of rolling bearings by the likes of Hardinge..In the first
place they don't use roller bearings but preloaded, angular contact ball
bearings, whose specification and tolerances put them up in the ABEC 7 region.

The cost of a replacement set of such bearings is more than the new cost of the
lathes that most of us use.

The other factor..not to be ignored is the cost of manufacturing and assembling
a properly designed, fitted and adjusted plain bearing nowadays.  These are not
exactly Oilite bushes y'know.

teenut

From: Robert Bastow <"teenut"@ hotmail.com>
Newsgroups: rec.crafts.metalworking
Subject: Re: Plain spindle bearings on lathes
Date: Mon, 17 Jan 2000 22:32:47 GMT

The Super 7 does have a taper bronze bearing at the front..But IIRC the rear
bearing is two opposed angular contact ball bearings fitted in a cylindrical
housing, so that they can be adjusted axially by a couple of fine threaded
collars.  This axial movement is what allows the clearance to be set so finely
in the front bearing.

This is the same arrangement that I was delighted to find on both spindles of
the Deckel Mill.

teenut

Clare@snyder.on.ca wrote:

> Myford Super 7 has tapered front and plain rear bronze bearings.
> I had to adjust mine - too tight they get hot, too loose they are
> inacurate. Set properly they are beautiful.

Newsgroups: rec.crafts.metalworking
Subject: Re: Plain spindle bearings on lathes
From: Robert Bastow <"teenut"@ hotmail.com>
Date: Tue, 18 Jan 2000 09:04:11 GMT

No!

Blame it on the fact that rolling bearings are cheaper to make and fit than a
properly designed plain bearing.

Blame it on a market place that has been "Brainwashed" by advertisements, into
thinking that roller bearings must be better.

teenut

tmartin@xtra.co.nz wrote:
 
> Blame it on carbide tooling.

> Fdmorrison wrote:

> > Various tapered solid bearing designs were used until well into the 20th
> > century.  Sometimes the spindle had an involute or a "Schiele" curve.
> >
> > It is surprising that these designs--at least with the apparent advantage of
> > the take-up feature--don't seem to have generally survived.
> >
> > Frank Morrison

From: Robert Bastow <"teenut"@ hotmail.com>
Newsgroups: rec.crafts.metalworking
Subject: Re: WTD Info:  Lathe Spindle material
Date: Thu, 03 Feb 2000 04:05:13 GMT

Hot rolled steel of one description or another...But almost always case hardened
and ground.

If the spindle runs in plain bearings, this is a must.

If it is mounted in rolling bearings, it will be OK for light use..Hardening
will not make it any stiffer..primary requirement for any M/c tool spindle.

However, under heavy use..epecially when chatter is involved, you should expect
the bearing seats to get hammered loose.

teenut

Marty Escarcega wrote:
>
> Forgive the newbie question :-)
>
> What material are lathe spindles usually made of? HRS? Are they typicall
> hardened and ground? Is it feasible to make a replacement in the home shop
> if so, what are the steps...just curious.
>
> Thanks,
> Marty