for someone else, and emailed it, not posted to RCM. Here it is, in case it
-----Original Message-----
Sent: Wednesday, January 23, 2002 2:11 PM
To: Steven Horace K Jr SPOR
Subject: Re: SB lathe instructions
damn, that was at least three years ago! And the instructions were in my
shop! It's possible I still have them, but not very likely.
Here's the edited version.
The bearing nearest the spindle I call the front bearing, the other bearing
is the back bearing.
On my lathe, the front bearing cap is held on with four capscrews that
fasten the cap to the saddle, with shims to create a variable amount of
clearance in the vertical plane. The rear bearing cap is similar, may have
only two capscrews, and additionally has a thrust bearing that is
adjustable by rotation. What you're aiming for is about .001" play in any
plane, when measured with a dial indicator, and putting reasonable pressure
on the spindle. you need to definitely overcome any residual oil left in
the bearings, so i try to get about 100 pounds of force on the spindle in
six directions - up, down, left, right and in/out. You're looking for
about a thou of play when you go from hard down to hard up, etc. I just
take off the chuck and stick a big bar in the through hole, and put
pressure on it.
These bearings were scraped in when fitted at the factory. If fitting new
bearings, you have to use blueing to establish the rubbing points. the way
that I did this was to remove the spindle from the lathe, and bench fit the
caps. I put blueing on the caps, rubbed them on the spindle, and found
that they were tight at the parting line - horizontal clearance was low on
the front bearing only. This bearing had no scraping marks, so I decided
that it must have been replaced at some time as it's beyond reason that a
60 year old well used lathe would have survived with too tight bearings
that were in perfect shape for so long! I scraped them using a wood
scraper and got the clearance better. Did the same thing to the saddle
bearings, and reassembled putting in shims to get the desired vertical
play. Set the thrust bearing by rotating it to get about .001" clearance
. Found that the lathe ran better, but would still seize up at high
speed. I examined the bearings and thought that the front bearings had
been changed, and had a sharp edge at the parting line of the saddle
bearing which I thought would scrape the oil off as the spindle spun. I
scraped a fairly large chamfer (1/8") on this edge to encourage the oil to
stay on the spindle. I also decided that a little more clearance in the
thrust bearing would be fine, as any tool pressure tends to push it one way
or the other, and I opened that up a tiny amount. For better or worse, I
don't torque the bolts very tightly - I frankly don't notice any difference
so I leave them nicely snug but probably not more than 10 ft pounds - saves
me making up a bunch of shims to figure out how much I need after torquing.
I have drip cups on top of the caps, and I tend to set them to flow a drip
every second or two. this puts a lot of oil through in a day, and I would
normally top up every second day or so. If I forget and leave the taps
open over night, they are totally empty in the morning. I've been using
10w30 motor oil, but I'll try some 0W mobil one and see what it does.
Hope this helps. Just understanding that the front bearings at least were
probably new, and that they need to be fitted by scraping essentially gave
me all I needed to do the job - it's not rocket science! Ping me back if I
can help at all. I'll look for the sheet.
Brian
>Brian, was reading your post on RCM about your SB lathe, with old style
>bronze journals.
>I have been trying to help a friend get one like that up and running, and
>would love to get a copy of those instructions. His is a 9" dated 1926
> My SB 16" is 1939, so 63 years old and has scraped in bronze bearings in
the
> spindle - not the same as the later ones, and I think that the cross-over
to
> the later bearings was just about 1940 or so. There are just bronze
liners
> to the bearing caps and saddles in the headstock, and the only adjustment
is
> by scraping and shims. Mind you, the oiling on mine is by drip cups on
top
> of the bearing caps, no felt wicks to oil cups on the sides of the
> headstock. If you lathe is actually 60 years old, it may be a transition
> design or something.
> Brian
> > > Hi Folks,
> > > Here I am, stripping down the 16" SB for a refurb. 2300# of parts
> strewn
> > > across the shop floor. I get to the head stock and pull the bearing
> caps,
> > > yank the spindle and find no bearings. All I see are scraped lands
> running
> > > parallel to the spindle bore. There is the felt wick in the hole at
the
> > > bottom but no bearings. The parts manual says yea to bearings, the
> picture
> > > shows a bearing, everyone talks about bearings, so where are mine?
> > I just finished reading both the 1942 SB and Sheldon's versions of How
> > to Run a Lathe, from Lindsay. One of them stated that cast iron
> > bearings were sometimes used for high-speed lathes since bronze is
> > good only up to 1200RPM. There was a brief description of the
> > Superfinishing process invented by Chrysler.
> > > While I have your ear, I am removing the 60 years of goop from the
bed.
> I'd
> > > like to use a chemical process but I can not find a hot tank big
> enough...
> > I used 5F5 covered with plastic sheeting, or Ziplock bags for the
> > smaller parts. It cuts through the original SB paint and filler
> > nicely. Avoid the methylene chloride fumes and WEAR *** GLOVES!
> > jw
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