Newsgroups: rec.crafts.metalworking
Subject: Babbitt metal
From: dave.williams@chaos.lrk.ar.us (Dave Williams) 
Date: 15 Jun 94 17:34:00 GMT

-> Does anyone have experience pouring bearings made of babbit?  How do
-> you do it? I have a need to pour a connecting rod bearing for an old
-> Witte farm engine.

 Here's something I posted in the hotrod mailing list a couple of years
ago:


 I've been reading a pre-WWII book on auto mechanics, and it has a
thorough discussion of how to pour and fit Babbitt bearings.  I'd always
thought that, y'know, you just flipped the engine over, took off the
pan, and poured it in somehow.  Nope.  First you get to chisel the old
Babbitt out, then you clean endlessly because any water or oil will make
the new metal bubble, then you clamp this wierd fixture across the main
web and put in a plug approximating the crank journal diameter (and
they're all different, do the thing is a "universal" fixture which
probably worked about as well as you'd imagine).  Then you heated the
Babbitt in your furnace and poured at red heat.  After it cooled, you
cracked the pouring fixture pieces loose and had this big wad of metal
(hopefully) stuck to the block, with fins, flashing, and drools of
escaped metal run down into the rest of the motor.  You got to spend a
while trimming off the excess, and then you got to repeat the entire
process for the rest of the bearings AND their main caps.

 Assuming you got through all that without Babbitting your foot or
setting anything afire, you got to fit the bearings.  In a large shop
you'd have a line boring machine available, much like large shops do
today.  A smaller shop might use a reaming stand and fixture.  If you
were in a small town, ye olde mechanic probably had to scrape the
bearings to fit.  This meant using metal scrapers, which were shaped
more or less like scalpels or midget fancy butter knives, and carving
the soft Babbitt metal to a reasonable fit to the crank.  Once the crank
would actually go in, he'd use Prussian blue to find the high spots,
scrape, blue, scrape, etc.  Of course, scraping too much would require
starting over again, so he'd be very careful.  Oh, yeah, he also got to
cut the oil grooves by hand, too, to the pattern required by the auto
manufacturer.  Not cutting the grooves would be a bad idea, since most
Babbitt bearing engines used dippers and splash lubrication rather than
pressure oiling.

 Once he had about a 75% fit between the crank and bearings, he'd clean
everything off, bolt the crank in, and (if he was a perfectionist) would
lap the crank in by running it with an electric motor.  Then it all came
apart again so the rest of the engine could be assembled.  All in all,
it sounds like a full day's work, and one requiring a fair amount of
specialized machinery (and that's even assuming the crank didn't need to
be turned due to flat spots or taper wear, which the book assures us
happened often).

 Nowadays we simply wipe everything out with a paper towel, pop in new
bearing shells, mike the crank to make sure it's round, and use a piece
of Plastigage to make sure the bearing manufacturer didn't have a QC
problem.  Voila!

 Ah, the good old days...

Newsgroups: rec.crafts.metalworking
Subject: Re: Babbit
From: dingbat@codesmth.demon.co.uk (Andy Dingley)
Date: Tue, 14 Jun 1994 22:54:18 +0000

In article <mwill.1.00110496@WichitaKS.NCR.COM>
           mwill@WichitaKS.NCR.COM "Mark Will" writes:

>Does anyone have experience pouring bearings made of babbit?  How do you
>do it?  I have a need to pour a connecting rod bearing for an old Witte
>farm engine.

Well I thought this was an arcane skill I'd *never* get asked about on the net,
but after all there are people here who make chainmail.  8-)
Casting whitemetal bearings is easy, scraping them to fit needs slightly more
skill. I've done this for a bunch of engines now, from small stationery
(farm) engines, up to a White Scout Car (WW2 armoured car) and a 12" diameter
steam engine connecting rod big end.


   You need:

Gas/blown air torch

Flux (zinc chloride / killed spirits)

Whitemetal/babbit metal. For bearings, this can be either tin based or lead
based. The terms "whitemetal" and "Babbit" are too vague to be useful here -
buy it ready-mixed from a bearing supplier such as Glacier. It's still
available, but you have to look hard. If you have a network of farm engine
collectors, as we have in the UK, then the specialist dealers will have it in
stock. I was at a vehicle show at the weekend where sticks of it were on sale.
Older bearings are generally lead based. '40s-'50s ones are tin based and
usually thinner.

Tinning solder. This will be 50/50 lead/tin solder for most bearings. Tin
based bearings in steel shells will use pure tin. Gunmetal or bronze shells
can use 50/50.

Casting stand. This is a heavy steel fixture, to which the bearing shell is
clamped during pouring. Mine is made from a piece of L girder, with a
half-tube of scaffolding pipe welded aginst one inner face. I use a welding G
clamp to clamp the bearing shell into place, with the scaff pipe taking the
place of the crankshaft. If your bearing also has thrust faces, then you may
need C shaped metal spacers too, to lift the bearing shell off the surface of
the fixture.

   The process:

Clean up the old bearing. Scrape or file off cracked & contaminated
whitemetal, then degrease. If you can't clean the whitemetal to a perfect
surface, then heat the whole bearing up and melt off the old metal. Allow to
cool, and paint the non-tinned surfaces with whitewash.

Tin the bearing shell. This is easiest in a tinning pot, but you'll probably
need to do it by hand, with a stick of solder. Warm the bearing shell up
evenly, trying to avoid oxidising the clean surface. Dip the solder stick in
flux, and wipe it over the heated shell. Don't over-heat the tinned surface,
as you want to avoid oxidising the solder. If the bearing shell has
sufficient heat capacity, it's best to warm it up first, then do the tinning
with this residual heat alone, not using the torch directly. In some cases, a
moleskin is needed. This is a thick pad of *cotton* corduroy cloth, or denim,
dipped in flux or tallow and used to wipe the solder over the cleaned area of
the bearing until it is all bright and shiny. Using a moleskin is *not*
regarded as good practice - careful heat control is much better.

Assemble the casting fixture. The bearing should be clamped into the fixture,
sealed with a rope of asbestos putty ("Moist-bastos" brand welder's
heat-shielding putty works). There should be sufficient clearance between the
bearing and the fixture to have enough bearing metal to allow machining and
fitting. Custom fixtures are not unusual. Before assembling the bearing shell
into the fixture, the fixture should be pre-heated to 200-250 oC.

Pour the bearing metal. Melt temperature should be as recommended by the
bearing metal maker, although 450 oC is a reasonable maximum. I use a
thermocouple to measure this, although there are also craft techniques
involving the time it takes squares of newspaper and stale bread to catch
fire 8-) Before pouring, flux the surface of the melt and skim off the dross.
Pour the melt in *one* swift operation (Important !). As it cools, the melt
will contract noticably - especially for lead based melts. If you don't have
enough pouring space to allow for this, then you *might* need to pour in a
little more metal.

If you have problems with trapped air in the shells (almost certainly) then
you'll need to either increase the spacing between the bearing shell and the
casting fixture, or use a puddling wire (thin welding rod) to work the still
molten melt gently up and down and allow the air bubbles out. You should be
able to feel the melt gradually solidifying from the bottom of the shell
upwards.

Once the bearing is poured, then it's a good idea to gently cool the *back*
of the bearing shell. This improves the adhesion between shell & bearing. Use
a damp cloth, or water-filled plant sprayer, from the bottom upwards.


Now the bad news - the bearing should really be metalled by tinning it,
assembling it into the fixture, and pouring the metal, all in one smooth
operation -- before the tinning solder has solidified ! Practice with it
cold, have everything ready, and have an assistant to do the clamps up.


If your bearing doesn't look right, melt it off and try again. Your first
couple probably won't be usable, so don't be surprised. Don't use a badly
cast bearing, it isn't worth the trouble. Don't re-use contaminated bearing
metal.


Once you're happy with the casting, you'll need to machine the bearings to
size, and then scrape them to a final fit. I'll leave someone else to
describe this bit  8-)

--
Andy Dingley     Codesmiths of Newcastle     dingbat@codesmth.demon.co.uk

Newsgroups: rec.crafts.metalworking
Subject: Re: Babbit
From: dave.williams@chaos.lrk.ar.us (Dave Williams) 
Date: 15 Jun 94 17:39:00 GMT

-> Once you're happy with the casting, you'll need to machine the
-> bearings to size, and then scrape them to a final fit. I'll leave
-> someone else to describe this bit  8-)

 Considering the cost of having the Babbitted block and rods resized
(here in the US line bores go from $125-$250, rod resizing $10-$30 each)
it might be a good idea to just have the block and rods bored, then turn
your own thickwall bearings out of 2024 aluminum tubing.  Having a shop
make a new set of bearings would be cheaper than reBabbitting if you
plan to keep the engine and put a lot of miles on it.

Newsgroups: rec.crafts.metalworking
Subject: Re: Babbit
From: dingbat@codesmth.demon.co.uk (Andy Dingley)
Date: Thu, 16 Jun 1994 22:06:34 +0000

In article <3323.106.uupcb@chaos.lrk.ar.us>
           dave.williams@chaos.lrk.ar.us "Dave Williams" writes:
>  Considering the cost of having the Babbitted block and rods resized
> (here in the US line bores go from $125-$250, rod resizing $10-$30 each)

Well first of all, this is a barn engine. I imagine it only has two main
bearings and a single big end to worry about.

Why not line bore it yourself ? A big end should fit into almost any lathe,
and even if you don't have a boring bar they're easy enough to make.

For re-boring main bearings on big steam engines (the sort that powered an
entire textile mill, via lineshafting), I've seen a number of boring
arrangements that were pretty much built up on-site, specially to bore this
one set of bearings. They're basically a pair of plummer blocks (ball races)
fastened to the bed of the engine, a bar between them, and a boring head that
traverses along the bar. The head is usually traversed by a leadscrew
attached to the bar. Each time the bar rotates, a star wheel on the end of
the screw strikes a fixed pin and gives 1/6 of a turn of feed. Setting up the
plummer blocks accurately requires shims, and slotted holes, and messing
about with a dial gauge on the bar, but it's time consuming rather than
difficult.

Finally, why bore it at all ? You can do it *slowly* with just a hand file
and a scraper. After all, if you're going to hand scrape the bearings to
finish them, then you don't need to be all that accurate about the boring.

--
Andy Dingley     Codesmiths of Newcastle     dingbat@codesmth.demon.co.uk

Gonna ride, gonna ride, gonna ride, gonna ride, my Space Hopper

Newsgroups: rec.crafts.metalworking
Subject: Re: Babbitt metal
From: dingbat@codesmth.demon.co.uk (Andy Dingley)
Date: Thu, 16 Jun 1994 22:14:57 +0000

In article <3322.106.uupcb@chaos.lrk.ar.us>
           dave.williams@chaos.lrk.ar.us "Dave Williams" writes:
> Then you heated the Babbitt in your furnace and poured at red heat.

*Much* too hot !   You'll oxidise the poor stuff to extinction.
If you do overheat it, it tends to form cracks through the bearing with
oxides deposited along the crack. Pretty soon these will propagate and allow
great chunks of bearing metal to pull out. This is mainly a problem with big
thick-layer bearings, where you can't get enough heat in to pour in one go,
without keeping the torch playing on the bearing.

There's a similar problem in re-using old bearings with unnoticed cracks in
them. It's much safer to melt off all the old metal and start from a clean
surface.

--
Andy Dingley     Codesmiths of Newcastle     dingbat@codesmth.demon.co.uk

Gonna ride, gonna ride, gonna ride, gonna ride, my Space Hopper

Newsgroups: rec.crafts.metalworking
Subject: Re: Babbitt metal
From: dave.williams@chaos.lrk.ar.us (Dave Williams) 
Date: 17 Jun 94 15:39:00 GMT

-> > Then you heated the Babbitt in your furnace and poured at red heat.

> *Much* too hot !   You'll oxidise the poor stuff to extinction.

 That's from Dykes'.  What temp would you prefer to pour Babbitt?

Newsgroups: rec.crafts.metalworking
Subject: Re: Babbit
From: jmorton@euler.Berkeley.EDU (John Morton)
Date: 15 Jun 1994 01:00:08 GMT

In article <771634458snz@codesmth.demon.co.uk>,
Andy Dingley <dingbat@codesmth.demon.co.uk> wrote:

>[excellent description of the art of bearing casting]

Then again, you can take the low road, as I did once for an old surface
planer mainshaft bearing:

Assemble the shaft and bearing cap as they will be in operation, with
a few shims under the bearing cap on each side, touching the shaft
surface.  Gasket material or brass shim stock are good for this.

Dam the open ends with some heat-resistant material, e.g. plumber's
oakum, or crumpled aluminum foil, whatever works.

Create an opening at the high spot of each side (upper and lower)
of the pour, and a vent or riser opening at the far end from the pour 
opening.  If you can't manage a neat job there will be a bit of a
mess - but that's OK.

Heat all the surrounding metal with a torch until it's too hot to
touch.

Pour both sides with molten babbit, until it rises from the riser
opening in each case.

There are probably a few things wrong with this procedure, but in
my case it worked, and the bearing is still in service after a
lot of occasional use.  The shims are removed and the cap
retightened as needed.

Have fun.

John Morton					University of California
jmorton@euler.berkeley.edu			Mechanical Engineering
{decvax,cbosgd}!ucbvax!euler!jmorton		Machine Shop