On many of the cast sites, we’ll
encounter discussions about Babbitt metal and casting boolits. Mr.
Babbitt was an inventor of various non-ferrous mixtures containing
lead, tin, antimony, arsenic, and copper, principally for bearing
applications. These alloys have been termed Babbitt metal in the
literature for many years. Babbitt metal has been used extensively
within the marine, railway, and large electrical generator
industries in particular. And, now are being used for boolit
material augmentation as well!
Boolit casters
are, by second nature, scroungers of lead appearing metals. Babbitt
can be encountered in scrap yards, and in obscure places not yet
classified as a scrap pile. I was recently at a scrap yard and asked
if they had any Babbitt, and received the “deer in the headlights”
look from the young attendant. He had no idea what I was talking
about. Babbitt is currently in use as it was seen recently for sale
on the McMaster-Carr catalog website.
Babbitt appears to the naked eye as lead. Many times Babbitt is
encountered in a glob form because some enterprising soul has melted
scraps down for a scrap sale. Babbitt occasionally can be found as
straight from the foundry in new bar form. These bars are typically
branded in a way, which helps us to decipher the composition.
Without identifying marks, the metal should be considered as junk
lead of unknown composition.
Babbitt has been used to cast boolits successfully. In fact, I once
melted down a batch of mystery metal to make water quenched Lyman
429360s for use in a Model 29 Smith and Wesson in .44 Magnum. When
attempting to size these in an old Ideal #45 sizer lubricator, I
almost broke the linkage and had to call upon a friend’s SAECO to
finish the job. Even when using the SAECO machine the sizing process
was hard and prompted the question from the owner, “What in hell are
these made from? I bet that is Babbitt.” However, Babbitt metal
should not be used in pure form for making boolits for this reason
and others indicated further below.
All Babbitt’s are not created equal. The table below lists only some
of the more common Babbitt compositions. Industrially speaking, the
tin based Babbitt's are used for high speed, low weight bearing
applications. The lead based Babbitt's are formulated for low speed,
heavy rotating weight systems. Their compositions also vary
considerably because of the casting requirements for the various
applications vary wildly. In addition, the charts below do not list
lead based Babbitt's with copper, and tin based Babbitt's with
arsenic. These compositions are just as plentiful as those shown
below, but perhaps not as common. Many formulations are custom made.
Tin Based Alloys - Chemical Composition (%)
Chart |
INDUSTRY NAME |
ASTM B23 |
Sn
(Tin) |
Sb
(Antimony) |
Cu
(Copper) |
Pb
(Lead) |
Marine 11 D |
- |
90.0 - 92.0 |
4.5 - 5.5 |
3.5 - 4.5 |
0.35 (Max) |
No. 1 |
Grade 1 |
90.0 - 92.0 |
4.0 - 5.0 |
4.0 - 5.0 |
0.35 (Max) |
Marine 11R |
- |
89.0 - 89.5 |
7.5 - 8.5 |
2.5 - 3.0 |
0.35 (Max) |
Nickel Genuine |
Grade 2 |
88.0 - 90.0 |
7.0 - 8.0 |
3.0 - 4.0 |
0.35 (Max) |
Marine 11 |
- |
88.0 - 90.0 |
5.5 - 6.0 |
5.0 - 5.5 |
0.35 (Max) |
4X Royal Nickel Genuine |
- |
87.5 - 89.5 |
7.25 - 7.75 |
3.25 - 3.75 |
0.35 (Max) |
Diesel Special |
- |
87.5 - 88.0 |
6.5 - 7.0 |
5.0 - 6.0 |
0.35 (Max) |
No. 11 |
Grade 11 |
86.0 - 89.0 |
6.0 - 7.5 |
5.0 - 6.5 |
0.35 (Max) |
SAE 11 |
- |
85.0 - 87.0 |
7.0 - 8.0 |
6.0 - 7.0 |
0.35 (Max) |
Imperial Genuine |
- |
85.0 - 87.0 |
6.5 - 7.5 |
6.5 - 7.5 |
0.35 (Max) |
Turbine |
- |
84.0 - 86.0 |
6.5 - 7.5 |
7.5 - 8.5 |
0.35 (Max) |
Royal Armature |
- |
83.5 - 84.0 |
8.0 - 8.5 |
7.5 - 8.5 |
0.35 (Max) |
Super Tough |
Grade 3 |
83.0 - 85.0 |
7.5 - 8.5 |
7.5 - 8.5 |
0.35 (Max) |
Maximum Allowable Impurities: Fe=0.08, As=0.10, Bi=0.08,
Zn=0.005, Al=0.005, Cd=0.05 |
Lead Based Alloys - Chemical Composition (%)
Chart |
INDUSTRY NAME |
ASTM B23 |
Sn
(Tin) |
Sb
(Antimony) |
Pb
(Lead) |
As
(Arsenic) |
No. 13 |
Grade 13 |
5.5 - 6.5 |
9.5 - 10.5 |
Balance |
0.25 (Max) |
Mill Anchor |
- |
4.0 - 6.0 |
11.5 - 12.5 |
Balance |
0.25 (Max) |
Durite |
Grade 15 |
0.8 - 1.2 |
14.5 - 17.5 |
Balance |
0.8 - 1.4 |
Star |
- |
5.0 - 5.5 |
13.5 - 14.5 |
Balance |
0.30 - 0.60 |
Silverstone |
- |
1.0 - 3.0 |
17.5 - 18.5 |
Balance |
0.25 (Max) |
Royal |
Grade 8 |
4.5 - 5.5 |
14.0 - 16.0 |
Balance |
0.30 - 0.60 |
Heavy Pressure |
Grade 7 |
9.3 - 10.7 |
14.0 - 16.0 |
Balance |
0.30 - 0.60 |
Special Sawguide |
- |
9.0 - 11.0 |
18.5 - 19.5 |
Balance |
0.25 (Max) |
Maximum Allowable
Impurities: Cu=0.50, Fe=0.10, Bi=0.10, Zn=0.005, Al=0.005,
Cd=0.05 |
The majority of foundry marked bars are specially fluxed and cooled
under strict temperature controls for a particular industrial
application requirement. Re-melting foundry bars into smaller bars
or boolits is a chancy undertaking at best for homogeneity sake.
Besides, lead based Babbitt typically contains too much antimony for
accurately shooting boolits; and, tin based Babbitt has too much tin
to make boolits cost effective. Any Babbitt flavor can possibly have
too much copper to cast any kind of boolit using home equipment,
and/or too much arsenic to be safe while being in the melted state
at home. Whenever the smell of garlic is noticed at ANY time, that
hot pot contains far too much arsenic. This composition MUST be cut
with another lead mix known not to contain arsenic until there is no
further smell in the mix being currently made. We are talking about
a 100 percent dilution minimum, and possibly a repeat dilution or
two to force the smell down to zero. On the other hand, too much
copper in the mix is not dangerous, but makes the physical act of
casting almost impossible due to extremely rapid cooling of the
liquid edges into a gummy solid. This feature can be checked in
advance by pouring the mix back and forth between wide containers
(cookie trays) before making boolits. If sheeting is noticed, then
the mix should be diluted in 25 percent increments until the
sheeting effect is no longer obvious.
Why mess
with Babbitt?
The main reason we use Babbitt is that they contain useful goodies
for augmenting a known shooting boolit mix which is not right for
the job being contemplated. The tin in Babbitt is worth its weight
in gold for making a boolit flow exactly into the mold pattern.
Antimony and arsenic are excellent hardeners for our boolit
material. The amount of tin, antimony and arsenic that we get from
wheel weight alloy has gradually decreased over the years, making it
imperative to find alternate sources when a particular boolit style
demands attention. It is extremely difficult and/or dangerous to
introduce elemental antimony, copper, and arsenic into our pots, but
luckily we have various Babbitt alloys already made up with these
elements for our immediate use. We just have to play Sherlock Holmes
when a bar or two of something appealing appears.
Some casters are serious seekers of high-speed applications. In my
experiences, the top speed that can be achieved with linotype metal
and wheel weight alloy is about 2400 feet per second in the .223
Remington. Faster boolits must be extra tough so they will not glide
over the rifling. This is where the copper content of Babbitt comes
into play. I recently alloyed some of my .223 boolits with lead
based Babbitt containing copper and shot the same boolits at 2600
feet per second with good accuracy and no leading. The copper
content in the mix is the “toughener” of choice, whereas the
antimony is the “hardener” of choice.
Pitfalls
in casting using babbitt
As I mentioned earlier, there are some pitfalls in using Babbitt
alloy. The first is identifying the content of the alloy that you
have. If it’s in bar form and marked, you’re in good shape. If it’s
in home made ingots, you’re taking chances, but it still could be
very worthwhile. If the ingots are dull and gray, you possibly have
a lead based alloy, if they’re shiny looking they might be tin
based. All newly formed Babbitt are at least somewhat shiny, and
therefore somewhat questionable as to what they are.
The real truth is that hardly any of us know what the stuff is that
we melt. To “know” is possible, as there are metallurgical tests
that can be performed on a particular batch of casting metal but
normally, the cost is beyond the budgets of most of us casters who
are frugal souls to start with and unless it’s a huge amount of the
same batch of metal, it’s not worth the expense of having it
analyzed.
The next problem is to see how it melts. This is preferably done in
something other than a bottom pour pot, because when there is any
amount of copper, you’ll have a clogged pot around the nipple that
will really enhance your vocabulary. Use the suggested sheeting test
as described earlier before putting any “final” mix containing
Babbitt into the casting pot.
Another of the main pitfalls of using Babbitt is the lack of
repeatability of the final formula. If the boolits cast good and
shoots good, I’m happy. Just be aware of this and process your metal
in batches as big as you can, label the ingots and don’t mix them.
Once you’ve identified a Babbitt alloy as useable and decided it’s
either lead or tin based, you’re ready to make use of it.
Using
Babbitt
The two types of Babbitt, lead based or tin based, can usually be
identified by weight after alloyed into something common like wheel
weights or pure lead. Use a pistol boolit mould of 150-200 gr. Cast
several that look good enough to shoot using each alloy, one with
the common metal alone, and the other mixed with the Babbitt alloyed
in. Weigh the boolits from each mix and calculate their averages. If
the boolits from the Babbitt mix average lighter, then the Babbitt
is tin based. Conversely, heavier boolits, or about the same weight,
but never less, would indicate a lead based Babbitt.
If this test indicates a tin based Babbitt, then you can safely
consider this babbitt as a tin enhancer substance by adding the
amount of Babbitt as would be required for adding 100 percent tin.
When you add it to a pot and stir, start looking for lumps rising to
the surface. These are compounds carrying copper and possibly other
impurities unknown, and might give you fits if you try to cast with
the mix. There is a way to deal with that, too.
Lower your pot temperature to 650 using a thermometer (one of the
Lyman manuals suggests 621 degrees), and for the next 10-12 minutes
resist all temptations to stir, flux, or otherwise disturb the mix.
After at least that amount of time passes, carefully skim the
surface (the copper will still be suspended there as inter-metallic
compounds). After this has been accomplished, adjust the temperature
back up to your normal casting temperature and start casting. This
procedure is called “freezing out” the copper content, and can be
used instead of dilution to lower the amount of copper in the pot.
Some Babbitt’s have the added benefit of arsenic which will aid in
water quenching or heat-treating of your finished boolits if you’re
so inclined.
If you have lead based Babbitt, this makes a good additive for wheel
weight alloy or even pure lead alloy to make it harder and also to
make it cast better. I’d add 10% or so of lead based alloy to pure
lead or 5% to wheel weight alloy if you like hard boolits. I like my
boolit for the most part soft so I’ll tend to make softer alloys
than most people.
Always take the Babbitt and introduce it into the melt a bit at a
time, by using an ingot of it dipped into the melt until I get the
amount of metal off the bar that I want in the mix. Do not drop a
whole ingot in, even if we know the analysis of the Babbitt. I’d let
this mix set a bit and see what happens in the way of stuff rising
to the top. Recommended is a ¼ to ½ pound of Babbitt to a 20 pound
pot for starters. Then cast a couple of boolits and see if all is
okay. Once you have the alloy you desire, cast the boolits, and
drain the pot into ingots marking them as to alloy for the next time
you want this special mix.
Is
Babbitt worth messing with?
Many of us will say NO due to the problems we’ve discussed. I’d say
a good 99% of us would elect to go through the process because we
are frugal and wish to use any lead appearing alloy, at least for
giggles and shouts.
I’d go through the process for the tin content, and I’d also go
through it for the copper content. Little boolits shot fast need all
of the reinforcement they can get.
Hopefully, this article will make you more familiar with Babbitt and
the problems and benefits you encounter in using it.
If casting boolits were easy, everyone would be doing it. I’m just
glad that there are a few hardy souls out there that need the
challenge of “show me”.
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