I was getting a little worried this month about finding a
suitable subject to take as this month’s article. Winter
restoration projects among the Northern Hemishpere members of the
ATIS stationary engine internet mailing list have been reaching
completion, with wonderful stories of engines coming back to life
after decades of silence, while those in the Southern Hemisphere
have been bringing home their new projects ready to work on over
the winter ‘down under.’ There didn’t seem to be much I
could pass on to the readers of GEM, until this little question
appeared:
What type lubricant is the best to use for honing?
The first set of answers were brief, but with a little
prompting, I was soon swamped with information, and back to the old
problem of reducing the quantity to a manageable size! To deal
first with advice on lubricants for honing:
I was taught to use a light oil like power steering or automatic
transmission fluid. It’s cheap and you’ve always got some
on hand.
I just use the lightest oil I have sitting around. Usually 30
weight.
It all depends on the hone type. My old Sunnen says dry on the
first two sets of stones and lard on the finishing or polishing
set. I would imagine each hone manufacturer has its own
preferences.
A rule of thumb I was always taught was, ‘use what ever
fluid normally runs in it.’ i.e., brake cyl = brake fluid,
engine cyl = engine oil.
On all the hundreds of cylinders I’ve honed over the years,
I’ve always used plain kerosene and lots of it. When operating
the hone I always had an open top tin half full of kerosene next to
the job with an old paint brush in it. Before starting I’d
brush some fluid around the top of the cylinder and start running
the hone through, reapplying the brush whenever it started to look
a little dry or squealed.
We got the best results just with ordinary WD40 or another
make-it loses rust particles, it smears and helps the dirty fluid
flow away quickly. While honing you can easily spray any amount you
like. To inspect the results, just a blow with brake cleaner and
the facing looks bright and shiny. Then you can decide whether to
stop or start honing again.
I was always told that Kero was the way to look after the stone;
kero would lubricate it but not clog the stone. Never use engine
oil.
Yes, kerosene is what most machinists use to clean their
sharpening stones. It will float the swarf out of the stone pores.
It is also why people use it for honing as the stones are basically
cleaning themselves during the honing process.
Also Kero here, and in its absence, Marvel Mystery Oil…
I am quite amused that no one has mentioned diesel fuel. It is
cheap, flushes the grindings from the stones, and is easy to clean
up afterwards.
Sunnen puts out its own cutting oil which appears to be about a
15w grade. It seems to leave a smoother hone pattern than Kero.
I’d still use kero as a more cost effective alternative.
My dad was a small engine mechanic; I have both of his Sunnen
hones. I don’t know how old they are. We always used the
roughing stones dry for quick stock removal. The finishing stones
use a light oil. I have a five gallon bucket of Sunnen honing oil
that looks like hydraulic fluid. This is kept in a squirt can and
applied continuously while honing. When using dry stones it is
important to have the cylinder clean and free of oil or grease.
These roughing stones will remove stock very quickly and
accurately, but if you use oil once, you must continue. I recently
bored an Aermotor .060 over in about 30 minutes from start to
finish. I trued a 2 HP Famous cylinder, removing .012′ in about
the same amount of time.
Clean out the bore thoroughly with detergent after honing. It
must be clean and dry. If you leave any film of the honing oil, it
will contain particles of abrasive and swarf, which will damage the
rings.
After I have finished honing with kerosene, I wipe everything
out and then run my hones over the cylinder dry to put on a very
lightly scratched surface which helps in seating the rings. At
least, this is my theory. Also, after honing, clean the cylinder
with kerosene till white paper towels come out clean. This makes
sure all the swarf that has been ground into the cylinder walls has
been washed out. Some people will wash the walls with soap and
water. What ever method used, it is imperative to wash out all the
honing dust (swarf) from the pores of the cast iron. If not, the
swarf will act like an abrasive and wear the
walls/rings/piston.
With the use of brake cleaner, the facing and the pores of the
cylinder wall becomes very clean and free of any grease. Then I use
a ‘Raagbol,’ it’s a tool that lookes like a dandelion
seedhead, but instead of the seeds at the end there are little
abrasive balls. I run this tool just a few times up and down (dry)
and this puts on a lightly scratched surface with crossed diagonal
lines which helps seating the piston rings. After cleaning again, I
put some cylinder oil on the surface to prevent it from rusting
until the moment of finishing the job.
A lot depends on the type of engine the cylinder is on. Meaning,
is it an open crankshaft type or an enclosed one with a crankcase
like an automotive engine. If it is of the open type, there is no
oil control ring and seating is not as important. With a closed
crankcase, you are concerned with ring leakage or blow-by. If the
cylinder is out of round, start with a course set of stones and
bring the cylinder dia. to within .0005′ per inch dia. Then use
a finer set of stones and bring the finish to polished surface.
Crosshatching the finished bore with a dry stone does help seat the
rings. If the bore is too smooth, the rings and cylinder wall will
glaze over and the rings will never seat correctly. When using a
hone of any type, never run the stones more than
1/3 of the length of the stone past the end
of the cylinder. If too much of the stone is allowed to exit the
cylinder ends, you will end up with an hourglass shaped
cylinder.
I have, over the years, honed a lot of cylinders from ?’
diameter to as large as 48′, and have used everything from
cleaning solvent mixed with a little oil to lard. I have found that
lard, (Crisco) works about the best for all sizes of cylinders.
With Crisco the grit and grime collects in it and can be wiped out
as you progress, and you don’t have the run-off that is a
problem with oils. Clean up is easier. You still have to get
everything super clean, as with any honing operation.
Once again, I hope some GEM readers will find this
information useful -maybe next winter, when there are new projects
on the ‘to do’ list!
Helen French helen@insulate.co.uk http://www.insulate.co.uk
http://freespace.virgin.net/french.bros/
