The Sherline Miniature Machinist's Newsletter
Number 19,
Sherline Projects
“Baby Beam” steam engine—a CNC
project/Alan Marconette
Alan’s project is seen before the socket head
screws were replaced with more period-appropriate fasteners.
“The "Baby Beam" Steam
Engine was inspired by the M.E. Beam engine published in '59, which was scaled
from the 1914 M.E. article by George Gentry. George did an accurate prototype
model of the engine. I've heard that it is of the form of engines designed by
William Fairburn around 1840-1850.
The engine is approximately
6" tall, 11" wide and 6" deep. Shown is a 5" flywheel made
using CNC, and the plans include an optional 6" flywheel of an alternate design. This engine was built using many CNC part files
and was entirely machined on the Sherline mill and lathe. This version was
built with a brass cylinder, steam chest and beam, although aluminum could be
used as well. The base is aluminum, and, although 10" long, was machined
on the Sherline mill as well!
The bore is 3/4" and the
stroke is 1 1/2". The design incorporates a slide valve driven
through considerable linkage. The piston drives the 6-1/2" beam through
the
Alan Marconett
KM6VV
This and other CNC projects can
be found on Sherline’s CNC
Projects page. Non-CNC projects can be found on the Sherline Workshop page.
Shop Tip of the month
A
fixture to keep from breaking small taps/Bob Shores
"I
have read many tips on tapping holes-some good, some not. Five years ago I
dreamed up a tapping method for small holes. I tap a lot of holes with 0-80 and
2-56 threads, and since I have been using this method, I have not broken a tap
in five years.”
This
simple fixture is easy to make and can help keep you from breaking expensive
small taps.
The
tap is held in perfect alignment by the chuck. When the chuck is loosened
slightly, the tap can be rotated using the disk and your fingers
, providing an excellent "feel" for the process. The tap goes
in straight making it less nlikely to break.
“After
drilling the hole in your part to the proper size for tapping, the drill bit is
removed from the chuck without disturbing the work. A 2" aluminum disk,
knurled on the outside and drilled and tapped for a 4-40 hex bolt grips the tap
just above the flutes. The end of the tap is gripped in the drill chuck and
lowered until it just touches the work. The chuck is then loosened to allow the
tap to turn freely. The disk holding the tap is turned with your thumb and
forefinger. The drill chuck acts as a guide to keep the tap running true, and
your fingers are very sensitive to the amount of torque being applied. To break
a tap you would have to apply a lot of force.”
—
This
and more than 50 other helpful tips for Sherline machinists can be found at www.sherline.com/tips.htm.
Product Spotlight
Chucks and Collets
4-jaw,
3-jaw, 4-jaw self-centering and drill chucks
The 1160/1178 set comes with 5 WW
collets, a drawbar, knockout bar and collet adapter.
Chucks
The
easiest and most versatile way to hold work in the headstock of a lathe is
through the use of a 3-jaw or 4-jaw chuck. There are several types and each has
its advantages and disadvantages:
1.
3-jaw self-centering chucks—Available
in 2.5” or 3.1” diameters, these chucks have three scrolling jaws, making it
possible to grip round or hexagonal parts. The disadvantage of scrolling jaws
is that centering accuracy cannot be controlled. Advantages include the ability
to grip work that is not perfectly round and ease of use.
2.
4-jaw independent chucks—Again
available in 2.5” or 3.1” diameters, these chucks have 4 jaws that are closed
independently. The advantage is, this lets you grip just about any shape part
either off-center or perfectly on center. The disadvantage is that it takes a
while to accurately locate a part. A 4-jaw can also make an excellent “vice”
for use on the mill.
3.
4-jaw self-centering chucks—Available
in 2.5” or 3.1” diameters, these chucks offer the quick closing advantage of a
3-jaw with the ability to hold round, square or octagonal stock. The
disadvantage is that, unlike a chuck with 3-jaws that will always be able to
find three points of contact, work must be accurately square or round to be
gripped in this chuck or all four jaws may not grip the part. Another advantage
is the ability to spread out the grip to an extra jaw, which can be helpful
when gripping thinwall tubing without crushing it. Runout on all 3- and 4-jaw
chucks is specified to be less than 0.003”.
4.
Drill Chucks—Available in
5/32”, ¼” and 3/8” sizes, these chucks made for holding drills or reamers.
Interchangeable arbors on the ¼” and 3/8” chucks mean they can be used in the
headstock of a lather or mill or tailstock of a lathe. Runout is specified to
be less than 0.003”
Collets
When
a runout of 0.001” or more is not tolerable, maximum centering accuracy can be
obtained using collets. A collet is essentially a small chuck that holds a
particular size part. Since they don’t have much closing range, the part must
be within .002” or so of the collet’s size, but collets are available size by
1/64” or 0.1 mm increments, so the size you need is always available. The
collets shown are WW collets, which have a ¼” through hole
and external threads and are sized up to 5/16” or 8.0 mm. They are placed in a
collet adapter that goes into the #1 Morse taper of the headstock and pulled
closed using a hollow drawbar from the back side. These are particularly
popular with watch and clock makers, but can be used in any machining
application where you must accurately hold a small round part.
Mill
collets are also available that have a #1 Morse taper and are pulled directly
into the headstock spindle with a drawbolt from the rear. These are used to
hold end mills that come in common shank sizes from 1/8” up to 3/8”.
Sherline
manufactures all its own 3-jaw and 4-jaw chucks, mill collets and WW collets in
order to control accuracy and keep price at an affordable level.
Did you know?
•
Illustrated instructions for the use of all Sherline accessories are posted on
our web site. Go to www.sherline.com/accessor.htm
for links to both HTML and PDF versions of each. This is a tremendous source of
free information on machining. A copy of the 48-page instruction manual can
also be found at www.sherline.com/InstVol6.pdf.
Also, if you’ve got a friend who might like a Sherline catalog, send them a
link to www.sherline.com/catalog8.pdf.
•
This month Sherline’s radius cutting attachment is on sale at 20% off, meaning
you can save $24.00. To learn more, see www.sherline.com/special.htm or
go to www.sherlinedirect.com and
click on the “Monthly Special” link to order on-line any time of day or night.
•
Two handy free calculators developed by Joe Martin are available on our web
site at http://www.sherline.com/calculators.htm.
One helps with gear tooth calculations and the other helps when cutting
threads. They are in the form of Excel spreadsheets.
Upcoming
Shows
•
WEME (Western Engine Model Exhibition),
•
GEARS (Gas Engine Antique Reproduction Show), September 19-20,
Joe Martin
Craftsmanship Foundation News
•
Two new craftsmen were added to the On-line Craftsmanship Museum in
the past month. Both exhibit somewhat unusual skills. GarE Maxton
makes very artistic and challenging metal puzzles, while Randy Boni
turns tree stumps into naturalistic works of art using a tool not usually
associated with precision work—a chainsaw.
•
Also added to the on-line museum is another all-wood steam engine by Australian
woodworker Harold Manwaring.
This time it is a stationary engine called “Mary” rather that a locomotive, but
equally impressive.
•
Thanks to Jerry Kieffer for his donation of 139 back issues of the NAWCC Bulletin magazine for our museum
library, bringing our collection of that magazine up to a point where only a
few of the more recent issues are missing. Others wishing to donate back issues
can contact Craig at craig@craftsmanshipmuseum.com
for a list of the issues still needed.
•
The Foundation’s Chairman of the Board, Paul Knapp will be displaying part of
his extensive engine collection at the WEME
Show in