Norton No. 28 Plain Lapping Machine Other

CATALOG NO. 1474-1

'.

no.

Plain

Lapping

Machine

FOR FLAT OR
CYLINDRICAL WORK

(

NO. 28tF
FOR FLAT WORK

NO. 28-C

FOR CYLINDRICAL WORK

Plain

Lapping

Gives you lower
production
highest

You

lap rapidly—at low cost—with the No. 28 Vertical

Lapping Machine. Further, its rugged dependability as

QUALITY

PRODUCTION

DUAL

/

CAPACITY

sures you long service in production of exceptionally fine
tolerances and finish in your lapping jobs. In performing
this work, the No. 28 gives you an extended profitable
return.

You may have the machine arranged for either flat or
cylindrical lapping. However, if both types of work must

be done but your requirements do not warrant separate

machines, the No. 28-F for flat lapping also provides a

cylindrical drive. This feature, with the addition of the
necessary laps and work holders, permits you to perform
cylindrical lapping.

quality parts

costs

... on



Additional advantages that result in lower overall costs

are that the machine is easily operated—and is very

EASILY

\

OPERATED

CHOICE OF
ARRANGEMENTS

easily maintained. Manual cycle termination is the stand
ard arrangement for both the flat lapping machine and
the No. 28-C for cylindrical lapping. Automatic cycle
termination arrangement to provide uniformity of results

with decreased operation attention is available for both
machines.

You may have the No. 28-C for cylindrical lapping

equipped with 24", 26" or 28" cast iron laps. The No.
28-F for flat lapping is available with cast iron 24", 26"
or 28" diameter laps for parallel face lapping
may purchase it specially arranged with a single 30", 36"
or 40" diameter lap for single face hand lapping.

—or you



j?

FAST • DURABLE

m

OUTON

No. 28-C

Lapping Machine
Arranged for

Cylindrical Lapping

N-5495

3Tdf OB 2*

No. 28-F
Lapping Machine
with Two-Piece Sprocket
Type Workholder for
Flat work

©Iff

When cylindrical work is to be lapped, the lap driving unit consists of a cast
iron body with a hollow-spindle running through the center. A bronze worm wheel
is attached to the lower end of this spindle and is driven by a hardened steel worm
on the main drive shaft.

Arrangement
for lapping

cylindrical

work

Within the hollow spindle which drives the lower lap is another spindle running
at a slower speed. Attached to this inner spindle is an adjustable slide which sup
ports a single eccentric drive pin for rotating the workholder. Adjustment of this
slide changes the eccentric movement imparted to the workholder. Parts to be
lapped are mounted in special workholders and positioned on the surface of the
lower lap to which a slight amount of abrasive of the proper
and mixed with a lubricant has been applied. The hole in the workholder engages
the single drive pin in the driving mechanism. The upper lap is then lowered until
its surface rests on the work. By means of the clutch lever at the front of the
machine revolution of the lower lap is started and stopped. The rotation of the
lower lap causes the pieces being lapped to roll.

The angular position of the work in the holder and the eccentric motion of the
workholder cause the work to slide. This combined rolling and sliding movement
brings the work in contact with the entire surface of both laps and, therefore, pro
duces the greatest possible amount of lapping action. At the same time even wear
on the surface of the laps is maintained.

grain size and hardness





i

Arrangement

for lapping
flat work

The lap driving unit for the lapping of flat work is practically the same as
cylindrical work, but the workholders and the workholder driving mechanism are
quite different. The driving mechanism is so arranged that a series of circular
movements are imparted to the workholder, approximating as nearly as possible
the actual motions of

This circular motion imparted to the workholder is derived from a stationary

gear around which rotates an internal gear and three pinions which are connected

to three drive pins. The workholder is driven from these three drive pins instead

of from a single pin as on
rated to provide spaces for excess

matter that the lap faces may be kept clean.

hand lapping.

the cylindrical work. Laps for flat work are usually ser-

abrasive and oil and fine particles of foreign

for

Workholder

for
cylindrical work

Spider Type Workholder for cylin
drical pieces having a hole through
the center such as piston pins



N-1007

N-3520

Hollow cylindrical pieces such as piston pins are
carried on a "spider type" workholder. This consists
of a center plate with hardened steel spindles in

serted about its periphery. These spindles are not
placed radially but have their axes tangent to a

small circle at the center. The pieces fit loosely over
the spindles and are held in position by an outer
ring provided with hardened steel thrust plates. Four
of the spindles are longer than the rest and the
outer ring is locked to these spindles.

Cylindrical pieces having no hole through them
are held in a plate type workholder having openings
the approximate shape of the pieces so that the
work piece is free to rotate but cannot change its
axial position which is the same as for hollow work,
tangent to a small circle.



Piston-Ring Type Workholder with

adapter for flat surface lapping

Workholders
for
flat work

Workholders used for lapping flat surfaces are of

two general types, one known as the "piston-ring

type" and the other the "two-piece type." The
workholders are driven by three drive pins in the
work driving mechanism.

In the piston-ring type holder the work pieces lie

in openings cut in a circular plate or disc which is

moved about and rotated between the revolving
lap faces. Small pieces are

inserts which lie in the plate opening.

In the two-piece type holder the work pieces are

held in adaptors which are rotated between a hub,
driven by the three driving pins, and a split ring of

'
i
I

5

about the same diameter as the laps. This retaining
ring is free to oscillate between the laps but cannot

rotate.

frequently

grouped in

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Capacity

Flat Work (Thickness by longest dimension)

Cylindrical Work (Diameter by length) .....

Laps

Diameter
Width of face

Speed of lower lap (not adjustable chosen to suit job)

Distance between laps, standard Maximum ...............

Floor Space (approx.) ..............

Height of machine (approx.) .

Motor

Weights—approximate, with motor

Net ..........................................

Domestic Shipping ...............

Export Shipping ....................

4" x 9"
4" x 9"

24", 26" and 28"

Up to 9"

45 to 65

41/4"

42"x

81"

5'3"

3 H.P. 1200 R.P.M., constant speed A.C.

totally enclosed ball bearing type

3800 lbs.
4200 lbs.
4500 lbs.

Cubics—boxed for export ...

%

Because of

variations in castings and equipment, exact weights cannot be given.

170 cu. ft.

The above weights are in pounds and cubics are in cubic feet. Motors are included.

The descriptions, illustrations and specifications in this booklet are correct
at the time of printing, machines built at later dates may differ in detail

due

to

the policy of Norton Company

to

constantly improve their machines.

.

Semiautomatic Cylindrical Grinders

fa

Universal Grinders .

MACHINES FOR

• CYLINDRICAL GRINDING

• SURFACE GRINDING

• CYLINDRICAL AND FLAT LAPPING

• UNIVERSAL TOOL AND CUTTER GRINDING

• UNIVERSAL GRINDING

• SPECIALIZED GRINDING

• CAM AND SHAPE GRINDING

• CRANKPIN AND CRANKSHAFT BEARING
GRINDING

• ROLLGRINDING

• ATTACHMENTS AND EQUIPMENT FOR

SPECIAL WORK

Grinding and Lapping

$14®? I'f

M3

Plain Cylindrical Grinders

MACHINE DIVISION OFFICES

Worcester 6—New Bond Street.
Hartford 7—1007 Farmington Avenue

Cleveland 3—1306 East 55th Street.

Detroit 8—5805 Lincoln Avenue

Chicago 32—4737 So. Christiana Ave.. .Lafayette 3-8700

New York Area—Green and North Streets,

Teterboro, N. J

-t.

.............

Pleasant 2-4641

... .Tel. No. 3-6462

.. Henderson 1-9500

Trinity 5-8991

.............

Bryant 9-6170

"

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