STYLES NO. 33 and 33L - The Tool Archivestoolarchives.com/sites/default/files/1953_Ex-Cell-O-Thread... · Grinding after hardening eliminates heat-treat ... accuracy of threads ground

B U L L E T I N 1 4 0 9 1

STYLES NO. 33 and 33L

Precision Thread Gr iEx-Cell-0 Thread Grinders have brought hardened and

ground threads within the means of every manufacturer whose product requires smooth performance, great strength, or long precision life.

Grinding after hardening eliminates heat-treat distortion, produces true thread forms and enables the lead and pitch diameter to be held within very close tolerances. Perfect thread mating and high finish reduce friction and eliminate noise; excessive heat, wear and loss of power are banished, giving you a most efficient, free-running thread system.

In addition to improving the parts themselves, you can

nding Is Economicalactually reduce manufacturing costs by production thread grinding. Fewer operations and less overall processing time are required; threads of ten pitch and finer can be ground directly from solid, hardened blanks. By easily holding close tolerances, spoilage is minimized and interchangeability of parts reduces assembly time by eliminating “ selective fits” .

The wide variety of parts that thread grinding has pro­duced better and at less cost, is indicated by the group shown above. Included are taps, aircraft engine parts, thread chasers, drive shafts, lead and adjusting screws, worms and many others.

Ex-Ce l l -O Style No. 33 Thread Gr inderThe Style No. 33 Ex-Cell-0 Thread Grinder is a high speed

precision machine for grinding extremely accurate external threads at low unit cost.

The machine can be set up for automatic operation after loading. The dresser is automatic in its cycle, including compensation for the amount dressed off the wheel. Un­usually high production and wheel economy is assured because the depth of each dressing cut and the frequency of wheel trueing is governed by the operator.

Work up to 6" diameter and 18" long can be accommodated between centers. A thread section 8" long can be ground anywhere in 12" measured from the head stock center.

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Right and left hand straight, tapered or relieved threads can be ground in one or both directions of table travel, in single and multiple pitches from 1 to 80 threads per inch, with U.S. Standard, 60° sharp “ V” , 29° Acme, Modified Buttress, Whitworth and special thread forms.

Whether grinding fine threads from the solid hardened blanks, or coarse threads that have been previously roughed and heat-treated, a tolerance of .0002" can be held on the pitch diameter; lead can be held within .0002" of nominal, when grinding any standard thread form.

Grinding Wheel Head. The quality of finish and accuracy of threads ground on this machine are made possible principally by the Ex-Cell-0 Precision Ball Bearing Spindle which rotates the 18" diameter grinding wheel. These bearings are so closely fitted that spindle end-play is eliminated.

An eccentric sleeve, fitted with adjustable hall bearings, supports the grinding wheel spindle body. By connecting the Believing Attachment to this eccentric sleeve, an oscillating motion is produced to back off taps and chasers. When not used with this attachment, the eccentric sleeve is solidly locked in place.

An adjusting screw swivels the spindle bracket verti­cally to conform with helix angles of various threads. The wheel spindle slide is operated by a graduated hand wheel and retracting lever at the front of the machine.

Grinding Wheel Drive. The wheel spindle is driven by an electric motor, mounted on a bracket at the rear, which is adjustable for angular position, for correct alignment and belt tension.

As the 18" grinding wheel wears down to 12", the minimum diameter used, the correct wheel speed is maintained (within 3%) by means of interchangeable two-step “ V” belt pulleys. As extra equipment, direct current motor drive and rheostat can be furnished by which wheel speeds can be conveniently controlled.

C o n s t r u c t i o

Work Drive System. The work spindle is fitted to a ground spline sleeve which is driven through a hardened and ground steel worm and a bronze worm wheel, by a “ V” belt from a two-speed reversible motor mounted at the side of the machine base. The right end of the spindle is supported in two Ex-Cell-0 Precision Hall Bearings at the left end of the work table.

Lead is generated by a master thread ground lead screw mounted on the left end of the work spindle and closely fitted in a split bronze nut. The lead screw may be reversed on its mount­ing to evenly distribute wear over the entire thread. To obtain different leads, other master lead screws and nuts of the desired pitches can be easily and quickly interchanged.

The lead screw and nut assemblies used in this machine are identical with those used in the style No. 31 and also No. 39 (Internal) Ex-Cell-0 Precision Thread Grinders.

Work Table. Smooth, free operation is assured by the hardened, ground and lapped rollers which support the work table in adjustable horizontally opposed “ V” shaped hardened and ground steel ways. The top of the table is equipped with a “ V” and a flat guide for the tail stock which may be adjusted to align the center with the work drive spindle.

Wheel Dresser Slide. Directly behind the grinding wheel is the dresser mounted on a slide controlled by a graduated hand wheel at the front of the machine. The grinding wheel is also advanced automatically by the dresser slide control to compensate for the dressing cut. A lock on the hand wheel prevents accidental movement.

The wheel dresser is driven through a flexible shaft by a reversible fractional horse power motor at the rear of the dresser slide. The dresser is easily acces­sible for setting up or adjusting while in place on the machine.

n F e a t u r e sCoolant System. A centrifugal pump direct-con­nected to an electric motor supplies the thread grinding coolant oil to the work. A fifty gallon coolant reservoir with baffles to remove grit from the oil is located at the rear of the machine.

The entire work head assembly is adjustably mounted to the left end of the machine base, so that the work driving center can be varied as much as 8" in relation to the grinding wheel. This adjustment is most useful in grinding thread sections in the middle of a work piece.

Work Speeds. A choice of eight work speeds is provided by the two-speed reversible work driving motor and the four-step “ V” belt pulleys. Motor speeds are selected by a switch on the control panel and also by adjust­able dogs mounted on the front of the work table which can be set to automatically actuate a limit switch at each end of the table stroke. Either of the two speeds may be used in either direction.

As desired, the operator can set the machine to stop automatically at each end of the table stroke, or to automatically reverse.

Fast, Accurate Duplication Of Size is easily perfoimed by the quick action Retracting Lever which withdraws the wheel any desired amount for loading subsequent pieces, and feeds the wheel back to the work; finish size is exactly duplicated without disturbing the hand wheel. By gradua­tions on the retracting mechanism the feed can be divided into increments for each cut.

Automatic Feed, synchronized with the table reversals may be used to feed the wheel for each cut; when exact size is reached the machine automatically stops. This device is especially designed for high production thread grinding; the total power feed, y±" on work diameter, can be arranged with coarse roughing feeds and a finer feed for finishing. Feed rates can be selected from .002" to .125" on work diam­eter while the machine is in operation, without removing covers or inserting loose cams.

Automatic Sizing is produced by the relative motions

of the wheel and dresser slides; the amount dressed off the wheel is automatically compensated. For setting up pur­poses of course, the wheel and dresser hand wheels can be independently adjusted.

Automatic Dresser, which is driven by an electric motor, provides simple, economical wheel trueing. After starting, the dresser automatically performs its cycle and stops. Accurate dressing under actual operating conditions is in­sured because the wheel is trued at grinding speed. A duplicate set of dresser controls is provided at the side and at the front of the machine for convenience in setting up and adjusting.

Lead Pick-up Device operated by a hand wheel on the front of the work head, provides a quick simple method to match previously cut or roughed threads with the grinding wheel.

Grinding Wheel Dressers. Ex-Cell-0 wheel dressers are simple, compact and readily accessible for setting up or adjusting. Either of two types of electric motor driven dressers may be furnished:

The PLAIN DRESSER (shown above) is adjustable to true U.S. Standard, 60° sharp “ V” and 29° Acme thread forms. Three natural stone diamonds, two to dress the sides and one to dress the flat on top of the wheel. are furnish­ed with this dresser.

The UNIVERSAL DRESSER (above right) will dress U.S. Standard, 60° sharp “ V” , 29° Acme, Whitworth and special

symmetrical forms with a side angle not less than 14j4°; Modified Ruttress and unsymmetrical special forms can be dressed with less than 14)4° angle on one side.

The form reproduced depends on a set of cams within the dresser. A pair of 60° cams produces all U.S. Standard and 60° sharp “ V” forms while another pair of 29° cams accom­modates all standard Acme threads. Select natural stone diamonds are used for dressing forms without radius.

In dressing Whitworth and other radius forms, a different pair of cams is necessary for each form desired. Commercial “ phono-point” diamonds are used for such thread forms.

Taper Attachment. Correct taper threads up to 3" taper per foot included angle, are ground without lead error by an attachment consisting of a linkage which engages an adjust­able former bar, graduated in taper per foot for quick setting. Special former bars with com­binations of taper or special shapes can be easily substituted at any time. A locking device holds the wheel taper slide against a positive stop when grinding straight threads

Thread Relieving Attachment. To obtain the highest production in grinding relieved threads, this machine will back off while grinding in one or both directions of work rotation. Right or left hand, straight or tapered taps and chasers can be relieved. As shown at the right the attach­ment consists of a lever engaging one of three formed cams mounted on the work spindle sleeve, and oscillates a trans­verse shaft at the back of the work table, which connects to the eccentric sleeve mounting of the wheel spindle.

The amount o f back off is easily controlled by the adjustable links in the mechanism. A convenient control lever disengages the back off motion and locks the mechanism against a positive stop when not in use.

Three cams of standard rise for 3, 4 and 6 flutes are regular­ly furnished with the attachment unless otherwise specified.

Style No. 33 L Thread GrinderTo accommodate longer thread sections and longer work, the Ex-Cell-0 Style No. 33 L is offered. With the exceptions of a longer master lead screw and a longer work table, the Style No. 33 L is identical in construction to the Style No. 33.This machine will grind thread up to 6" diameter and 20" long on work up to 36" long between centers. The lead screws are the same as used on the Ex-Cell-0 Style No. 31 L. Short lead screws, however, such as used on the Style No. 31, 33 and 39 (Internal) can also be used on the Style No. 33 L. Thus, short work can be ground on this machine without investing in longer screws except when necessary.The Style No. 33 L can also be arranged with an extra large work head with provisions for inserting long pieces through the hollow work spindle.

SPECIFICATIONSSTYLE No. 33

Size 6 x 8 x 18 'Maximum diameter of work ground........................................ 6"Maximum length between centers.............................................18"Maximum 8" o f thread can be ground anywhere in 12" measured from head stock center.Grinding wheel size........................18" dia. x y s" thick x 9" holeMinimum grinding wheel diameter........................................... 12"Maximum taper (included angle)......................... i . . . . 3" per ft.Grinding wheel speeds........1485, 1575, 1670, 1780, 1910, 2040,

2150, 2290, 2450, 2640 r. p. m.Work Drive M otor........1 h. p. 900 r. p. m./'2 h. p. 1800 r. p. m.Work speeds. .. . (900 r. p. m. motor speed) 6, 8, 20, 30 r. p. m. Work speeds (1800 r. p. m. motor speed).. 12, 16, 40, 60 r. p. m.Wheel drive motor............................................ 2 h.p. 1800 r. p. m.Coolant pump motor......................................34 h.p. 1800 r. p. m.Wheel dresser motor.................................. 1/20 h.p. 1800 r. p. m.Maximum helix angle setting of wheel........ 20° either directionCoolant tank capacity.................................................... 50 gallonsOverall height..............................................................................54"Floor space required.........................................................74" x 74"Net weight of machine......................................Approx. 6000 lbs.Weight of machine, crated for domestic ship. Approx. 6650 lbs. Weight of machine, boxed for foreign ship. Approx. 7200 lbs. Size of box for foreign shipment................... Approx. 188 cu. ft.

STYLE No. 33 LSize 6 x 20 x 36"

The Style No. 33 L is the same as the Style No. 33 except for the following:Maximum diameter of work ground........................................ 6"Maximum length between centers.............................................36"Maximum threaded portion of work from head stock center 20"Maximum table travel.................................................................20"Floor space required..................... 130" wide x 74" front to backNet weight of machine......................................Approx. 6300 lbs.Weight of machine, crated for domestic ship. Approx. 7050 lbs. Weight of machine, boxed for foreign ship. Approx. 7800 lbs. Size of box for foreign shipment....................Approx. 232 cu. ft.

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Standard EquipmentThe Style Nos. 33 and 33 L Ex-Cell-0 Precision Thread Grinders are regularly furnished with electrical equipment and switches for 220 or 440 volt, 60 cycle, 3 phase A.C. motors; wheel driving motor; two speed reversible work driving motor; direct connected motor driven coolant pump; coolant tank; 50 gallons coolant oil; one grinding wheel spindle with wheel adapter; one 18" grinding wheel; one master lead screw and nut (for a standard pitch—except metric—as selected, with- ,in the range of from 4 to 32 threads per inch); head stock center; tailstock center; one universal wheel drive motor mounting block; work positioning device; automatic feed; five wheel spindle pulleys; one adjustable work dog driving plate for spindle nose; wrenches; belts; guards; piping; and necessary electrical wiring installed in conduits on the machine.

Two types of grinding wheel dressers are avail­able as described on page 7.

Extra Standard Equipment

In addition to the Dressers, Taper and Relieving Attachments described on preceding pages, the following equipment can also be furnished:Quick clamp type index head for single, double,

triple, quadruple and sextuple indexing.Direct Current wheel drive, including D.C. motor,

magnetic starter and rheostat control.Work Drive dogs for diameter as selected.Dresser Diamonds.Universal Dresser cams.Cam Grinder for Universal Dresser cams.Wheel Spindle.Spindle Pulleys.Master Lead Screw and nut assemblies (U.S.).Master Lead Screw and nut assemblies (Metric).Bench type lead pick-up fixture;.Head Stock Centers.Tail Stock Centers.Head Stock Center Grinding Attachment.Wheel Balancing Stand, with arbor.