US2413795A

US2413795A - Apparatus for cutting quartz oscillator blanks

Info

Publication number: US2413795A
Application number: US511204A
Authority: US
Inventors: William C Speed
Original assignee: REEVES ELY LAB Inc
Current assignee: REEVES ELY LAB Inc; REEVES-ELY LABORATORIES Inc
Priority date: 1943-11-20
Filing date: 1943-11-20
Publication date: 1947-01-07
Anticipated expiration: 1964-01-07

Description

Jan.7, 1947. I w, c; SPEED 2,413,795

APPARATUS FOR CUTTING QUARTZ OSCILLATOR BLANKS Filed Nov. 20,1945 2 Sheets-Sheet 1 nA 3 VIII l0,

/// my ,w 44

' INVENTOR. l Vf/fl'a Wr 6. J eed BY G M YM ATTORNEYS Jan. 7, 1947. w. 0. SPEED I 2,413,795 3 APPARATUS FOR CUTTING QUARTZ OSCILLATOR BLANKS Filed Nov. 20, 1945 .2 Sheets-Sheet 2 IN VEN TOR.

W/W/am C iaeed BY A TTORNE Y5 Patented Jan. 7, 1947 UNITED STATES PATENT OFFICE- APPARATUSFOR CUTTING QUARTZ OSCILLATOR BLANKS.

William C. Speed; New York, N. Y-l, assignor -to Reeves-Ely Laboratories, Ina, New'York, N. Y., a corporation of New York Application November 20, 1943,.SerialN0.511;.204

11 Claims. 1

This invention relates to quartz oscillator plates and has ior'itsobject certain improvements in apparatus for sawing blanks from quartz crystals.

A varietyof types of sawing machines and sawing techniques have been proposed forthe making of oscillator plates. In all cases a device is used to hold the quartz crystal in'proper orientation for sawing. The crystal is oriented and then-mounted so it can be fed to the saw or the saw brought to the crystal. The crystal is, for example, solidly imbedded in plaster of Paris or otherwise cemented to a base made of plywood, glass, etc. The base is then clamped to the cutting table. A natural face, or a trued surface, of

the crystal is usually used as a base for the mounting; the face or surface being, for example, aligned with the surface of the cutting table; The table is then turned to bring the crystal'in the desired angle of cut with respect to the saw.

This practicehas a number of serious disadvantages. It isdifficult to align the crystal accurately unless it has a natural'face oi sufiicient size. Crystal with such natural faces are now the exception rather than-the rule. This is one of the reasonswhy the crystals are given-preliminary cuts to obtain a trued section with a flat surface that can be used to positionthe crystal on the cutting table. Special steps must, therefore, be taken-to obtain trued sections, and there are nevertheless opportunities for error in mounting and aligning the crystal to the saw. These difficulties are, of course, greatly increased when workingwith raw crystals that do not have any, or ample, natural faces.

I have discovered that these disadvantages may be substantially overcome. The quartz crystal may be readily and accurately cut into cs-- cillator plates. It may be mounted and aligned with respect to its axes and may be cut or sawed Without disturbing the alignment. As a result of these improvements, substantial economies may be effected over the practice heretofore followed and oscillator plates of predetermined angle of cut maybe regularly obtained.

In accordance with the method of invention, the. optical and electrical axes of a quartz crystal,- or section of crystal, are placed in predetermined relationship with a given reference lineremovedfrom .thecrystal. The crystal is then cut at a predetermined angle of cut with respect to the reference line while maintaining the optical and electrical axes of the crystal fixedintheir relationship to the reference line.

The apparatus. comprises a cutting machine,

an adjustable guide support, .a removable quartz holder" adapted to engage the guidesupportin a predetermi'nedpo'sition, means associated with the holder for maintaining the optical andelectricalaxesoi-a quartzcrystal mounted thereon in predetermined fixed relationship to a reference part of'theholder, means for placing theguide support'and hence-the holder andcrystal at 'a predetermined angleof cut with respect to-the cutter; and'means-for advancing the guide support, holder andcrystal-asa unit to thecutter atsuch'predetermined-angleof out while maintaining the optical and electrical axes of the crystal fixed in theirpredetermined relationship to thereferencepart oi the holder.

"The invention will be better understood by reierringto the: accompanying drawings, taken iniconjunction with.the following description, in which:.

Fig. 1 is-aside:.elevation,.partly. in section, of an apparatusillustrative.oi, and adapted for, a practice of the. invention;

;2-. is a plan-view'oi the same apparatus;

Fig.3 isan:enlargedi side view-0f a portion of the apparatus, partlyt'in section; and

Fig. 4 Ban enlarged plan view ofa portion of the apparatus.-

Theapparatus shown comprises a sawing machineltla quartzcrystal holder I I, an adjustable guide. support. I2 anupper carriage l3, and a lower carriage Hi, all of which are suitably mount'edon a base [5, which is in turn supported by a framework, notshown, to place the carriages -andholder at a convenient level for the operators of the apparatus.

Referringt'o Fig. 1',,the apparatus shown includes a:circular saw it, mounted on ashaft l1 extendin'gthrough'the free .end of a pull-down arm I'B. The pull-down arm is pivotally secured to'ashaft' i9near'its'other end, the shaft being rotatably'supportedbya pair of spaced vertical supports 26]. is provided with -an-adjustable counterweight 2 5. An uprightarm' 2'2"issupported on a cross-arm extending across the vertical supports. The pulldown arm is movably interconnectedto the upright-arm by means of a pneumatic shock absorloer 23 'ot conventional construction. When the saw is pulled downwardly, bypulling down the pull-arm, the casing of the shock absorber .also movesdownwardly away irom a stationary pistonl-not shown) securedt'o theupper endof the upri'ght armr Air then rushes into the space between the' pistonhead and the lower part of the casing; When-=-the saw-is released, the'coun- 'terweight forces it -upwardly into an inoperative Therear end of the pull-down arm position. The upward action of the pull-down arm is retarded when the casing of the shock absorber rises around the piston, by permitting the air in the casing to exit therefrom in regulated amounts.

Shaft i9 is provided with a pulley 24 which is in turn fitted with a drive belt 25 connecting a source of power, not shown. Shaft I9 is also provided with a pulley 23 and shaft I! with a pulley 21. A drive belt 28 connects the two pulleys so that rotating power may be transmitted to the saw.

The particular quartz crystal holder shown is more fully described and claimed in my copending application Serial No. 511,198, filed November 20, 1943. It comprises a series of superposed supports or bases: a fixed base A, a lower tiltable base B, an upper tiltable base C and a rotatable base D. Bases D and C are pivotally tiltable at right angles to each other as well as toward and away from base A. Base D is rotatable laterally on base C. A quartz crystal 3!) is shown mounted on base D.

Base A is provided with an inverted guide channel 31 open at both ends, rectangular in crosssection, and adapted to fit over guide support 12, also rectangular in cross-section. The part of the holder that defines the channel is advantageously used as a reference part to which the optical axis and an electrical axis of the crystal may be suitably adjusted. A pair of spaced

pivot posts

32 and 33 is integrally secured to and centrally of the base at opposite ends; the upper ends of the posts being rounded, as shown, so that base B may be supported and readily tilted thereon. A pair of spaced

bolts

34 and 35 is integrally secured to base A at diagonal corners, the bolts being sufficiently long to extend through and a convenient distance above base B.

Base B is provided on its underside with a spaced pair of concave recesses which are adapted to receive and to accommodate the rounded upper ends of

pivot posts

32 and 33 respectively extending above base A. The opposite sides of base B have cut-away portions to provide free working space above

bolt slots

44 and 45 respectively in base A. Base B is also provided with a pair of slotted bolt holes, not shown, at diagonal corners to accommodate

bolts

34 and 35, with nuts 46 and 41, respectively in base A. A pair of spaced pivot posts 48 and 43 is integrally secured to and centrally of the base at opposite sides, the upper ends of the posts being rounded, as shown, so that base C may be supported and tilted thereon. These pivot posts are aligned at right angles to pivot

posts

32 and 33 of base A. A pair of spaced bolts 50 and is integrally secured to base B at diagonal corners, the bolts being sufficiently long to extend through and. a convenient distance above base C.

Base C is provided on its undersid with a pair of spaced concave recesses which are adapted to receive and accommodate the rounded upper ends of pivot posts 48 and 49 extending above base B. The diagonal corners are cut away, as shown, to permit ready access to

bolts

34 and 35 extending above base B. Base C is also provided with a pair of slotted bolt holes, not shown, at the other diagonal corners to accommodate bolts 50 and 5| with

nuts

64 and 65, respectively, in base B. The upper side of base C is provided with a circular recess 66 adapted to receive and accommodate the lower portion of base D. A

spaced pair of threaded bolt holes, notnshown,

extend through base C at opposite sides, and ac commodate bolts 6'! and 68.

Base D consists of a circular bottom disk 80, preferably of metal, integrally secured to a smaller circular top disk 8|, preferably made of fiberboard or the like. An outer annular clamping shoulder 82 is provided by the bottom disk due to the smaller diameter of the top disk. A pair of clamps 83 and 84 is attachable to base C by bolts 61 and 68, respectively in base C. Each clamp has a zig-zag configuration, the outer end being provided with a narrow depending shoulder portion adapted to rest on the top of base C and to pivot thereon. The other end of the clamp consists of a laterally extending portion adapted to be pressed downwardly on the top of base D when bolts 61 and 68 are tightened.

Guide support 12 is in turn secured to a base Qt located at the bottom of tray 9| which is adapted to catch cutting liquid used on the saw when cutting quartz crystals. Base is provided with a pair of

bolts

92 and 93 extending through the guide support and

slots

44 and 45 in base A so that it and the lower fixed base A of the holder may be suitably secured to one another. The base and tray are in turn rotatably secured to an outer hollow shaft 94, the lower end of which rests slidably on a stationary collar 95. An inner solid shaft 96 is secured to the upper side of the collar and extends upwardly within the hollow shaft. The construction is such that the outer shaft and hence the tray, guide support, and the holder may be swiveled around the inner shaft. A set screw 91 extends through the Wall of the outer shaft so that the two shafts may be locked in any desired position. v The outer surface of the outer shaft is provided with a suitable scale I00 so that the guide support and hence the holder and crystal may be swiveled a predetermined amount with respect to the line of cut of the saw. The movable parts may then be locked in their adjusted position by the set screw.

Collar 95 is in turn secured to a table IUI on upper carriage 13 which is slidably interlocked with a table I02 on lower carriage M. The two table are adapted to slide relatively to one another among zig-zag surfaces I03. A threaded shaft N14 is secured at one end to table HH and connects near the other end with collars IE5 to prevent lateral movement thereof and a handle I05, the collars being secured to a carriage frame 10?. A similar threaded shaft IE8 is secured at one end to table H12 and connects at the other end with collars I09 to prevent lateral movement thereof and a handle H0, the collars being being secured to a carriage frame I l I. In the con struction shown, the shafts are at right angles to one another and the carriages are therefore adapted to be moved in right angle relationship to one another.

The apparatus may be operated as follows to saw oscillator blanks:

Crystal 30 is mounted on the holder with its optical axis fixed in predeterminedrelationship with a given or reference part of the holder, which in the apparatus shown is the inverted, guide channel 3| in fixed base A. The optical axis may, for example, be determined and fixed in the manner disclosed in the copending application of Harry Berman, Serial No. 511,199, filed November 20, 1943. It is advantageously placed in parallel relationship with the guide channel, for example, the sides thereof. The electrical axis of the crystal is also fixed in predetermined relationship with a, given or reference part of the holder,which in the-apparatus shown is also guide in the'copendingapplication of Harry Ber'man, 'Serial No; 511,201, filed November-20, 1943. In

practice it is advantageous to place the electrical axis perpendicular to the top of the guide channel. The holder is secured to the sawin -apparatus by fitting-guide channel 3| in base A over adjustable guide support I2.- ln'other Words; the guide support will then fit in the 'guide channel fa-irlysnugly so that thetwo may function in effect as a reference line or partforthe cutting operation. Bolts $2 and 93 in

slots

44 and 45 of base A are then tightened so that the holder is rigidly secured to the guide'support. In the present construction the guide support is disposed horizontally. This leaves the optical axis of the crystal in horizontal relationship and the electrical axis in vertical relationshipthereto.

Saw-|ii is placed in perpendicular relationship to the guide support and therefore also guide channel3l.

Since the optical and electrical axes of the cry.-

tal and the line of cut of the saw are placed in this predetermined relationship, any-desired angle of cut may be obtained by swiveling adjustable guide support [2, This is accomplished by looseningset screw 97 and suitably swiveling the holder and'outer hollow shaft 9 about fixed solid shaft 95 until the predetermined angle of cut H2 is obtained. This is visually indicated on scale "38. Set screw d? is then tightened to fix the parts in their adjusted position.

With the optical and electrical axes of the crystal fixed in predetermined relationship with saw IS; the crystal may be moved to a suitable position under the saw by suitably turning handle we of carriage l3 and handle I i ii of carriage l4. Pulldown arm iBis then lowered to bring the saw in contact with the crystal. Power is applied to

belts

25 and 28, and the saw rotates about its shaft i1. One blank after another may then be cut from the crystal, the thickness of the blanks being regulated by the amount carriages i3 and 14 are moved by handles 5% and HG. It will be clear that the reference line or part may be Varied. For example, the various elements going into the apparatus may be so constructed that an edge or a face or even a line, as shown, through the center of the top of adjustable guide support l2, etc., or an edge or a face of guide channel 23, etc., may be employed. The important thing is to select a suitable reference line or part and then to operate the apparatus with respect to that reference line or part in order to obtain the advantages of the invention.

I claim:

1. In apparatus for manufacturing quartz oscillator plates, the improvement comprising a cutter, a guide support, a removable quartz crystal holder adapted to engage the guide support in a predetermined position; said holder comprising a fixed base, a lower tiltable base pivotally supported by the fixed base, an upper tiltable base pivotally supported by the lower tiltable base, and a rotatable base supported by the upper tiltable base, the tiltable bases being tiltable with respect to each other and the fixed base; means associated with the holder for maintaining the optical and electrical axes of a quartz crystal mounted thereon in predetermined fixed relationship to a reference part of the holder, a swivelly adjustable mountin for placingthe guide support and hence the holder-and crystal at a predetermined'angle of outwith"- respect to the "cutter; and' ineans for "advancing the guide support, holder 'and crystal as a:-'-unit='tothe cutter at such predetermined angle of out while maintaining *the eoptical' and 'holderadapted to engage the guide support in a predetermined positiony-said holder comprising-a fixed base provided with at "least two pivot posts, a lower tiltable base-supported; by'-- said pivot-posts; the lower tiltablebase also being provided with at'least two pivot posts; said two sets of pivot posts beingaligne'd' atright-angles to each other, an upper tiltable" base supported by the latter pivot posts, and a rotatable base supported'by the'upper tiltable base, said tiltable bases-being 'tiltable with respect to each other and said fixe'dba'se; means" associated with the holder'for maintaining the optical andelectrical axes of 'a quartz crystal-mounted thereon in pre-. determined fixed relationship to areference part of the holder, means for placing'the guide support andvhence theho'lder and crystal at a predetermined angle of cut with respect to the cutter, and means for advancing the guide support, holder and crystal as a'unit to the cutter at such predetermined'angle 'of out" while -maintaining the optical and'ele'ctri'cal axes of the crystal'fixed in their predetermined relationship to the reference part of the holder.

3. In apparatus for manufacturing quartz oscillator plates, the improvement comprising a cutter, a guide'support, a'rem o-vable quartz crystal holder adapted to engage the g'u'ide'support in a predetermined position; said holder comprising a fixed base, a lower tiltable base 'piifotally sup-- ported by the'fixed base, anupper 'tiltable base pivotally'supported by the lower'tiltable base,

and a rotatable base supported by the upper tiltable base theftiltable bases being tiltable with respect toeach other andfthefixed base; means associated'with the holder for maintaining the optical and electrical axes of a quartz crystal mounted'thereon inpre'determined fixed relationship to areference "part of the holder, means for p-lacing 'the guiclesupport and hence the holder and crystal at apred'etermined angle of cut with respect td'the -cutter, said-"means for placing the guide support comprising a rotatable base supporting the guide support, means associated with the latter rotatable base for determining the amount of rotation thereof with respect to the cutter, and means for advancing the guide support, holder andcrystal as a unit to the cutter at such predetermined angle of cut while maintaining the optical and electrical axes of the crystal fixed in their predetermined relationship to the reference part of the holder.

4. In apparatus for manufacturing quartz oscillator plates, the improvement comprising a cutter, ag'uidesupport, a removable quartz crystal holder adapted to engage the guide support in a predetermined position said holder comprising a fixed base, a lower tiltable base pivotally supported by the fixed base, an upper tiltable base pivot'allysupported by the lower tiltable base, and a rotatable base supported by the upper til-table base, the=ti-ltab1e bases being tiltable with respect to each other and the fixed base; means "associand" 'electricalaxes (if a uartz crystal mounted thereon in predetermined fixed relationship to a reference part of the holder, means for placing the guide support and hence the holder and crystal at a predetermined angle of cut with respect to the cutter, and means for advancing the guide support, holder and crystal as a unit to the cutter at such predetermined angle of out while maintaining the optical and electrical .axes of the crystal fixed in their predetermined relationship to the reference part of the holder, said latter means comprising an upper carriage supporting the guide support and being movable laterally at right angles to the cutter, and a lower carriage supporting the upper carriage, the lower carriage being movable laterally in a direction generally parallel to the cutter and at right angles to the direction of travel of the upper carriage.

5. In apparatus for manufacturing quartz os cillator plates, the improvement comprising a cutter, a guide support, a removable quartz crystal holder adapted to engage the guide support in a predetermined position; said holder comprising a fixed base, a lower tiltable base pivotally supported by the fixed base, an upper tiltable base pivotally supported by the lower tiltable base, H

and a rotatable base supported by theupper tiltable base, the tiltable bases being tiltable with respect to each other and the fixed base; means associated with the holder for maintaining the optical and electrical axes of a quartz crystal mounted thereon in predetermined fixed relationship to a reference part of the holder, means for placing the guide support and hence the holder and crystal at a. predetermined angle of cut with respect to the cutter, said means for placing the guide support comprising a rotatable base supporting the guide support, means associated with the latter rotatable base for determining the amount of rotation thereof with respect to the cutter, and means for advancing the guide support, holder and crystal as a unit to the cutter at such predetermined angle of out while maintaining the optical and electrical axes of the crystal fixed in their predetermined relationship to the reference part of the holder, said latter means comprising an upper carriage supporting the guide support and being movable laterally at right angles to the cutter, and a lower carriage supporting the upper carriage, the lower carriage being movable laterally in a direction generally parallel to the cutter and at right angles to the direction of travel of the upper carriage.

6. In apparatus for manufacturing quartz oscilla-tor plates, the improvement comprising a cutter, an adjustable guide support, a removable quartz crystal holder adapted to engage the guide support in a predetermined position; said holder comprising a fixed base, a lower tiltable base pivotally supported by the fixed base, the lower tiltable base being tiltable with respect to the fixed base abouta straight line axis at a fixed distance from the fixed base, means connecting the fixed base and the lower tiltable base for-locking the two bases when the lower tiltable base is adjusted to a desired position, an upper tiltable base pivotally supported by the lower tiltable base, the upper tiltable base bein tiltable with respect to the lower tiltable base and the fixed base about a straight line axis in angular relationship to the other straight line axis and a fixed distance from the lower tiltable base, means connecting the lower tiltable base and the upper tiltable base for locking the two tiltable bases when the upper tiltable base is adjusted to a desired position, a rotatable base supported by the upper tiltable'base, and means connecting the upper tiltable base and the rotatable base for locking the two bases when the rotatable base is adjusted to a desired position; a swivelly adjustable mounting for placing the guide support and hence the holder and crystal at a predetermined angle of cut with respect to the cutter, and means for advancing the guide support, holder and crystal as a unit to the cutter at such predetermined angle of cut.

7. In apparatus for manufacturing quartz os cillator plates, the improvement comprising a cutter, an adjustable guide support, a removable quartz crystal holder adapted to engage the guide support in a predetermined position; said holder comprising a fixed base, a lower tiltable base pivotally supported by the fixed base, the lower tiltable base being tiltable with respect to the fixed base about a straight line axis'at a fixed distance from the fixed base, means connecting the fixed base and the lower tiltable base for locking the two bases when the lower tiltable base is adjusted to a desired position, an upper tiltable base pivotally supported by the lower tiltable base, the upper tiltable base being tiltable with respect to the lower tiltable base and the fixed base about a straight line axis in perpendicular relationship to the other straight line axis and afixed distance from the lower tiltable base, means connecting the lower tiltable base and the upper tiltable base for locking the two bases when the upper tiltable base is adjusted to a desired position, a rotatable base supported by the upper tiltable base, and means connecting the upper tiltable base and the rotatable base for locking the two bases when the rotatable base is adjusted to a desired position; a swivelly adjustable mounting for placing the guide support and hence the holder and crystal at a predetermined angle of cut with respect to the cutter, and means for advancing the guide support, holder and crystal as a unit to the cutter at such predetermined angle of out.

8. In apparatus for manufacturing quartz oscillator plates, the improvement comprisin a cutter, an adjustable guide support, a removable quartz crystal holder adapted to engage the guide support in a predetermined position; said holder comprising a fixed base, a lower tiltable base pivotally supported by the fixed base, the lower tiltable base being tiltable with respect to the fixed base about a straight line axis at a fixed distance from the fixed base, means connecting the fixed base and the lower tiltable base for locking the two bases when the lower tiltable base is adjusted to a desired position, an upper tiltable base pivotally supported by the lower tiltable base, the upper tiltable base being tiltable with respect to the lower tiltable base and the fixed base about a straight line axis in angular relationship to the other straight line axis and a fixed distance from the lower tiltable base, means connecting the lower tiltable base and the upper tiltable base for locking the two tiltable bases when the upper tiltable base is adjusted to a desired position, a rotatable base supported by the upper tiltable base, and means connecting the upper tiltable base and the rotatable base for locking the two bases when the rotatable base is adjusted to a desired position; means for placing the guide support and hence the holder and crystal at a predetermined angle of cut with respect to the cutter, and means for bringing the guide support, holder and crystal as a unit and the cutter into cutting position at such predetermined angle'of cut.

In apparatus for manufacturing quartz oscillator plates, the improvement comprising a cutter, an adjustable guide support, a removable quartz crystal holder adapted to engage the guide support in a predetermined position; said holder comprising a fixed base, a lower tiltable base pivotally supported by the fixed base, the lower tiltable base being tiltable with respect to the fixed base about a straight line axi at a fixed distance from the fixed base, means connecting the fixed base and the lower tiltable base for locking the two bases when the lower tiltable base is adjusted to a desired position, an upper tiltable base pivotally supported by the lower tiltabl base, the upper tiltable base being tiltable with respect to the lower tiltable base and the fixed base about a straight line axis in perpendicular relationship to the other straight line axis and a fixed distance from the lower tiltable base, means connecting the lower tiltable base and the upper tiltable base for locking the two bases when the upper tiltable base is adjusted to a. desired position, a rotatable base supported by the upper tiltable base, and means connecting the upper tiltable base and the rotatable base for locking the two bases when the rotatable base is adjusted to a desired position; means for placing the guide support and hence the holder and crystal at a predetermined angle of cut with respect to the cutter, and means for bringing the guide support, holder and crystal as a unit and the cutter into cutting position at suchjpredetermined angl of out.

10. In apparatus for manufacturing quartz oscillator plates, the improvement comprising a cutter, an adjustable guide support, a removable quartz crystal holder adapted to engage the guide support in a predetermined position; said holder comprising a fixed base, a lower tiltable base pivotally supported on pivoting means secured to the fixed base, the lower tiltable base being tiltable with respect to the fixed base about a straight lin axis at a fixed distance from the fixed base, means connecting the fixed base and the lower tiltable base for locking the two bases when the lower tiltable base is adjusted to a desired position, an upper tiltable base pivotally supported on pivoting means secured to the lower tiltable base, the upper tiltable base being tiltable with respect to the lower tiltable base and the fixed base about a straight line axis in perpendicular relationship to the other straight line axis and a fixed distance from the lower tiltable base, means connecting the lower tiltable base and the upper tiltable base for locking the two bases when the upper tiltable base is adjusted to a desired position, a rotatable base supported by the upper tiltable base, and means connecting the upper tiltable base and the rotatable base for locking the two bases when the rotatable base is adjusted to a desired position; means for placing the guide support and hence the holder and crystal at a predetermined angle of cut with respect to the cutter, and means for advancing the guide support, holder and crystal as a unit to the cutter at such predetermined angle of out.

11. In apparatus for manufacturing quartz oscillator plates, the improvement comprising a cutter, an adjustable guide support, a removable quartz crystal holder adapted to engage the guide support in a predetermined position; said holder comprising a fixed base, a lower tiltable base pivotally supported on pivoting means secured to the fixed base, the lower tiltable base being tiltable with respect to the fixed base about a straight line axis at a fixed distance from the fixed base, means connecting the fixed base and the lower tiltable base for locking the two bases when the lower tiltable base is adjusted to a desired position, an upper tiltable base pivotally supported on pivoting means secured to the lower tiltable base, the upper tiltable base being tiltable with respect to the lower tiltable base and the fixed base about a straight line axis in perpendicular relationship to the other straight line axis and a fixed distance from the lower tiltable base, means connecting the lower tiltable base and the upper tiltable base for locking the two bases when the upper tiltable base is adjusted to a desired position, a rotatabl base supported by the upper tiltable base, and means connecting the upper tiltable base and the rotatable base for locking the two bases when the rotatable base is adjusted to a desired position; means for placing the guide support and hence the holder and crystal at a predetermined angle of cut with respect to the cutter, and means for bringing the guide support, holder and crystal as a unit and the cutter into cutting position at such predetermined angle of cut WILLIAM C. SPEED.