Universal work holders for assembling curved laminated units
United States Patent 1191 Lappin, Jr.  
 [451 Apr. 22, 1975 1 1 UNIVERSAL WORK HOLDERS FOR ASSEMBLING CURVED LAMINATED 211 Appl. No.: 325,309  
 [51] Int. Cl. B27h 1/00; B25b ll/02; E04f 11/18 [58] Field of Search 29/200 J, 428. 464, 466, 29/468, 467; 33/174 G; 52/187; 156/443; 144/254-258. 288 R, 288 B; 269/45, 37, 321  
 F, 321 S, 321 W, 55, 71-73, 104, 105  
 [56] Reierences Cited UNITED STATES PATENTS 348,908 9/1886 Horrocks 5.2/187 424.533 4/1890 Belles 2,399,348 4/1946 Hobbs 144/256 3,331,134 7/1967 Jackson ct a1. 33/174 N X 3,732,609 /1973 Cirgcnski. Jr. ct a1 29/428 Primary E.\&#39;anzinerRoy Lake Assistant E.\&#39;aminer--Neil Abrams Attorney, Agent, or Firm-C. Yardley Chittick [57] ABSTRACT The invention includes a universal work holder or jig for use in making curved supports and railings and the like from a plurality of associated laminas, the supports so made and the method of making the same. In the preferred configuration, each support will be in the form of a helix and its principal use at present is in a so-called flying spiral stairway. Pairs of approximately dimensioned helical supporting units may be used to carry the individual stair treads and other appropriately dimensioned helical units may be used with the stairs as inner and outer handrails carried by balusters mounted on the tread supporting units. The invention however is not limited to the manufacture of elements to be used in spiral stairways.  
  927,975 7/1909 Kaufman ct a1. |.754 375 4/1930 Sturgcs ..52 1s7x 6Clalms, a g gur s F3 F92 I i 46 l 7 4 2 22 26 H G F E D l L m v1 C M L K J 22 B A I 10\ l b?) L+7 145T&#34;: 1| I UNIVERSAL WORK HOLDERS FOR ASSEMBLING CURVED LAMINATED UNITS BACKGROUND OF THE INVENTION Spiral staircases are old and well known and have come into extensive use in places where it is not possible or convenient to install the more conventional type of stairs. In the typical spiral staircase, there is a central axially located metal column on which angularly dis-- posed metal treads are mounted in cantilever fashion. The treads at their outer ends carry upwardly extending balusters which support a helical metal handrail. Since the treads extend inwardly to the central column, they are necessarily of small horizontal dimension at their inner ends and, at this inner area, of practically no use as steps. The maximum radius is usually limited to about three feet thus presenting the user with a steep, sharply turning staircase.  
  These deficiencies have been noted and attempts have been made to increase the radial dimensions of the treads by adding vertical supports for the outer ends of the treads. In some instances the interior central column has been eliminated by using inner and outer helicalsupporting columns thereby to create the so-called flying spiral stairway. One such construction is shown in my US. Pat. No. 3,473,275 of Oct. 21, 1969. In this patent the inner and outer helical supporting columns are formed from an assemblage of identical castings bolted together. The castings include mounts for the horizontal treads which extend radially from the inner helix to the outer helix. Since the treads are supported at both ends, the width of the usable part of the tread may be increased by increasing the overall diameter without changing the extent&#39;of the angular turn in going from one floor to the next with the risers remaining at any selected height.  
  It will be recognized that helical supports such as shown in my patent referred to above are in the nature of large helical springs and that if proper stiffness is to be maintained without supplemental bracing, the diameter must be limited and the individual castings must be of adequate strength. On occasion where the vertical rise between floors is more than usual and/or the stair diameter is extra large, additional exterior vertical supports may be added. 7  
  An additional requirement of spiral stairways is suitable handrails. The central column type have only a single outer handrail which limits the users security. The flying spiral stairway such as shown in my patent permits the use of inner and outer handrails which are carried by suitable balusters generally in the form of strong steel rods mounted vertically on the stair carrying castings. The handrails must of course be of helical shape corresponding to the pitch and radius of the inner and outer helical supporting columns. Experience has shown that great difficulty is encountered in bending an initially straight metal or wooden rail to the exact matching helical shape. If when finished the bent rail is of incorrect pitch or radius, it cannot be rebent or otherwise modified but must be scrapped to be replaced by another which hopefully will have been more precisely shaped.  
  The prior art does not, as far as I am aware, disclose means for making helical supporting elements in continuous lengths to exact pitch and radius requirements.  
 SUMMARY OF THE INVENTION With the above background of the invention in mind, the present invention is directed to an adjustable work holder or jig having a plurality of work receiving stations which stations may be positioned in a succession of selected locations spaced axially and radially so that a plurality of bendible elongated strips of material (wood, metal, plastic, etc.) placed therein will assume the exact curved shape desired. In the present disclosure the work receiving stations will preferably be positioned to create a helical support or unit of predetermined pitch and radius. The invention. however, is not limited to the creation of a helical unit. By changing the locations of the work receiving stations to coincide with the formula requirements of any other selected non-planar curve, then the strips of material or laminas as they may herein after be called, will assume the shape of such other selected curve.  
  When the elongated laminas in any selected number and size to give the necessary strength and overall re quired cross sectional dimensions have been placed in position in the succession of work receiving stations, the laminas with their facing and abutting curved surfaces are then permanently bonded together.  
  The laminated unit produced by the adjustable work holder in the manner generally described above will, for reasons to be explained, be found upon removal from the work holder to be initially precisely dimensioned and to be thereafter dimensionably stable while awaiting installation in a helical stairway either as the tread support or the handrail.  
  For convenience in further explanation, the work holders will be adjusted for use in the production of helical handrail units of any selected pitch and radius. Also, the elongated laminas that are assembled in the work holders will be dimensioned to produce a handrail of comfortable size for general use by adults. It will also be understood that by increasing the width and number of the laminas, a stronger helical unit may be produced that will be adequate to support the treads and to act as a substitute for the assembled helical columns shown in my patent above referred to.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of the adjustable work holder with the work receiving stations spaced equidistant axially, angularly and radially thereby to present an array of of stations defining a helix.  
  FIG. 2 is a vertical section taken on the line 22 of FIG. 1 showing the angular indexing means used in setting the stations at the correct angular positions.  
  FIG. 3 is a vertical section taken on the line 33 of FIG. 1 showing twelve work holding stations and their supporting arms spaced 30 apart.  
  FIG. 4 is an enlarged detail taken on the line 44 of FIG. 3 showing the assembled laminas passing between two spaced work holding and guiding fingers at one of the stations.  
  FIG. 5 is an elevational detail taken on the line 55 of FIG. 4 with a clamp added.  
  FIG. 6 is an enlarged detail taken on the line 6-6 of FIG. 3 with a clamp added.  
  FIG. 7 is an enlarged vertical section taken on the line 7-7 of FIG. 1 with the radial arm broken away to conserve space and with the helical unit omitted.  
  FIG. 8 shows two finished helical units, the inner one of small radius, the outer one of larger radius, but both of the same pitch. These units represent a pair of finished handrails and/or a pair of helical stair supports made through the use of the work holders.  
  FIG. 9 is an enlarged plan view taken on the line 9--9 of FIG. 8 showing joints in some of the laminas.  
  FIG. 10 is a plan view to greatly reduced scale showing one of the laminas which may be of any selected dimensions and preferably bendable within its elastic limit to conform to the required curve. The lamina is shown as being made in three sections.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT and l4, 16 respectively, the legs being rigidly mounted on bases 18 and 20.  
  On the cylindrical bar 2 are a plurality of identical collars 22 shown in more detail in FIG. 7. Each collar is split as at 24. A screw 26 threaded into one side of the split at 28 enables the collar to be clamped on the bar in any selected angular and axial position. Each collar has attached thereto a radially extending arm 30, preferably in the form of a strong pipe in screw threaded connection with the collar as at 32.  
  On each arm 30 is a cylindrical sleeve 34 maintainable in any selected position along the arm by one or more set screws 36. Each sleeve 34 carries a pair of strong parallel fingers 38 and 40 preferably in the form of short pipes in screw threaded connection with the sleeve as at 42 and 44 respectively see FIG. 4. The spacing between fingers 38 and 40 will be adequate to receive there-between the selected number of laminas of which the rail or stair support is to be made.  
  From the description thus far it will be understood that the collars 22 may be located at selected axial positions along bar 2 and that the arms 30 may be swung to and maintained in selected angular positions by clamping their respective collars to the bar.  
  To assist in setting the several arms 30 at the desired angular locations about bar 2, there is affixed to the end of the bar a large disc 46 marked off in degrees. A plumb bob or other vertical element 48 is located in front of and close to disc 46. The use of disc 46 in placing the arms 30 at the correct angular positions will be explained hereinafter.  
  The foregoing described structure enables a succession of work holders each in the form ofa pair of parallel fingers mounted on axially and radially adjustable supports to be fixedly located in space about the bar 2 to define any selected non-planar curve falling within the maximum dimensions of the bar 2 and the arms 30. In the preferred case, the work holders will be arranged to define a helix of predetermined pitch and radius.  
  In order to understand the operation of the invention more precisely, the details of the positioning of the work holders and the introduction therein of the laminas will now be explained in relation to the manufacture of a handrail to be used with a flying spiral staircase.  
  Let it be assumed that a handrail such as that shown at 50in FIG. 8 is to be made. This handrail is to be used with a spiral staircase of the following assumed dimensions. The height of the staircase is 10 feet, the distance from the floor below to the floor above. Each riser (the vertical distance between steps) is to be 8 inches so there will be 14 steps between the landings at the two floors. The steps are to extend through a complete circle of 360 spiraling in the nature of a right hand thread. The outside radius of the staircase is 4 feet and the inside radius 1 foot. Since the handrail 50 must conform to the helical curvature defined by the steps, it follows rail 50 must have a pitch of 10 feet and an outside radius of 4 feet. The 10 foot pitch is indicated at P and the 4 foot radius at R in FIG. 8. The pitch of the inner handrail 52 will be the same but the inner radius is 1 foot and indicated at R.  
  With the above known dimensions to be met the jig is set up as follows. Experience has shown that in the making of a relatively large diameter rail, the angular spacing of the individual work holders at 30 will produce a uniformly curved rail with no appreciable deviation between the holders. Accordingly the arms 30 will be spaced angularly 30 apart. To provide a helix of 360 with the holders spaced at 30 and having a pitch of IO feet, 13 holders will be used and the arms 30 and their related collars will be spaced axially along the bar 2 at a distance of 10 inches 10 feet 12 [0 inches).  
  Referring now to FIGS. 1, 2, and 3, the collar of the first arm 30 (now designated A with the other arms in alphabetical sequence for clarity) is clamped to the bar 2 with arm A vertical and aligned with indicator 48 and 0 on disc 46. Sleeve 34 on arm A is adjusted along the arm until the interior side 54 of finger 40 (see FIG. 7) is 48 inches (the outer radius of the rail) from the axis of bar 2.  
  Disc 46 and bar 2 are then rotated clockwise as viewed in FIG. 2 for exactly 30, bringing the 30 mark into alignment with the vertical indicator 48. The next arm B is then aligned with indicator 48 and spaced 10 inches axially away from arm A. The collar of arm B is then clamped to bar 2. The sleeve 34 on arm B is similarly adjusted so that its finger 40 is 48 inches from the bar axis.  
  Disc 46 and bar 2 are then again rotated clockwise for another 30 bringing the 60 mark into alignment with the vertical indicator 48. The next arm C is then aligned with indicator 48 and spaced 20 inches axially from A. The collar of arm C is then clamped to bar 2 and the sleeve 34 of arm C is adjusted radially until finger 40 is 48 inches from the bar axis.  
  The foregoing procedure is followed with all of the remaining required arms, D, E, F, G, H, I, J, K, L and M. When this has been completed, there will be 13 arms spaced axially 10 inches apart. Arm A will be in alignment with arm M and corresponding points on the sleeves 34 of arms A and M will be inches apart.  
  All of the fingers 38 and 40 on the sleeves 34 will be parallel to the bar 2 axis and to each other. The 13 identical work holders each consisting of a sleeve 34 and fingers 38 and 40 are now so located in space as to define a perfect helix having a 10 foot pitch and an exterior radius of 4 feet.  
  The next step in the fabrication of the helical handrail 50 (FIG. 8) is the preparation of the laminas and their introduction into the work holders. By calculation, it will be found that the length of the handrail will be about 27 feet. If the rail is to be made of wood, oak or cypress is the preferred material. Since it is virtually impossible today to get knot free planks of such length, the individual strips used in making the handrails will ordinarily consist of two or more pieces each 3 inches wide and slightly over one-eighth inch thick.  
  The necessary number of laminas, usually about or 11 to make a handrail of 1 /2 inches thickness, are prepared and laid flat on a bench near the jig. Adhesive is applied to the faces of two or three of the laminas and they are then placed one on top of the other. (No adhesive, of course, is applied to the outer face of the outer lamina.) These several piled up laminas are then carried by workmen or machine to the jig and progressively inserted in the work holders so that they lie between the l3 sets of fingers 38 and 40 and pressing radially outward against fingers 40 with their edges abutting the sleeve 34 as illustrated in FIG. 6 and with their ends extending somewhat beyond arms A and M.  
  As soon as the first two or three laminas are in place an additional two or three more with adhesive between them are brought to the jig and worked into position in the work holders in the available space between fingers 38 and the previously inserted laminas and in facing relation with the first inserted laminas. This process is repeated until the required total number of laminas are in place in the work holders, filling the radial space between the sets of fingers 38 and 40 and butting against the side of each sleeve 34.  
  The assembly just described is illustrated in FIGS. 4, 5, and 6. FIG. 9, a plan view taken on the line 9-9 of FIG. 8 shows in greater detail the exact arrangement of the lamina at one selected position.  
  After all laminas are in place in the work holders they will have collectively assumed the form of a perfect helix with a pitch of 10 feet and a radius of 4 feet. The bending of each lamina will be along an infinite number of lines parallel to the axis of the bar 2. The extent of the bending preferably will be within the elastic limit of the material and because of the closeness of the angular spacing of the work holders, the curvature of the assembled unit will be uniformly circular as shown in FIGS. 3 and 5.  
  The next step is to apply clamps to the assembled laminas whereby the adjacent faces will be permanently bonded together by the adhesive when it has set. Any suitable type of clamp may be used, but the clamps must be of such character and number that proper pressure will be applied to the laminas throughout the whole length of the rail to insure that all of the layers are set in immovable relation to each other. As many as four or five conventional wood working clamps may be used between successive work holders. The faces of the clamps preferably will have pads that conform to the curvature of the inner and outer faces so that the clamping pressure will be uniformly distributed. One clamp is shown in FIG. 5 at 56 as illustrative of the general clamping procedure.  
  If because of the slippery character of the unset adhesive there is any tendency for the laminas to slide laterally out of alignment with each other, additional clamps acting across the other dimension to hold the edge of all laminas against the sleeve 34 may be used. Such a clamp is shown in FIG. 6 at 58 and may comprise a small collar 60 from which extends a short arm 62 on the end of which is screw operated means 64 adapted to press a pad 66 against the edge of the laminas causing them to be maintained against sleeve 34 in exact alignment.  
  Thus, with aids of clamps 56 and clamps 58 if needed, the assembled laminas are rigidly held together in the exact helical form of rail required. After the adhesive has thoroughly set. the clamps are removed and the entire completed handrail may then be removed I from the work holders to be taken away from the jig as a finished unit.  
  Since the laminas are thin and very securely bonded together in face to face relation, there is complete and permanent dimensional stability. That is. the helical unit even when unsupported prior to installation on the flying stair case has no tendency to uncoil or otherwise change shape. Thus the pitch and diameter remain constant so that the rail will fit perfectly on the balusters that extend vertically from the stair treads into suitably located predrilled holes in the underside of the rail. A few such holes are shown at 70 in FIG. 8.  
 In order to protect the outer surfaces of the rail from possible damage by the clamps 56, it is preferable that two extra protective laminas be used. These are shown in FIG. 9 at 72 and 74. These laminas have no adhesive on their inner faces so when the unit is removed from the jig these outer layers are removed leaving the attached laminas collectively indicated in FIG. 9 within the bracket 76 which constitutes the laminated helical unit.  
  In FIG. 9 is also illustrated one method of connecting the ends of laminas together to produce strips of sufficient length. The ends of laminas 78 and 80 are cut away in complementary fashion, overlapped and glued together along the line 82. To increase the strength of the jointed sections in the unit, it is good practice to place continuous laminas such as those indicated at 84, 86, 88, 90, 92 and 94 on both sides of the jointed laminas 78, 96, 98, 100, 102 and 104. On the other hand the joints may all be at the same location or scattered at random throughout the length of the rail.  
  With the rail removed from the jig, it is then sanded and finished to present a highly desirable appearance. The baluster holes, previously mentioned, are drilled at the proper angle at determined locations in the underside of the rail. The unit is then ready for final installation.  
  In the manufacture of the inner rail 52 shown in FIG. 8, the same procedures are followed modified only to extent that the number of work holding units may be reduced as the arms .30 will ordinarily be spaced 60 apart and the axial spacing between the work holders correspondingly increased.  
  In the illustration given above, the height between floors was said to be 10 feet and the staircase was to turn through 360 with risers of 8 inches, but it will of course be understood that the vertical distance between floors can be any distance and the turn of the staircase can be through any selected degree. Then with the height of the risers known, the axial spacing of any selected number of work holders can readily be determined. The axial spacing of the work holders is of course a function of their angular spacing.  
  It will also be understood that the invention as to the jig is not limited in dimensions and the work holders may readily be positioned in space to define non-planar curves other than a helix. Similarly the laminas which may be placed between the fingers 38 and 40 for assembly into a curved unit may be of materials other than wood such as metal or plastic for example.  
  If it should be desired to make stronger helical units capable of supporting the stairs, then steel or aluminum for example in the form of long thin strips of suitable width could be assembled in the jig and welded or bolted together thus to produce a unit of proper strength and dimensional stability to act as a substitute for the assembled castings shown in my patent above referred to. The jig is of general applicability in the production of curved units for any purpose.  
  The above disclosure will suggest to others skilled in the art modifications which are within the scope of the invention as defined by the appended claims.  
 I claim:  
  1. A jig for use in the production of an elongated laminated unit shaped in the form of a continuous nonplanar curve, said jig comprising a center post, a plurality of arms mounted on said post in selected spaced axial positions and in selected spaced angular positions, each arm being unconnected at its outer end with the next adjacent arm, and lamina receiving guides mounted on said arms in positions defining a nonplanar curve, said guides being in the form of radially spaced elements of which at least one of said elements on each said arm is fixed in said curve defining position prior to the insertion of any of the lamina of said elongated unit into said guides, each of said guide elements having a work engaging surface which extends parallel to the axis of said center post and is long enough to extend diagonally across said laminas, the lamina receiving opening between said guide elements terminating at said arm to which the elements are affixed, whereby when a lamina is inserted into said guides, the pitch of the lamina is controlled by its engagement with said arms and the diameter is controlled by its engagement with the said guide elements.  
  2. The jig set forth in claim 1, said arms being carried by collars which are adjustable axially and angularly on said post and said guides being radially adjustable on said arms.  
  3. The jig set forth in claim 2 and a device associated with said post for indicating the angle at which each said arm is secured to said post.  
  4. The jig set forth in claim 2, said post being rotatable about its axis and a device associated with said post for indicating the relative angular positions of said arms.  
  5. The jig set forth in claim 1, said arms being equally spaced along said post, said arms being equally angularly spaced about said post, and said guides all being equidistant radially from the axis of said post, whereby said guides define the path of a helix and whereby a plurality of lamina placed in said guides will take the form of a helical unit.  
  6. A jig for use in the production of an elongated laminated unit shaped in the form of a continuous curve, said jig comprising a center post, a plurality of arms mounted on said post in selected spaced axial positions and in selected spaced angular positions, and lamina receiving guides mounted on said arms in positions defining a non-planar curve, said arms being carried by collars which are adjustable axially and angularly on said post, said guides being radially adjustable on said arms, said post being rotatable about its axis and a device attached to said post for indicating the relative angular positions of said arms, whereby a plurality of laminas may be placed in face to face relation in said guides to form a unit in the shape of said curve.  
 FORM PO-IOSO (10-69) UNITED STATES PATENT OFFICE fiERTIFICATE 0F CORRECTION Patent 3,879,026 Dated April 22, 1975 Inventods) James B. Lappin, Jr.  
  It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:  
 In the abstract lines 7 and 8 &#34;approximately&#34; should read appropriately Signed and Emaled this second Day Of September 1975 [SEAL] A ttesr:  
 C. MARSHALL DANN (mnmixsimu&#39;r vj&#39;launts and Tradcmurkx RUTH C. MASON Atlesring Officer USCOMM-DC 60376-P69 u.s. GOVERNMENY PRINYING OFFICE: 930