Pipe joint intersection contour scriber

A novel multifunctional contour scriber is disclosed for the use in scribing the intersection contour when an arbitrary geometric body intersects a pipe at arbitrary angle. This multifunctional contour scriber can also be used for scribing at any angle a circle, equally spaced points along a circle, an ellipsoid, a hyperbola, a parabola, an inner or outer cycloid, or an involute of a circle, etc. on a plane, a concave or convex surface. The invention consists of a magnetic base, a rotary unit, a hinge unit, a locking unit, a longitudinal rod, a longitudinal rod disc, a transverse rod, a transverse rod disc, guide sleeves, and scribing units. When scribing the intersection contour on the main pipe, the scriber is secured by the magnetic base on the main pipe. While scribing on the branch pipe, the scriber may be either secured on the ground or fixed in the internal wall of the branch pipe using three strute bars, thus it is readily adapted to delineating intersection contours directly onto the main pipe or branch pipe of various sizes without the necessity of making any developed view or template.

BACKGROUND OF THE INVENTION 
The present invention relates to three dimensional contour scribers and 
more particularly to a pipe joint intersection contour scriber. 
In machine working and manufacturing industry, traditionally employed 
method to delineate an intersection contour between a body with arbitrary 
geometric configuration and a cylindrical pipe intersecting the former at 
arbitrary junction angle includes tedious processes, such as drafting the 
contour on a developed surface, making a template, etc. Errors may thus be 
accumulated in these processes and lead to an unaccurate intersection 
contour being delineated. Yet there may be no way to draft the developed 
view for an undevelopable geometric body. Circular index, height gauge and 
other auxillary tools are therefore utilized to scribe a circle, an 
ellipsoid, a hyperbola, a parabola, or equally spaced points along a 
circle, etc. with an arbitrary angle on a plane, a negative or a positive 
camber, a convex or a concave surface, but these tools usually cannot be 
used for large size machine parts, thus auxillary tools have to be 
employed and they may cause serious errors. 
DESCRIPTION OF PRIOR ART 
Some portable devices have been developed for accomplishing the scribing 
and/or cutting intersection contours. In example, U.S. Pat. No. 4,277,894 
discloses a pipe joint intersection contour scriber which consists of a 
three disc-assembly two of the discs have gear-tooth formed on the 
periphery thereof to engage worm gears. In operation, a template must be 
made in advance and inserted into the scriber unit, a follower disc then 
moves along the template contour and a scriber point delineates the 
intersection contour on the pipe to be cut. Necessarily, some 
disadvantages inhere in the scriber. The pipe to be cut should be 
positioned through the three central holes of the three disc-assembly. The 
diameter of central holes set a limit on the maximum external diameter of 
the pipe to be cut, this scriber therefore can only be used for a limited 
range of pipe sizes; Different templates with different sizes must be 
prepared for different types of pipes; Yet manufacturing worm screws and 
gears will be somewhat difficult. It is therefore time-consuming and 
laborious. 
U.S. Pat. No. 3,835,541 discloses another pipe joint intersection contour 
scriber termed "ellipsoid marker and template tracer". In operating this 
scriber, the main pipe and branch pipe must be connected together using a 
band and a clamp mechanism to secure the scriber to the main pipe and an 
expanding chuck to mount the branch pipe to the scriber. Apparently, these 
mounting and clamping accessories can only be used in a limited range of 
pipe sizes. It is especially difficult to mount a large size branch pipe 
to the scriber. A sheet paper wrapping a replica of the branch pipe 
therefore must be used in this case to form a templete, and the accuracy 
of the template depends on how may points are made by successive 
measurements to form the templete. The operating procedure is complicated, 
resulting an unaccurate intersection contour being delineated. 
Other patents disclosing similar art may be found, but they all can only 
scribe the intersection contour of two cylindrical pipes, and each of the 
scribers usually has only one function. Therefore, they are not 
satisfactory in my professional field in which scribing the intersection 
contours for a cylindrical pipe intersecting an arbitrary geometry body as 
well as the pipes with different diameters intersecting each other in 
different manner is in urgent need. 
OBJECT OF THE INVENTION 
A primary object of the present invention is to provide a three dimensional 
contour scriber for delineating the intersection contour of a cylindrical 
pipe intersecting an arbitrary geometric body at arbitrary angle, and for 
scribing at any angle a circle, equally spaced points along the circle, an 
ellipsoid, a hyperbola, a parabola, an inner or outer cycloid, an involute 
of a circle, etc. on a plane, a concave or a convex surface. The scriber 
should be readily adapted to various sizes of pipes and various 
intersection contour curves. 
Yet another object of the present invention is to provide a simple 
structured, readily adjusted and installed pipe joint intersection contour 
scriber which can delineate intersection contour directly onto the main or 
branch pipe without the necessity of making any developed view or 
templete. 
BRIEF DESCRIPTION OF THE INVENTION 
The present invention of pipe joint intersection contour scriber comprises 
a magnetic base, a rotary unit, a hinge unit, a locking unit, a 
longitudinal rod, a lingitudinal rod disc, a transverse rod, a transverse 
rod disc, guide sleeves and scribing units. 
Four permanent magnet switches are attached on the magnetic base. When the 
base is put on working surface and the switches are turned on, the 
magnetic base will be attracted securely onto the working surface. The 
upper and lower surfaces of the mangetic base are parallel to each other. 
On the lower surface, there is a V-shaped groove whose central line 
perpendicularly crosses the axis of the magnetic base. This makes the axis 
of the longitudingal rod naturally cross the pipe axis. Two level gauges 
are mounted on the upper surface of the magnetic base. 
The rotary unit includes a 360.degree.-graduated disc whose axis coincide 
with the axis of the magnetic basc. The 360.degree.-graduated disc is 
mounted on the magnetic base and can rotate in a full range of 360.degree. 
relative to the latter. The rotary angle is indicated by an angle 
measuring slider on the magnetic base. A surpporting bush is used to mount 
a hinge unit. A bow-shaped 180.degree.-graduated disc is verticaly mounted 
on the magnetic base. 
The hinge unit includes a hinge shaft which is rotatably mounted in thc 
supporting bush. A radial hole on the hinge shaft is used to fix the 
longitudinal rod whose bottom end is thus hinged to the 
360.degree.-graduated disc and can rotate with the hinge shaft in a plane 
perpendicular to the magnetic base within the range of 0.degree. to 
180.degree.. The rotary angle is indicated by an angle measuring slider on 
the bow-shaped 180.degree.-graduated disc. 
Locking unit on the above mentioned hinge shaft is used to lock the said 
longitudinal rod at a predetermined position. 
The Longitudinal rod disc is slideably mounted on the other end of the 
longitudinal rod and can slide along the latter. 
The transverse rod is dismountably fixed to the transverse rod disc, and 
the latter, in turn, is rotatably mounted on the longitudinal rod disc. 
Hence, the transverse rod can rotate about and slide along the 
longitudinal rod. 
The two guide sleeves are mounted respectively on the longitudinal and the 
transverse rods with the same structure, and they not only able to slide 
respectively along longitudinal and transeverse rods, but also able to 
rotate respectively about these rods. 
The two scribing units are the same, each comprising a scribing pointer, a 
scribing arm and a connecting bush. The scribing arm is hinged to the 
connecting bush, hence the angle between the scribing arm and the 
longitudinal or the transverse rod can be changed if necessary. The 
scribing pointers are connected to the scribing arms in the same way, 
hence the angle between the scribing pointers at the lower ends of the 
scribing arms can be replaced by torch cutters or other cutting tools.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The preferred embodiment of the present invention will be described in 
detail below with reference to the attached drawings. 
Referring to FIG. 2, the magnetic base (1) of the pipe joint intersection 
contour scriber of the present invention is a disc-shaped part whose upper 
and lower surfaces are parrallel to each other, two level gauges being 
attached on the upper surface. Located on the lower surface is a V-shaped 
groove symmetrical to the axis of magentic base, its axis perpendicularly 
crossing the axis of the magetic base. The V-shaped groove is mainly used 
for cylinders or cones with various sizes. There are four holes equally 
spaced on the magentic base, which are used to install four magnetic (2a) 
and four permanent magnet switches (2). When scribing, the V-shaped groove 
of magnetic base (1) is put on the cylindrical surface of the pipe, the 
permanent magnet switches are turned on, and the magnetic base is then 
attracted securely on the workpiece. On the upper surface of magnetic base 
is then attracted/securely on the workpiece. On the upper surface of 
magnetic base (1), there is a T-shaped circle groove circle groove for 
accommodating the bolts with T-heads. A bore is formed at the centre of 
the magentic base (1) for centering a 360.degree.-graduated disc (3). 
FIG. 2 shows the rotary unit (3) which comprises a 360.degree.-graduated 
disc (3) a cylindrical flange of which is fitted within the bore of the 
magnetic base (1). This makes the 360.degree.-graduated disc (3) be 
aligned with the magnetic base (1) and be able to rotate about the axis of 
magnetic base within the range of 0.degree. to 360.degree.. An angle 
measuring slider (4) on the magnetic base indicates the rotating angle of 
360.degree.-graduated disc (3), on which there are two holes symmetrical 
to the axis of the disc and being aligned with the circle groove for 
passing through the fixing bolts. When the bolts (50) are tightened, the 
360.degree.-graduated disc is fixed to the magnetic base. On the 
360.degree.-graduated disc (3), a supporting bush (5) and a 
180.degree.-graduated bow-shaped disc (10) are mounted. Their axis are 
aligned with each other. 
The hinge unit includes a hinge shaft (6) which is rotatably mounted in the 
supporting bush (5). A moving bush (7) is mounted on the top end of the 
hinge shaft (6) with its end surface abuts against the end surface of the 
supporting bush (5). A hole is drilled through the moving bush(7) and the 
hinge shaft (6) with its axis perpendicular to and intersecting with the 
axis of the hinge shaft (6) and, at the same time, being aligned with the 
axis of 360.degree.-graduated disc (3). This drilled hole is used for 
installing the longitudinal rod (9). The other end of the hinge shaft is 
threaded. 
The locking unit includes a locking nut (8) on the threaded part of the 
hinge shaft (6). When screwing up the locking nut (8), the hinge shaft (6) 
carrying the longitudinal rod (9) and the moving bush (7) moves toward the 
supporting bush (5) and stop at the limitation of the supporting bush (5), 
which is fixed on the 360.degree.-graduated disc. The longitudinal rod (9) 
is thus locked. Unscrewing locking nut (8) allows the longitudinal rod (9) 
to rotate around the intersection point between the axis of the hinge 
shaft (6) and the magnetic base (1) in a plane perpendicular to the lower 
surface of the magnetic base (1) within the range of 0.degree.-180.degree. 
a fixing bush (11) with an angle measuring slider is fixed on the 
longitudinal rod (9). The rotation of the angle measuring slider along the 
outer circumference of the bow-shaped 180.degree.- graduated disc (10) 
indicates the rotating angle. 
With reference to FIG. 1 and FIG. 3. The longitudinal rod (9) and the 
transverse rod (13) both are made of pipes with thin walls and the same 
diameter. Each of them has a long slot with the width of 2.5 mm and 
graduations showing the axial length. 
The longitudinal rod disc (12) comprises a disc (12a), a square bush (12b) 
and a threaded shaft (12c). The axial length of the square bush (12b) is 
approximately the same as the diameter of the disc (12a). One face of the 
square is fixed to the surface of the disc. The threaded shaft (12c) with 
a circle groove protrudes out of the center of the disc (12a). In the 
center of the square bush (12b), there is a bore whose inner diameter is 
fitted with the outer diameter of the longitudinal rod. The axis of the 
bore is perpendicular to the axis of the disc. On one side of the square 
bush (12b), there is a slot to accomodate the length measuring slider 
which, together with the graduations on the longitudinal rod, shows the 
axial position. On the other side of the square bush (12b), there are two 
holes of M6 for fixing longitudingal rod (9) in the hole of the square 
bush. On the bottom side of the square bush there are two holes of M4, see 
FIG. 3(A) Screwing in fixing bolt (51) in the hole of M4, the unthreaded 
part of bolt (51) extends into the long slot of the longitudinal rod (9), 
thus allows the longitudinal rod disc (12) to move up and down axially 
along the longitudinal rod (9). Unscrewing the bolt (51) in the hole of M4 
enables longitudinal rod disc (12) to rotate about as well as move along 
the longitudinal rod (9). On one end of the square bush (12) are mounted a 
fine adjusting nut (15) and a fixing bush (16). On the other end is 
mounted an angle measuring slider (18). 
The transverse rod disc (14) comprises a 90.degree.-graduated disc (14a), 
two connecting plates (14b) protruding out on both sides of the disc with 
the distance between the two plates (14b) being at least larger than the 
diameter of the longitudinal rod disc (12), and two sleeves (14c) 
laterally protruding out of the connecting plates (14b). The two sleeves 
(14c) have coaxial inner bores which are perpendicular to and intersecting 
with the axis of the 90.degree.-graduated disc (14a). Each of the sleeves 
has a threaded hole for mounting the transverse rod (13) with the same 
diameter but different lengths in terms of the necessity of scribing 
different contours. The transverse rod disc (14) is fixed to the 
transverse rod (13) when a fixing bolt (53) is screwed in. 
In the center of the 90.degree.-graduated disc (14a), there is a round 
flange with a hole in its center. The assemblage of the transverse rod 
disc (14) and longitudinal rod disc is shown in FIG. 3. When the round 
flange of the transverse rod disc (14) is fitted into the circle groove of 
the longitudinal rod disc (12), the threaded shaft (12c) protruding out of 
the longitudinal rod disc (12) is also inserted into the hole at the 
flange center of the transverse rod disc (14), thus ensuring the alignment 
for the axis of the longitudinal rod disc (12) and the transverse rod disc 
(14), allowing the transverse rod disc (14) to rotate around the 
longitudinal rod disc (12), and ensuring the axis of the transverse rod 
and longitudinal rod to intersect in the same plane. The transverse rod 
disc (14) is connectcd with the longitudinal rod disc (12) by the nut (17) 
and two blots (52). On the disc (12a) of the longitudinal rod disc (12), 
there are two threaded holes, and accordingly there are two circle grooves 
to accommodate the fixing bolts (52) symmetrically placed on the 
90.degree.-graduated disc (14a) of the transverse rod disc (14). 
Unscrewing the nut (17) and the two fixing bolts (52) enables the 
transverse rod (13) to change the intersecting angle with longitudinal rod 
(9) within the range of 0.degree. to 90.degree.. The angular graduation of 
the 90.degree.-graduated disc (14a) corresponding to the reference line of 
the angle measuring slider determines the angular relationship between the 
longitudinal rod (9) and the transverse rod (13). 
FIG. 4 shows the structure of the guide sleeve units which is similar to 
that of square bush (12b) of longitudinal rod disc (12). The guide sleeve 
(19) comprises a round pipe (19a) and a connecting plate (19b) protruding 
out radially of the round pipe. The inner hole of the round pipe (19a) 
accommodates the longitudinal rod (9) and two thin metal rings can be 
placed in the two ends of the inner hole to protect the longitudinal rod 
(9) from wear. On the lateral wall of the round pipe (19a), there is a 
milled plane tangential to the inner diameter of the round pipe (19a), on 
which is mounted a length measuring slider (20). After being mounted, the 
graduations on the slider mating with the graduations on the longitudinal 
rod (9) indicate the relative displacement of the guide sleeve (19) to the 
longitudinal rod (9). The guide sleeve (19) may move axially along 
longitudinal rod (9) after the longitudinal rod (9) being installed into 
the guide sleeve (19), two bolts (55) are screwed into hole of M4, and the 
unthreaded part of the bolt being extended into the long slot of 
longitudinal rod (9). Unscrewing the bolts of M4 enables the guide sleeve 
(19) to rotate about the axis of the longitudinal rod (9). Screwing up the 
fixing bolt (54) of M6 fixes the guide sleeve (19) to the longitudinal rod 
(19). A fine adjusting nut (21) and a fixing bush (22) can be mounted on 
the end of guide sleeve (19), see FIG. 1. On the round part of the guide 
sleeve (19) is welded the connecting plate (19b), one face of which is 
aligned with the axis of the round part of the guide sleeve (19a). A 
drilled hole on the connecting plate (19b) is used to accommodate an inner 
hexagon-headed bolt. 
A similarly structured guide sleeve is also mounted on the transverse rod 
(13). 
The guide sleeve units and scribing units are mounted both on the 
transverse rod (13) and on longitudinal rod (9). The scribing unit 
comprises a scribing arm connecting bush (23), a scribing arm (24), a 
scribing pointer connecting bush (25) and a scribing pointer (26). The 
scribing arm connecting bush is hinged to the guide sleeve (19) by an 
inner henxagon-headed bolt (55), see FIG. 1. One end of the scribing arm 
(24) is fixed in the scribing arm connecting bush (23) by a fixing bolt 
(56), another end is fixed in the scribing pointer connecting bush (25) by 
fixing bolt (57). The scribing pointer is fixed on the lower end of the 
scribing arm by another inner hexagon-headed bolt (58). 
Referring now to FIG. 5, one end of the scribing arm connecting bush (23) 
forms a sleeve, the inner diameter of which is fitted with the outer 
diameter of the scribing arm (24), while another end forms a plate 
protruding out axially. One face of the plate is aligned with the axis of 
the sleeve. A threaded hole on the plate is used to fix the scribing arm 
(24) into the sleeve by a fixing bolt (56). The plane surface of the plate 
of the scribing arm connecting bush (23) aligned with the axis of the 
sleeve is in contact with the plane surface of the connecting plate (19b) 
of guide sleeve (19) aligned with the axis of its round pipe (19a). To fix 
the angle between the scribing arm (24) and the longitudinal rod (9) (or 
transverse rod (13)), the bolt hole of the guide sleeve (19) is aligned 
with the threaded hole on the connecting bush (23), the inner henxagon- 
headed bolt (55) being inserted and tightened. Unscrewing the inner 
hexagon-headed bolt (55) enables the scribing arm (24) to rotate about the 
hinge shaft. Since the axis of the scribing arm (24) and the longitudinal 
rod (9) (or transverse rod (13)) are in the same plane, the angle between 
the scribing arm (24) and the longitudinal rod (9) (or transverse rod 
(13)) can be changed. 
The structure of scribing pointer connecting bush (25) is the same as the 
structure of scribing arm connecting bush (23). To fix the scribing 
pointer (26) on the lower end of the scribing arm (24), this end is 
inserted into the hole of the sleeve of scribing pointer connecting bush 
(25), the fixing bolt (57) of the scribing arm is screwed up, and the 
inner hexagon-headed bolt (58) of the scribing point is tightened after 
the slot of scribing pointer (26) is aligned with the threaded hole on the 
plate of scribing point connecting bush (25). Unscrewing the inner hexagon 
bolt (58) of scribing point enables the distance between scribing point 
and the axis of fixing bolt (58) to be adjusted and enables scribing 
pointer (26) to rotate about the hinge shaft so as to adjust the angle 
between scribing point (26) and the workpiece. 
Since the scribing units are connected to the longitudinal rod (9) and 
transverse rod (13) respectively by the guide sleeves (19), the scribing 
units can move axially along as well as rotate about the longitudinal rod 
(9) and transverse rod (13), thus ensuring that the scribing point always 
contacts the surface of the workpiece. 
The guide sleeve (19) and scribing units mentioned above apply to both 
longitudinal rod (9) and transverse rod (13). This ensures 
interchangeability and universality of the commonent parts, and cost 
reduction as well. 
When scribing on large size workpieces or workpieces being far apart from 
the ground, The three strut bars (27) as shown in FIG. 6 may be mounted on 
the magnetic base (1). The threaded ends of the strut bars (27) are 
screwed into the threaded holes equally spaced along the circumference of 
the magnetic base (1), the other end contacts the internal wall of the 
workpiece. The lengths of the strut bars (27) are to be adjusted as to 
align the axis of the magnetic base (1) with the axis of the workpiece. 
The intersection contour is then scribed. 
A cross-shaped bush (28) as shown in FIG. 7 may be mounted on the 
transverse rod (13). The transverse sleeve part of the cross-shaped bush 
(28) is put on the transverse rod (13). The axis of the transverse sleeve 
part of the cross-shaped bush (28) is then aligned with the axis of the 
transverse rod (13), and the axis of the longitudinal sleeve of the 
cross-shaped bush (28) accordingly is parallel to the axis of longitudinal 
rod (9). There is a threaded hole on the transverse sleeve of the 
cross-shaped bush. Screwing in a fixing bolt through the hole fixes the 
cross-shaped bush (28) to the transverse rod (13), while unscrewing the 
fixing bolt enables cross-shaped bush (28) to slide freely along and/or 
rotate freely about transverse rod (13). The longitudinal sleeve of 
cross-shaped bush (28) may be used to mount scribing arm (24), scribing 
pointer connecting bush (25) and scribing pointer (26). The mounting 
procedure is the same as mentioned above. The height of the scriber is 
then increased when the cross-shaped bush (28) is mounted, so that it can 
be used in the case when the workpiece is far apart from the ground. 
Index accuracy, large range of height adjustment, interchangeability of 
component parts and regulation flexibility feature the multifunctional 
contour scriber of the present invention. It can be used to scribe any 
contour curves directly and precisely on a plane, a convex or concave 
surface of a box, a pump case and a shell, etc. for complicated large size 
workpieces. No indexer, height gauge, or other auxillary scribing tool is 
needed. 
Operation 
Example 1 Scribing the Intersection Contour of the Main Pipe 
Referring to FIG. 8, the magnetic (1) is put on the main pipe (30). The 
V-shaped groove on the lower plane of magnetic base (1) makes the axis of 
longitudinal rod (9) automatically intersect the axis of main pipe (30). 
Magnet switches (2) are turned on as to make the magnetic base (1) be 
attracted securely on the surface of the main pipe (30). The longitudinal 
rod (9) is turned about hinge shaft (6) until the angle measuring slider 
(11) on the longitudinal rod indicates at the bow-shaped 
180.degree.-graduated disc (10) the correct angle .alpha. already known in 
terms of the intersecting angle between the main and branch pipes. Locking 
nut (8) is tightened to lock the longitudinal rod (9). The transverse rod 
(13) is moved along longitudinal rod (9) and is at a position lower than 
the guide sleeve (19) on longitudinal rod (9). The scribing pointer (26) 
mounted on the end of the scribing arm (24) of the longitudinal rod (9) is 
then used to measure and obtain the radius r of the branch pipe along 
transverse rod (13), thus the radius r is the vertical distance between 
the scribing point and the axis of longitudinal rod. The inner 
hexagon-headed bolt (55) on guide sleeve (19) is tightened in order to fix 
the angle between the scribing arm (24) and the longitudinal rod. The 
transverse rod (13) is then removed off the transverse rod disc (14). If 
the radius of branch pipe is small, the cross-shaped bush may replace the 
transverse rod disc(14). The longitudinal sleeve of the cross-shaped bush 
is put on longitudinal rod (9), and transverse rod (13) is then put in the 
transverse sleeve of the cross-shaped bush. After the radius of the branch 
pipe is measured and obtained, the transverse rod may be removed off the 
cross-shaped bush. Then, the guide sleeve (19) is allowed to move along 
and rotate about the longitudinal rod (9) so as to maintain the contact of 
scribing pointer (26) with the surface of the workpiece. A closed curve 
scribed when the scribing unit rotates around the longitudinal rod (9) 
which represents the pipe joint intersection contour on the main pipe. 
Example 2 Scribing the Intersection Contour of the Branch Pipe 
Referring to FIG. 9, the magnetic base (1) is put on the ground and the 
intersection point of the longitudinal rod (9) and transverse rod (13) is 
adjusted to be at the central axis of the branch pipe (31), set the 
longitudinal rod (9) at right angles with the transverse rod (13), then 
set the scribing pointer (26) at the end of the scribing arm (24) on the 
longitudinal rod (9) to measure and obtain the radius R of the main pipe 
along the longitudinal rod (9) thus the radius R is the vertical distance 
between the scribing point and the axis of the transverse rod (13). When 
the zero mark of the angle measuring slider (4) on the magnet base (1) 
coincides with the zero mark on the 360.degree.-granduate disc (3) unscrew 
the locking nut (8) of the locking unit and rotate the longitudinal rod 
(9) to make the right-hand and left-hand transverse rod (13) both contact 
with the branch pipe's external diameter. Then, rotate the 
360.degree.-graduate disc (3) to the left until the meausring slider or 
the magnetic base (1) indicates the known angle .alpha., screwing up the 
bolts (50) in order to fix the angle between the left-hand transverse rod 
and the axis of the branch pipe (31) , the left-hand transverse rod (13) 
remain in contact with the branch pipe (31) but the right-hand transverse 
rod (13) disengage from the branch pipe (31). The guide sleeve (19) is 
then allow to move along as well as rotate about the left-hand transverse 
rod (13) in order that the scribing pointer (26) remains in contact with 
the surface of workpiece. A curve scribed when the scribing point rotates 
around the left hand transverse rod which represents half of the pipe 
joint intersection contour on the branch pipe (31). Another half of the 
pipe joint contour can be scribed in the same way by the guide sleeve unit 
and scribing unit on the right-hand transverse rod or by turning the 
left-hand transverse rod to the right. 
It is noded that instead of using the invention as a pipe joint 
intersection contour scriber it could be used to scribe a circle, an 
ellipsord a hyperbola, a parabola etc. 
As changes may be made in various parts of the invention without departing 
from the spirit and scope of the invention, the invention is not to be 
limited to the exact parts described which have been given by wayof 
illustration only.