Panel joint

A self-clamping spline and mortice joint is utilized at each of the corners of a rail and stile door. Mortices in each of the rail and stiles extend to the top or bottom edges of the door and a spline is received in the mortices and is exposed along the top and bottom edges of the door. Screws extend through the spline in opposite directions and into the rail and stile functioning to pull the rail and stile together around the spline. The self-clamping joint requires no external clamping. The self-clamping joint may be used on a plank-type door where the spline is L-shaped with one leg extending into the mortices and the second leg extending horizontally over the door end edges to cover the ends of the vertical grooves in the faces of the door. Weatherstripping on the door frame engages the horizontal leg of the spline and prevents transmission of air and moisture from the outside to the inside through the grooves.

BACKGROUND OF THE INVENTION 
A butt joint used in working with wood materials may include splines or 
dowels. The splines and the dowels are all hidden when the joint is fully 
assembled. It is common to use glue between the splines, dowels and wood 
pieces being interconnected and then clamps are applied to hold them in 
compression while the glue dries. 
This procedure is time consuming and expensive and requires special 
equipment. 
Another problem with the typical hidden joint is that the dowel or the 
spline is sized precisely to the mortice into which it fits in both of the 
pieces being connected. If there is the slightest disalignment of the 
pieces the splines and dowels will not line up making the joint difficult, 
if not impossible. 
A further problem encountered with plank type doors is that the vertical 
grooving makes it difficult, if not impossible, to give a tight weather 
seal along the top inside edge of the door due to the grooves remaining 
open and allowing air and moisture to move from the outside to the inside. 
The weatherstripping cannot seal tightly against the grooved surface. 
SUMMARY OF THE INVENTION 
A self-clamping butt joint is provided utilizing a spline to interconnect 
the wood pieces. A wide variety of wood panel-like wood pieces may be 
interconnected and a good application for this joint is in entrance doors. 
A mortice is provided in each of the panel pieces which opens to a side 
edge which is coplanar with the side edge of the other panel piece. A 
spline is inserted into the two aligned mortices and has a size such that 
the outer edge of the spline is coplaner with the adjacent edges of the 
panels. Screws are then utilized by extending them through the spline 
angularly outwardly in opposite directions and into the adjacent panel. 
Tightening of the screws will impart a longitudinal pulling force on the 
panels thereby drawing them together and towards the spline. Glue that has 
been applied to the spline and the mortices will now dry without any 
further clamping action being required through the use of external clamps. 
The assembled panel or door is ready to use immediately. 
A common access opening to the screw holes can be provided in the spline 
and later plugged to conceal the presence of the screws and give a smooth 
exterior finish appearance. 
In the case of plank-type doors where a plurality of vertical grooves 
extend the length of the door all the way to the top edge on the inside 
surface, a spline having a horizontally extending leg can be used which 
will fit into a notch running the width of the door along the inside upper 
edge opposite weatherstripping on the door frame. The horizontal leg of 
the spline will cover the ends of the grooves and be engaged by the 
weatherstripping thereby sealing the interior from the exterior of the 
building and preventing passage of moisture and cold air through the 
grooves. 
There are occasions where splines are required inwardly of the ends of the 
panels such as on rail and stile doors. 
Splines cannot be exposed along one side edge to exterior and screws cannot 
be used. To overcome slight disalignment problems the spline can be sized 
to provide a tight fit with one of the panels and a loose fit with the 
other panel such that there will be room to compensate for any 
misalignment that may be present. If misalignment in only one plane is a 
problem then the other two surfaces that do not represent an alignment 
problem can be sized for a tight fit but still allowing for adjustment of 
the spline as required to make the connection. Glue is utilized to 
complete the bond and the screws in the corner self-clamping joints will 
function to clamp the joints inwardly of the top and bottom edges of the 
door. 
Thus it is seen that a universally adapted self-clamping butt joint has 
been provided which is simple to use and less expensive than conventional 
joints as well as permitting a very efficient assembly method requiring no 
special equipment, not even clamps.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The self-clamping spline joint of this invention is referred to generally 
by the reference numeral 10 in FIG. 3 and is seen being used on a rail and 
stile door 12. 
The joint 10 interconnects a rail 14 and a stile 16 and includes, as seen 
in FIG. 10, mortices 18 and 20, respectively, which open to the top edge 
22. A spline 24 is positioned in the aligned mortices 18 and 20 and has a 
top edge 26 which is coplanar with the door top edge 22, as seen in FIG. 
7. 
Oppositely extending screw holes 28 and 30 are provided in the spline 24 
and receive screws 32 which extend into the adjacent rail and stile panel 
members 14 and 16. It is seen that the screws by extending at an angle 
develop a horizontal pulling force which draws the rail and stile panel 
members together around the spline thereby functioning as an exterior type 
clamp. Glue is utilized around the spline and in the mortices and will be 
allowed to dry without any further clamping being applied. Excess glue 
will flow into the glue grooves 38. 
It is seen that the screw access holes 28 and 30 intersect at a common 
access opening 40 which allows for a minimal amount of defacing on the 
exposed outer edge 26 of the spline 24. A plug 41 may be used to close the 
common access opening 40 and give the outer edge 26 a smooth finish 
appearance. 
In FIG. 3 it is seen that each of the four corners of the door 12 include 
the joint 10. 
Between the top and bottom ends of the door 12 in FIG. 3 it is seen that 
there are four additional joints 42 which are shown in detail in FIG. 11. 
The joints 42 include a spline 44 which is fitted to tightly fit in a 
mortice 46 in the rail 48 while the opposite end of the spline 44 is 
loosely received in the oversized mortice 50 in the stile 16. Since 
disalignment problems may occur only in a vertical plane there need be 
only additional space above and below the spline to compensate for any 
disalignment that may be present. Thus the thickness of the spline may 
correspond to the width of the opening and provide a tight fit. Glue 
grooves 54 are provided in the spline 44 for any excess glue. The 
self-clamping joints 10 at each corner of the door will effectively clamp 
the joints 42 without the assistance of external clamps. 
The self-clamping joint of this invention is seen in FIG. 12 being utilized 
on a plank-type door 56 comprising six plank or panel members 58 
interconnected in a rib and groove fashion, as seem in FIG. 14. This is a 
true plank-type door. Vertical grooves 60 are formed at the interface of 
the planks 58 and extend the full length of the door from the bottom edge 
to the top edge. As seen in FIG. 16, a notch 62 is formed along the inside 
top edge of the door and extends to the mortice. A modified spline 24A is 
utilized which has a vertically disposed leg 64 and a horizontally 
extending leg 66 which fills the notch 62 and provides a top surface 68 
coplanar with the top surface of the door. 
A door frame 70 includes weatherstripping 72 which engages the outer 
surface of the spline leg 66. It is seen that the horizontal leg 66 covers 
the upper ends of the groove 60 and thus prevents any cold air or moisture 
from entering the house from the outside through the grooves 60. As shown 
the spline is L-shaped but could be T-shaped and extend across the entire 
top end edge of the door 56. 
The prior art doors are seen in FIGS. 5, 6, 13 and 15. The rail and stile 
door A of FIGS. 5 and 6 utilizes conventional dowels B to connect the 
rails C to the stiles D. The mortices in which they fit are sized to 
provide a tight fit. The dowels are totally hidden and cannot utilize any 
supplemental screw type fastener to provide the selfclamping action 
provided in applicant's joint 10. The plank type door E, shown in FIG. 13, 
is of an imitation design as it merely includes routed grooves F to give 
the appearance of individual planks making up the door. This is not a true 
plank type door and thus suffers from an artificial appearance. It is also 
noted that a solid one-piece plank door is subject to warping and other 
weather-related problems. 
It is also to be appreciated that the side lights 80 in FIG. 1 and 82 in 
FIG. 2 are constructed by utilizing the joints 10 at the corners and the 
floating spline joint 42 inbetween the top and bottom ends to interconnect 
the stiles and rails.