Bob met with Simpson Door Company general manager Jim Fielder in the yard outside the plant to begin his tour of the Mastermark® Door manufacturing process. The plant produces approximately 3000 stile and rail doors each day utilizing Western hemlock and Douglas fir from mills in California, Oregon, Washington, and Canada.
At the sorter the lumber is sorted by length, restacked and tallied. Between each layer in the stack thin pieces of wood or "stickers" are inserted to allow space for air flow when the lumber enters the dry kiln.
Defect-free lumber is carefully selected for use in the production of veneers. The slicing cants are first prepared with moisture and heat so that the cut will be smooth and clean. They are then sent through a slicer where a a 1/16" veneer is shaved off the bottom. The remainder of the cant circles around through a bath of hot water to be prepared for another cut.
The veneers are sent through a dryer where they are graded and separated. A moisture meter monitors the moisture content in each piece of veneer.
The dry kilns are used to dry all of the lumber to a target moisture content of 8-10% range. To keep the wood from checking, splitting, or warping and to increase its dimensional stability, it is allowed to dry for nine to fourteen days. Once cured, the lumber is moved into the cooling shed where it is allowed to equalize before being planed.
Many critical decisions have to be made on the cutline. This is where the wood is evaluated for its usefulness. Defects must be removed and the lumber must be cut to the needed lengths—all within the context ofmaximizing the yield from the lumber. Each piece is then graded and tallied. Selected pieces too short to use are sorted for use as finger-jointed core. Pieces not suited for use for use as core material are used as fuel for the dry kilns so that none of the resource is wasted.
The short pieces of wood recovered from the cutting process are fed through a finger jointer where they are profiled and glued together on both ends. The pieces are cut into specific, usable lengths and then graded and sorted for use as core stock. The finger-jointed core is better than solid wood because the offsetting grain patterns resist the tendency to warp or twist.
The multiple rip saws cut the wood into the widths needed for various door components. Depending on the size and grade of the lumber, it could be used as glass bead, decorative moulding, stile edge bands or fluted dowels.
To extend the width of the lumber for use as panels and rails, individual pieces of lumber are first machined to exact sizes. Then glue is applied to the edges and the pieces are pressed together and fed continuously into the edge gluer. The glue is cured by radio frequency (to expedite drying time), and an automatic saw cuts the glued lumber to the desired widths.
Once the core stock is trimmed smooth, glue is applied to the edges. Edge bands are bonded to the core material, with the glue then cured by radio frequency.
Once the edge bands have been applied, the stile core is ready to be veneered. At the laminator, stiles are glued in batches of 16 to 18. After glue is applied to the core, the veneers are carefully positioned and the stiles undergo heat and pressure to cure the glue bond. The ends and edges are trimmed, and the stiles are graded and tallied.
Before becoming Simpson Innerbond® panels, the panel blanks are resawn into thinner sections. The twin band saw method allows 1 3/4" thick stock to be sawn into three equal pieces which will form panel component parts.
The two panel blanks are then glued together with their grain patterns reversed to form one panel. This ensures that the panels will never split completely through. After gluing, the panels are put in a cold press for 30 minutes.
The panels are finish-sanded, graded and stacked on pallets for shipment to the warehouse.
Once all the different pieces have been dried, cut and glued, they are ready to be moved into the cutstock warehouse. From here, the various components are ready to be supplied for final machining and door assembly.
The computer numeric controlled stile boring machine drills the holes for the dowels which will hold the stiles and rails together. After boring, the stiles are profiled and then inspected.
Cutstock is machined into rails by first passing through a double end tenoner, which has the accuracy to control dimensions within one-thousandth of an inch. After the ends are profiled, the rails pass through a moulder for profiling the long edges, then on to a final inspection. Like the stiles the rails must also be drilled to accommodate the dowels. The three-in-one process first drills the rails, then injects glue into the holes, and finally inserts a dowel into each hole.
Stock rustlers pull the various component parts needed to build specific door designs. The door asemblers or "sappers" then take those pieces - the stiles, rails and panels - and loosely assemble the doors by hand. Only the stiles are glued. The other pieces are assembled without glue allowing them to expand and contract with the weather. From here the doors are passed on to the hydraulics to be squeezed together in the final assemby.
Doors that require glass are glazed prior to sanding. Great care is taken to align and seal each piece of glass and to ensure that the moulding around the glass fits properly. Doors are then sanded to a smooth finish by drum sanders and pre-fit to net height and width specifications.
Doors that have decorative glass and special moulding are brought to the raised moulding area. Here the decorative glass is installed and the raised moulding is carefully cut and fit to the door.
Every Simpson Mastermark door undergoes a final inspection by a skilled artisan. Any minor imperfections are repaired at this point. The finished doors are then ready to be packaged and sent out to customers.
|
Habitat for Humanity - 
Related Articles
Related Tips
Related Videos
