Custom Cabinet Doors 101 – step-by-step Kitchen cabinet door replacement
If you are thinking about replacing your cabinet doors here are a few tips than can make the process go more smoothly and save money too.
The first decision is whether you intend to re-use your existing hinges or upgrade to newer style canceled hinges. Continue reading
12 FEBRUARY 2014 BY JIM HILL
This research is intended to present an overview of Cabinet Doors in general, then drill more deeply into the specific design features that make possible the thousands of different cabinet door styles. Continue reading
One approach is to optimize manufacturing efficiency by limiting the sizes manufactured and maximizing employee productivity. This approach is referred to as “Modular Cabinets”.
The Modular Cabinet manufacturer usually makes the cabinet boxes with widths starting at six-inches and increasing in two-inch steps. This maximizes employee productivity by manufacturing one cabinet box size one shift and another size the next shift.
While working on an assembly line making 10,000 of the same thing might not be the most challenging or rewarding of jobs, productivity certainly increases and labor costs are reduced.
The modular manufacturer simply adjusts his schedule to maintain a readily available inventory of cabinet boxes in his warehouse.
Modular Cabinet Manufacturers usually offer a selection of cabinet doors to give the finished Modular Cabinet a more “Custom” look.
Entry-level home builders typically install Modular Cabinets. These cabinets are also stocked and sold by all the Big Box Stores across the country.
For the past several years, Modular Cabinet manufacturing has been moving to Asia, with China becoming the largest manufacturer. American manufacturers have been finding it impossible to compete with the lower labor and regulatory costs found on the far east.
The second approach to manufacturing cabinets is referred to as “Custom Cabinet Manufacturing”.
Unlike Modular Cabinets coming in 2-inch increments, Custom Cabinets are manufactured to the actual size needed.
Also unlike Modular Cabinets, Custom Cabinets are made in the United States by thousands of Custom Cabinet Shops. These shops typically have between ten and fifty employees who design and build each cabinet to the exact size requested in the design plans. If the architect requires cabinets in 1/16″ increments, that’s what the Custom Cabinet Maker builds. Cabinet Makers in Custom Cabinet Shops tend to be highly skilled, and well paid, professionals with years of experience mastering their profession. These Cabinet Makers are not tied to an individual workbench, but tend to move between many skilled positions within the manufacturing process. The Custom Cabinet Shop uses a creative approach which utilizes the skills and experience if the Cabinet Maker, as opposed to an assembly line which stresses repetitive action to compensate for the lack of motivation and inexperience of the minimum-wage workforce.
Most high-end Home Builders and Furniture manufacturers utilize Custom Cabinet Makers because of the large difference in overall quality of the cabinets.
The quality differences are usually visible and include differences in workmanship, wood grain and color matching, sanding and finish quality, overall appearance, and reliability.
Custom Cabinet Makers purchase woods harvested in the United States, and almost 100% of American woods are grown and harvested using sustainable processes.
This is not usually the case with woods harvested in Asia or South America.
Another major difference between Modular and Custom Cabinets is with the Cabinet Doors installed on the cabinets.
Modular Cabinets from Asia have doors made in Asia. These doors should be expected to show the same levels of quality as the cabinets.
Modular Cabinet Door quality levels are generally lower, sanding and finishing are less stringent, an unskilled or under-aged workforce is commonly recruited, and no importance is given to the sustainability of the woods used or the harvesting methods.
American Custom Cabinet Shops, on the other hand, typically purchase cabinet doors from a few large cabinet door manufacturers, or the hundreds of smaller manufacturers.
These dedicated Custom Cabinet Door Manufacturers will offer from dozens to thousands of cabinet door styles built in every sustainable wood type that grows in the United States or Canada.
Major Cabinet Door Manufacturers are producing thousands of doors per shift using skilled labor and most use computerized machinery to guarantee accuracies modular manufacturers simply cannot match. Modern American door manufacturers will measure door size tolerances with accuracies within 15-thousandths of an inch. Door thickness will be uniform across the door within 5-thousandths of an inch, and sanding quality is considered by cabinet makers to be “stain ready”.
In summary, the differences between Custom and Modular Cabinets are visible in appearance, obvious in quality, and the difference in expected lifetime is triple, with Custom Cabinets often being kept in the home and simply refinished after generations of useful service.
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There are three key steps in manufacturing 5-piece Cabinet Doors that will determine the sizing accuracy of the finished door. If each of these steps is held within a tight tolerance, the finished product will be accurate to within the desired 1/64 inch, or about 15-thousandths.
The first of the three critical operations is moulder accuracy (sometimes americanized as “molder”).
The second critical operation is stile & rail length cutting accuracy and the third is consistency in stock removal during the operation of machining the outside edge.
Our standard is to hold each of the three critical operations to a tolerance of 5-thousandths of an inch. This produces a finished cabinet door with a worst-case sizing tolerance of 15-thousandths, of 1/64-inch.
The stile stock moulding operation starts the process of insuring sizing accuracy and, without close attention to this step, consistency in sizing the finished door is almost impossible.
When cabinet door stile stock is moulded, the width of this stock is the most critical factor in accurately sizing a 5-piece cabinet door. If the moulded width of the stile stock is held within a tolerance of 5-thousandths of an inch, the subsequent operations that affect sizing can be standardized.
At CabinetDoors.Com length cutting of stiles and rails is performed on CNC machinery so achieving our 5-thousandths tolerance for this operation is actually easy. Cutting accuracies of better than 5-thousandths are normal.
The outside edging operation is more difficult to hold because the edging cutter’s diameter changes from sharpening, so slight variations do occur. Our average edging tolerance does achieve the 5-thousandths inch goal, but the standard deviation shows a range from 2-thousandths to 9-thousandths inches.
Because the moulder accuracy is key to finished door sizing, let’s look at some examples of inaccurate moulder adjustment and the effects these errors will have on the finished size of a 5-piece cabinet door.
First let’s assume the moulder is set up correctly and the stile stock, which is targeted at 2 1/4–inch width, is actually oversized by 5-thousandths (2.255 inches). Assuming the rail length cutting and the edging operations are both perfect, the finished door will be 10-thousandths oversized. Most cabinet makers will be measuring the cabinet doors with a tape-measure, so the 10-thousandths error on this door will be considered perfect and within the acceptable range of even the most demanding cabinet professional.
Now let’s assume the moulding operation is not within a width tolerance of 5-thousandths and is actually over by 15-thousandths of an inch. That will make the stile width 2.265 inches, with the additional 15-thousandths doubled to 30-thousandths by the same error in each of the two stiles. This door will be oversized by 1/32 inch even if the other critical sizing operations are perfect.
This 1/32-inch error, while acceptable by the standards of the industry, is detectable with a tape measure.
The challenge to the cabinet door manufacturer is to size the door as accurately as possible by setting tight measurement quality tolerances on the operations that affect door sizing.
The variable beyond the control of the manufacturer is the normal swing in relative humidity and the effects humidity changes will have on the moisture content of the wood in the doors. All cabinet doors will react to changes in relative humidity by either absorbing, or giving-off moisture. Unfinished doors will react sooner to humidity changes, but even properly finished doors will eventually reach a balance between the relative humidity and the door’s internal moisture content. These moisture content variations will result in dimensional changes to the stiles and rails of the cabinet door.
These dimensional changes can be huge and are usually far greater than the total manufacturing sizing tolerances.
The definitive study on humidity and its effects on wood moisture content, and the changes it causes to wood dimensions was conducted by the US Forest Service, a department within the US Department of Agriculture.
The Forest Service, published the Wood Handbook: Wood as an Engineering Material in 1999 (and 2010), which outlined the expected moisture-content caused dimensional changes in various woods. The 1999 study focused on wood flooring but applies to all wood products kept inside the house and subjected to normal fluctuations in relative humidity. The 2010 study is extensive and covers almost all commercially used woods.
The 500+ page 2010 study can be viewed or downloaded here (Chapters 4 & 13 deal with Moisture and expansion properties)… http://www.fpl.fs.fed.us/products/publications/several_pubs.php?grouping_id=100&header_id=p
I’ve tried to simplify the findings by focusing on plainsawn (Flat Sawn) Red Oak for this example. But, woods other than Red Oak and differing sawing-grain directions, like quarter-sawn, have different Coefficients for Dimensional Change. Because plainsawn woods are more popular and tend to have a greater dimensional reactions to moisture variations, I have used plainsawn in my example.
The bottom-line finding of the USDA research is that a 4% change in the moisture content of the 2 ¼-inch stile of a 5-piece Red Oak cabinet door will be expected to cause a dimensional change of 0.0332 inches, or about 1/32-inch, per stile. That means that a 4% change in moisture content is expected to expand, or shrink the width of a 5-piece Red Oak cabinet door by 1/16-inch, which dwarfs the 1/64-inch worst-case tolerance of the cabinet door as it finishes the manufacturing process.
This 1/16-inch moisture-caused change is 4-times the combined total tolerance of the critical steps in the making of a cabinet door, and certainly needs to be considered when designing cabinets. This is especially true when considering the spacing between butt-doors on cabinets. Without proper spacing, butt-doors may not close properly during high humidity periods.
These humidity-caused sizing swings may seem extreme, but keep in mind that these calculations reflect the humidity of the worst-case the country has to offer; the desert regions of the southwest. In the southwestern deserts relative humidity routinely changes from 5% in the dry month of June, to over 90% when the monsoon storms come in July. This wide humidity swing accounts for the 4%+ change in the moisture content of wood products in the southwest. Cabinet doors installed in other parts of the country will typically be expected to experience about half this dimensional change, or about 1/32-inch.
Design provisions to accommodate dimensional changes in the raised panels of cabinet doors are in place allowing the panels to float within the stiles and rails. The panels used in recessed panel doors are either Medium Density Fiberboard (MDF) or MDF core with wood veneers, which are dimensionally stable and react very little to humidity changes.
Looking at the once popular, and hopefully never to return to popularity, Slab Cabinet Door as an example , you can see the makings of a dimensional train-wreck. With the Slab Door we are not just dealing with the moisture-related dimensional properties of a 2 1/4-inch stile. We are now looking at the dimensional properties of a glued-up slab between 12 and 24 inches wide.
Using the same moisture-content calculations for plainsawn Red Oak from the Forest Service Study, we would expect to see a 12-inch wide slab door react to a 4% moisture content change with a width change of over 3/16-inch and a 24-inch slab changing width by over 5/16-inches.
Clearly width changes of these magnitudes are unacceptable and homeowners requesting slab doors need to be made fully aware of the dimensional instability of this cabinet door design.
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