2015 Kiln Remodel
As of spring 2015, we are proud to announce that we are in the process of remodeling our dry kilns! Through the use of improved technology, innovative components and good, old-fashioned hard work we have custom-designed and are beginning to construct our new state of the art dry kilns.
Included below are photos of our progress; from the initial stages of maintenance and demolition to the our current stage of development. More photos will be added as progress continues.
   
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Initial Stripping of the Kilns & Re-Insulation |
Ceiling Rehabilitation & Replacement of Exterior Walls |
 
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Installation of New Coils, Boiler, and Towing Winch |
Finished Kilns & First Load |
 
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Completed Kiln Doors & Controls |
How to Buy Wood
How to Buy Wood
The first consideration is the way the wood is cut. When the wide face of the board is parallel to the annual growth rings the cut is called flat sawn. When the rings are perpendicular to the wide face, it is called quarter sawn. When the board is somewhere in between, it is called mix grain or bastard cut. The cut is important because the natural tendency of wood is for the annual growth rings to flatten out plus the shrinkage of the wood is greater across the grain (flat sawn) than through the grain(quarter sawn). For these reasons, builders should normally choose quarter sawn wood for greater stability.
Along with the type of cut the builder should look carefully for straight grain on both the face and the edge of the wood. This is easier on quartered pieces because the straight lines in the grain are obvious but with practice it can be done with flat grain.
After determining the cut and straightness of the board, look carefully at the quartered face of the piece or at the end gain. Are the lines or growth rings more or less uniform or are there big differences in the size of the rings? More uniform is more desirable.
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Next, examine the piece for defects that would compromise the strength of the piece or its attractiveness. Obviously, cracks, checks, knots or other structural defects are not acceptable but fungus or mineral stains or spots are only an aesthetic consideration. Tension wood or fuzzy grain usually caused by a leaning tree is an unacceptable flaw.
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I will always remember my instructor at the hardwood inspector trade school, Mr. Otis Goolsby, telling the class: “Boys, when you are grading wood, don’t look for flaws, look for clear wood that will make the grade”. This advice, given to me nearly 50 years ago is timeless and applies to much more than grading wood.
Jerry Hibdon builds his first guitar.
Last Updated: March 19, 2013.
Jerry has recently enrolled in a class to build a guitar at Midwest Guitar. He is being taught by Master Luthier, Michael Boggeman. We will be updating his status and pictures as the guitar comes along. Due to the large number of photos, we have moved this story HERE!
Forest Management and Harvesting Methods in Mexico
Most of the wood we acquire in Mexico comes from the Mexican states of Quintana Roo and Campeche. Forestry in these states is based on the ejido system set up by the Mexican government to accommodate the Maya communities that have been there thousands of years. The Maya are very community oriented and this system (which might be considered socialist elsewhere) satisfies that desire.
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Basically, the communities (of which there are hundreds) are granted a concession of the land, usually around 150,000 acres, which only they can utilize. The Maya workers locate the trees in the forest so that government foresters can mark them for cutting if they qualify. The trees are cut, dragged to log landings by 4-wheel-drive skidders. The logs are transported to the sawmill by truck where they are selected by ourselves and other buyers for veneer, instrument wood and lumber. Quotas are established by the government foresters based on forest surveys. As part of the system, the ejidos are required to maintain tree seedling nurseries and to replant logged areas each season. For this season, the ejido of Tres Garantias will plant 100,000 seedlings of Honduras Mahogany.
Kiln Information & Process
- Stage 1: Initial conditioning.
- We establish the initial temperature, the initial depression (a low number = high humidity), and the duration of stage one.
- Above, the initial temperature is set to 100 degrees F., the initial depression to 6 degrees, and the duration of phase one is one day.
- The controller will maintain the initial values for the specified period of time before advancing to stage two.
- Stage 2: Raise temperature and depression slowly over time.
- During phase two, the depression is increased slowly -- the humidity is reduced slowly. Slope 1 (set to 0.7, above) is the desired increase in depression per day. The controller continuously recalculates setpoints, so the depression will be changed very slowly.
- The temperature setpoint is also continuously recalculated, and is a function of the initial and terminal temperature, the depression @ terminal temperature, and the current depression. In the example above, we are telling the controller that we want it to hold a temperature of 100 degrees when the depression is 6 degrees, 135 degrees when the depression is 25 degrees, and ramp the temperature proportionally between those two points.
- Phase two continues until the depression is "stage 3 start' -- 20 degrees in the above example.
- Stage 3: Raise temperature and depression a little more aggressively.
- The controller logic in stage three is identical to that in stage two except that the wood is closer to dry and so it is less likely to be damaged. We can now increase the rate at which we increase the depression -- slope 2 is 1.2 degrees per day above.
- Stage three terminates when the depression reaches the terminal value (32 degrees above).
- Stage 4: Final conditioning.
- In stage four the controller will maintain the terminal temperature but will leave the kiln vents closed causing an increase in humidity. The wood's core is, unavoidably, somewhat wetter than the shell -- the rise in humidity in the kiln helps to balance the humidity throughout the wood.
Most hardwood kilns are operated on stepped schedules i.e. run a temperature/depression until your sample is at some given moisture content. Then, increase temperature, decrease humidity, and run until your sample is at another given value. More modern control systems will control the temperature and depression based on sensors in the kiln which continuously detect the moisture content of samples or the weight of samples or the weight of the entire load. The weight decreases as the wood loses moisture.
We mainly dry mixed loads of dense, difficult to dry, and expensive exotics. They are of diverse species, thickness, specific gravities, and in various stages from green to well air-dried. Attempting to run from kiln samples, is unrealistic. Our schedules are established on the basis of our experience, and we err on the side of too slow. An extra few days costs less than damaging an entire kiln charge. The simulator allows us to play with the various values and determine what the schedule will look like and how long it will take to complete.
The kiln is loaded, the decided upon values are keyed into the controller, and we stand back and watch. The controller operates a gas-fired boiler to maintain the temperature, actuates a powered vent to decrease the humidity, and a solenoid valve on a water spray line allows it to increase the humidity. Much of our wood, by the way, gives up water so slowly that we frequently need to add moisture to the kiln. We take occasional samples to determine the moisture content of the wood and can adjust the schedule, if necessary.
