Items of Interest

Logs to Guitars | Kiln Drying Methods

 

Tom Rein repairs an African Blackwood peice.

This article is very interesting and very informative.

It is in word format for now, the think is HERE!

Jerry Builds His First Guitar....

 

 

 

 

 

Jerry has recently enrolled in a class to build a guitar at Midwest Guitar. He is being taught by Master Luthier, Micheal Boggeman. We will be updating his status and pictures as the guitar comes along. Due to large number of photos we have moved this story HERE!

 

RED STRIPE LOG - Due to arrive early 2012
Click Here - To see new red stripe sets!

Here is a unique log that we recently purchased in Guatemala. The Mahogany log is 60" in diameter at the base and 43" at the top and was 26' long. The tree, due to it's approximate age of 125 years had begun to decay some years ago and was about 50% unuseable. However we were able to obtain about 500 back and side sets and a large number of neck blanks.

The unifrom red stripes clearly visible in the end grain make this log unique. In my 30 years experience buying Mahogany logs, this is the first figure of this type I have seen.

Forest Management and Harvesting Methods in Mexico

Most of the wood we acquire in Mexico comes from the Mexcican 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.

 

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.

 

 

 

Below is a view of our Windows program which allows us to visualize the effect of modifying the various parameters which control the dry kiln.

• 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 -- 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, etc. 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 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 blowing up wood. 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.

©2006 Hibdon Hardwood, Inc.