Print

Cutting Wood

Here I refer to the cutting of the logs.

Divides to the timber, an optimum possible compromise between high quality raw tone wood and the equally expensive purchased sloping wood residues must be done.
There ask yourself the following questions:

  • How do I zerteile a geometric cylinder in such pieces that I can use for my purpose?
  • For what instrument I need the wood? Am I building violins, cellos, double basses, guitars, lutes, etc? Each instrument requires certain standard dimensions and since I am not Tausensassa on all instruments of course, I have to focus on certain dimensions. Fallen radicals on, I need to know in what extent I can continue to divide, possibly may be somewhat smaller timber Yes resell?
  • Which machines, options can be used for further processing?

Theoretical geometry:

Tonewood for generating sound is optimally divided, if at the thinnest possible wood is present the highest stiffness. This one has when present in ceilings, floors and frames only standing annual rings. This is called vertical annual rings when the rings are parallel to the narrow outer surface (or at right angles to wide). The aim of Tonholzgewinnung it must be to get as many useful sections from a trunk diameter. The following are some theoretical considerations it.

I use a stem portion and attempts to produce only guitar tops as boards and wedges for jazz guitar, bring Schachtelungsversuche such results were:

Only wedges Wedges and ceiling

If you divide the trunk into 60 wedge-pieces a 6 ° and considering doing about 2cm edge layer is not to be used and 8cm core, the root has to 85cm in the left case and be 88cm thick in the right case, (30 boards and 30 wedges)!

Multiple optimization

In the above optimization you get with a diameter of 75cm has 34 wedges and 32 boards.

Neck blocks

With a diameter of 60cm could produce 36 pieces neck blocks with lying annual rings and 12 with standing annual rings.

As I of course understand that there is no wood in a quality that I could plan the cutting on the drawing board, so I brought the study of the subject but at the Sägevorrichtungsplanung a little further. Which angle and what thicknesses have to be cut?

Standard dimensions for Tonholz:

The below values ​​are given in dry matter! It is essential to note that through the drying process, the wood shrinks. Each type of wood has special values ​​for the dimensional changes. Franz Jahnel specifies the following values:

Species radial % tangential % along % Volume
Spruce 3.6 7.8 0.3 4.1
Sycamore 5.0 8.0 0.4 5.0
Jacaranda 5.3 9.9 0.4 6.3
mahogany 2.4 4.4 0.1 1.4
Ebony 3.1 6.5 0.2 3.1
  • ** radially: along the radius
  • * tangentially: along the years ring
  • *** along: length along the trunk

Usual Tonholzmaße:

Guitar (Classical) Ceiling / floor 2Stück 530 x 190-200 x 4-5
Sides 2Stück 800 x 110 x 3
Fretboard 500-510 x 60-70 x 8-9
Neck blank 650 x 80 x 25
Guitar (Western) Ceiling / floor 2Stück 560 x 215 x 5
Sides 2Stück 850 x 125 x 4
Fretboard 700 x 76 x 8
Neck blank 650 x 80 x 80
Guitar (jazz) Ceiling / floor  
Sides  
Fretboard  
Neck blank  
Guitar (electric) Cap strips 2Stück 500 x 190 x 10-20
body 2Stück 500 x 190 x 52
Neck block 700 x 100 x 26/30
Fretboard 500 x 75/55 x 8
Bass (E-) Fretboard 45/70 x 730 (4-String)
52/85 x 730 (5-string)
60/97 x 730 (6-string)
Cap strips 2Stück 550 x 190 x 10-20
body 550 x 190 x 45/52 2Stück
Neck block 870 x 110 x 26/30
     
     

Columns or saws?

As mentioned above, good tone wood as many must have "standing annual rings". This is actually not quite correct. Often it only talked about the easily visible cross-sectional area at the cut. More specifically has the annual ring and perpendicular to the third dimension (depth) are so located geradwinklig pull through the whole board.
If you look at the trunk as a bundle of straws against (cells of the wood structure look simplifying like this), you have the part try the boards to win so that as few straws are cut laterally.
In timber with vertical annual rings can be seen especially in the coveted spruce "Mark Spiegel". If you look at a finished Instument with spruce top again against the light, so it can be seen in light tilting the guitar backwards, if one of the mirrored ceiling halves slightly darker looks like the other. This is a sichers sign that the ceiling was sawn. The different dark act, the halves, the more cell fibers ("straws") have been cut. If one looks raw Tonewood for a ceiling, one can notice similar to the bending resistance of the boards. Can a board that is lighter than other boards turn with the grain, important wood fibers have been severed - the better take firmer.

So much for the introduction columns or sawing.
Optimalstes Tonholz is split, because it separates the cell walls. Now you remember at the last chopping wood. Spruce can be easily split, but maple !? For hardwoods, there is general agreement that good judgment when sawing sufficient to obtain good tone wood. Spruce roundwood is best pre-split and then further separated on the saw.
The more manual labor is in the finishing process, the more expensive the product is. This is also the reason why most industrially produced Tonholz is almost entirely cut. It is faster and cheaper the tribe first cut on the whole length into quarters or eighths, as the tribe first cut to length on 50-65cm pieces, these cleave then and then cut the quarters or eighths small.

cut eighths and quarters

Here you can see the columns of a spruce section.

My tribes saw when sawing as follows:

Halve Halve and turning
Quartering Eighths

This quarter and eighth tribes now have to be cut to Rohholzlänge. I cut mostly on 650 and 900mm length.

Next part Next part
Loading Stacks for further processing

If the wet spruce wood is not further processed within the next 2-3 days, it begins to tear at the end faces. This has the cause that the cells at the end faces are open and here more moisture can be discharged. In this way, the wood dries unevenly and there are stress cracks. This can be avoided, that the wood is either stored cool and damp or the end faces are sealed. For this purpose, there are professional polyester compounds in dispersion, are much easier and cheaper latex paint or glue cheaper.
Maple is not as critical here. If you this for a few days on the face, so "running" the water downright out. Here again, care must be taken that the faces do not begin to penetrate to a halt and rot and discoloration in the wood.

Sealed with glue waiting for saws
Waiting for saws Ingrown barbed !!!

Processing on the band saw:

I have processed the stem portions on a normal Schreinerbandsäge. This had a diameter of 600mm and roll was driven by a 2.2 kW motor. So that I could set different angles and thicknesses, I built a variable stop. About marks on the saw and the stop I was able to adjust to the desired section thickness or the angle of cut.
The saw blade was 30 mm wide and very strong geschränkt umd the wet chips easy to carry off. The saw blade has been sharpened in this period a total of 3 times!
With great effort, the sections must be laid on the table. With moderate force the wood against the fence and the blade must be pressed.

The large master quarters had a weight of 50-60kg well!
What I first could not believe: Maple can be processed better by far than the much lighter and softer spruce! The cause lies in the fact that spruce chips have much more resin which release the blade, smearing, thus hindering the chip transport greatly. Approximately every hour had the blade with a special agent from the resin to be cleaned (Please Hanschuhe and glasses set up - not just healthy stuff!).

Sawing at stop Sawing at stop
Sawed floor Sawing neck blanks

My opinion from today's perspective to the band saws:

  • The drive motor was actually too weak, 4 or 7 kW with manual feed are much better. For cutting depths of a little more than 30cm (!) In a normal hardwood saw is overloaded quickly. I built an indoor / Außentermometer with the outdoor sensor between the cooling fins of the motor to the saw. So I could see at any time how much the motor was loaded and could also take a break when it was too hot. By the way you could also reference to the temperature to see how the sharpness of the blade subsided! Also important is the control of an optimum engine ventilation.
  • The roller diameter should be greater, as it is then possible to use a 40-50mm wide saw blade. Wider blades do not run as strong. The blunt the saw was, the more went namely Baltt and the chump had to be trained rapidly.
  • The blade guide must be well greased and oiled always, otherwise it breaks
  • A mechanical feed erleichter work uncommonly