Do wooden arms warp


I hate to sound stupid or pedantic, but I have historically done a lot of woodwork - turning/routering/bedmaking. The single biggest problem is locating wood that does not warp.
Wood cut and left to settle over 50 years continue to warp, likewise, even very old wood warps as well. In my experience when a piece is smaller/thinner it is more pronounced unless there is some lamination (not always a cure). I am yet to come across or find a treatment which stops warping. It would be nice if a manufacturer of such an arm chimes in on this thread, because arms such as: Durand, Shroder, Reed etc all have wood arms/options and they really are the most expensive arms out there.
lohanimal

Showing 3 responses by ilikmangos

In questioning the OP's opening post, It is not necessarily that all wood warps. In most any wood, a warp can be induced, but, in old, very well seasoned woods, the main reason for warpage is internal tensions within the wood. These tensions exist , mainly due to environmental conditions which the tree was subjected to while still alive, like living on a windward slope, exposed to high winds, uneven weight due to the tree leaning, tensions set due to heavy branches, and countless other individual circumstances.

Most likely, any wood that has been correctly stored and seasoned for many years, yet is still warping, either it is due to internal tension, or it is a species that is less stable.

In the case of Ebony, or Cocobolo, or similar extremely dense, and/ or resinous woods, no matter how long they have been seasoned, it is a good idea to let them rest again after rough milling to a dimension close to the final dimension, as moisture will only move through solid timbers of these species to a degree and no more. When they are cut into, they need to season some more so that the exposed bits can come to equilibrium.

Yes, it is very possible to make an item like a tonearm wand that will predictably hold it's shape, and not warp. The main factor is how carefully the piece is made, mainly in 'working with the wood' and not against it's nature.
I am a life long woodworker, and have extensive extensive experience with many different species of woods. I have built nearly 1600 plinths for the LP12, the Garrard 301/401, and the Thorens TD124. I made the armwands for the Teres Illius tonearm, and have been working on a tonearm design of the past several years. I also build instruments as a hobby.

Wood is a great material for a tonearm wand, what separates the end results, are exactly what wood is chosen, species, grain orientation, age, moisture content, how it is worked, and how it is finished.

Some woods are more susceptible to continuous change corresponding with environmental changes than others. Some wood species, if there is no internal tension, are very stable after the sap moisture in the wood has come to relative equilibrium. Changes in relative humidity have less of an effect on some of these woods. Internal tensions can be mostly sorted out in the wood selection stage, and can be very effectively further checked in the preparation stages of turning the wood into arm wands, or whatever.

Quality instrument makers prepare neck blanks by rough milling, and then storing them. Then years later, roughing out the neck shape, cutting the neck top plane, and neck sides, then leting the blanks 'rest' again. After some time, if the blank has proven itself to be stable, it is finished into a neck. This is a relaible method for taking the factor of warpage out of a wooden item like a tonearm wand.

Vacuum wood stabilization is very effective in checking wood movement, as well as increasing the damping factor in a given wood. To someone above who questioned the 'integrity' or 'ethics' of stabilizing wood, or whether or not stabilization with vacuum impregnated polymers turns the wood into plastic, no, it is still wood. And how many metal arms out there that employ some sort of damping strategy to reach a desired end result? Many top instrument builders say that the finish actually does more than just protect the wood, that the finish is part of the synergy that comes together in tempering an instruments 'sound'. The changes that occur to a piece of wood that is vacuum stabilized, still leave the treated piece of wood well within the range of mechanical characteristics that make wood a desirable material to work with, only more stable, and perhaps with more desirable sonic characteristics, in the case of a tonearm wand.

I have one of those Cherry tonearms that were sold here on agon, it was given to me by a customer who I built a deck for . It IS warped. However, it is clear from looking at it, that very little was done to prevent warpage. It is not stabilized, and it is not shaped in a way that would tend to prevent it from warping. To compare those Cherry tonearms with a Reed, or a Schroeder, is like comparing apples and oranges, it has no relation.
The comment about a human being able to survive for 45 minutes at over 400 degrees fahrenheit has very little to do with wooden tonearms, as well as being untruthful. I suspect that in a sealed chamber, at that temperature, the first real breath and a human body would know that death is very close.

I believe the comment about the level of heat generated at the stylus/ vinyl interface during replay was made in counter to someone else's comment suggesting that movement within a wooden tonearm due to atmospheric variations would be sufficient as to make an accurate and stable cartridge setup with a wood-wanded tonearm, impossible, or even difficult, which is just not true. Someone laid out some figures about movement in wood without telling the whole story. First, different woods move different amounts. Second, wood movement occurs radially at a much higher rate than it does in a longitudinal direction. Making a tonearm wand that stays true to it's axis can be accomplished easily enough if care is taken. Change in length of a wooden tonearm wand is pretty much a non issue given the short length of the wand, the fact that it is stabilized, and that wood just does not move that much longitudinally.

Also, that significant heat is generated at the stylus is not really a problem. Who knows though.. maybe the next significant advances in cartridge technology will come with nano-liquid cooled cantilevers ;)