Klarinet Archive - Posting 000040.txt from 2007/08

From: "Curtis Bennett" <curtis.bennett@-----.com>
Subj: Re: [kl] Machining wood
Date: Thu, 09 Aug 2007 11:57:08 -0400

Clark - you may know, but I'd like to point out that Cocobolo wood is
actually toxic when worked. Be careful.
http://en.wikipedia.org/wiki/Cocobolo

On 8/9/07, Clark W Fobes <claroneman@-----.net> wrote:
> Hi Tom,
>
> I will try to respond to most of your questions.
>
> There is no doubt that some heat is generated when machining wood, but
> the greatest amount is created when the blank is initially through bored. I
> use a very sharp, 0.5" drill bit for the initial bore and it generates a lot
> of surface friction. The less wood that has to be removed the less heat is
> generated and we experience the least amount of change. This is why I pre
> bore the tenons to just under the final dimension.
>
> Depending on how green the wood may be, we can see the wood "sweat" as
> the drill bit pierces the blank. It has become very clear to me that African
> Blackwood is naturally very wet. The wood I am working through now was
> bought from Theodore Nagel in 2005 and they said it had been on the shelf at
> least 10 years. We still see the material sweat as we work on it, but it
> dries quite well once the blank is through bored. I think your point that
> clarinets must be machined over several days if not weeks is well taken.
>
> As to wood actually "smoking" when it is machined, I have never had this
> experience with African Blackwood. I did observe that once with Cocobolo,
> but I was experimenting with a tool that was obviously not right for the
> job. Smoke would indicate that a tool was very dull or being forced too
> quickly through the wood. African Blackwood is notoriously hard on tools and
> the bits must be changed when they begin to get dull. When a cutting bit
> becomes very dull it slows down the process immensely and the cuts are not
> as clean.
>
> Tool chatter (which causes roughness or patterned surfaces) is another
> matter. The position of the bit in relationship to the surface and the angle
> of the bit are critical to a clean cut. If the tool is positioned
> incorrectly it will tear the grain rather than cut. It may also chatter. But
> this should be apparent with the first few cuts and any decent machinist
> would recognize the problem and reposition the bit before proceeding.
>
> I have seen some custom made barrels that have a "scalloped" bore. This
> is caused by the reamer. If you are reaming a barrel by hand (the only way
> you can really control the dimensions) you must have a special wood cutting
> reamer. Not only are the flutes sharpened differently than from a high speed
> reamer, but the flutes (if it is not a spiral flute reamer) must be offset
> from each other by a few degrees. If the flutes are evenly spaced the tool
> will chatter and create an uneven or "scalloped" surface. I also know that
> some makers prefer to make the final bore of their barrels with the lathe
> and a boring bar, but the bore lacks a smooth finish. Hand reaming also
> allows me to play test and adjust the barrels in a few minutes.
>
> I am working on a set of photographs of the entire process we use in
> making the barrels and at some point I hope to have a slide show of the
> process on my website.
>
> Clark
>
> Clark W Fobes - Clarinet & Saxophone products
> www.clarkwfobes.com
>
>
>
> ------------------------------------------------------------------
>
>

--
Curtis Bennett

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