[Harp-L] Help with Chromatic repair

["eskeene@xxxxxxxx" <eskeene@xxxxxxxx>]

Joseph, Thank you for this post! I've long wondered why has continued to use wooden combs in the Super Chromonica, when it seemed as though plastic would be easier and cheaper. We laypersons forget that there are limits to what can be done with plastics.  My better, craftsman-made tin whistles all useDelrin parts. Along with its functionality, it also has a certain beauty. I shall be anxiously awaiting the new combs another poster said they will be offering for sale. Cheers, emily Date: Sat, 18 Jan 2014 12:18:15 -0500
From: Joseph Leone <3n037@xxxxxxxxxxx>
Subject: Re: [Harp-L] Help with Chromatic repair
To: Music Cal <macaroni9999@xxxxxxxxx>
Cc: Harp L Harp L <harp-l@xxxxxxxxxx>
Message-ID: <667F8863-751A-4CAC-AB0E-A3D0335E975F@xxxxxxxxxxx>
Content-Type: text/plain; charset=windows-1252


On Jan 17, 2014, at 7:17 PM, Music Cal wrote:

> Is the CX12 comb the only major manufacturer comb made of ABS?

No, most manufacturers are going to abs. 

> Are all
> other plastic combs acrylic?

No, less and less. 

> Kind of odd given that acrylic is rather
> brittle compared to ABS.

Yes, and like plexiglass, it gets more brittle with age. 

> Anybody know what drives the decision to use
> acrylic?

Shrinkage. Acrylic shrinks less and that means that the molds can be made closer to final 
dimensions. Abs shrinks and the mold has to be engineered larger in ALL dimensions. This 
presents a problem with chromatics as the combs are way more intricate. AND there are 
more rejects with abs. Plus there is less sprue with acrylic. Sprue is plastic you loose 
to get the mold operating. And then at the end of the run, you loose more sprue as the 
molding process is emptied of material.   But they're getting better and better at it.
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