X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 29 Apr 2009 16:29:43 -0400 Message-ID: X-Original-Return-Path: Received: from web83903.mail.sp1.yahoo.com ([69.147.92.101] verified) by logan.com (CommuniGate Pro SMTP 5.2.14) with SMTP id 3610784 for lml@lancaironline.net; Wed, 29 Apr 2009 14:12:52 -0400 Received-SPF: neutral receiver=logan.com; client-ip=69.147.92.101; envelope-from=paulhershorin@bellsouth.net Received: (qmail 85474 invoked by uid 60001); 29 Apr 2009 18:12:17 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=bellsouth.net; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=JlcyDTldmckJ08p0r9S40tICylvL3HYpr0FP4eT6Yx4NxLdB8Ar6O5Qft735VIgRfGqkpGhGM/Ga+HIhLIvbxX5bHQLjeZ0gr58igiifEPpdkcuG43IedZwtBQmeHZ4T7YVEa+QgLYnxKG/aShkuWRubjs0yXGNh9DLAQCjCFkM=; X-Original-Message-ID: <150651.78044.qm@web83903.mail.sp1.yahoo.com> X-YMail-OSG: aYHj0KUVM1kh5az4cmegKJKaSgr08SccFwhKMHY8xVDUuxo2ezU77uB3UlQ4R79816HEcwdOQEYRVArf.3wisERsBlX2b3xG_Fwd_dZsdIx2nTiWNjVtFen9O2EwCYlEGSmhXMtHw0ptJm16tL1RXgfIgfjzQx4wiwDF8nRR.xHoeYe5m90778_hMeHqneDC9KOiae0vRA3Of0VTsz2UOBUHoIyox.B98A5xFGafKE82qtzs740JtIBmAMbIUED8h2cRJdVwWinVOxKeGZQ0.eCK.bWSUlXi8sVGejTaq45fPPTUns5fKoJSf4jw1NCFYj1GgfLlRTcFE3OAxE42788BDMJj2A-- Received: from [98.64.90.87] by web83903.mail.sp1.yahoo.com via HTTP; Wed, 29 Apr 2009 11:12:16 PDT X-Mailer: YahooMailRC/1277.35 YahooMailWebService/0.7.289.1 References: X-Original-Date: Wed, 29 Apr 2009 11:12:16 -0700 (PDT) From: PAUL HERSHORIN Subject: Re: [LML] Tungsten and other heavy metals X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1071079599-1241028736=:78044" --0-1071079599-1241028736=:78044 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable I used powered tungsten--is was very easy to work with and when mixed with = epoxy--it took the shape of where I needed it--if to heavy i just drilled s= ome out or added more if necessary--room was not a problem.=0APaul Hershori= n=0A=0A=0A=0A=0A________________________________=0AFrom: Gary Casey =0ATo: lml@lancaironline.net=0ASent: Wednesday, April 29, 20= 09 10:20:33 AM=0ASubject: [LML] Tungsten and other heavy metals=0A=0A=0AThe= re was some discussion on the use of tungsten as a balance weight, so I did= some research on the density of various materials - here is a list of appr= oximate specific gravities:=0ATypical epoxy resin - 1.5=0AAluminum - 2.6=0A= Steel - 7.8=0ALead - 11.3=0Atungsten - 19.2=0A=0AIt would appear that the h= igher density of tungsten would allow a more compact balance weight, allowi= ng the weight to be more concentrated to the extremity of the available spa= ce, reducing the overall weight. =A0But things are not usually as simple as= they at first seem. =A0In order for lead to be effectively used it has to = be cast in a shape to fit the space, which is what I did. =A0It is hard to = get all the air bubbles out, but a lead casting can be reasonably dense. = =A0The tungsten, however must be used in the form of powder or rods held to= gether by an epoxy matrix. =A0I don't have directly-related experience, but= I would guess that it would be very difficult to get a 90% by volume tungs= ten mixture in epoxy (resulting specific gravity =3D 17.4) and if one was a= little too casual and wanted to get an easily pourable mixture he could en= d up with a 50% mixture (specific gravity =3D 10.4), less dense than a lead= casting. =A0With reasonable care, which means careful measuring of the epoxy and thoroughly mixing without trapping too much air= I would guess a 70% mix is reasonable and 80% is possible, but not likely.= =A0In comparison, rods perfectly nested in a linear pattern, not hexagonal= , will be 78% "packed." =A0A 70% mix will yield a specific gravity of 13.9,= 23% greater than lead. =A0Will that reduce the overall balancing weight by= 23%? =A0No, because only part of that weight is at a small radius - the we= ight savings is more likely to be about 10% or less. =A0Is it worth the tro= uble? =A0It might be if an accurate lead casting is particularly difficult,= but otherwise I doubt it - at least that was the reasoning when I decided = to use lead.=0A=0AGary Casey=0A --0-1071079599-1241028736=:78044 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
I used powered tungsten--is was very easy to work with and when m= ixed with epoxy--it took the shape of where I needed it--if to heavy i just= drilled some out or added more if necessary--room was not a problem.
= =0A
Paul Hershorin
=0A

=0A
=0A
=0AFrom: Gary Casey <casey.gary@yahoo.com>
To: lml@lancaironline.net
Sent: Wednesday, April 29, 2009 10:20:33 AM
Subject: [LML] Tungsten and other = heavy metals

=0A
=0A
There was some discussi= on on the use of tungsten as a balance weight, so I did some research on th= e density of various materials - here is a list of approximate specific gra= vities:
=0A
Typical epoxy resin - 1.5
=0A
Aluminum - 2.6<= /DIV>=0A
Steel - 7.8
=0A
Lead - 11.3
=0A
tungsten - 1= 9.2
=0A

=0A
It would appear that the higher density = of tungsten would allow a more compact balance weight, allowing the weight = to be more concentrated to the extremity of the available space, reducing t= he overall weight.  But things are not usually as simple as they at fi= rst seem.  In order for lead to be effectively used it has to be cast = in a shape to fit the space, which is what I did.  It is hard to get a= ll the air bubbles out, but a lead casting can be reasonably dense.  T= he tungsten, however must be used in the form of powder or rods held togeth= er by an epoxy matrix.  I don't have directly-related experience, but = I would guess that it would be very difficult to get a 90% by volume tungst= en mixture in epoxy (resulting specific gravity =3D 17.4) and if one was a = little too casual and wanted to get an easily pourable mixture he could end= up with a 50% mixture (specific gravity =3D 10.4), less dense than a lead = casting.  With reasonable care, which means careful measuring of the epoxy and thoroughly= mixing without trapping too much air I would guess a 70% mix is reasonable= and 80% is possible, but not likely.  In comparison, rods perfectly n= ested in a linear pattern, not hexagonal, will be 78% "packed."  A 70%= mix will yield a specific gravity of 13.9, 23% greater than lead.  Wi= ll that reduce the overall balancing weight by 23%?  No, because only = part of that weight is at a small radius - the weight savings is more likel= y to be about 10% or less.  Is it worth the trouble?  It might be= if an accurate lead casting is particularly difficult, but otherwise I dou= bt it - at least that was the reasoning when I decided to use lead.
= =0A

=0A
Gary Casey
=0A

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