PSN-L Email List Message
Subject: Re: knife edge materials & horological update
From: ChrisAtUpw@.......
Date: Wed, 14 Nov 2007 08:11:40 EST
In a message dated 14/11/2007, holmstro@.......... writes:
The HSN website has some preliminary information on knife edges for horology
located at http://www.hsn161.com/knife.php A rounded edge is the key to
success as Chris points out. If done properly, knife edge supported pendulums
for clocks can be a great success - Reifler clocks for example.
Hi Bob,
Making a triangular rod and then accurately rounding, lapping and
polishng the edge involves precision engineering. However, milling a short flat
section on the tip end of say a 60 deg rod and then milling a small 90 deg V
slot in this face to support a small diameter circular rod is quite possible.
You can clean the components and glue the rod in place with two part acrylic
glue.
One other consideration not mentioned is that the materials need to be
very resistant to oxidation / corrosion if used in damp air. Martensitic
Stainless Steel, Tungsten Carbide and Sapphire are obvious 'candidates'. Materials
suitable for use in high vaccum are more limited. If you use metals, you are
likely to get welding when the protective oxide coats wear off. Some hard
ceramics like sapphire are likely to be successful.
Regards,
Chris Chapman
In a message dated 14/11/2007, holmstro@.......... writes:
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=3D2>The HSN=20
website has some preliminary information on knife edges for horology locat=
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at http://www.hsn161.com/knife.php A rounded edge is the key to=
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success as Chris points out. If done properly, knife edge supported=20
pendulums for clocks can be a great success - Reifler clocks for=20
example.
Hi Bob,
Making a triangular rod and then accurately=
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rounding, lapping and polishng the edge involves precision engineering. Howe=
ver,=20
milling a short flat section on the tip end of say a 60 deg rod and=20
then milling a small 90 deg V slot in this face to support a=20
small diameter circular rod is quite possible. You can clean the components=20=
and=20
glue the rod in place with two part acrylic glue.
One other consideration not mentioned is that t=
he=20
materials need to be very resistant to oxidation / corrosion if used in damp=
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air. Martensitic Stainless Steel, Tungsten Carbide and Sapphire are=20
obvious 'candidates'. Materials suitable for use in high vaccum are mor=
e=20
limited. If you use metals, you are likely to get welding when=20
the protective oxide coats wear off. Some hard ceramics like sapph=
ire=20
are likely to be successful.
Regards,
Chris Chapman
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