Re: [CAD_CAM_EDM_DRO] re: glass scale expansion vs steel
Posted by
Ken Lowther
on 2000-03-18 09:52:58 UTC
Elliot Burke wrote:
glasses, including CTE. I don't know the site off hand. BK7 would have
the advantage of being a "common" glass, though it is still relatively
expensive. I think pyrex would have a closer CTE. More common and
cheaper. Depending on the setup, you might be able to do some effective
heat synching between the two units.
Did a quick search before posting. I don't do windoze much anymore and
the catalogue is actually a windoze program.
http://www.schottglasstech.com/catalogs.htm
--
Ken Lowther
Youngstown, Ohio
http://www.atmsite.org
ATM FAQ and more
Good starting place for amateur telescope makers
>Schott glass has an online catalogue with info for a lot of different
> From: "Elliot Burke" <elliot@...>
>
> For curiousity, I calculated the temperature change needed to cause a length
> measurement error of 0.0001"/ft between glass and cast iron.
> The glass is BK7, a typical borosilicate glass used for many purposes in
> optics, including scales. CTE=3.8 10^-6 /°F.
> Cast iron CTE is taken to be 6 10^-6 /°F, per my materials book.
> Then a temperture change of about 4 °F causes a 0.0001"/ft differential
> expansion between the glass and iron.
glasses, including CTE. I don't know the site off hand. BK7 would have
the advantage of being a "common" glass, though it is still relatively
expensive. I think pyrex would have a closer CTE. More common and
cheaper. Depending on the setup, you might be able to do some effective
heat synching between the two units.
Did a quick search before posting. I don't do windoze much anymore and
the catalogue is actually a windoze program.
http://www.schottglasstech.com/catalogs.htm
--
Ken Lowther
Youngstown, Ohio
http://www.atmsite.org
ATM FAQ and more
Good starting place for amateur telescope makers