[Jewelry making - Article 00017] - Re: [Orchid] Casting at high altitudes

[dan]

========[ Invite a Friend - http://www.ganoksin.com/invite.htm  ]========


    The thing to remember is that you have less air pressure to push into
    the vacuum.  It is quite possible to pull a vacuum down to below 500
    microns or less (25,400 microns to an inch of vacuum, with 0 being an
    absolute vacuum) There are several "tricks" to doing so: One is to be
    able to measure accurately. Most compound gauges are very inaccurate.
    A simple and effective gauge is made using tubing bent in a U and
    filling with mercury so that a 30 inch offset is possible; 15" up on
    the vacuum side, 15" down on the atmospheric side. The reading may be
    dependant on atmospheric pressure due to altitude. To get the most
    out of your Vacuum pump run the pump for an extended time with the
    gas ballast open and the output valved off. This helps to purge
    moisture from the pump. Change the oil out frequently.  The seals in
    many pumps can be relapped by changing the oil and leaving the pump
    running for 24 hours straight or longer. If you run as large a line
    to your vacuum table as possible and install a vacuum chamber as
    close as possible to your table that would aid in getting a quick and
    hard pull at casting, making the most of your lower air pressure. I
    dehydrate refrigerant systems using a vacuum pump and the moisture
    pulls out at about 1500 microns. Sometimes it takes days. Also if
    water is sitting under oil I can not pull it out unless I 
    heat or agitate the oil. 

____________________________________________________________________
T h e   O r c h i d   L i s t
Open Electronic Forum for Jewelry Manufacturing Methods and Procedures
____________________________________________________________________
Orchid FAQ:
~ http://www.ganoksin.com/orchid/faq.htm
Orchid Archives:
~ http://www.ganoksin.com/orchid/archive
Orchid Galleries:
~ http://www.ganoksin.com/orchid/gallery.htm
Invite a Friend:
~ http://www.ganoksin.com/invite.htm
____________________________________________________________________
Tips From The Jeweler's Bench - Article Archive
~ http://www.ganoksin.com/borisat/tip_sear.htm
The Jeweler's Selected Bibliography List
~ http://www.ganoksin.com/jewelry-books
Buy Orchid Jewelry:
~ http://www.ganoksin.com/shop
____________________________________________________________________
-Unsubscribe:
-Email: orchid-request AT ganoksin.com Body=unsubscribe subject=blank
____________________________________________________________________