On Saturday 17 January 2004 18:25, Chimpsarecute wrote: > ...The remainder of the world uses ISO metric fasteners almost exclusively, > due to their superiority in proportions, fatigue strength, pitch, size and > specification designations, and international availability.
Pro metric, but propaganda BS none the less. > 3.. Metric fasteners for all aerospace applications are made readily and > easily available at "rock" bottom price to all NASA and contractor > employees via NASA GSFC Fastener Inventory. True, if you call over $10 PER SCREW "rock bottom." The prices are comparable to the price of non-metric space qualified fasteners: all are shockingly expensive. > It appears from part c that there are metric fasteners available for use in > aerospace. Yet for some reason the link is a dead end. Yes, space qualified metric fasteners are indeed readily available, even in the U.S. They are not ISO standard, but are dimensionally compatible with ISO fasteners. For example, you can put a NA screw in an ISO hole, or vice-versa. Unlike the ISO standard (as far as I know), the NA standard is specialized for aerospace use. I encourage my coworkers to use metric fasteners where possible, but there are still places where you have to use a "standard" fastener to mate to a non-metric part. I'm sure there are plenty of metric and standard fasteners on the Spirit rover, but I can't tell you what proportion. John
