Thanks for the comments, Andy. I've done more reading and looked at the
charts and I am beginning to understand the give and take. I had a course
in fluid mechanics in college and its slowly coming back to me.

Bob

"Andy Dingley" wrote in message
...
On Sun, 23 Nov 2003 04:13:52 GMT, "Bob Davis"
wrote:

The famous website on dust collection is adamant that you should use 6"
ducts from the collector all the way up to your tools, then reduce down
to
4" to get into the tool.

2HP is rather on the borderline. I'd go with 4" though, because 6" on
an underpowered DC fails more drastically than 4" suffers through
friction. If your workshop is big enough that you need 6" because of
run lengths, then make sure then fan is big enough !

If I was plumbing in a whole workshop from scratch, then I might do a
shared roof-level backbone in 6", but I'd certainly do the drops to
each machine in 4". Sucking vertically in 6" just doesn't work if
you're at all marginal.

--
Die Gotterspammerung - Junkmail of the Gods