No one will use it if it doesn't turn on automatically. It *must* be automatic.
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No one will use it if it doesn't turn on automatically. It *must* be automatic. I've read that using less than 3" ducts with a large 15-16" blower is a problem.
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I drew up some plans based on
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I drew up some plans based on these resources:
* http://www.youtube.com/watch?v=7zlNimxZgqw
* http://www.youtube.com/watch?v=7zlNimxZgqw
* [[File:Blast gate.doc]]
* [[File:Blast gate.doc]]
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This is a 2.5" duct, 'cause I originally planned to use the shop vac. The hole can just be enlarged to 3" w/o other changes. For 4" or 6" gates, the plates should be enlarged, and linkages will probably need lengthening. I made a lot of paper models to get the geometry right. Someone with experience modelling moving parts with CAD could probably do the scaling more quickly.