Ned Simmons wrote:
Throttle the input or output and try again. Many blowers use maximum
power when moving maximum air volume. ...

Artemus wrote:
You're overloading the motor. Go down to section 3 (about
1/2 way down the page) and read the Amp Meter Tests overview.
http://billpentz.com/woodworking/cyc...easurement.cfm
You'll need to add some ducting and/or baffles to get your blower
back in it's design range.

You're right - this is a great NG, ain't it?

I did the ammeter tests discussed in the ref'ed URL. The motor didn't
have a FLA on the nameplate, but it is a 1/2 HP motor, so I'd expect FLA
about 5 A (?). Measured, the "no load" (wide open duct) current was
13A(!), closed off (minimum) was 3+, and 60% blocked it was about 5A.

The max air speed was about the same wide open & 60% blocked (60 mph).
But the CFM would be 60% less. The air speed varied so much across the
opening that I'm going to de-rate the max speed by 1/2 to get the
average. That gives me 660 CFM. But that is so low compared to similar
Grainger blowers that I'm going to experiment some more.

Stay tuned,
Bob