[TheForge] Too much air (Was: Welding SS)

[Jerry Frost]

----- Original Message -----
From: "Mike Spencer" <mspencer@tallships.ca>
To: <theforge@mailman.qth.net>
Sent: Saturday, September 13, 2003 6:48 PM
Subject: [TheForge] Too much air (Was: Welding SS)


>
>
> Say you have a blower that blows too much air.  For some reason you
> can't change it.  If you just restrict the air flow, you load up the
> motor and make it more noisy.
>

>
> Now you can throttle the air to the firepot and at the same time, the
> excess draft is vented through the stem of the tee and the motor
> doesn't load up and whine.
>
> I did this on one of Sam Allen's forges at MIT where the (excessively
> powerful) blower and (hopelessly inadequate) speed control had been
> installed by licensed electricians and could be changed only via
> slow, protracted and painfull bureaucratic process [1].  Worked great.
>
> - Mike
>
> [1] See http://home.tallships.ca/mspencer/alien/bulb-mit.html

I considered making a bypass but when I mounted the blower there wasn't
enough room. Still, I'm using a 1/2 hp motor so it wouldn't notice if I
blocked it completely anyway. Blocking the intake on the other hand reduces
the load on the motor and makes it "happier". I can't hear the motor nor
blower over the sound of the fire so I'm happy too. <grin>

When I was going to include a bypass I'd planned on directing it up the
stack for an induction draw. What I came up with for the valve is a bit
different though. It's more hassle to make (maybe) but easier to operate.
For the valve I was going to cut about 4" of 3" exhaust pipe, "T" the supply
and tueyre at 180* and the bypass at 90*. Using my trusty hole saw cut two
discs and make a close fitting rectangular butterfly valve 3"- x  4"-,
attach it to a rod, slide it into the valve body, slip a disc on each end of
the valve rod and weld them to the body. (Welding takes place after making
sure everything moves freely of course)

The valve mounts horizontally and the control rod extends to just under the
front edge of the forge table. You can adjust the blast to bypass ratio with
one easy to reach lever, knob, etc.

I have a similar control rod running the damper plate on the blower intake.

Frosty
------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.