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

[Mike Spencer]

Fosty wrote;

> ...had to severely restrict the blower and air grate.  At full tilt
> you can't stand within 6' of the forge, well, not for long
> anyway. <grin> Even after blocking the motor side intake and 3/4 of
> the other side I had to plug (dropped rivets in the holes so I can
> open it up as needed) all but five of the 3/8" holes in the air grate
> to make a controlable fire.

Maybe everybody already knows about this but FWIW:

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.

Remove the duct from blower to firepot.  Make a tee tube of suitable
diameter(s) and put throttle plates in the stem and in one arm of the
crossbar.  Make little cranks on both of the throttle shafts and
connect them with a link so that as the plate in crossbar closes the
one in the stem opens. Install the crossbar of the tee between blower
and forge with the arm containing the throttle toward the forge.  Add
a control lever that you can reach from the work position.  (Doesn't
require careful workmanship.  If it leaks air, so what?  You already
have to much, right?)

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

-- 
Michael Spencer                  Nova Scotia, Canada       .~. 
                                 						   /V\ 
mspencer@tallships.ca            						  /( )\
http://home.tallships.ca/mspencer/						  ^^-^^

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