[TheForge] Electric forge blower

[Lynn and Susan Lang]

Hello
Not all motors with brushes are universal...and take kindly to speed
control. You could find a motor with brushes and it could be a
"repulsion start induction run motor". I would not put a speed control
on it.
lynn

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Paul
Sent: Saturday, June 18, 2011 1:29 PM
To: theforge at mailman.qth.net
Subject: Re: [TheForge] Electric forge blower

1 PSI is roughly equivalent to 28" of water coulomb, which is what wc 
represents. 16 Oz/si would equal 1 psi which equal 28" of water coulomb.

Reducing the voltage on a AC synchronous motor will reduce the rpm, but 
it can damage the motor unless it is designed to be speed controlled.

A better solution is to use a AC/DC universal motor, IE: one that has 
brushes. These respond very nicely to variable speed controls.

see:
http://www.solorb.com/elect/solarcirc/pwm1/
http://focus.ti.com/download/trng/docs/c2000/TI_MotorControlCompendium_2
010.pdf

They also work with scr controllers like the cheap ones at HF.

I found an old champion blower and after a through cleaning of the 
commutator, it runs great.
A quick Google search for dc blowers didn't turn up much that was
useful.

The higher static pressures that a coal forge requires are the result of

a larger diameter blower wheel, a squirrel cage blower is designed for 
large cfm's at lower pressures, and often will not easily overcome the 
back pressure in a forge as easily as a proper blower... that's why the 
hand crank blowers have a large diameter blower wheel.
I have been looking for a cheap source for 115v dc fractional HP motors,

if I find some I will post them here.

-- 
Paul
WB9HCO
My Grandfather WAS a blacksmith...
and it didn't do me one damn bit of good.
All opinions are the personal beliefs of the author, and are based on
decades of experience... so use your best judgement, I'm just a lowly
crafstman.
  "The difference between genius and stupidity is that genius has its
limits." -Albert Einstein
"Life is hard...it's harder if you're stupid" John Wayne - Sands of Iwo
Jima





On 6/18/2011 11:45 AM, Paul N wrote:
> Thanks Jim,
> That's a good link. I had been looking at those, but I really don't
know
> what the output requirements for a coal forge are. That's why I looked
> at the blacksmith suppliers. Unfortunately, the 164 CFM and "40oz PSI"
> doesn't quite compare directly with the nice specs at Grainger, which
> give you the CFM at various SP levels. I'm assuming that the Kayne
> blower is really 40" SP @0 CFM, not 40oz PSI, which is a mixed metric,
> unless it's really 40oz Per Sq. Inch as opposed to the conventional
use
> of PSI (Pounds per Sq Inch).

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