[TheForge] Electric forge blower

[peter fels]

Boy, was i wrong on that one!

On Jun 18, 2011, at 3:20 PM, Lynn and Susan Lang wrote:

> 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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