Subject: Rewiring FORGE MOTOR (& PB-50 warning)

From: "daryl (d.a.) bender" <[email-masked]>
Date: Wed, 14 Aug 1996 10:25:00 -0400 [/PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/;bcars520.b.810:14.07.96.14.30.16]

In message " Rewiring FORGE MOTOR", [email-masked] writes:

>daryl (d.a.) bender wrote:
>
>Daryl 
>Thats certainly some description but as my squirrel cage blower is
>only 12v. The most cost effective power supply option Is still the
>Battery charger. I used an old car battery across the output.
>Maybe I should have have used A capacitor, Any suggestions?
>regards 
>Colin Morton

Hi Colin

A battery charger may well be cheaper but be careful what you pick. You 
want it to be able to deliver good current continuously (not trickle). 
They also have funny rectification methods so I'm not sure what the 
output waveform would look like but an additional capactior (or battery 
- a battery acts like a humongous capacitor) would not hurt and would 
likely make a smoother waveform (slightly quieter motor). Likely it 
isn't nescesary.

The thing you would lose is the variable speed. I love this feature on 
my forge as I can set the airflow to exactly what I want with a minimum 
of background noise. I'm not sure how a dimmer/charger combo would work 
(may be fine, I don't know).

An AC motor is very difficult to make variable speed. Contrary to 
Centaur Forge a dimmer is not the way to go. I bought thier PB-50 
blower. Thier speed control is a dimmer (bad for the motor). DUHHHH. For 
some STUPID reason they chose a 3400rpm motor (as opposed to a 1725rpm) 
to go with it. DUHHHH. This means the dimmer (even though bad for the 
motor) doesn't have a hope. You either blow trees over 100ft away or at 
a reasonable airflow get a groaning Waaaaaaaaa Waaaaaaa Waaaaaaa from 
the motor. DUHHHH. It was after I payed about CDN$300 (DUHHHH) for this 
thing that I came up with *MY* unit. I still have the other thing in my 
garage (needless to say I'm pissed) but figure I'd loose even more 
sending it back and figure some day I'll chuck the AC motor for a DC 
unit and use it in a permanent set-up. The rotary vane part *IS* good 
but for the money spent I feel that thier design execution was haphazard 
and people should be warned.

Fooled me once
Daryl

---

From: "daryl (d.a.) bender" <[email-masked]>
Date: Fri, 16 Aug 1996 10:04:00 -0400 [/PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/;bcars520.b.192:16.07.96.14.05.56]

Dem

OK, now you got me going. *My* squirrel cage can push air! On first real 
fire up it blew all the coal dust out of the firepot. Please re-read my 
post on how it blows. I had to ditch my Centaur forge blower because IT 
WAS EXCESSIVE. Hook a champion 400 to a 3400rpm motor. Picture that - 
can you crank that fast. I want to blow air through the firepot and not 
recreate Mt St Helens! So I would say YOU DON'T REALLY NEED A 
CENTRIFIGUAL, "VANE-TYPE" BLOWER TO BURN COAL OR COKE. I will say that 
it is easier to go wrong with squirrel cages if you don't know what you 
are doing. I just have trouble with blanket statements however. It was a 
statement like that that worried me when I was building my forge. When I 
called a member over to see it, stating my concern, as soon as I fired 
it up he rolled his eyes in a what are you worrying about fassion.

So I would have to say that if properly designed a squirrel cage works 
fine for a home forge. For example I kept my air tube down to 6", only 
enough to fit the on/off slide gate. Later my forge on its maiden run 
was putting out so much heat we could barely look at it while standing 
in front of it manipulating our metal, and it was only running 0-1/2 (ON 
THE DIMMER) all day. Sure a vane type blower puts out more pressure but 
given that I'm running 0-1/2 on the dimmer why do I want more?

I would agree that DC is far superior to AC. Who can afford proper AC 
speed control?! My warning on the PB-50 (ignoring the price) was in how 
poorly thought out the package was. In my view the motor needs to be 
replaced either to a 1725rpm (still bad but workable and could be 
offered for the same price) or better to a DC unit and let the customer 
get/make the variable speed control. It *would* work if you choke it out 
with a slide gate but that in my mind is a noisey waste. I'll take my 
quiet powerhouse anyday over that. I also have a slide gate but use it 
not to set airflow rate but mearly on/off - metal in/out. Hence my 
blower is always running at the minimum required. I say again quiet yet 
powerful.

Cheers
Daryl

In message " Rewiring FORGE MOTOR (& PB-50 warning)", 
[email-masked] writes:

>The big lie out there is that you can use a squirrel cage fan for a 
forge
>blower.  For the most part, squirrel cages (read Dayton) are meant to 
move
>CFM (read lots of oxidation) instead of pressure.  I know that there 
are
>plenty of people that do good work with this type of air source, BUT 
YOU
>REALLY NEED A CENTRIFIGUAL , "VANE-TYPE" BLOWER TO BURN COAL OR COKE 
(read it
>again, if you like).
>
>This is one of the reasons why everybody wants a Champion 400 or equal.  
They
>don't feel like much if you put your hand over the exhaust, but they do 
push
>the air through a firepot (read positive pressure).  The possible 
exception
>to the squirrel cage dilemma is the 12VDC setup because the static 
pressure
>goes up quite a bit when the rpm's start cranking.  The potentiometer 
type
>speed controls work better with DC, too.  For our purposes, speed 
controls
>don't work on AC unless a brush-type motor is used, which is the type 
found
>on old electric Buffalo and Champion forge blowers.
>
>Dem's my 2 cents.         hollis
>

---

From: [email-masked]
Date: Fri, 16 Aug 1996 21:11:52 -0400

My squirrel cage works great. It is a WEED EATER leaf blower from HOME
DEPOT for 29.95 that needed to be choked back to keep hot coal out of the
exhaust chimney. Hooked to a 1500 watt rheostat it gives me all the
versitility
this novice needs.
          
Joe

---

From: [email-masked]
Date: Fri, 16 Aug 1996 23:46:06 -0400

Oooooh - it seems we hit a nerve with this squirrely cage discussion.  Sure,
they can push air - why else are they used in HVAC systems?  I still say the
vane-type is better for forge applications but I'm real happy you like your
setup.  A while back I saw a lecture on forges by knife maker Tim Zowada
(bear in mind that this was gas - not coal).  His business was making
Damascus knife blanks in a production environment, so he forge welded and
heat treated all day long.  His comments were that he could not accurately
control the air pressure with a squirrel cage blower so he switched to a
positive pressure (read vane-type, centrifugal) fan.  He was using gate
valves to control both fuel and air and he wanted infinite control.  Although
I am not quoting him verbatim, I believe his summary was that squirrel cages
were either "on" or "off" and they stalled when choked with a restriction
(like an air gate).

My first try at an electric blower was a Dayton 300 cfm squirrel cage mounted
to a Centaur firepot.  It had a Grainger speed control and DID NOT have an
airgate - which I think is a necessity with an electric blower - and  I
fought it constantly.  It got very hot but I burned a few things now and
then.  Prior to switching to an electric blower, I used a Champion 400.
 Yeah, I got tired of cranking - that's why I switched.  My current unit is a
factory-complete Buffalo forge with vane-type blower, a factory rheostat and
a sliding airgate.  It was about fifty years old and  practically unused when
I bought it, so I was able to see how Buffalo meant the forge to look as
designed.  A friend of mine who is knowledgeable on the subject said these
blowers were really designed to be able to run more than one firepot, i.e.,
large shops would buy a blower and install Y-fittings to several forges.  The
fan was set on High and each smith adjusted his own fire with an airgate
(makes sense if you think about it).  On a single firepot, they are really
overkill and I never run mine over the second setting (it has six!!)

Now, everybody has their own way of managing a coal/coke fire and I've seen a
lot of styles.  What works best for me is to put the fan on the first setting
and use the gate to control the blast, leaving the fan on constantly.  The
best part is that I can either have a whisper of a fire or "Mt.St. Helen's"
with a flick of the wrist.  The fan doesn't get turned off until the work is
done or I have to pull a clinker.  Contrary to what you might think, this
does not really waste fuel as the fire is always hot and the clinker forms
more slowly without the constant stops and starts.  The whole thing depends
on what you are used to and what works for you.  Last year, I had a noted
demonstrator at my shop for two days and his technique was to disregard the
airgate and use the rheostat.  Unfortunately, the lowest setting on my blower
is too high for most applications, so he burned a few things and made a lot
of big clinkers.  My blacksmithing skills are infantile next to his, but I
don't have the trouble he had because I'm used to it.  I'll concede that your
blower will make a plenty hot fire, but maybe you are getting more oxidation
than you should.  Of course, this is in turn partly controlled by the depth
of the fire, so there you have another variable thrown in for good measure.

I hope you have great luck with your squirrel cage, but I still say a
centrifugal fan is better and you ain't changing my mind (that's what America
is all about and none of us better forget it).

Cheers,
Hollis

---

From: "daryl (d.a.) bender" <[email-masked]>
Date: Mon, 19 Aug 1996 11:51:00 -0400 [/PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/;bcars520.b.568:19.07.96.16.01.06]

Hi Hollis

Yes a nerve was hit as squirrel cages work great for many applications 
and blanket statements are never fully true. People should not be scared 
away (like I nearly was) from this common air mover rather they should 
be made aware that it works *but it has limitations too*. In my case I 
got scared into a PB-50 then went squirrely as it were. 8^) Reread my 
post. I never said they (squirrel cages) were better I said;

1) They can be fine for a home forge.
2) They are easier to go wrong with if you don't properly design.
3) DC is superior to AC for inexpensive speed control.
4) My centaur forge PB-50 blower was excessive because the motor was not 
suited for for it. Why don't you hook up a 350cu in V8 to a windmill and 
control it by pouring sugar in the tank? It will work. 8^)
5) Vane type blowers are capable of more pressure.
6) I like speed control to keep my blower at min speed rather than 
blasting the motor and choking it with my slide gate. (given that I have 
both I could do this "the blast and choke" way too).
7) Keep your air tube short.

Not quite sure how I'd get *more* oxidation as a mass rate of flow is a 
mass rate of flow. I only blow as much as I need. How could a vane type 
blow more but with less oxygen. The way I see it it takes more airflow 
to get more oxidation. Maybe what you are saying is that a squirrel cage 
may not be able to push the air through a *DEEP* coal pile and the 
bottom of that fire may be oxidized by swirling "stalled but 
recirculated" air whereas a vane type with it's higher pressure would 
push the air through making the fire burn more evenly. While I haven't 
experienced this it could very well be true (see 5 above). 8^) It is 
also true that a vane type may not be able to push air through a really 
really deep coal pile. How deep do you want to pile? How big is your 
fire? Maybe you *want* to hook up to a super sonic wind tunnel. If you 
do the PB-50 is for you! 8^)

Cheers
Daryl

p.s. In case I have not made it *explicitely* clear the PB-50 is a good 
blower with the wrong motor and the super cheap (bad) speed control can 
only compensate to a certain degree. Hooked to the right motor it would 
work excellent. I just feel for the money the combo could have been more 
thought out. Does it cost much more for a 1725rpm motor rather than a 
3400rpm? The speed control might have had a chance on a 1725rpm motor. 
This is the last I will say on the PB-50 as if I were to go on about it 
it would just be a lot of hot air 8^)

---

From: [email-masked]
Date: Mon, 19 Aug 1996 23:37:32 -0400

Does anyone know if Centaur is reading this bulletin board?  If so, maybe
they'll get the message on the PB-50...blanket statements aside (and a tip of
the hat to Daryl)...it appears that several people have experienced problems
with this setup.  Does Centaur know they have a problem?

hollis

---

From: [email-masked] (John & Cynthia/ MidLife Crisis Ent.)
Date: Tue, 20 Aug 1996 09:09:25 +0200

>Since Daryl has spoken his last on the PB-50 blower (and well said it
>was), I will add a footnote:  it's always an amazement (not to mention
>disturbing and down right aggravating) that a company such as Centaur
>Forge, which ostensibly specializes in blacksmithing tools and
>equipment, would design a blower with such an inappropriate motor and
>speed control so as to make the unit all but useless; and it's not as
>though it's inexpensive either (how's that for a run-on sentence?)!
>Frankly, it pisses me off.
>
>D.C. Hufford

Hay all you PB-50 owners and would be owners....  Write letters to Centaur
Forge and lodge your complaints.  Maybe better yet, copy all that has been
said on this thread and send it to them!

Back to my patina play!!!

John

John Dach and Cynthia Thomas
Maiden Metals
a div. of
MidLife Crisis Enterprises       The present is where we live and all we have,
PO BX 44                             yet we know it as small and fleeting.
Philo, CA  95466
707-895-2635(phone/fax)

---

From: [email-masked] (Clay Spencer)
Date: Mon, 26 Aug 1996 13:15:28 -0400

>David C. Hufford wrote:

I missed the original post on this while I was at the Rocky Mountain Smiths
conference in Colorado.
I wholeheartedly agree with David.
It is not good engineering to put a speed control such as Centaur uses for
varying the speed of a synchronous motor. It works very poorly and is very
expensive.
Clay

---

From: [email-masked] (Clay Spencer)
Date: Mon, 26 Aug 1996 13:15:31 -0400

At 2:31 PM 8/23/96, Jim McCarty wrote:
>[email-masked] wrote:
>>
>> The big lie out there is that you can use a squirrel cage fan for a forge
>> blower.  For the most part, squirrel cages (read Dayton) are meant to move
>> CFM (read lots of oxidation) instead of pressure.  I know that there are
>> plenty of people that do good work with this type of air source, BUT YOU
>> REALLY NEED A CENTRIFIGUAL , "VANE-TYPE" BLOWER TO BURN COAL OR COKE (read it
>> again, if you like).
>>
>> This is one of the reasons why everybody wants a Champion 400 or equal.  They
>> don't feel like much if you put your hand over the exhaust, but they do push
>> the air through a firepot (read positive pressure).  The possible exception
>> to the squirrel cage dilemma is the 12VDC setup because the static pressure
>> goes up quite a bit when the rpm's start cranking.  The potentiometer type
>> speed controls work better with DC, too.  For our purposes, speed controls
>> don't work on AC unless a brush-type motor is used, which is the type found
>I will ditto what Hollis said -- BAM made that mistake on the forges
>we built for the 94 conference. Prior to that event we test drove the
>forges at the Ozark Conference and Doug Wilson struggled to get any
>kind of heat from those timid squirrel cages -- he finally begged us
>to rip it off and replaced it with one of Bill Gichner's 400s. The
>difference was amazing.  Squirrel cages suck.

You can get squirrel cages to operate a forge. They have to be larger
diameter and higher velocity. Generally you have to keep poking at your
fire to keep it very open.

Vane type blowers are much, much better for forge use. A 10" dia at 1750
RPM will handle nearly all forges with plenty of pressure and CFM.

The best/easiest/quickest air control is a simple gate.

Clay

---

From: [email-masked] (Elton O Grubbs)
Date: Mon, 26 Aug 1996 14:16:07 -0700

You wrote: 
>
>> 
>> As an extension of the forge blower discussion, I would like to ask 
if 
>> there is any reasonable way to rig a 3500 rpm induction motor (such 
as 
>> is on the PB-50 blower) to run at half speed, or 1750 rpm?  
>
>Nope. Induction motors run (almost) synchronous with line frequency.
>If you have a 50/60 Hz motor, it will have different rpm's for 50 and
>60 Hz. 3500 vs 1750 is achieved by putting a different number of poles
>in the windings inside the motor. No way to change this.
>
>A great way to speed control an induction motor is to supply it with
>110VAC and vary the frequency. This is not a trivial thing to do. 
>
>Replace the motor. Get a used one from a furnace repair shop. Go armed
>with the outside dimensions of the motor and mount plate. Try for a
>motor with the same HP rating. You should be able to find one for
>$15-20 used. You can also look in the local junkyards (excuse me,
>recycling centers). Bring a line cord, and try the motor out. If it
>works, the price will probably go up, but then you get a good motor!
>
>Your replacement motor may need to be reversed to run the other
>direction. This is pretty easy on most motors--write me if you need to
>do this.
>
>--
>Steven O. Smith
>[email-masked]
>

I've never seen the PB-50 but if I had a motor running to fast I"d 
think about changing the pulleys to make it run slower. If it doesn"t
have a belt put one on it. 
Seems to me.
Buster

---

From: "daryl (d.a.) bender" <[email-masked]>
Date: Mon, 26 Aug 1996 22:01:00 -0400 [/PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/;bcars520.b.289:27.07.96.02.05.09]

>in the windings inside the motor. No way to change this.
                                  ^^^^^^^^^^^^^^^^^^^^^^^^
OOOOooooo another blanket statement!!!!! 8^) I have changed a motor from 
600V 3 phase to 240V single phase. It ain't easy but it can be done. 
Never say never! 8^) In my case it was an intergral gear motor for a 12" 
shaper and it was cheaper (for me) to do than a 5KVA phase converter and 
step-up transformer. 

>110VAC and vary the frequency. This is not a trivial thing to do. 

It's not that complex but it is expensive and it is usually used more 
with three phase input. 

>direction. This is pretty easy on most motors--write me if you need to

All the above is good advice on how to fix your brand new PB-50. Sorry 
but I couldn't resist 8^)

Daryl - the squirrely guy with the idle PB-50. 8^)

---

From: "Harold E. McKinney" <[email-masked]>
Date: Tue, 27 Aug 1996 10:19:51 -0400

For what it's worth, One of my forges is a little riveter's or farrier's forge that had a burned out 12V DC motor on a small squirrel-cage blower attached to the air inlet of a little cranked vane-type blower, a sort of two blowers in one arrangement.  I took off the whole 12V arrangement, got a little Dayton squirrel cage blower from Centaur, bolted it on, then spent about $18 for a little sewing machine speed foot control.  Haven't used it much, but it works fine for little stuff and if you really want it to heat up you can get both blowers going.  I'm no electrician, so I don't know what it would do to the motor if I used it much.
Mac

----------
From:  [email-masked][SMTP:[email-masked]]
Sent:  Tuesday, August 27, 1996 12:19 AM
To:  [email-masked]
Subject:  Re: Rewiring FORGE MOTOR (& PB-50 warning) 

OK, I am going to open up the wormy can and ask the question - aren't
brush-type AC/DC motors capable of speed control with the cheap little pots
that WWGrainger sells?  I'm not an electrical engineer so I don't know WHY
they work, but for the moment, let's assume they do.  That being the case,
wouldn't a sewing machine motor (I think they are brush motors) work on a
vane-type blower.  It's late, but stay with me a minute, I'm brainstormin'.
 How 'bout if a person built a centrifugal fan (Dave Gingery has a fine book
on how to do it), hooked up a sewing machine motor and put the speed control
on the floor.  Step on the speed control and you get blast!!!  Obviously, you
wouldn't be able to walk away from the forge, but at least you won't burn the
work while your back is turned.  Seriously, though, this might be a workable
solution in lieu of the infamous squirrel cage.

Hollis

---

From: [email-masked] (Clay Spencer)
Date: Tue, 27 Aug 1996 12:35:33 -0400

At 9:18 AM 8/27/96, Steven O. Smith wrote:
>You are correct. Brush type AC/DC motors are also called "universal"
>motors. They commonly show up in sewing machines and vacuum
>cleaners. You speed control them by how many volts you feed them with,
>quite different from induction motors which track AC frequency.
>
>I'm not sure what you mean by 'cheap little pots'. You could certainly
>put a pot (variable resistor) in series with a universal motor to
>speed control it. The only trick is making sure that the pot will
>handle the motor current without burning up.
>
>The other trick here is that I suspect a sewing machine motor is way
>too small to run a vane type blower, at least not a Champion. How
>about a blower out of a car?  They put out lots of air. Vary the 12V
>DC supply and you vary the speed. Then you can sell your champion for
>the amazing bucks folks have been talking about!

I used a vacuum cleaner as a blower for years on my forge with a light
dimmer switch. Most of them will handle 600 watts and the heavy duty will
handle more. The blower and motor were mounted in a bucket so I could get
the air to a pipe. Noisy and cheap, but it could blow the fire right out of
the firepot on high speed.
Clay

---

From: "Harold E. McKinney" <[email-masked]>
Date: Wed, 28 Aug 1996 16:20:57 -0400

Discussing possible motor arrangements--Yesterday  I was observing a
 friend of mine who runs an upholstery shop.  He was using a rather large sewing machine.  It had a substantial-sized 1/3 HP motor on it and the foot pedal went to some sort of clutch arrangement.  The motor, it seems
 rotated at a constant speed and the clutch controlled the drive speed.
   May be another way to go.  

Mac

---

From: "John Kelly" <[email-masked]>
Date: Fri, 30 Aug 1996 19:35:09 +0600

There was a fine article in the last (not current) Home Shop 
Machinist about the use of shunt wound and Permanent magnet DC motors 
with speed control.
Plans for the speed control are included.
This type of converter allows a wide speed range with little loss in 
power.
Hope this may be of some help.