Subject: re:Rewiring FORGE MOTOR

From: "daryl (d.a.) bender" <[email-masked]>
Date: Tue, 13 Aug 1996 18:34:00 -0400 [/PRMD=BNR/ADMD=TELECOM.CANADA/C=CA/;bcars520.b.581:13.07.96.22.34.06]

Hi Collin / the forge

I work in the power group here so have access to otherwise expensive 
parts. Having said that my blower is a surplus jeep heatercore blower 
hence 24V I can't remember the amperage but it was under 10A (I think it 
peaked at 8A steady but would surge a bit higher on start-up). A 12V 
motor of equivalent power would have twice the current. I'm copying 
"theforge" as this has come up a few times. Cynthia are you listening 
8^). Cut and paste description follows. Remember the world's slickest 
forge post, and no I still haven't mounted the BUN-O-MATIC coffee 
machine to my forge ..... yet. Can you visualize me competing with a 
power hammer after 8 beer steins of coffee 8^) );

---forwarded description--->
My blower (as far as I can tell) is an army surplus jeep heater blower. 
It is cast aluminum and has a 3" dia outlet which is perfect for the 
flex metal tube connection. It is a 24Vdc squirrel cage. For some 
strange reason it currently smells like pee??!?. Probably some bizarre 
hazing ritual 8^).

I ditched the heater core etc. I have made a very simple supply for it. 
I have a 20ft cord. Power passes thru a 600W (5A) dimmer before hitting 
the primary side of a 120/25V 10A transformer (Hammond was the brand 
167S25 about $50.00 new). The secondary is connected to a full bridge (I 
used a 25A metal bridge with sil pads for isolation), a 20A 1mH inductor 
($33.00 again Hammond but 10A would suffice $10.00 - 157D), 6600uF 40V 
electrolytic (then to the motor). 

So far the dimmer seems to withstand the starting surge of the 
electrolytic probably because I put it on the primary side (lower 
current and hydro is a poor source compared to the batteries we use here 
- I'm sure I'd hit 2000A on a battery). 

The net-net of all that is a strong quiet motor that can blow your hair 
straight back and jiggle your cheeks if you want, yet can run steady but 
as softly and quietly as an old dog's fart.

To sum up an on/off/dimmer controlling the primary of a transformer. The 
secondary going to a fullwave bridge. An inductor in line with the +24V 
rail. Then a capacitor across the output. Not a great supply but it's 
simple, robust with loads of power but big and heavy (what isn't in 
blacksmithing eh?!). 

I could have gone with a switched mode power converter but feared 
whether a high tech supply would withstand the riggers of rough use.

The supply is all slickly packaged in a box complete with 
terminal block etc and mounted under my portable forge. The top is light 
metal but the base is 0.125" plate lined with 0.75"angle (like a plate 
with the sides folded up to receive the box shaped top). This plate is 
sturdy enough to mount all the power supply stuff and also acts as a 
forge gusset (aluded to earlier). Dimmer location is in a side mounted 
electrical outlet box.

The blower output immediately hits a slide gate for air ON/OFF 
control (once the level is set by the dimmered supply). There is a 
bracket that steady's the gates sliding rod complete with turned wood 
handle. From there flex tubing gets it to the tuyre (sp?) about 6" away.

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

>Daryl Bender wrote
>
>I can tell you how to make a supply (I have a 24Vdc motor on my forge)
>but unless you know a surplus electronics store it will cost a few
>bucks. Otherwise it's battery city.
>
>Cheers
>Daryl
>
>Daryl  I would like to Know the amperage of your 24v Power supply?
>Also Are you able to Email me with acircuit diagram And a parts list.
>
>Regards Colin Morton
>

---

From: Colin Morton <[email-masked]>
Date: Wed, 14 Aug 1996 10:58:11 +1000

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