I use a bouncy castle blower on my portable forge, air flow is controlled by a 2" ball valve on the discharge. It works fine but I'm wondering if I could control the motor speed with like a light dimmer switch or similar? Would it knacker the blower motor if it was continually running below it's designed speed?
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hotponyshoes
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I would keep going with the ball valve or get a gate valve.
I have messed about with a few stepped controls on forges and none of them react fast enough.
Especially when the bosch gets blocked up with clinker, you want to be able to give it some short sharp blasts to clear it out and an electronic control just wont do it.
The motors also seem to last longer if you run them at full power constantly as well.
I have messed about with a few stepped controls on forges and none of them react fast enough.
Especially when the bosch gets blocked up with clinker, you want to be able to give it some short sharp blasts to clear it out and an electronic control just wont do it.
The motors also seem to last longer if you run them at full power constantly as well.
brightspark
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why do you need a speed controll or a bypass . the motor will still run at full speed with the outlet shut off . it will spin the air in the fan and actualy use less power to run it than freeflow as that has to push the air along the tube 
i did do a test on my woodchip blower using a clamp meter. running it fully blocked it ran at half an amp less . it takes more power to move air along a pipe than circulate it. if you have half an hour read on it tells you the technical version of it and how it works Fan Calculator (Axial & Centrifugal) | pressure & flow | CalQlata
i did do a test on my woodchip blower using a clamp meter. running it fully blocked it ran at half an amp less . it takes more power to move air along a pipe than circulate it. if you have half an hour read on it tells you the technical version of it and how it works Fan Calculator (Axial & Centrifugal) | pressure & flow | CalQlataYep, @brightspark has it right. Furthermore, i don't think pwm works with induction motors, but that's something in my head, I've never tried it. Actually, it sounds right, induction motor speed is set by the frequency, pwm just chops the sinewave, it doesn't change the frequency.why do you need a speed controll or a bypass . the motor will still run at full speed with the outlet shut off . it will spin the air in the fan and actualy use less power to run it than freeflow as that has to push the air along the tube
Brad93
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What about heat build up is that not an issue?why do you need a speed controll or a bypass . the motor will still run at full speed with the outlet shut off . it will spin the air in the fan and actualy use less power to run it than freeflow as that has to push the air along the tube
the artfull-codger
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As BS says if you shut the air off it uses less power, I have a yellow bouncy castle blower for my coke fired foundry furnace, & on the circular inlet I just cut a circular piece of 3mm alloy big enough to cover the inlet with a lug to bolt it on with a spring to hold it in any position from fully closed to fully open & just slide it open to the amount you want to blow to, no fan**ing about or expense making electronic controls etc, can't beat the "kis method" ie keep it simple !! '& it works a treat.
Same question, same responses, in an earlier thread:
Bouncy Castle blower on a speed controller?
Hair brain idea to build our own forge and use a bouncy castle/snail blower to move the air, mainly because I have three and they’re £5 each or free. Little experience with speed controllers on fans, so would be interested to hear if it would at all be possible to add a plug in speed controller...
www.mig-welding.co.uk
Thanks fellas, It's ok as it is. I use a ball valve rather than a gate valve as it's open or closed with just a quarter of a turn on a long handle behind the forge. As I only use maybe 50% of the air from the blower I thought I could maybe slow the motor or, have it just ticking over to keep the fire lit. Not a problem, I can keep it lit with a piece of wood as always.
brightspark
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not for the motor its seperate from the fan
