Drum Roaster driveline for BREWERY

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  #1  
Old 10-28-11, 11:08 AM
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Drum Roaster driveline for BREWERY

Hey all,

We've got an old 1/6 hp blower motor, scavenged from our brewery's old heating system. I'd like to use this motor to drive a drum roaster.

As near as I can tell, we're going to need about 220.5 lb-inches of torque at axis to turn the loaded drum. Also, we'd ideally be able to adjust the speed, anywhere between 30-120 rpm.



How might we be able to accomplish this? I was thinking we'd be able to use a potentiometer to control the motor's speed, and a big step-down pulley/sprocket linkage to get the thing rolling. I'm not exactly an EE. . . Any thoughts?

THANKS!
 
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  #2  
Old 10-28-11, 12:19 PM
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Does the motor you want to use say it's rpm? Many turn at 1'075 rpm though I have seen some as fast as 3'000. The type of motor may be helpful to others coming up with a way of making it variable speed.

I have had good luck finding cheap Zero Max gearboxes on online auction sites. There are a lot of home brewers looking for motors and especially variable speed ones in the size you need, but many people don't know about the Zero Max gearboxes. They are often sold with a 10:1 reduction 90 degree output that drops the rpm below the useful range for a grain crusher but the 90 degree gearbox is an easily removed assembly. If you can find one with the 90 degree gearbox in place you have a good chance of getting it really, really cheap and it's perfect for what you want. Infinitely variable rpm with full torque at all speeds and built in torque limiting.

If you want to stick with your existing motor you're going to need about 10:1 reduction which will get the RPM down where you want it and increase the torque by a factor of 10. You can do it with a chain drive or belt & pulleys. You want the big pulley or sprocket on the drum of the roaster and it needs to be 10x the size of the smaller one on the motor. Everything is exposed so make sure you guard it. The exposed belt/chain and pulleys/sprockets can draw in loose clothing & fingers and makes a nasty mess.

Another option is to find an old but working transmission from a small lawn mower. The input shaft of the transmission would somehow connect to your motor while the drum roaster connects where a wheel used to be.
 
  #3  
Old 10-31-11, 11:51 AM
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Originally Posted by jdallas View Post
I was thinking we'd be able to use a potentiometer to control the motor's speed, and a big step-down pulley/sprocket linkage to get the thing rolling.
A potentiometer will not control the speed of a motor. It will burn it up. You need a variable frequency drive (VFD) controller to reduce the motor speed electronically which is more than likely going to be out of your price range on the project. You'll have much better luck either buying a used multi-speed motor on Craigslist or similar scrap dealer or rigging up a mechanical transmission with pulleys or gears to reduce the speed.
 
  #4  
Old 11-01-11, 08:42 AM
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Thanks guys for your input.

As for this motor's rpm, it's listed at 1725. If I were to run a series of step-down pulleys maybe it would get the drum's rotation down to a reasonable speed, but I'm liking the sound of the zero-max drives.

One aspect of using a variable speed drive (ala zero-max) that sounds appealing is having a clutch. IF i were to go the route of direct drive (ala step-down pulleys), am I going to burn out my motor? I'm envisioning having to give the drum a push before the motor will be able to turn it over. Any thoughts?

Thanks again for the tips thus far.
 
  #5  
Old 11-01-11, 09:38 AM
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Originally Posted by jdallas View Post
IF i were to go the route of direct drive (ala step-down pulleys), am I going to burn out my motor? I'm envisioning having to give the drum a push before the motor will be able to turn it over. Any thoughts?
I think it should be able to start the drum turning. You can't really know for certain without a rigorous engineering analysis or rigging up a real world test.

Thanks again for the tips thus far.
I'll let you know where to send a couple 12 packs.
 
  #6  
Old 11-01-11, 10:12 AM
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It's hard to say for certain but I think your 1/6 hp motor would be able to start turning your drum since you'll have to reduce it about 15:1 and especially if you started the drum turning before loading it with product.

With the Zero-Max if you do overload your drum or jam it then the gear box will make a noticeable, loud clicking. Sort of a built in alarm. The key is finding one cheap since they are an expensive bit of machinery. The straight ones seem to bring a higher price on eBay while the ones with the 90 degree output can be sometimes found dirt cheap.
 
  #7  
Old 11-01-11, 12:29 PM
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A potentiometer will not control the speed of a motor. It will burn it up.
Looking around at different ways to accomplish some kind of variable speed, I've seen rheostats being used to control speed for routers, fans, etc. Would a rheostat burn out my motor too, or is this problem only something specific to a pot's design?

And twelve packs? If you guys make it out here to Portland you'd better bring an extra suitcase that can handle a half-barrel!
 
  #8  
Old 11-01-11, 12:41 PM
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Drum Roaster driveline for BREWERY

Needed to repost this original message. . . sorry for the confusion!

Hey all,

We've got an old 1/6 hp blower motor, scavenged from our brewery's old heating system. I'd like to use this motor to drive a drum roaster.

As near as I can tell, we're going to need about 220.5 lb-inches of torque at axis to turn the loaded drum. Also, we'd ideally be able to adjust the speed, anywhere between 30-120 rpm.



How might we be able to accomplish this? I was thinking we'd be able to use a potentiometer to control the motor's speed, and a big step-down pulley/sprocket linkage to get the thing rolling. I'm not exactly an EE. . . Any thoughts?

THANKS!
 
  #9  
Old 11-01-11, 12:58 PM
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Originally Posted by jdallas View Post
Looking around at different ways to accomplish some kind of variable speed, I've seen rheostats being used to control speed for routers, fans, etc. Would a rheostat burn out my motor too, or is this problem only something specific to a pot's design?
It's specific to the motor design. A DC (direct current) motor can be speed controlled using a simple potentiometer or rheostat. High RPM universal motors (routers, drink blenders, etc) can be controlled with a simple dimmer too. For other AC motors you need to know exactly what kind of motor it is, how it was wound, and what taps you have available in the wiring compartment. If Furd chimes in he knows a lot in this area and might be able to recommend something better than I could.

And twelve packs? If you guys make it out here to Portland you'd better bring an extra suitcase that can handle a half-barrel!
Haha, my wife might get suspicious when I bring a 100 lb. suitcase and wear the same shirt all week.
 
  #10  
Old 11-01-11, 01:31 PM
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What's the outer diameter of your roasting drum. The 15:1 ratio might be easiest to do with chain by wrapping the chain around the outer circumference of your drum and around the sprocket on the motor shaft. In some cases the friction of the chain against the drum is enough to prevent it from slipping.
 
  #11  
Old 11-01-11, 05:44 PM
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If Furd chimes in he knows a lot in this area and might be able to recommend something better than I could.
I don't know if that is true but I'll ad my nickel's worth. I have not read the entire thread in detail so I might be missing some important parts.

If you do a roughly 15:1 reduction almost any cheap surplus motor will have sufficient torque to start the drum rolling, especially if it is empty when starting. Once you get it rolling it won't take much to keep it rolling. I would more likely as not use a double reduction rubber band (aka V-belts) drive rather than chain or transmission as it will be less expensive and less prone to abnormal wear if the alignment isn't exact.

If you need variable speed control then I would seriously look into surplus direct current (DC) motors. New DC motors cost an arm and a leg whereas surplus motors are only an ankle or wrist. There are generally two voltages available, industrial equipment at about 90 volts and military equipment at 24 volts. If you can find a 24 volt motor of the required size you will save a considerable amount of money. There are also 24 volt DC gearmotors available that might be even better for you r needs. Google is your friend when looking for surplus.

Variable speed drives (electronic devices) are available for the smaller AC motors "relatively" cheap but still more than $100. There are 24 volt DC drives available to control the surplus military motors for around $50 if I correctly recall. You CAN use a BIG rheostat or several low-ohm resistors to give some manner of speed control on the DC motors fairly inexpensively.
 
  #12  
Old 11-08-11, 10:25 AM
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Thanks all for the input! I had a eureka! moment the other night when I was loading laundry into the dryer. . . which is suspiciously similar to a drum roaster. Sooo got an old dryer off CL for a couple bucks. Time control, 1/3 hp motor, mounting brackets, idler pulley, etc. all in one convenient little package.

Our plan is to run a couple step-down pulleys. Hopefully it will work out! I'll be sure to post up some pics of the finished product (drum roaster, i mean, not beer. although maybe beer too)

Thanks again.
- j
 
  #13  
Old 11-08-11, 12:08 PM
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Glad to hear you are thinking outside the box.

What are you roasting? Are you malting your own grains?
 
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