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Mill motorizing help needed.

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Plan9

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I'm trying to motorize my Crankandstein mill.
I have a 1/2" 550 rpm drill. I sized a belt and pulleys to step it down to 180 rpm.
I got everything put together and started to test it out.
It's running fine, speed looks good. Drop a little grain in, looks good.
Drop a handfull of grain in, mill binds, drill keeps spinning.
I've tried loosening and tightening the belt, it just spins when a fair amount of grain is in.
I widened the gap, with the same result.

I've hooked the drill directly to the mill and there is no stopping it. The speed is just too fast.

I would prefer to use the pulleys, is there something I'm overlooking to stop the spinning?
 

Fletch

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What are the sizes of your sheaves (proper name for "pulleys" used in belt drives)?
 
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Plan9

Plan9

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1.5" on the drill, and i think it's a 3" on the mill.
 

Fletch

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Yeah, you've got the smallest possible drive sheave. I'm guessing it's the drive sheave that slips? Switch to larger sheaves, but keeping the same ratio. Larger sheaves = more contact area between belt and sheave = more friction = less likelihood of slippage. Also, your belt tension probably isn't high enough. Push against the belt midway between the sheaves - if they're 12" apart or less, you should barely be able to move the belt.
BTW, the Crankandsteins can be run at 250-300 rpm with no problems.
 
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Plan9

Plan9

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Yeah, I'll probably move the 3.5" to the drive, and pick up new belt and a 8" for the mill.
 

Cliff897

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Use moisture to condition your grains the night before. Then speed will be much less of an issue
 

BrewBeemer

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Have you looked into a HTD belt drive system instead? Use it with a short jackshaft suported by a couple cheap pillow bearings with the drill motor on one end of the jackshaft. At the other end a sprocket plus your speed ratio reduction sprocket on the mill with a HTD belt drive. This is a more positive drive without adding extra side loading to the mills 841 oilite bushings.
Check below, sprockets, belt and pillow bearings are cheap from a good bearing supply house. A 25.4mm or 1" wide belt will handle 100# working load, 226# breaking strength per 1/8" of width. Clean, strong, no slipping or oil and wear of a chain drive.
http://www.sdp-si.com/D795/79501012.pdf
 
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Plan9

Plan9

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I think a jackshaft may be overkill with the small speed reduction I'm doing here.
Most guys motorizing mills are stepping down from a few thousand rpm.

I do like the idea of the pillow bearing. I'll probably use a longer shaft with the drill, and support the end with the bearing. That will help keep it lined up.

I'm also going to step up from a 3L to a 4L belt. I think that was a little undersized.
 

BrewBeemer

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I think a jackshaft may be overkill with the small speed reduction I'm doing here.
Most guys motorizing mills are stepping down from a few thousand rpm.

I do like the idea of the pillow bearing. I'll probably use a longer shaft with the drill, and support the end with the bearing. That will help keep it lined up.

I'm also going to step up from a 3L to a 4L belt. I think that was a little undersized.
The added jackshaft was for two reasons, 1st to maintain belt tension in a fixed position, 2nd was to allow the drill motor to be mounted or be supported by the jackshaft. Simple, takes care of two problems plus a HTD belt drive instead for less belt tension on the mills bushing for a longer life.
 
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Plan9

Plan9

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When you mentioned a jackshaft, I pictured a 2 belt system with 4 sheaves. A double stepdown system.
That would have been overkill. :D
 
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