Pulley Setup For Grain Mill Help!?

[komodo]

Guys,

Im looking to run my monster mill MM3 grainmill off a motor using a pulley setup.
The motor I am looking at using is a 1/2hp (0.37KW) capacitor start motor with a 5/8 drive shaft which spins @ 1425 RPM
the smallest pulley I can get for such shaft is 1.25" and I wanted to try to keep the pulley on the MM3 to 10" or less if possible. So 1425/10*1.25= 178RPM at the mill. Cool were close to 200 RPM and between the suggested 150 - 250 RPM monster mill recommend.

Next what size pulley? well I dont want too bit of a pulley so lets go for 12" center to center

cool all set - lets punch it into a calculator to work out belt length http://www.csgnetwork.com/pulleybeltcalc.html ok so 44" belt should be mickey mouse - hold on 138 deg belt wrap? is that going to have enough grip to drive the loaded mill?
Am I doing this right? is 138 degrees of wrap enough ?

Do i need to go a bigger set up pulleys? but isnt that going to end up with the same problem? Do i need to space the pulleys further appart - ie longer belt? but wont that be more likely to jump off ?

advice from people in the know or people who have motorised their mills in the past would be appreciated.

Regards,
Komodo

 

[glaab]

just did this excercise. long story short, was recommended to have 17" centre to centre but my pulleys are 12" and 1.75", yours shouldnt be much different. as long as you align them with a straightedge when you mount it all you shouldnt have any probs with it jumping off. :icon_cheers:

 

[komodo]

Awesome glab. Looks like I dont fully understand wrap angle properly. Either way I typed in your pulley sizes and distance and compared the results to mine and the difference less than 6 degrees (138 for me Vs 144 for yours) I dont think im going to have a drama with my desired setup. Phew.

That said I think I have worked out the wrap angle - I think (and I'm happy to be corrected) that the angle specified is the point the belt wraps too from the depature point from the input plain not actually how much it wraps around which is why I kept thinking 138 degrees was going to give me heaps of belt slip. ie I though I would be with an opening of 138 degrees when in reality its 42 degrees - 180 degrees less 138 = 42.

 

[fergi]

just did this excercise. long story short, was recommended to have 17" centre to centre but my pulleys are 12" and 1.75", yours shouldnt be much different. as long as you align them with a straightedge when you mount it all you shouldnt have any probs with it jumping off. :icon_cheers:

View attachment 33167

wow nice bit of bling glaab, very neat mate.
fergi

 

[komodo]

Glaab what size motor are you running?

 

[glaab]

thnx fergi, still gotta paint it and add belt guard and bigger hopper.
Komodo, the motor is 3/4hp IIRC, mill does 132rspm. 12" centre to centre sounds a bit close to me, it might be easier to get your belt tension right if you made it more like 16". Cheers :icon_cheers:

 

[komodo]

Cheers for the tips Glaab. Think I'll order the pulleys tomorrow and build a bench and hopper and wait to work out pulley length once I've done all that.

 

[Andyd]

Another way to shroud and enclose it all...

http://www.aussiehomebrewer.com/forum//ind...mp;hl=rainy+day

My motor's off an old bench press, with a 1.5" minor pulley and a 12" major... works a treat!

Andy

 

[warrenlw63]

Could be difficult to explain but here's what I did. Just mounted the motor to a hinged board... Then the weight of the motor acts as tension on the belt. No slipping (touch wood).

FWIW I went 12" on the mill and 1.5" on the motor. Motor is 1425rpm. From memory I'm getting around 150rpm but who's counting? Seems to work.

Warren -