Motorising the mill

[James P]

My dearest father in law has handed over an exceptionally old steel drill which runs at 500rpm and if it gets stuck, will throw you.... hard.... so I guess it has enough torque to run as a mill motor.

Now I want to reduce the rpms to between 150 and 250, however I'm having no luck finding a supplier that provides pulleys (v or similar) with a 3/8ths bore which is the drive shaft size my mill came with.

Does anyone have any ideas or contacts as I have to go from here?

[James P]

To be honest crabbey I have no idea... all the literature I can find has mills running at 150 ish. Northern Brewer say just run it at 500rpm on their website. I should experience to see what the crush is like, and check it's not ripping the husks then.

Looks like I will have to get a 3/8ths to 1/2 inch bushing if I want to use pulleys....

[Horace]

I ran mine off a variable speed drill for a while - worked alright just holding the drill also had it set up with saddle clamps holding the drill. That was OK but awkward plugging and unplugging the drill for start/ stop.

Now have electric motor driving it with pulleys. 3/8" - 1/2" bushing works well. Just clean well and use Loctite. Leave to set for the required time. Will hold very well for rotational force without the need for grub screws.

TradeZone is a great place to go for that sort of thing. Atleast up here.

These are the guys in CHCH:
TradeZone
George Henry & Co
47 Manchester Street
ph 03 366 5186
www.georgehenry.co.nz

[James P]

Cheers Horace, I'll take a look at george henry.

Alternatively I was going to look at an assembly to push the trigger in slowly via a wheel to achieve gradual speed increases. I'm no engineer though, so I can see that going pear shaped really early! :)

(Best to stick to the tried and true methods.)

[Steve Baker]

I'm thinking of doing this too. These guys have the pulleys, now I need to get some bush:
http://www.johnbrooks.co.nz/?action=products&type1=V%20Belts/Pu...

[Nick T]

If anyone is still doing this, I have just been to John Brooks here in Chch, two pulleys at 1:8 ratio (12 inch and a 1.5 inch) was about $130 ish.(I need to reduce down from 1400 RPM, Monster recommend 150 - 250 RPM). If you have a slower motor to start with then your costs should be quite a bit less as you won't need sucha 'monster' pulley. I have just dropped the larger pulley off at a machine shop in Sockburn that was recommended to me, to get a sleeve put in it (half inch bores are the smallest you can get for pulleys it seems) and redrilled for the grub screw, will let you know what that costs. Second hand pulleys do not seem to be a big feature item on Trademe!

In retrospect, should have purchased the half inch shaft for the mill, didn't realise the significance of this until it was here. No need for a sleeve, and not the same risk of the shaft either bending under the weight of the large pulley, or being over-torqued!

[Steve Baker]

I'm still tinkering away. I've scored a free dryer and am currently trying to resurrect the 1/6hp motor inside it. The motor has a 1/2" shaft.

I'm thinking of getting these pulleys:
http://blmarshall.co.nz/shop.php/-general-hardware/aluminium-v-pull...

What kind of bore do your pulleys have? I called John Brooks and they seemed to imply that they were tapered.

[Nick T]

Hi Steve, they are straight bores, with a grub screw through them to tighten down onto the shaft. From my reading of the Monster Mill page, you will need a capacitior start motor of at least 1/4 HP (I got a secondhand 1 HP motor, although I was looking for 0.5 - 0.75HP at the time). http://www.monsterbrewinghardware.com/faq.html#q6 The pulleys on the blmashall page seem to come in packs of 10, and only up to 6 inch? I guess if your motor is running at about 800 - 1000rpm then you will be OK on this count.

[Steve Baker]

I thought the packs of 10 were only for delivery of stock to hardware stores - I could have misinterpreted it though.

I'm aiming for a 1:3 ratio to bring the rpm down to 475rpm. Apparently the Barley Crusher Malt Mill will run at 500rpm. So a 2" and 6" pulley should do it.