I made a mill

[Matplat]

Wassup peeps... check it out, I made a mill! #stoked

I made the rollers from 6"NB pipe which works out to 139mm OD in real money, and they are 150mm wide.

The motor i was given to me and its 0.37Kw 2800rpm, it turns a 1 1/2" pulley stepped up to a 14" pulley which means the rollers should be doing 300ish rpm.

I got a mate to knurl the drive roller (I left the slave roller smooth), and I told him to do it quite light as the rollers are bigger than most homebrew mills. Originally i wasnt going to knurl them at all... when I saw what he did, I thought it was too fine and would get caked up and stop drawing the grain through, but it seems fine so far.

I set it first at 1mm gap, but it seemed like it ripped the husks too fine, so I knocked it back to 1.3mm which seems alot better, opinions appreciated. I will post the 1.3mm photo in the next post so you know which is which.

 

[Matplat]

1.3mm gap crush sample.

Oh yeah, I dunno if it makes much difference, but both these test samples were done using some spec malt rather than base malt.

 

[blotto]

Seems to me like your still doing a bit of damage. I wonder if having such a large heavy idle roller is causing a lot of tearing. I have heard of people putting an o ring on one or both of the rollers to get the second one turning. If you give that a go it might then pull your grain through nice and gentle .

Edit: fantastic job though!

 

[Maheel]

is it just "pipe" and you made centers and got them nicely centered?
if yes how did you center it for the ends etc?
what sort of "pipe" is it etc.

eg weld on the end rods onto flat plate and lathe it for the pipe or something ?


i have a workshop full of the right tooling but have never seen any "free" solid rod big enough to play with....

 

[MickGC]

Looks awesome mate!
one thought, having rollers with such a large diameter, you may need to slow them down a fair bit,
i have a kegking 2 roller, and it is recomended to run at 180 RPM,
with rollers approx 30mm Dia@180 rpm it gives a surface speed of 28cm/Sec
with your 139 Dia rollers@300rpm you have a surface speed of 219cm/Sec

could be worth a shot if you can find a way to try running a slower speed, might not rip the grain so much
The calculator i used says 39 rpm would give a surface speed of 28cm/Sec

http://www.onlineconversion.com/wheel_surface_speed.htm
this was the calculator i used for surface speed.

I could also be completely wrong and it not work at all

 

[Matplat]

Yeah its just 6"NB medium wall pipe, so wall thickness was approx 4-5mm. I used 1"round bar for the axle, then cut appropriately sized discs to fit inside the ends of the pipe.

Weld the discs to the shaft, turn down the outside so its centered, slide the pipe over the discs, weld the pipe in place then turn the outside down until its all concentric.

 

[Benn]

Nice job Matplat,

 

[Matplat]

Yeah, I wondered if it might be going a bit quick... I will give a brew a go, keep some rice hulls on hand and see how the efficiency fairs!

 

[Benn]

Keep us posted mate, I'm in the process of building a mill too. Rollers are 150mm cast iron industrial bearing things for moving steel beams around factory floors or something. Apparently they're just about un-knurlable but a steel guy is putting them in a machine that will cut an even spacing of fine 'V' grooves around the circumference.

 

[Danscraftbeer]

Wow. Too many questions to ask.
This gives me a feeling that my standard cordless drill mill will inevitably fail me someday and I will look back on this. B)

 

[Weizguy]

Nice engineering!

I thought that the grist pictured above was a bit torn up, and believe the 300 rpm will do that. I have 60 mm rollers and find that hand-cranking at about 100 rpm (approx) does it right, with lots of cracked grain that break apart when touched, and little husk tearing.
You got some big rollers and a lot of surface speed. Some research is in order to maximise your milling. I think you may need to slow it down quite a bit to get the best efficiency.

Was also thinking it's fine if you Brew in a Bag, but then again I don't, so I cant't be certain.

Your project has begun. Good luck with fine tuning.

 

[Weizguy]

Keep us posted mate, I'm in the process of building a mill too. Rollers are 150mm cast iron industrial bearing things for moving steel beams around factory floors or something. Apparently they're just about un-knurlable but a steel guy is putting them in a machine that will cut an even spacing of fine 'V' grooves around the circumference.

IIRC, larger rollers fare better without a knurl, as they can grip and pull the grains through easier due to the angle between the rollers. I've been reading a lot about grain mills recently, in order to work out if I need to motorise my mill.

I think I can cope with hand-cranking a few more years until the arms get weak. I'm really happy with around 90% efficiency (combination of milling and sparge technique). Testify!

 

[rude]

I made one years ago & power it with a windscreen wiper motor
Not sure of the speed but pretty slow

Might be an option for you to try

Forget my gap but its large 1.4mm ? 50mm rollers

 

[Benn]

How's the windscreen wiper motor go for torque? I would have thought it would burn out. I'd considered using one but found a big 240v thinking a ww motor wouldn't handle the load.

 

[Weizguy]

Forgive me for butting in again, but DC motors provide far more torque than AC. Maybe read through 33 pages of the Mill Motors thread to get more info.

http://aussiehomebrewer.com/topic/44766-mill-motors/ (* edited to add the link)

 

[Benn]

There's a 33 page mill motor thread?!!
..I'm chuckin a sickie tomorrow!

The compactness of a ww motor would be ideal, and there's not a massive belt n pulley for me to tangled in,

 

[Matplat]

Damn... guess I should have given it a go without knurling first. Lesson learned for you Benn... If the grain husks are damaged too much, is there a risk of tannin extraction? Or more just a stuck mash?

I brew on a 1v recirc, bigW malt pipe...

Considering I got the motor free, I could afford to get a new one at 1400rpm and use the current gearing. As I understand it, you can't slow down AC motors with a speed controller as the current draw goes up and it overheats.

Otherwise i might need a lay shaft to step the gearing down again... but that's getting a bit bloody complicated and expensive.

I will try opening the gap a fraction more to see how it goes.

 

[Benn]

You could change your pulley sizes to slow the roller speed, from what I've heard it's best to run with a small pulley on the motor so it's not working too hard but it all depends on the load I guess. Maybe you could get away with a slightly larger pulley at the motor end if your still getting a dodgy crush after gap adjustments are made.

 

[Matplat]

Yeah I would need a smaller pulley than what I already have on the motor... at the moment it is 1 1/2" on the motor and 14" on the roller I think 1 1/4" is the smallest you can get, which gets me down to 250rpm... but I think I may do that as well as halve the motor speed...

 

[Topher]

Good work. Mad skills! You made an entire mill!

Compared to me who spent 30mins swearing while cutting a hole in a bucket to make a hopper.