Mill Motors

[bcp]

"The best speed to run all of the drill driven mills at is around 150-250 rpms. Does it have to be exactly 200 rpms? NO WAY. A range of 100-300 is fine, and if you are willing to have a little more flour, then you can run it a little faster. I generally tell folks to run it as slowly as your drill will run it without stalling plus a little more. It usually takes a little more torque to get the mill going than to keep it going, so you will have to give it some more power to start the mill, and then slow it down once you are milling. You should experiment with faster/slower speeds and see what it does to your grain."

http://www.monsterbrewinghardware.com/faq.html

 

[Sammus]

that's all well and good, but remember in the commonly used mills here the roller diameters vary between 1.5" and over 2.5" for the millmaster... that's going to give a substantial increase in the surface velocity of the roller. 300rpm on a crankanstein is fine, 300rpm on a millmaster is equivalent to more than 500rpm on the crankanstein, which is getting a bit too quick.

 

[motiondynamics]

Ok, heres how I see it... I figure you need at *least* 350-400 watts, 180 RPM and between 13-17Nm of torque, the shaft size according to the specs is either 1/2" for the millmasher or 3/4" for the monster mill or 3/8 for the Crankenstien, so the coupling link must accommodate all the different mills so its probably easier to source the coupling on one side to suit the motor and the other in a small size so I can have them drilled out locally depending on the shaft size of the particular mill (which you would have to specify). You'd need a gearbox. You can't get away without one because the rpm would be too high and the torque would be too low.

For DC its going to be cheap and easy, probably around ~$110 for the geared motor and coupler, which will be either the same as or similar to Oatleys 450w model (Depending on what quality you want), but with changed gearing to suit mills rather than scooters/bikes, so 180 RPM and about 1Nm extra torque, (minus power supply). The main reason this style of geared motor is inexpensive is simply because theres an abundance of these type of motors being manufactured for motorized scooters and ebikes which are very popular, so the more manufacturers the cheaper the price becomes but the lower the quality gets.

For AC its going to be a lot more, the main reason being that for AC the gearboxes boost the cost dramatically.

The cost for the AC option will be around ~$330 inc GST and for the GPG motor and a 7.5:1 gearbox and a coupler. The combo is very high quality with reliability that will probably outlast all of us. You could also run the mill 24/7 if you wished. Its a very very cheap price for the motor and gearbox, but it'd definitely be a one off because I'd have to buy 150 of the same motor with the same ratio to get them cheap enough to sell them that low (look at the 120w on my website with a 7.5:1 gearbox! its $275, lower quality and I'm also the cheapest in Australia)

So I'd have stock for years to come (though normally that particular combo would retail for around $460 if I was to buy my usual qty's).


Failing that I could search for something cheaper again in the AC as I don't doubt theres cheaper out there, but what type of quality do you want?

 

[razz]

You've got me interested motiondynamics. Do you have a particular coupler in mind?

 

[Sammus]

I got one of these a while ago, and a 10" and 1.25" aluminium A-section pulley and belt for $50 or $80 or something. Gives me 920/8 = 115pm, and cost about $300 all up give or take. Works like a charm. I'm guessing your AC quote is slightly more due to using proper gears instead of pulley reduction?

FWIW had you been around when I motorised mine, I would've jumped on the chance to do it with gears instead, but the only options then that I could find were in the $500+ range, and thats before you even thinking about coupling it to a nonstandard 12mm shaft.

 

[motiondynamics]

Well... theres a few ways to mount these... I'm not at all familiar with milling tables so forgive my ignorance, but the coupler would probably have to be an anti-shock, not so much for the motor but for the mill itself. The motor has torque, so you don't want that initial torque shock to break the mill shaft when you flick the power switch, (you'll get metal flakes in your beer)

The mill specs posted earlier made it look like a small tabletop unit, so I figure you could either turn it into a table and mount the motor underneath with belts or chain or if you aren't that adventurous you could connect the motor straight onto the end of the shaft via the coupler when you need to use it. Though you'd have to have the motor mounted to something or it would literally take off and if it twisted it could potentially damage the mill because the mill would bend and break before the motor does.

But I don't know enough about the mills themselves to really give the best advice here, but for my money, some sort of quick connect coupler would seem to be the most suitable for easy connect/disconnect/storage/convenience.

 

[motiondynamics]

Hi Sammus,

I'm actually hoping I can do them a little cheaper again, but for a straight motor with pulleys for $300.... well... you got shafted (motor joke there) haha.. The motors are cheap... its the gearboxes that add the cost. And believe me when I say, you wont find a better motor and gearbox cheaper anywhere, period.

 

[Sammus]

Hi Sammus,

I'm actually hoping I can do them a little cheaper again, but for a straight motor with pulleys for $300.... well... you got shafted (motor joke there) haha.. The motors are cheap... its the gearboxes that add the cost. And believe me when I say, you wont find a better motor and gearbox cheaper anywhere, period.

Well, I was happy with it, considering the 10 million power tranmission suppliers I rang quoted me over $600 for anything similar (920rpm around 500W) - claiming they were rare and never used and blah blah blah so would have to be a one off import. Then I saw it on ebay for $240 I was stoked haha. If you reckon I got shafted mate I wish youd been around then to get it for me cheaper

 

[motiondynamics]

They are actually rare if you don't have a gearbox and you just need the motor. As I mentioned earlier for most applications they run too fast and have virtually no torque so for pretty much anything except maybe expensive fans or (people wanting to make their own gears) they are pretty useless.

But depending on the responses received here and the interest, I can always go out and find something cheaper again in the AC if people don't want to spend too much.
At the end of the day it's ultimately what the customer wants.

 

[warra48]

What sort of battery or power supply would we use to run a DC motor?

I have a battery which runs my walk behind MGI brand golf buggy. Would that do it? If it would, I already have the charger as well, of course.

 

[motiondynamics]

What sort of battery or power supply would we use to run a DC motor?

I have a battery which runs my walk behind MGI brand golf buggy. Would that do it? If it would, I already have the charger as well, of course.

Well, it depends on what sort of motor I can find, but it'll probably be a 24Volt motor.

Your buggy will either use 12v/24 or rarely 36 Volt, so you'd really have to be more specific about the voltage

 

[warra48]

Well, it depends on what sort of motor I can find, but it'll probably be a 24Volt motor.

Your buggy will either use 12v/24 or rarely 36 Volt, so you'd really have to be more specific about the voltage

It's a 12v battery.
It has enough charge to propel my buggy over two 18 hole rounds on a single recharge.
The charger output seems to be noted as 3.5 amps (don't quite know what it means, my eyes glaze over with technical electrical details).

 

[motiondynamics]

It's a 12v battery.
It has enough charge to propel my buggy over two 18 hole rounds on a single recharge.
The charger output seems to be noted as 3.5 amps (don't quite know what it means, my eyes glaze over with technical electrical details).

Too small, it'll run the DC 24 motor but at half the rated speed and torque. Thats the problem with DC, not everyone has the batteries or the know how to set everything up. The charger output of 3.5 amps just means it charges the batteries a little faster.

 

[glaab]

Hi Sammus,

I'm actually hoping I can do them a little cheaper again, but for a straight motor with pulleys for $300.... well... you got shafted (motor joke there) haha.. The motors are cheap... its the gearboxes that add the cost. And believe me when I say, you wont find a better motor and gearbox cheaper anywhere, period.

How do you work out sammus got shafted spending $300 when you want $330?
If motors are so cheap then sell the guys some cheap motors, who needs a gearbox, stick some pulleys and a belt on it.
I got one of these from royce cross for $150, they were flexible when I walked in and paid cash

http://www.roycecross.com.au/product_list/...le&Variable[ProductCodeID]=S-37B6CREMX

 

[Back Yard Brewer]

Slower speed and higher torque is the go, if it runs to fast it wont actually crush the grain, just tear it to pieces . 200Rpm is a good starting point

Mills need lots of torque at startup,

This is one theory that I will be testing shortly.
My previous mill was an old "Valley Mill" that I used my trusty drill on to mill my grain. Nice and slow. My efficiency was on average around the 80% mark. I now have a ball busting millmaster that is motorised at around 200rpm. Now with out getting into a debate / pissing contest I am a herms brewer who circs constantly for the entire mash process. I now struggle to achieve more than 70%. I as others "may" agree, tend to think that my mill rips the grain instead of just cracking it. I also now find since using the the faster cracking speed of my millmaster that during circulation my flow tends to slow down. If I scrape the FB with my paddle it then returns to what the "normal" flow was. Again my issue is based on practical fact. My brewing process's have not altered other than the changing of what mill I am now using and at what speed I crush at. I have tried widening the gap on my millmaster but can't seem to get the happy medium I am looking for.
A fellow brewer locally has a millmaster with a direct drive motor than runs at around 100rpm. This week-end I will be brewing and intend taking my grain to his mill to test my theory. Will see if I can remember to report back. Nowadays I tend to lurk and this post may get buried in the archives unless I check my previous posts.

How do you work out sammus got shafted spending $300 when you want $330?
If motors are so cheap then sell the guys some cheap motors, who needs a gearbox, stick some pulleys and a belt on it.
I got one of these from royce cross for $150, they were flexible when I walked in and paid cash

http://www.roycecross.com.au/product_list/...le&Variable[ProductCodeID]=S-37B6CREMX

Exactly the same place I bought mine. Delivered for $135 including a 3" drive pulley which I may change to a 1.5" to reduce my rpm.




BYB

 

[motiondynamics]

How do you work out sammus got shafted spending $300 when you want $330?
If motors are so cheap then sell the guys some cheap motors, who needs a gearbox, stick some pulleys and a belt on it.
I got one of these from royce cross for $150, they were flexible when I walked in and paid cash

http://www.roycecross.com.au/product_list/...le&Variable[ProductCodeID]=S-37B6CREMX

Hi Glaab,

The shafted bit was a motor joke (ie motor shaft). And to pay $300 for a straight shaft motor and a few pulleys isn't the best value (as you mentioned you got it much cheaper), nor is it the best option for the longevity and reliability of your setup.

The reasons I didn't put that forth as a suggestion was quite simple! Please let me explain.

A) Its always a hassle chasing around getting the right pulleys or gears that you require to run your mill at the best speed for your particular brew.
B) You need to either get a custom short belt or chain prepared at the proper length or if you cannot get the correct length you'll need to get a longer one and move the motor further away which reduces efficiency, reliability and requires additional tension between the pulleys.
C) You need to tension the pulley which is an extremely bad idea for the radial load on both the motor bearings and the mill bearings, excessive side (radial) loads are never good for bearings unless specifically designed for it.
D) The loss through the belt is much greater than you might think, adding greatly to the operating costs.
E) Its not so simple for a beginner to get it all setup and working and most people these days prefer a simple setup with reliability.
F) The motor table and belts are a more fixed solution requiring a dedicated setup.

A precision gear head, with the removable coupling is more reliable, is much stronger, is not prone to slippage or belt stretching, is able to transfer the full torque load without anywhere near the loss, is easier on the bearings on both the motor and the mill, the motor can easily be connected/disconnected to the mill any time you use it in just a second and most importantly, the operating costs over a year in electricity usage alone would more than make up the difference in the cost between the motor with straight shaft output VS the motor with gearbox cost difference (its called operation efficiency)

The initial installation will be as simple as mounting the motor to a table so it wont move as it operates, and pushing the other end of the coupling onto the mill shaft and screwing the grub screw into place.
The operation is just a matter of putting your motor in place on a prepared spot and pushing the couplings together and away you go.
As for the speed differences, I can just bring in additional ratios, that is not an issue provided people tell me the exact speed they require.

Now if we look at your motor supplier, you'll see a very similar motor to what I put forth as a proper solution for MORE than twice the price that I have offered to the members here for.

But, if you feel it should be cheaper and more comparative to your motor supplier, then I am happy to comply and provide a simple straight shaft motor for a good price with drive pulley.


This is just the way we work, we'll always offer the most suitable product first at the best price, especially when it comes to building relations and a good reputation in a new community.

 

[Andyd]

Thanks for all the info john. As you've notice things warm up quickly here ;-)

Given that quite a few of us already have belt drive rigs, how hard/expensive would it be to switch to direct drive?
I know its probably gear dependant, so what info would you need?
Thanks,

Andy

 

[Ducatiboy stu]

Wow.....


Good to see someone who knows their stuff and doesnt mind putting a bit of effort into getting the right product for the job

 

[motiondynamics]

It wouldn't be worth changing over if you have a current setup that works properly because you would have to replace the motor completely with a geared motor (the picture I added earlier was of the motor WITH the gearbox attached). Its more of a 'proper' solution rather than a backyard one and its probably more suitable for people who don't want to hack around so much.

But to answer your question simply you'd need a motor with gearbox and the shaft size of your mill and the speed you required.

 

[Sammus]

I wish I'd seen you back in the day, I was chasing a DD for exactly all the reasons you mentioned. The only gearboxes I could find that had the right reduction and torque handling were $600+ for just the gearbox, all up it was going to cost well over $1k to set up, and even then noone seemed to want to help me out getting a gearbox to fit a unheardof 12mm drive shaft, so I wouldve had to backyard bodge that up too... I spent weeks on the phone trying to chase this stuff :\

shit aye... and you guys suck that got that motor for like $150 or whatever...makes it sound like I defo got shafted now. I wonder why all the local mobs (as in anywhere between wollongong and newcastle, all of sydney included) that I could find wanted such a ridiculous price for them...

I guess I take some solace in the fact that it wasn't hard earned money that payed for my setup, it was actually some creative accounting that landed me a second one of those kruddy bonuses that was meant to stimulate the economy which was apparently in some kind of crisis