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My DIY, low-budget, concrete-roller grain mill

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-TH-

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First off I have to say I'm pretty fortunate to have access to a lot of scrap parts, metal, and stuff where I work. If I see something "valuable" like a gear-motor for instance in good shape on its way to the dumpster, I'll grab it and throw it in my cabinet. Also we have drawers full of things like bushings, hardware, belts & pulleys, etc. Ok you get the idea, now on to the project....

I had been wanting to build a grain mill for quite some time. I probably spent more time thinking about this project then actually working on it (can you tell I'm an engineer?). I have access to our machine shop after hours which has a lathe but I couldn't get my hands on some nice round metal bars for the rollers so I thought I'd give concrete a try. Making the rollers was tricky, because I needed to find somthing to use for a mold that would hold the axles perfectly centered, but yet be removeable once the concrete cured. After one failed attempt using empty shortening containers (rollers were out of round because the axles weren't centered well), I used two quart-sized paint cans - the kind made from plasic with only the top being metal. The tricky part was making sure the holes in top and bottom of the can were perfectly centered. I actually put the cans in a lathe to spin them and then mark them with a marker. I punched out the holes with 1/2" hollow drill bit normally used for drilling paper. The axles are 1/2" dia. steel cut to length and a roll pin pressed into them (after being drilled) to make sure they don't spin inside the concrete. The rollers ended up being about 4-1/4" in diameter.



With the axles in place I filled the cans with concrete, vibrated the heck out of them with a palm sander to get the air bubbles out (otherwise the roller surfaces would be very pitted), and pounded the covers on. BTW I used a topping mix which contains little or no aggregate, I added a little more portland cement, and also acrylic fortifier. I have a book on concrete countertops that helped me with that somewhat. I think the concrete ingredients were the only things I had to buy for this project.



I used some self-aligning bronze bushings which work nice in sheet metal and won't bind up if things aren't perfectly aligned. You can see from then next picture how I made the gap adjustable.



I discovered along the way that I needed something to keep the grain from falling past the ends of the rollers since they can't be mounted up nice and tight to the side frames. Therefore I made some pieces out of UHMW plastic to prevent that.



The gearmotor was one I've had in my cabinet for years just waiting for the opportunity to be used. Its 67 RPM. I wish it had a little more torque but oh well.



The hopper was a reflector left over from our factory lighting retrofit. We installed flourescent a couple months ago and threw the HID's out. This reflector was never used, it was a spare.





I thought 67 RPM would be slow enough as is but I found I needed to gear it down even more to gain me some more power. I also had to add an idler bearing to keep the timing belt from hopping on the motor pulley. It really takes alot of power to crush the grain. I had a small hand crank on for testing purposes once and I was able to turn it only if I did just a little grain at a time.



And the crush...



Let me know what you think, I'd love to hear your comments!!!

EDIT: Here's a video of it in action:

 
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samc

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Cool - I would call it the Jimmy Hoffa Crusher! (buried in concrete)
 

HSM

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That is really sweet!!! Stone Ground old school!

What's it weigh?
 

wilserbrewer

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That is pretty damn cool. When you going to start selling them!

Parts and labor to assemble would probably be $1,000.00 before any profit. Who buying??

All kiding aside, nice job w/ the mill. You are skilled and patient to design/ build something like that.
 
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-TH-

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Parts and labor to assemble would probably be $1,000.00 before any profit. Who buying??
That sounds about right. BUT each mill would be a unique creation depending on the scrap parts I have on hand, and I would personally sign each one!

I weighed it just now and its 29.8 lbs. Not as bad as I would have guessed. I was planning on adding some handles but I haven't found anything that will work yet.
 

riromero

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You could sell everything except the concrete and let customers pour the concrete into the molds themselves. That shouldn't be too hard.
 
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The results are far better than I expected when I read the title. Nice craftsmanship and creativity! I'm interested to see how the rollers hold up over time.
 

BrewBeemer

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The diameter of your large drive rollers ate your torque big time besides the surface speed of the rollers. As you have done is geared it way down. I gave up on the 5mm pitch belts 25mm wide on my gas scooters I was eating teeth all the time. For the mill drive I plan on #40 sprockets and chain as the gearbox to jackshaft spacing is only 6 1/2" centerline to centerline shafts away. I'll use Epic wax base bicycle chain lube that becomes dry and wax coated for less dirt, dust and flour collecting as used on mountain bike chains for a reason.
These fully cast iron worm drive gearboxes are for even thermal expansion of the boxes taper bearings maintaining proper preloading. If you can get a motor with gearbox as a single assembly that would be great. I plan on using a 1/3 hp right angle gearbox as a single unit with 28.75 rpm output at 565 in/lbs TQ. This with a 1,750 rpm Baldor motor unit with a Prefection Gear gearbox that was used for disability chairs replacing stairs powered by 120 volt motor.
This motor Baldor box unit a 60:1 gearbox will be chain driven to 89 rpm's the mills roller speed on its 2" diameter rollers powered off a jackshaft directly to the Monster Mill. I rather have no side loading this being a bushing grain mill instead of ball bearings. What were they thinking besides going cheap when counter bored end plates with flanged and sealed ball bearings could of been used? The eccentric adjustment must be built larger in diameter allowing for the bearings OD vs thin wall bushings that is the only major modification I can see. WinSmith is another gearbox company used for disabilty chairs that has 40:1 ratio but powered by a 24 VDC 30 amp 1750 rpm motor for 43.75 rpm output at 625 in/lb TQ that I have plus another at 20:1 that has shaft drive in and out of the box, rated input of .86 hp. I have another unit that has 1/2 HP 120 volt belt drive into the box with a 1 1/2" output shaft at 39 rpm's with over 1,200 in/lbs TQ. With this motor and box unit with forward and reverse, 24 volt relay controls must weigh 90 pounds plus. Replacement cost I was told over $2K. This has a brake drum on the opposite end of the worm from the motor on the thru drive of the worm gearbox input drive. Slow speed and the minimum of flour adds what, 10 minutes longer grain grinding time while doing other things on brew day or the night before. With brew day taking hours 10 minutes longer milling is nothing besides I want the minimum amount of flour.

Many months ago another member built his own mill out of 6" or 8" pipe and welded on end plates then finish cut the mills surfaces. A many pounds a minute machine.
 

airbalancer

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riderkb

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Nice job. I made a concrete roller mill, too, but yours is much better. I used 4" PVC for the molds and turned wooden plugs for the end caps. The wood lathe drive center left a centered mark that I used to start an auger bit for the axle hole.

Now I have access to a metal lathe, so someday I'll get around to making a new one.
 

EvilTOJ

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I've actually made concrete rollers as well, but it never worked because I could never center the axles exactly. I guess I feel better that it took you having a lathe (which I don't have) to get them exactly centered.
 

wilserbrewer

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.... I could never center the axles exactly. exactly
Yes a lathe is probably key here! I did read a DIY concrete roller project where the guy cast the rollers, then trued them with a grinder while spinning them. Interesting approach I thought.
 
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-TH-

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UPDATE - In case anyone is wondering I used this a few weeks ago for my first AG. It worked awesome! There seems to be a bit more pitting in the rollers now than before so hopefully that won't get worse. We'll see as time goes on.
 
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-TH-

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Here's a video of it in action:

[ame=http://www.youtube.com/watch?v=UobT0qR2gxU]YouTube - DIY concrete-roller grain mill in action[/ame]

As you can see its not screaming fast, but the hopper holds at least 12 lbs and it will crush that in less than 10 minutes.

The rollers are holding up really well. I think the crush could be a little better if I closed the gap a little more but I'm not sure if the motor would handle the extra torque required. I'm getting about 75% eff. pretty consistently and I can live with that.
 

brewmonk

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It looks slick!

I'm about to start a second attempt at one.

For anyone interested in pipe forms, I don't use my lathe, I use my router with a circle cutting jig (it's a trammel - a piece of board screwed to the base, with a scrap of wood held on the bottom with one screw, and rotated into the cutter until the screw is the center of my hub/wheel/table-top/etc).

Be careful, or else don't do it! (rough it out with a bandsaw or jigsaw first).
[insert legal warnings here]
 

JewBrew

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I plan on doing something similar.
To form the rollers a 6 inch by 3 inch diameter pvc pipe will be fitted with a 3 inch to .5 inch reducer an each end (see pic below) and and have a .5 inch threaded rod centered in the two fittings. Once the form is assembled with the rod in place it will be filled with cement and left to cure. Once cured the pvc mold is cut away leaving a perfectly round roller with a perfectly centered shaft.
Since the PVC pipe is perfectly round and so are the fittings everything is centered.

What do you guys think???

Here is a pic of the reducer from flexpvc.com
 
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