Grain mill shaft and lovejoy couplings

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Smellyglove

Smellyglove

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I'm looking into motorizing my mill. First brew with the new mill (MM3 2.0) consisted of 90 minutes of grinding for a 10gal batch...

I slaughtered a kitchen-appliance and took out the motor and gears.

After doing some research here i understood that lovejoys are the way to go. I've read some build-threads but I'm missing one thing.

It seems like the lovejoys have a hole on their side. Does this mean I have to drill a hole in the shaft of the grainmill, and use some sort of locking pin through it?
 
The hole on the side has a set screw in it. you put it onto the shaft then tighten it down. If your mill shaft has a flat side you line the flat side up with that screw.
 
Chrisl77 said:
The hole on the side has a set screw in it. you put it onto the shaft then tighten it down. If your mill shaft has a flat side you line the flat side up with that screw.
Click to expand...

Aha! Excellent. Thanks!

But a lovejoy will work no problem with a shaft which has three flat grooves, for a drill-chuck?

And. How snug must it be to work? The gear-shaft is in mm. It's 12mm. 1/2" is 12.7mm. 0.7mm is 0.0275591 inches. Will it work?
 
Smellyglove said:
But a lovejoy will work no problem with a shaft which has three flat grooves, for a drill-chuck?
Click to expand...

Some folks file a little bit wider flat on one of the sides so the screw has more area to bite. But yes, they work with that style shaft.


Smellyglove said:
And. How snug must it be to work? The gear-shaft is in mm. It's 12mm. 1/2" is 12.7mm. 0.7mm is 0.0275591 inches. Will it work?
Click to expand...

That's the really cool thing about spider couplings like the ones from Lovejoy, they're available in lots of different shaft sizes, including metric! Just get one that's 12mm. They don't have to be the same size on both halves. The halves just have to be from the same series so the center spider fits with both sides.
 
reynolds5520 said:
Some folks file a little bit wider flat on one of the sides so the screw has more area to bite. But yes, they work with that style shaft.




That's the really cool thing about spider couplings like the ones from Lovejoy, they're available in lots of different shaft sizes, including metric! Just get one that's 12mm. They don't have to be the same size on both halves. The halves just have to be from the same series so the center spider fits with both sides.
Click to expand...

Allright. I allready see myself grinding more than 5 grains at a time!

Guess I'll have to do some more searching then, the reason I asked was because I couln't find 12mm.
 
And one final Q.

Will I be fine even if the gear-shaft has grooves in it? I don't know how to describe it (And I'm off work, hence no (camera)phone) but, sort of threads, just that they don't twist. They were there to keep the plastic I removed to stick. I can shave down an area to make the locking-screw to make a good contact. I just don't know if it's the screw which is the key element to making the lovejoy not to slip.
 
The locking screw is the only thing that's going to keep the coupler from slipping. Your motor output shaft is splined, but you could file a flat for the screw. As long as the coupler doesn't slip or wobble you should be ok...

Cheers!
 
reynolds5520 said:
How many splines are on that shaft?

Lovejoy has a jaw for a 12mm shaft with four 1.8mm splines.
Click to expand...

A lot, lots of small ones. I'd say about 20-30. I will order one jaw for the dim I measure on the outside, and shave down some of them for the locking screw. If that doesnt work I'll shave them all down and order a new jaw with smaller bore.
 
Smellyglove said:
No. It's only me and my dremel.
Click to expand...

I'd say try and fit a lovejoy over the splines first - if they are close enough spaced this won't be a big problem, and the set screw should be able to bind to the splines enough to transmit torque.

For next bit, there's a warning: I have only basic machining experience and this may well be a stupid idea. But it might work well enough to avoid finding a machinist.

If the above doesn't work, you could try mounting the motor firmly, then running the motor. With the motor running, hold the dremel against a point on the motor mount, and use the dremel to gradually remove material from the turning motor shaft. Basically use the motor as a lathe, and the dremel as the cutting tool. Because the dremel is spinning much faster than the shaft, you shouldn't need to apply any significant radial force on the shaft, and you should get a concentric cut.
 
The drive bolt on my mill recently snapped off flush to the mill, rather than drilling it out and tapping the hole, I rigged a flexible coupling using a piece of heavy vinyl tubing and two hose clamps as a shaft coupling, similar in concept to left photo in this link but heavier const.

http://www.rcgroups.com/forums/showthread.php?t=2171718

Seems quite robust, and less than $5 at the local Ace Hardware around the corner and 5 minutes to install....no comparison to a proper coupling, but it appears to work well and be plenty strong for the intended purpose. One end of the tubing is hose clamped to the mill shaft, the other end I inserted a deep 6 point hex socket and hose clamped, the mill is then driven with a hex bolt chucked in a 1/2" low speed drill.

Using a 1/2" drill would not require a coupling...

http://www.harborfreight.com/12-in-variable-speed-reversible-heavy-duty-d-handle-drill-69453.html

http://www.harborfreight.com/1-2-half-inch-heavy-duty-spade-handle-drill-93632.html

and the 20% off coupon
http://www.harborfreight.com/20off-...medium=aff&utm_campaign=wts-coupons&hftref=cj
 
Yeah. I love my dremel so I guess I'll be able to at least give it a try with it. If not then my third option will be to get a short piece of steel pipe, fit it over the splines and weld those pieces together.
 
dyqik said:
If the above doesn't work, you could try mounting the motor firmly, then running the motor. With the motor running, hold the dremel against a point on the motor mount, and use the dremel to gradually remove material from the turning motor shaft. Basically use the motor as a lathe, and the dremel as the cutting tool. Because the dremel is spinning much faster than the shaft, you shouldn't need to apply any significant radial force on the shaft, and you should get a concentric cut.
Click to expand...



It'll work, I've done the same thing in my drill press, and used a high speed grinder with a Rol-Loc sanding disc.

Go easy on the Dremel though, as it will not take a lot of side loading.
 
It seems like I'll need to connect the 1/2" mill shaft with a 20mm motor shaft. What should I search for amongst the lovejoys? Seems like a size difference and they don't match?
 
I think I'm after the L090 series which have big enough bores and fit together.
 
This might be å stupid question. But one of the jaws says "no keyway". Will this get me in trouble?

I actually don't know what this means.
 
You only need a keyway if one of your shafts (motor or mill) has a key in it. Basically, it is a slot w/ a metal key or "tab" in it. The keyway is a slot in the Lovejoy that slides over the key in the shaft.
Not all motors/ mills have a key. Mine does so I ordered one Lovejoy w/ the shaft diameter opening for the motor w/ a keyway. My mill shaft only has a small flat area so you can tighten the set screw in the Lovejoy more securely.


Sent from my iPhone using Home Brew
 
govner1 said:
You only need a keyway if one of your shafts (motor or mill) has a key in it. Basically, it is a slot w/ a metal key or "tab" in it. The keyway is a slot in the Lovejoy that slides over the key in the shaft.
Not all motors/ mills have a key. Mine does so I ordered one Lovejoy w/ the shaft diameter opening for the motor w/ a keyway. My mill shaft only has a small flat area so you can tighten the set screw in the Lovejoy more securely.


Sent from my iPhone using Home Brew
Click to expand...
FWIW, I have found that using a coupler with a keyway for a mill shaft with a flat provides a much more secure connection. I filed a square key down in one dimension for fit. This results in a much larger surface contact area over just the set screw by itself.

I have read reports of couplers loosening and spinning with only a set screw tightened to the mill shaft flat.
 
Lucky in a way. My gear reduction motor came w/ a keyway & key in the shaft. Not a std size but not too difficult to modify.


Sent from my iPhone using Home Brew
 
Thanks for all your help, now I'm a bit wiser. I found a new small industrial motor which I'll pick up tomorrow and continue my brewing, 2 weeks since last brew and I have heavy abstinences.
 
I totally forgot about this thread. Thanks for all your input. For the few weeks I've been milling my grains in about 90 seconds. And everything is awesome.
 
90 Seconds was a ballpark guesstimate. But I don't think I'm that far off. about 7 KGs @241 RPM (241 is with no load on the motor).
 
Finding a gear motor with enough power is the tricky part. The 2" rollers require quite the torque. I've been looking for a 200 RPM-ish gear motor at 1HP and 120 volts for a long time now.
 
Mine is a 0.5HP with a 6:1 gear ratio built in. I tried sticking some grains in between the rollers before powering up, then it couldn't turn the rollers. But if I do it "normally" (just pour in the grains and power up the motor) it works great.

My motor is three phase/single phase. Just need to rewire it to get single phase. Maybe you should add three phase in your searches and ask if it's possible to rewire it to single phase.
 
Smellyglove said:
Mine is a 0.5HP with a 6:1 gear ratio built in. I tried sticking some grains in between the rollers before powering up, then it couldn't turn the rollers. But if I do it "normally" (just pour in the grains and power up the motor) it works great.

My motor is three phase/single phase. Just need to rewire it to get single phase. Maybe you should add three phase in your searches and ask if it's possible to rewire it to single phase.
Click to expand...

Where did you get the motor? I'm shopping for one too.
 
Bobby_M said:
The 2" rollers require quite the torque.
Click to expand...
I'm guilty of thinking of mill speed in terms of RPM when I should be thinking surface speed. A 2" roller will crush grain almost twice as fast as a 1-1/4" roller at the same RPM's. It's the surface speed of the roller at the grain contact point that's important, not the roller's shaft RPM. If we're saying that 200RPM is good for a 1-1/4" roller mill like a Barley Crusher, than around 125RPM will give you a similar crush and crush rate with a mill having a 2" roller. The same HP motor can be used in either case because the additional torque required by the larger roller is offset by the mechanical advantage gained by using a gearbox or sheaves to reduce the surface speed.
 
That's true. To date, the only thing I ever used for my 1.5" crankandstein is my dewalt cordless on "low speed" which is listed at 575 RPM. I'm sure the load pulls that down a little, maybe to 450rpm. So, 1.5*3 is 4.5" of travel per revolution x 450 for 2025 inches per minute.

Since 2" * 3 = 6, 2025/6 = 337 RPM

While I do want my shop mill to make good time, I'm also considering the dust impact of running it fast. I figured 200 RPM would be good then. Finding a 200 RPM motor that still pulls over 100 inch pounds means 3/4HP or more (I'm pretty sure). I've seen some nice small motors listed for 140in/lb and then see that it's geared to 20 RPM. Great.

PS: yes, I'm aware I'm calculating with pi rounded down to 3. I'm building a Timex, not a Rolex.
 
sandyeggoxj said:
Where did you get the motor? I'm shopping for one too.
Click to expand...

I'm living in Norway, EU so I guess it won't help you much. But I found one on what would be CG for you guys.

As a (a bit funny sidenote) I found a guy who has over 40 metric tonnes of motors stowed away in almost every corner in his house, yard, garage, shed and you name it. Picture an Emmet Brown from Back To The Future, but with motors. An eccentric guy. After about 30 minutes about motor-talk, which I know nothing about, I sort of hinted that I should be going by getting back into my car. Mr Brown here didn't stop talking so I had to roll down my window (after I startet the engine) and continued to talk with him as I was slowly pulling out of his driveway as he walked by the car almost sticking his head into my window. Great guy.
 
AnOldUR said:
I'm guilty of thinking of mill speed in terms of RPM when I should be thinking surface speed. A 2" roller will crush grain almost twice as fast as a 1-1/4" roller at the same RPM's. It's the surface speed of the roller at the grain contact point that's important, not the roller's shaft RPM. If we're saying that 200RPM is good for a 1-1/4" roller mill like a Barley Crusher, than around 125RPM will give you a similar crush and crush rate with a mill having a 2" roller. The same HP motor can be used in either case because the additional torque required by the larger roller is offset by the mechanical advantage gained by using a gearbox or sheaves to reduce the surface speed.
Click to expand...

So how fast am I actually milling if my motor is 241RPM (don't mind the load) and I have 2" rollers? Should I get a slower motor, in a perfect world?

Sorry, but I suck at math. A thirdgrader would out-math me.
 
That's equal to about 380RPM with a 1-1/4" roller mill. Still a reasonable number. To a large extent, it's about how happy you are with the results of your crush. Too fast can shred the husks and effect lautering.

The earlier discussion had more to do with HP requirements and that larger rollers will require a higher horsepower motor for the same RPM at the roller. If you're not stalling you mill, you're good.



edit to answer your question:
You're milling at about 125 SFM
(Is my machinist is showing through? :cross:)
 
AnOldUR said:
That's equal to about 380RPM with a 1-1/4" roller mill. Still a reasonable number. To a large extent, it's about how happy you are with the results of your crush. Too fast can shred the husks and effect lautering.

The earlier discussion had more to do with HP requirements and that larger rollers will require a higher horsepower motor for the same RPM at the roller. If you're not stalling you mill, you're good.
Click to expand...

But I'm doing a 2" roller mill.

Nevertheless. I'm happy about it, it's giving the same results as my LHBS which I used for about a year and half. They have a six-roller. Doesnt mean much to me other than my calculations when it comes to crush and extractions are more or less the same, gives med me maybe 1 or 2 points on the good side. I'm just happy I'm saving a fortune (after the mill, motor, gas expenses for the car driving to and forth the LHBS , etc has been "paid down", which will take my whole lifetime, but still). I'm rolling stock MM-setting. The LHBS cost at getting it crushed there is about 20% extra.

I''ve been so happy with the crush (even though it's finer than I expected when buying own mill and motor) that I don't feel the need moistning the grains to get more intact husks. If I feel I need softer crush with the current setting I can always moist the grains before crushing.
 

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