What single phase motor is suitable as an industrial shredder?

[electromateria]

My dog eats raw meat and bone and it's too time consuming to make her food, so I'm making a shredder / grinder.

I have various gearboxes, 8:1, 50:1, 160:1 planetary and can make custom ratio as needed. I hear 30:1 is usually best but I think I might go 160:1 for less speed but maximum torque. This should make things easier on the motor I'd imagine?

I'm looking for a CHEAP but powerful and reliable single phase motor (at least 60 minutes or continuous duty cycle). It needs to be able to spin 5 or 6, 1" thick steel teeth, and slowly crush bone as thick as cow femur. The shredder will be single shaft.

I already own some motors I'm considering: food processor motors, general 1hp shop motor, 1-2hp treadmill motors with control unit. I'm really looking for advice because if I build it around the wrong motor it's going to be a huge waste of time.

[Doctorandus_P]

It's not that simple.
To do it properly you have to match the parts to each other.
Some motors are high rpm low torque, while another motor may have the same power but with lower RPM and higher torque, and thus needs a different gear ratio.
I'm guessing your treadmill motor probably has the most torque, but if it's not matched to the gearbox or the size of the shredder itself then mechanical parts will get damaged.

Shredders are easy to overload, and often some system is built in that when the motor current (and thus torque) gets above some preset limit, it reverses for a while and then continues. This rearranges the parts being shredded.

Apart from the mechanical aspects, I wonder what's good for your dog. (Too many) sharp bone splinters may be quite unhealthy. Maybe something that resembles a rock crusher, or even just a simple manual arbor press to crack the bones a bit is a much better idea.

Why give your dog minced meat that it can gobble up in a few minutes (and then get bored again) instead of keeping it busy for half an hour while getting at the bone marrow itself?
I don't pretend to know much about dogs, but I do think they like to play with their food for a bit.

[electromateria]

It's not that simple.
To do it properly you have to match the parts to each other.
Some motors are high rpm low torque, while another motor may have the same power but with lower RPM and higher torque, and thus needs a different gear ratio.
I'm guessing your treadmill motor probably has the most torque, but if it's not matched to the gearbox or the size of the shredder itself then mechanical parts will get damaged.

Shredders are easy to overload, and often some system is built in that when the motor current (and thus torque) gets above some preset limit, it reverses for a while and then continues. This rearranges the parts being shredded.

Apart from the mechanical aspects, I wonder what's good for your dog. (Too many) sharp bone splinters may be quite unhealthy. Maybe something that resembles a rock crusher, or even just a simple manual arbor press to crack the bones a bit is a much better idea.

Why give your dog minced meat that it can gobble up in a few minutes (and then get bored again) instead of keeping it busy for half an hour while getting at the bone marrow itself?
I don't pretend to know much about dogs, but I do think they like to play with their food for a bit.

That's really interesting about the feed reversal, super cool feature! I'm trying to keep things basic though. In my application I'll be pulling down on a lever to run the meat into the blades so I have manual control of feed rate. Not trying to fully automate this as I need it done asap and for low cost.

I don't understand which mechanical parts will get damaged? The motor will burn up or? It seems as long as the ratio is over 1:30 it should be ok? Especially once you get into super high ratio like 1:160 planetary that's really taking stress off the motor I think. In my head that's how it works at least 

Dogs an old girl now, 11 years old large breed (Akita). She's been eating raw meat on and off since she had puppy teeth. Her teeth are still in ok shape but trying to make things easy on her. She has allergies and is on some anti-histamines but I want to run an elimination diet which isn't really possible with kibble. I'm a big advocate for raw feeding but it's a hell of a lot of work, grinder will make it easy for me.

[Doctorandus_P]

If the gearbox is the weakest point, then teeth may break off.
If the shredder is the weakest point, then the axles may get bent.
If the motor is the weakest point it may burn out.
If the bones are the weakest point you may get sharp splinters.

[tooki]

That's really interesting about the feed reversal, super cool feature! I'm trying to keep things basic though. In my application I'll be pulling down on a lever to run the meat into the blades so I have manual control of feed rate. Not trying to fully automate this as I need it done asap and for low cost.

Even the most basic paper shredder has a reversal feature (manual on cheaper ones, automatic on expensive ones) because if you don't have it, there's no way to release a jam. It's really not optional. I've never seen a shredder, no matter how cheap, that doesn't have automatic stall detection to turn off the motor if a jam occurs.

The other reason for a reverser. whether automatic or not, is to guide the object to be crushed into the jaws. Things can get stuck floating at the edges sometimes, and I cannot emphasize enough that you absolutely, positively do not ever want to be inserting your hands in there to move something while it's on -- nor a tool, because then the tool can get crushed into the grinder, too!

With that said, I suspect you'll need to do multistep grinding if you're starting with beef femurs: a coarse grind through your shredder, then a finer grind through a grinder. Otherwise I'd be concerned about shards that are juuust the right size that the dog (cute dog, by the way!) can swallow them without chewing, which might be sharp and cause problems.

The other concern is how you clean the thing. The last thing you want is bits of meat and bone rotting inside some inaccessible crevice of the device!

[BeBuLamar]

Single phase AC motor isn't good for reverse. DC or 3 phase motors are better. You can run either DC or 3 phase AC motor with single phase AC power by using a drive.

[Zero999]

WARNING: You need guarding, safety switches and an emergency stop, to prevent you from shredding your arm, or worse.

[Berni]

Yep reversal feature is as much of a convenience as it is a safety thing.

Shredders are designed to pull material trough them so if something gets lodged in there it is often impossible to get back out without running the shredder in reverse. They always have a ton of gear reduction because they need a LOT of torque and not much speed, while motors like to run at low torque and high speed. So you usually can't move the shredder mechanism even when it is off since the gearbox has too much mechanical advantage (takes a huge amount of force to backdrive). As a practical result this means that trying to shred something too tough will stop the shredder and make it very difficult to dislodge the problematic piece out of it. This also encourages you to poke around inside of it in an attempt to free it up. Then as a bonus if you do end up getting your fingers sucked into the shredder you will not be able to get your hand back out without cutting your own fingers off.

That being said one of the best places to look for a drive motor is an electric winch. Those motors will already have a reduction gearbox on the motor that turns it into really low RPM at a ridiculous amount of torque, exactly what you want for driving a shredder. As a bonus these motors also come with a reversal switch wired in already, so you get a shredder manual reverse feature already included.

[Doctorandus_P]

If you manage to put the tip of your tie in your self built shredder with the emergency stop just out of reach I'll give you a darwin award.

[eugene]

I don't understand the problem. You have a functioning shredder in the form of a dog. Not only does it apparently enjoy the job, but if you take that job away then it will just need to find something else to do.

[electromateria]

If the gearbox is the weakest point, then teeth may break off.
If the shredder is the weakest point, then the axles may get bent.
If the motor is the weakest point it may burn out.
If the bones are the weakest point you may get sharp splinters.

I have 3 gearboxes: 1) 1:160 planetary from a 2000lbs winch 2) massive planetary from a transfer case (could do 1:100+ with modification) 3) 1:8 transmission (?) from a go kart or something, it has a reverse lever - could be modified to very high ratio and takes belt drive from the motor.

Axle will probably be 5/8 or 1" shaft.

I've never seen a shredder, no matter how cheap, that doesn't have automatic stall detection to turn off the motor if a jam occurs.

The other reason for a reverser. whether automatic or not, is to guide the object to be crushed into the jaws. Things can get stuck floating at the edges sometimes, and I cannot emphasize enough that you absolutely, positively do not ever want to be inserting your hands in there to move something while it's on -- nor a tool, because then the tool can get crushed into the grinder, too!

With that said, I suspect you'll need to do multistep grinding if you're starting with beef femurs: a coarse grind through your shredder, then a finer grind through a grinder. Otherwise I'd be concerned about shards that are juuust the right size that the dog (cute dog, by the way!) can swallow them without chewing, which might be sharp and cause problems.

The other concern is how you clean the thing. The last thing you want is bits of meat and bone rotting inside some inaccessible crevice of the device!

Adding jam detection and auto reversal adds a lot of complexity to the project  I'm motivated to learn how since I find it interesting but can't put time investment into that right now. It's something I'll add later down the line.

I think if I make the torque ratio super high and have a beast of a motor no bones can ever jam it 



^ This is what I want to make a cheap version of, single shaft and less blades, rotating at 1/20th of the speed.

Single phase AC motor isn't good for reverse. DC or 3 phase motors are better. You can run either DC or 3 phase AC motor with single phase AC power by using a drive.

What specs you recommend for a DC motor?
 
Can't run 3 phase at the moment and VFD are out of budget.

WARNING: You need guarding, safety switches and an emergency stop, to prevent you from shredding your arm, or worse.

Yea will do

Yep reversal feature is as much of a convenience as it is a safety thing.

Shredders are designed to pull material trough them so if something gets lodged in there it is often impossible to get back out without running the shredder in reverse. They always have a ton of gear reduction because they need a LOT of torque and not much speed, while motors like to run at low torque and high speed. So you usually can't move the shredder mechanism even when it is off since the gearbox has too much mechanical advantage (takes a huge amount of force to backdrive). As a practical result this means that trying to shred something too tough will stop the shredder and make it very difficult to dislodge the problematic piece out of it. This also encourages you to poke around inside of it in an attempt to free it up. Then as a bonus if you do end up getting your fingers sucked into the shredder you will not be able to get your hand back out without cutting your own fingers off.

That being said one of the best places to look for a drive motor is an electric winch. Those motors will already have a reduction gearbox on the motor that turns it into really low RPM at a ridiculous amount of torque, exactly what you want for driving a shredder. As a bonus these motors also come with a reversal switch wired in already, so you get a shredder manual reverse feature already included.

Yea winches have beautiful gearsets and are definitely well suited to grinding. What capacity winch should I use though? My current one is rated for 2000lbs which maybe too low.

I definitely never want anything getting stuck. I can just imagine how annoying that will be without reverse. I think if the motor and torque ratio are good then it should blast through everything I throw at it and never jam. I could add jam detection and auto reverse in the future just as a precaution.

If you manage to put the tip of your tie in your self built shredder with the emergency stop just out of reach I'll give you a darwin award.

Ok but that's a big IF. And right now you're currently up for the nagging nancy award 

I don't understand the problem. You have a functioning shredder in the form of a dog. Not only does it apparently enjoy the job, but if you take that job away then it will just need to find something else to do.

If I give my dog a lamb shank she will eventually eat all the meat but only 20% of the bone / knuckle. When she was young she'd eat the whole thing no problem. If I don't break up the bones sometimes she won't even touch it. She definitely prefers it broken up now that she's old.

[bdunham7]

A 4-pole (1800 RPM) agricultural "farm duty" single phase reversible motor will have an appropriate torque curve and service factor for this application.  Here's an extreme (pricey) example, you can probably shop for cheaper ones and 1.0 HP may be good enough.

https://www.witmermotorservice.com/FDL3610TM-Baldor-3HP-Farm/Agriculture-Duty-Electric-Motor-1750-RPM/item/FDL3610TM

[Berni]

Yea winches have beautiful gearsets and are definitely well suited to grinding. What capacity winch should I use though? My current one is rated for 2000lbs which maybe too low.

I definitely never want anything getting stuck. I can just imagine how annoying that will be without reverse. I think if the motor and torque ratio are good then it should blast through everything I throw at it and never jam. I could add jam detection and auto reverse in the future just as a precaution.

The motor might not even need to be particularly big since the inertia of the motor might help give it the kick when needed. The spinning rotor of a async motor stores a fair bit of kinetic energy, so if a large bone suddenly tries to stop the grinder the inertia of the motor might be able to exert a huge peak force before it stops and the motor stalls. So it is likely more of a case if the gearbox can survive these short peak forces. But if you get enough of these big bone bites in the grinder in quick succession the inertia might get robbed away from it in steps until the RPM falls too low and the motor stalls. The single phase async motors only produce a lot of torque when somewhat near the rated speed, having a motor with a run capacitor might help produce more torque down lower. You could even give it a heavy flywheel on the fast motor side to store more energy, but the gearbox might not be happy about it.

Quite a few single phase motors can be wired up to run backwards too. Reversing the start winding will reverse the motor direction. No need to have an automated stall detector, you are going to be standing there feeding the bones in anyway. Just nice to have a manual switch that you can flip to quickly stop the motor, back it up a bit and give it a run up for the next bite so it can use the inertia to bite trough a particularly tough bone.

Cheapest source of large motors is going to be cannibalizing old junk equipment or flea markets (farmers love to collect large motors for running stationary farming equipment)

No idea how much power it takes to get trough those bones, but sounds like a shredder drum would be of a similar diameter to a winch, so if it can lift 2000lb it should also be able to bite down on bones with 2000lb, sounds like enough for bones unless you throw some really hefty ones in there.

[langwadt]

get a band saw

[wizard69]

I really have to wonder if running bones through a shredder for dog food is a wise thing.   Dogs love bones but I really doubt that they will enjoy splinters in their insides.

As with others here, I'm not at all convinced this is a wise move from the safety standpoint.   If you buy a meat grinder and take off some of your body parts then at least you have somebody to take to court.

[SmallCog]

You may find some inspiration from Colin Furze



Note the first motor he uses isn't grunty enough, there's a few videos of the build, and rebuild.

[electromateria]

A 4-pole (1800 RPM) agricultural "farm duty" single phase reversible motor will have an appropriate torque curve and service factor for this application.  Here's an extreme (pricey) example, you can probably shop for cheaper ones and 1.0 HP may be good enough.

https://www.witmermotorservice.com/FDL3610TM-Baldor-3HP-Farm/Agriculture-Duty-Electric-Motor-1750-RPM/item/FDL3610TM

Looks great! Thanks

The motor might not even need to be particularly big since the inertia of the motor might help give it the kick when needed. The spinning rotor of a async motor stores a fair bit of kinetic energy, so if a large bone suddenly tries to stop the grinder the inertia of the motor might be able to exert a huge peak force before it stops and the motor stalls. So it is likely more of a case if the gearbox can survive these short peak forces. But if you get enough of these big bone bites in the grinder in quick succession the inertia might get robbed away from it in steps until the RPM falls too low and the motor stalls. The single phase async motors only produce a lot of torque when somewhat near the rated speed, having a motor with a run capacitor might help produce more torque down lower. You could even give it a heavy flywheel on the fast motor side to store more energy, but the gearbox might not be happy about it.

Quite a few single phase motors can be wired up to run backwards too. Reversing the start winding will reverse the motor direction. No need to have an automated stall detector, you are going to be standing there feeding the bones in anyway. Just nice to have a manual switch that you can flip to quickly stop the motor, back it up a bit and give it a run up for the next bite so it can use the inertia to bite trough a particularly tough bone.

Cheapest source of large motors is going to be cannibalizing old junk equipment or flea markets (farmers love to collect large motors for running stationary farming equipment)

No idea how much power it takes to get trough those bones, but sounds like a shredder drum would be of a similar diameter to a winch, so if it can lift 2000lb it should also be able to bite down on bones with 2000lb, sounds like enough for bones unless you throw some really hefty ones in there.

Tyty this is a really helpful and insightful comment.

I'm tempted to try a food processor motor, it's kind of small (1/4 HP) but it delivers a lot of torque. Also I have a much bigger 1 HP pool pump motor 115/230v -- 15/7amp. Good tip on the flea market and also flywheel use. Appreciated!

get a band saw

I have one but it's not ideal for raw feeding. It makes unnatural angles on bones that can crack dogs teeth. They act like a wedge in between those back teeth shaped like mountain peaks. The pic in OP was a t-bone steak she got for her bday but it's extremely rare I give her any meat cut with a bandsaw.

I really have to wonder if running bones through a shredder for dog food is a wise thing.   Dogs love bones but I really doubt that they will enjoy splinters in their insides.

As with others here, I'm not at all convinced this is a wise move from the safety standpoint.   If you buy a meat grinder and take off some of your body parts then at least you have somebody to take to court.

They already sell meat grinders for raw feeding dogs the issue is they're cheaply made and overpriced. It's $1000 for a grinder that can only crush chicken bones, it can't even do turkey.

Bones are only 15-20% of the feed, it will be mixed with lots of meat, fat and organ. I'll make sure the consistency is good and I keep all my fingers, no worries.

You may find some inspiration from Colin Furze



Note the first motor he uses isn't grunty enough, there's a few videos of the build, and rebuild.

Love that guy haha, Colin is the best!

[Ground_Loop]

Let's keep it simple and just answer the question.  This one:  Baldor L1430T General Purpose AC Motor, Single Phase, 184T Frame, ODTF Enclosure, 5Hp Output, 1725rpm, 60Hz, 230V Voltage.  I have one of these on my 80Gal air compressor and it's a true 5HP motor.  If you set up your rig for standard 184 or 56 frame size you can experiment with different motor HPs.

Also, Plain steel plates might cause some corrosion problems.  I've designed a couple industrial shredders and you'd be surprised how much power it actually takes for satisfactory results.

[electromateria]

Let's keep it simple and just answer the question.  This one:  Baldor L1430T General Purpose AC Motor, Single Phase, 184T Frame, ODTF Enclosure, 5Hp Output, 1725rpm, 60Hz, 230V Voltage.  I have one of these on my 80Gal air compressor and it's a true 5HP motor.  If you set up your rig for standard 184 or 56 frame size you can experiment with different motor HPs.

Also, Plain steel plates might cause some corrosion problems.  I've designed a couple industrial shredders and you'd be surprised how much power it actually takes for satisfactory results.

(Attachment Link)

Damn that's a nice motor Was just looking at some similar ones this morning. generic no name 5hp 230v motor is around $500-700 CAD, out of my project budget at the moment

https://www.princessauto.com/en/5-hp-open-drip-proof-electric-motor/product/PA0008513533 cheapest I've seen

Some nicer ones here:

https://www.lenmark.com/products/5-hp-industrial-electric-motor-5
https://www.lenmark.com/products/7-5-hp-industrial-electric-motor-2 ~ would love to get my hands on this beast lol wonder what the amp draw is

My highest HP motor is a 120v 2HP treadmill motor. The way I'm trying to overcome the lack of power is:

1) Single shaft

2) Reduced blade count

3) Extremely high gearing

4) Very small grinding area (fit one bone at a time)

Basically it should run super slow but annihilate anything - in theory. I think a lot of energy is wasted in grinders because there's usually a HUGE area of spinning blades, that's a lot of weight to move and keep moving, and when you get tough materials hitting a wide surface area it all adds up. By reducing that as much as possible (I'm only using four 1" thick teeth total) hopefully it will make up for my weak motor.

I was gonna buy 1" stainless plate but it was a pain to source in the size I need, I was unsure if I could case harden it, and also cutting and drilling it maybe a nightmare for me. I have a bandsaw and drill press but I think that stainless plate of that thickness needs CNC waterjet.

For the corrosion issue that's definitely something I'm worrying about. I've been thinking that after cleaning I'll spray water mixed with baking soda (keep PH super high) then dry with heat gun. On the look out for other food grade products that will keep off rust. Might use cooking oil, I'll probably test various things. I'm gonna use thin stainless for the feeder and case.

If you have some pics or video of your shredder pls share would be cool to see it

[Ground_Loop]

Sorry no pics, but the last one was designed similar to the one in the video above. It had 20 one inch plate pairs and was used to recycle tailings of trash bag plastic film.  Although, the 50 HP motor was geared down 30:1, if the operator was not careful loading the hopper it would stall the motor.  So, as stated earlier, they need lots of power.  And, required torque is proportional to plate diameter.