What motor to use for DYI soil sifter trommel?

I'm thinking about building my own soil sifter trommel. What motor would require for something like this? I assumed I need variable speed controlled and at least 1hp?

I found this Century Electric UST1152 1 1/2-Horsepower Up-Rated Round Flange Replacement Motor but I'm not sure it can be used for something I'm trying to build.

I would also appreciate help in linking to site that sell some of these need parts such as the belt, wheels or rollers and whatever is require to make the trommel turns.


Thank you for any suggestions!

 

That "linked to" motor is for a pump. You'd want a motor that had a flat on the shaft for pulley installation. I think a 1hp 240v motor would be ok for that application. Variable speed for a motor like that will drive the cost of the project up quickly. You'd need to use a VFD (variable frequency drive). That control would run $150-200.

Pulleys as shown in the video are available from Graingers, McMaster-Carr and places like ebay.
Actually... most of the parts can be had from ebay. If you buy new..... it will be an expensive project.

Check out his other video in construction of the trommel (drum). That will be the hardest part.

 

First thing that came to my mind was a small cement mixer with the drum modified with screening to allow the fines to escape, then dump the rest.

not sure how much you need to sort but i have built and use a 4x8 frame covered with screening. Set at an angle it provides a nice small quantity of clean gravel or dirt depending on input.

Enjoy,
Bud

 

Yikes. - I can't see spending $160 for the motor on a DIY gardening project.

Next garbage day, keep an eye out for people throwing out used vacuum cleaners. Average vacuum cleaner has a 12 amp 120v motor, i.e. just under 2 hp. If you can't find one for free, grab one from a thrift shop for $10-$20.
Those ~2 hp motors usually have step-down gearing to run the carpet beater, AND they also have some sort of height (e.g. tension) adjustment for the carpet beater.
So, I'd kludge together a big rubber-band from a truck inner-tube, run that around the circumference of the trommel/sifter, run the innertube through the carpet beater as the drive wheel, and let the vacuum cleaner turn the beater bar to drive the dirt sifter.

PostScript about a trommel/sifter-
Uncles were farmers. If they were going to sift dirt, they would have picked up some #23 or #26 gauge (?) wire mesh about 3 feet wide, scrounged up a pair of bald car tires, and just stapled the wire mesh to the circumference of the car tires to make a mesh-cylinder/trommel. Probably add a ratcheting tie-down to each tire to make sure they're tight.

 

A vacuum motor spins too fast. The carpet brush is a different motor.

If you look for things to scrap..... look for an old washing machine.

 

Well,it's the newer no-bag air-swirly vacuums run the beater off the main motor.
See schematic below, right towards, bottom, motor #1, drives wheel #2, which drives belt #15, which drives beater assembly #18.


01. Motor 1JC0290000
02. Grommet 1881130000
15. Style 5 4 Belt 1540310001
18. Brush Roll Assembly 1ji0015000 2JI1055600

 

The belt, rollers & motor are going to be the easy part of the project as they are readily available and there are a lot of options that will work. I would first focus on making the trommel drum as that will require the most skill and specialized tools.

You will need a proper sized mesh for the sifting you are trying to do. The drum will also need some structure. If having the drum rolled of perforated metal it could be strong enough on it's own but if using hardware cloth it will need some framework. At each end you will need/want a smooth band of metal for the rollers to run on. At least one band will need a flange to act as a stop to prevent the drum from sliding downhill.

A old washing machine motor would have been my guess for a motor but you can buy a new motor if you want. You can vary the trommel speed by changing the pulley size. If you have a idea how fast you want it to turn you can do the math based on your drum diameter than see what size pulley on the motor you'll need. Once you know those two diameters (trommel, motor pulley) you can figure out what size belt will be needed.

Just wrapping a belt around the trommel will give it some drive. If you position your motor below you can mount the motor on a hinged table so the weight of the motor tensions the belt. If you mount the motor above the trommel you'll have to spend more time on the frame as the drum will have to be held down to resist the up tension of the drive belt.

---
A trommel is great if you want to sift a large volume of material. That much material you'll probably need a tractor to move the material. If doing it by hand I'd consider making a shaker table instead. It's just a box frame with screen. You attach a motor to the frame and a offset weight to the motor's shaft. Hang the screen so it's free to move. When you turn the motor on the offset weight will cause it to shake like mad. This also will allow you the most flexibility in motor size as it's much less fussy than a trommel.

 

Ok....in that Dirt Devil vacuum..... the vacuum motor spins over 23k rpm. I don't how fast the brush spins but that motor is not usable for anything other than a vacuum.

 

I'd just get a general purpose single speed motor, maybe 1750 rpm, and put a set of pulleys like you see on wood lathes on it... 3 different sizes to adjust speed with. Then match the driven pulley to get the average desired rpm with the center pulley on the motor, then you can slow down or speed up just by moving the belt over one way or the other. Let the motor hang on a hang so that the weight of the motor keeps the belt tight and moving the belt would be easy.

A washing machine motor would fit the bill easily. With the drive ratio being reduced so much by the pulleys, it wouldn't take much hp to do this. 1hp is way overkill IMO with that kind of reduction. You only want this thing spinning somewhere between 50 and 150 rpm. You'd probably drive it with a 1/4hp motor easily I believe (assuming it's a normal general purpose farm type motor). 1/2 for sure.

 

Pilot Dane,

At first I was thinking of the shaker table instead but I couldn't find any vibration motor. It seems rotational motor are more available.

Hal_S and PJmax, I have an old Dyson DC17 vacumme that I don't use anymore. However, it seems I can't use the DC17 since it spins pretty fast, I guess.

Thanks for all the responses. I'll see if I can find a slower motor or a vibration motor.

 

Seems like this washing machine motor might work but I'm not sure how to connect from this motor to a belt.

 

Okay, looks like this motor has variable speed. Even though it says 17,500 RPM max, with the variable speed controller, I can make it go down to 50 to 150 RPM, correct?

 

Okay, so I have also found a shaker motor: Concrete Vibrator Vibration Motor 30W AC 110V 3600rpm Aluminum Alloy Vibrating Vibrators for Shaker Table (30W) Perhaps this might be easier to design than a trommel.

 

Dyson motors are very small and very high rpm. Totally unsuited for what you need.

No, you cannot slow down a 17'000 rpm motor to 50-100 unless you use a very high reduction gearbox. But I could not see anywhere the motor you linked says it's 17k rpm.

To connect a motor to a belt you will need a pulley. The key is that the motor's shaft and bore of the pulley must match. This will be harder to do with a washing machine motor but if you find an industrial motor will have a standard size shaft and keyway.

The shipping cost of the motors on Ebay can be high because motors are heavy. Check your town for a motor or alternator repair shop. They should have a pile of used motors lying around.

 

SHORT
3,600 RPM vacuum cleaner motor @ 4:1 reduction = 900 RPM @ beater bar.
900 RPM beater bar @ 36:1 reduction = 25 RPM @ soil sifter.
4:1 pulley driving 36:1 pulley = 144:1 ratio.
3600 rpm low torque @ 144:1 gear train = 25 rpm high torque

LONG
The basic vacuum cleaner motor runs around 3,600 rpm. The "beater bar" is driven by a 1/4" diameter spindle and a rubber belt turns the 1" diameter beater bar. Belt/gear turning ratios can be determined by the ratio of the diameters. A 1/4" diameter pin driving a 1" diameter beater gives a 4:1 stepdown. The 1" beater bar will thus rotate at 1/4 of the speed of the 3600 rpm motor = 900 rpm for the beater bar.

Now assume the 1" diameter beater bar is used to drive a 36" diameter soil sifter using an old inner tube cut into a big rubber belt that goes around the 36" diameter sifter and around the 1" beater bar. The rate of rotation for the soil sifter is determined by the ratio of the diameter of the soil sifter to the diameter of the beater bar. That's 36:1, so a 1" beater bar at 900 rpm turns the 36" diameter soil sifter at 25 RPM.
Right around the speed you want for sifting dirt. And the gear train gives the ~2HP vacuum cleaner motor a 144:1 mechanical torque advantage.