Introduction: Trommel Compost Sifter

Picture of Trommel Compost Sifter

This Instructable shows how to build a trommel (rotary screen) for sifting compost or shredded leaves. The purpose of sifting is to separate coarse unfinished compost materials from the finished product or to separate out trash and debris from other organic materials before use in the garden. My city has trucks that go around sucking up all the leaves in the fall. These leaves are then placed in a huge pile and allowed to decompose. I can go get decomposed leaves from them as needed but they often contain trash and rocks that need removed so I'm planning to use this trommel to sift that material as well as compost. Sifting also makes organic materials appear more uniform which is desirable if you are using them as a top dressing or mulch.

Step 1: Materials

Picture of Materials

Materials needed:

- 1/2 inch hardware cloth
- two large surplus bicycle rims
- 4 rollers and bolts to attach
- a little over 8 feet of dimensional lumber
- misc. wires for connecting the hardware cloth to the rims

Step 2: Remove the Spokes From the Rims

Picture of Remove the Spokes From the Rims

The fastest way is to cut them if you have some really strong wire or chain cutters. I used a really ancient fencing tool and that worked great! NOTE: You may also want to save the spokes to make plant markers.

Step 3: Cut the Hardware Cloth to Fit Inside the Rims

Picture of Cut the Hardware Cloth to Fit Inside the Rims

My rims (inside) measured about 21.4 inches in diameter so multiplying 21.4 x pi gives me a 67.2 inch minimum length. Add about 4 inches for overlap of the seam and cut at about 71 inches. I used standard 36 inch width hardware cloth.

Step 4: Attach the Hardware Cloth to the Rims

Picture of Attach the Hardware Cloth to the Rims

Place the hardware cloth inside the rims and attach with wires through the spoke holes. I used plastic coated #14 household electrical wire. To fasten the seam of the tube I used #18 wire. (Be careful not to over tighten the wire or the wire will break.) Make sure the wire on the outside of the rim is lying flat so that the rollers don't bump over it.

Step 5: Build the Roller Box

Picture of Build the Roller Box

This is a pretty simple structure so I won't go into a lot of detail. I used 2x6 lumber because I happened to have several short pieces on hand that were just the right size, but 2x4s should work fine too and would be a little lighter. My side pieces are 34 inches long and the ends are 19 inches long which leaves a gap of 16 inches in the middle. Note that one end needs to be ripped down 2.5 inches lower than the other because the drum needs to overrun the box slightly so that the coarse materials spill out of the drum. Since I used 2x6s (1.5 x 5.5) my spillway end piece was 3 inches wide. If you are using 2x4s (1.5x3.5) Then your end piece would need to be one inch wide.

Note that these dimensions assume that you are using the same diameter rims that I used. If you use different size rims then obviously you will need to modify the dimensions to accommodate your particular arc.

To align your rollers place the finished drum onto the roller box and then mark your roller positions. You may want to attach the rollers first with simple drywall screws (as I did) to test their positioning and then drill and bolt them later once you are happy with the alignment.

Step 6: Done

Picture of Done

Once the roller box is complete you are ready to try the trommel out. Mine fits perfectly on top of my wheelbarrow which is handy so you may want to take your wheelbarrow size into account when planning your dimensions. You could also place the trommel on sawhorses or make permanent legs if you prefer. Just make sure the output side of the trommel is slightly downhill from the input side.

If you have a large quantity of material to screen you may want to find a buddy who will keep turning the drum while you continue shoveling jmaterial. If you are working alone then you will have to load a couple shovelfuls into the drum and then give it a few turns yourself before loading more compost. Or if you are really mechanically inclined you could figure out how to hook up an electric motor like this guy did.

Step 7: One More Detail

Picture of One More Detail

Once I tried the trommel out I discovered that if you pile a couple shovelfuls of material in the uphill end of the drum and then turn it yourself some of the coarse material tends to spill uphill and out of the drum. To solve this problem I made a simple partition out of plywood to prevent this from happening. I don't think this would be a problem when operating the trommel with a buddy since the material wouldn't build up into such a large pile as you have when working alone.


Xriva made it! (author)2015-06-30

Followed your example - works great ! Nice fine top soil in wheel barrow - junk falls out the back.

Mine is turned by "Kids Power" - hence the wooden strips length wise. The kids grabs those to rotate the drum.

Added input chute and splash board on far side.

When in use have bin under output area.

Tsu Dho Nimh (author)2015-05-19

New version ... easier to make and store. Side rails bolt to sawhorses.

And ... all it takes to divide the fines from the coarse stuff coming out the end is a board leaning on the sawhorse.

franglish9265 (author)2015-05-05

To make this easier to scale to different rims etc.

How many radians is the distance between the two rollers?

As my current build is approx. 30" rims and 36" long 1/4" hardware cloth.

I experimented:

The best distance - gives the best combination of support and stability - is whatever puts the supporting wheels so they are about 90 degrees apart on the rims. If you draw lines from center of trommel through the axle of the support wheels, it should be a right angle.

Closer together and the trommel is top heavy and falls off easily when you spin it with a full load.

Farther apart and it tends to be harder to roll.

Has something to do with vectors of force and the fristion and that's out of my security clearance area.

franglish9265 (author)2015-04-22

If only it could be pedal powered, then that would be much more efficient energy wise.

VeitoM (author)2015-03-16

I love this!!!! Made a flat box sifter at home, but I think I'll use this idea for the kids at the Boys and Girls Club :)

33453 made it! (author)2014-07-11

Thanks for the nice instructions.

The rims i got for free had extra room to attach a spar. Very handy for turning the barrel. Installed four spars of 1/1 wood using a 3 inch deck screw. The back splash is a must. So much dirt spill off the side and makes a dirty mess. A nice shoot also helps direct the rocks into a bucket.

jonjmeyer (author)2013-08-18

Here is my version.

boffer (author)2009-09-22

When you get older, you have to work smarter. A motorized trommel. I'm working on phase two-an auto feeder using a post hole auger. for more pix

SteveGerber (author)boffer2013-03-08

Wow, that's really awesome! It looks like it might be a bit awkward to retrieve the sifted fines from the drawer. Have you considered designing it so that the fines would drop directly into a wheel barrow or your tractor bucket? By the way, what is the device shown in picture 100_1360? (

sdsmithies (author)boffer2012-06-01

Great photos and nice work boffer.

Mike4Online (author)2013-03-07

This trommel exceeded my expectations. It was easy to build, and is MUCH easier to operate than my old compost sifter. Compost can be sifted as fast as it can be shoveled in.

With an assistant, I was able to sift about 8 cubic yards of compost last weekend. In two more weekends, the entire pile (35 feet long and 15 feet wide) will be sifted. Everyone with a sizeable compost pile would do well to build one of these.

Incidentally, I added 2 aluminum strips (about 1.5" wide, with an "L" profile) to the inside of the screen, to help lift compost as the drum turns. But I don't think these pieces made much difference.

SteveGerber (author)Mike4Online2013-03-08

That's great to hear, I'm glad this project has been a success for you!

RedMayor (author)2012-05-14

Fantastic Instructable! I just made my own, fitted to the top of the empty third section of my compost bin with recycled bed frame wheels. Thanks so much for posting, it has already saved the strain on my back!

load_nikon (author)2009-08-21

I've made this and love it. I love it, the compost loves it, my back loves it, the neighbor kids love it. I used 2x3 from Lowe's because it's way less expensive and I enjoy the "weathered" look that the frame has. Also had to use swivel casters due to no rigid casters available at the time. They still work if they're pointed in towards the wheels. Zip-ties were used instead of wire but it does make it quite bumpy on account of the locking end of the tie lies within the groove of the rim. I think this helps a little by jarring the load every few degrees of rotation, however I reused the rim liner and this has reduced the bumping a bit. I told my dad about it and he wants to build one too. Maybe I'll expand on this idea some. Great 'able, thanks!

RoBear613 (author)load_nikon2012-04-28

"but it does make it quite bumpy on account of the locking end of the tie lies within the groove of the rim."

Try putting the locking end on the inside instead of the outside.

load_nikon (author)RoBear6132012-04-28

Yeah, I totally had to redo all the ties that way. Still works super though but I need to make up a feed-side hopper.

load_nikon (author)load_nikon2009-08-28

Form < Function

SteveGerber (author)load_nikon2009-08-28

Great work! Thanks for posting a picture!

baristabunny (author)2012-04-11

Very late posting a thanks, but thanks. Well written and a nice idea. I came across a non-functional wheelchair. The handrims make for a nice way to rotate the device and keep the material turning inside a little longer, which I find beneficial. Yours is the first instructable I ever built. Thanks again for sharing your idea. The supports are two simple Aldo Leopold benches that have many uses. Plans can be found by searching "ALDO LEOPOLD BENCH". I found them here:

pldehoff (author)2011-10-21

Excellent Instructable. Consider unscrewing the spokes from the rim rather than cutting them. Ends are not a sharp and less metal is lost. The inside of the rim should have a spoke holder that you can unscrew with a slotted screwdriver.

James__D (author)2011-08-26

I used tin snips, ant they worked well!

I also found free bike tire rims from a local bike co-op. They also suggested the local metal recycle business for free bike tire rims.

I got 26" rims free. (24.5" inside diameter for 77" hardware cloth minimum length)

Thanks for this well built instructable. (I always want to read this as Indestructable!)

tnman (author)2011-06-26

Steve, great job building your trommel! Your instructable was well written and executed. It was built with simplicity in mind, so the everyday gardner could build one, if they so desired. I too, will be building one of these for my gardening needs. Each year, my wife and I recycle materials for our compost bin. When spring time comes, we have lots of black compost that needs sifting through, to remove any large pieces of leftover material. This has always been a chore, but had to be done! I also like the comment left by OldBean, where he uses 1/4 inch wire mesh, placed inside present screen, to sift out smaller finds. I enjoy reading the post, as I always find a easier and better way of doing things, encountered during everyday life!

RichardBronosky (author)2010-06-25

I can't help but feel that you are missing out on a major opportunity by removing the hub and axle. Wouldn't it be nice to remove all but about 8 spokes (for passage/loading) and mount the axles to an A-Frame? I imagine that the metal on wood design here would be high friction and lend itself to lateral drift. I could be wrong though.

/me is embarrassed! I totally missed the wheels you added. Wow. Sorry. Your design is much better than my idea.

Divotfiller (author)2009-09-07

This could be modified for pedal power, but that makes it a two person operation. I am in the process of making a smaller diameter version of this for harvesting worms from castings, right now the tube and rims are complete and I'm working on a wood frame.

Damien59 (author)2009-06-15

So, I've been trying to make a motorized version of this... Heres some pics from my first attempt, which, didnt work so well, because the belt would slip if i put in a full shovel of dirt/rock... Ill put up some pictures of my new drive mechanism tomorrow

Tsu Dho Nimh (author)2009-02-08

Marvelous idea! It's working beautifully and it's far less work than the usual compost screen. I made some small changes to your idea. 1: There is a third bicycle rim in the center for added strength, and because I had it. 2: I laced the rim to the wire mesh with steel wire, in a running stitch in and out the spoke holes. It can be pushed flat against the wheel. 3: It was built to sit on my garden cart, so I screwed 4 small posts to fit in the holes that would hold slatted sides onto the cart. More secure. 4: It sits almost touching the input side of the frame, so I don't need the blocker like you do.

SteveGerber (author)Tsu Dho Nimh2009-02-08

That's great! Can you post a picture somewhere so we can all see how yours turned out?

Tsu Dho Nimh (author)SteveGerber2009-02-09

Sure ... here they are. It sifts an amazing amount of compost compared to the hand-rubbing through a wire mesh method. All I need now is a way to make it dog-powered.

SteveGerber (author)Tsu Dho Nimh2009-02-09

Sweet! Your trommel turned out great! Have you tried operating it with a buddy turning the drum continuously? You can really sift a lot of compost fast with a helper and the helper's job is really easy because the trommel can easily finish sifting the heaviest materials (the fines) before you can shovel a second scoop.

maryann47 (author)SteveGerber2009-03-30

If you mounted some casters on the sides of your stand, locate them where the bicycle rims are, the trommel would turn more easily.

Tsu Dho Nimh (author)maryann472009-05-12

There are wheels, just like Steve's trommel, but I didn't take pictures of them. I just showed the differences.

Tsu Dho Nimh (author)SteveGerber2009-02-10

Buddy? Buddy refuses! That's why I need the dog and a turnspit apparatus:

Because the sifter part is a bit wider and longer than my cart, I lose some fines out the sides and at the last few inches of the trommel. It's not enough to be a problem, but if you want to go for maximum recovery and minimum work, putting the trommel on sawhorses over something wide enough to catch all the fines would work.

A landscaper saw it today and was most impressed. He's going to build a couple of longer ones (with some angle iron for strength) to fit over his trailer so he can get the trash out of mulching materials.

SteveGerber (author)Tsu Dho Nimh2009-02-10


Ha, ha, ha! That's hilarious! I notice they hung a nice big ham hock out in front to tantalize him. ;)

bobdog (author)2009-05-10

The classic way to motorize a ball mill, tumbler or rotary sifter is to mount it on caster or old dryer bearings, then use a dryer motor and pulley with a long drive belt looped over the drum itself. In this design, I'd add another rim to run the belt in unless the casters are closely spaced and a belt can be run outside then on one of those rims.

bobdog (author)bobdog2009-05-10

BTW, I'd gut an old treadmill and use the motor, driver board and speed control instead of the dryer motor. Take care shielding the motor from dust and weather (I like to use clean black planting pots and cheap home furnace air filter fiber). Washer/dryer motors are nearly bombproof unless left in the weather, treadmills are a little more delicate.

Tsu Dho Nimh (author)2009-02-24

Made another modification: it's getting wobbly, so I put angle brackets inside the corners to hold it square.

Using this, I sifted out 4 cubic yards (25-30 garden carts full of compost) of finished compost in a week, to use on a lawn renovation project. The yield is highest if you run the stuff through twice. Although it's a lot like being a hamster in a wheel, it's much less stress than bending over a "rub it through" sifting screen.

oldbean (author)Tsu Dho Nimh2009-04-18

Easy enough. No need to make another drum, just add a 1/4"mesh inside the 1/2" drum. Mine is made from 3/4" mesh, 'cos that's what I had, with a 1/2" sleeve inside. I did it this way to make the drum stronger. If you made a 1/4" drum, it would bend too easily when you accidentally knocked it. To stop spills in the input end, you can use a disc cut from an old car tyre, that you then use to grow plants in (with your sifted compost). With the SUV low profile tyres, you should be able to get one the right dia for your drum that still has a big enough hole for loading. I made a 12' long sieve for charcoal about 15 years ago. It can separate six sizes in one pass using two concentric drums with three mesh sizes in each. There's a dust extractor on it too so I could collect powder.

SteveGerber (author)Tsu Dho Nimh2009-03-08

This past week I was (miserably) back to using an 'old fashioned' shallow box sifter because I wanted some 1/4 inch extra fines for a specialized carrot growing raised bed. Boy, that was a drag! :( If I had very much to do I would make another drum using 1/4 inch mesh but I don't think I would really use it that often. 1/2 inch is fine for most purposes and I would probably get too low a percentage of fines if I tried to use 1/4 inch for everything.

annelavin (author)2009-02-19

Brilliant. This is absolutely brilliant - and the instructable itself is very well done. Can't wait to make one of these this spring. My compost pile has been languishing, awaiting a screening, and I've been putting it off because it's so much work. This will fix that. Hurray!

koncept (author)2009-01-18

yeah, damn good idea is right. That is so simple, genius, i will build one this spring for my compost. Thanks for sharing!

carpespasm (author)2008-12-22

That's a damn good idea. How'd you come up with it?

juanangel (author)2008-07-06

Try using a smaller diameter rim at one end. keeping that end higher will avoid spills and you can add more leaves and turn it without fear. It is a great idea.

Mr. Rig It (author)2008-07-01

Very cool and well written. Great use of materials. I could use one of these. Good Job.

uguy (author)Mr. Rig It2008-07-02

Ditto! Thanks for sharing!

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