Slightly Over-engineered Homemade Gravel Trommel

[MrDhammon]

What size v-belt are you using?

[wardomon]

@MrDhammon I'm pretty sure that I went with the larger 5L. Getting the length right was another thing. Two tries to get the motor to drive shaft correct and three to get the drive shaft to drum. It's a good thing that the Fleet Farm is only 7 miles away. You said that you're using 22" rims. I had a pair of 27" that I salvaged from an old bike and picked up the 3rd from a bike shop for $6. If you aren't too far along, see if you can build a larger drum.

[MrDhammon]

@wardomon I need to get the v-belt, pulleys and small wheels for the drum to ride upon. I have the frame, and drum completed. I guess one could say that all I have left are the mechanics...

[wardomon]

@MrDhammon You're at the fun part of construction. I got my wheels at a surplus store for about $5 each. They've got ball-bearing inserts in a steel wheel and wide rubber tires. I figured that a plastic hub on a threaded rod would wear out too quickly. If you have a Fleet Farm nearby, they have a wide assortment of drive components. Be sure to build in ways to adjust belt tensions.

[wardomon]

Thirty six inches.  I got a roll of 36" hardware cloth (1/4" mesh galvanized screen). The drum is more than 7' in circumfrence. I think I had to buy 10'. Get fencing wire to lace the screen to the rims. Sew it on. Out one spoke hole, in the next. Once I had it laced, I twisted "Z" bends into the wire on the outside of the rim. You'll have to fudge around with pulley sizes to get the drum speed into the 24 - 30 rpm range.

[MrDhammon]

How long is your drum? You state that you have a 27" diameter drum. I'm collecting parts now. I have rims that would make a 22 1/2" diameter drum.

[wardomon]

@MrDhammon I found a pulley calc here: blocklayer.mobi/pulley-belteng­.aspx

1725 rpm motor w/ 2" pulley to a 12" pulley = 287rpm

345 rpm on a shafted 2" pulley to a ~22" drum = ~25rpm

Keep the speed under 30rpm or you be "spin drying" the dirt rather than sifting it.

[winkdogg]

the possibilities are endless your project is an inspiration! coin sorting , seperating mixed hardware , quality control sorting of candy , ball bearings , widgits etc! sure there are pourpose build machines for these tasks but are usually industrial sized high dollar drum machines that cost a fortune!

[winkdogg]

I also have been known to "over complicate" some of my diy project / homemade tools etc so I think this sucker is great! and at any time you can change the mesh size or drill a solid barrel to the proper size to sift whatever you like! You could magnitize it to seperate metal or heat or cool it to thermo sort different material.

!

[wardomon]

@winkdogg : Thanks. I thought about an magnets to get the nails and bottle caps but I had to hand sort wood chips, bones and shards of glass from the mix anyway. It didn't seem like it would be worth the effort. Look at the other video I posted. I used a fan to blow light organic material (grass and roots) out of the gravel.

[shexdensmore]

it looks like you could mass produce yours. Every one else's you build your self and hope it works. Being made out of rough cut timber.

[wardomon]

@shexdensmore : Thanks. It's all 2x4's & 1x4's combined with hardware from a big box store and mechanics from the local surplus dealer. I really should have drawn up plans as I built it.

[shexdensmore]

@wardomon

Well you can still draw up a plan of how it is built. Just take it apart. lol

[wardomon]

@shexdensmore : Funny! I used so many screws I had to get more.

[wardomon]

That was my initial thought as well, what's gonna keep the drum from flopping all over the place. It's amazing how strong it is. The fence wire exerts lot of force on the screen. I also laced the overlap together lengthwise using the wire that was wrapped around the roll of screen.

I should have taken more pictures and taken measurements. If I thought that there was any money in it, I'd sell plans.

[MrDhammon]

other than the wire mesh connected to the bike rims, what keeps the "basket" rigid?

[wardomon]

I laced it on with fence wire. In one hole out the next as tightly possible. I used a needle-nose pliers to tension it further by putting a z-bend in the wire between every hole.

I'll have to replace the screen. Three yards of gravel was a bit more than it could handle.

[MrDhammon]

how did you fasten the wire to the bike rims?

[hastolloy]

I found the motor to be a 1hp motor....That should be enough power



[wardomon]

That's great! I was thinking that you'd need extra power if the drum was that long.

[hastolloy]

Just scored a free 1/2 hp motor from a friend I work with

[wardomon]

Six feet is about right. The cement mixer motor is probably 1/3hp. I've been putting a 4"x6"x1/2" chunk of rock in with the mix to grind up the clumps.

[hastolloy]

I was thinking of building my trommel with a electric motor from a cement mixer, thinking that the compost I sift would be a lot lighter then concrete that the motor was built for...And I have plans to make my trommel 6' long, only because I have the frame portion done from a previouse project that I dont use anymore....

[wardomon]

It's a 1/3 hp 1725rpm motor and it needs every bit. I'd change up to 1/2hp if I found a free one. Pulleys are 2" at the motor to a 10" at the shaft, then a 2" running the belt to the 27" drum. The drum turns at around 26rpm. I added a 4" lip (visible starting at :40) to the output end to keep the mix in the drum longer. I was getting a lot of mud balls in with the aggregate. If I was making another, I'd make it longer and I'd try to find 28" (700c) bike rims. Bigger is better.

[hastolloy]

First of all you have there a great piece of equipment, nothing wrong with over engineering something.....I have plans to build a trommel with a ID of about 24".....My only hang up now is how to get the trommel to turn...I see you used a electric motor which I like but how did you reduce the speed so that the material gets sifted properly? All I plan on sifting is compost so I dont think I need a high hp motor...I would like to get my hands on a motor used for a cement mixer...