Building a Trommel

[akflyer]

Howdy guys. Planning my first trommel build. Normally I use a highbanker playing in the creeks around here but I recently went and played in the pay dirt at a buddies mine that is made up mostly of nice sharp broken and decaying bed rock. The funky shapes and sharp edges don't really play well with the high banker so I am thinking a trommel is the way to go. I am one of those guys that cant stand to buy something I can have fun building so I am drawing up parts to have sent to the waterjet guy to cut them out so I just have to brake and weld for the most part.

I am keeping it relatively small so I can either put it in the back of the side X side or toss in the plane and fly out to remote locations with it. Barrel is 8" X 32" with 13" of classification using 1/2" holes.

For the barrel, would you rather have steel with the holes cut in it, or use flat expanded metal in it for the classification? I have seen the plans with the expanded metal in it but am not sure if that will become a lot of little traps for the sharp rock versus say 1/2" holes in the barrel that are waterjet cut.

Any thoughts?

 

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[arizau]

A squeegee of sorts (maybe a piece of stiff belting or even a piece of softwood?) mounted on the outside of the drum may help to discourage rocks from lodging into the holes, square or round. With round holes you will probably get better washing of the rocks but the area of openings will probably be less than with screen. Lifter bars, installed inside the drum such that they lift the rocks up and kind of angle them backwards before they drop, will help washing regardless of opening type. Pieces of kerf cut wood* (replaceable wear item) or maybe even belting should be flexible enough to be used for these too to make the installation simpler. Just my thoughts.

Good luck.

*https://www.google.com/search?q=how...ome..69i57.17239j0j7&sourceid=chrome&ie=UTF-8

 

[akflyer]

Good thoughts. Excited to get home and bust out his project! The nice part of the trommel is if I don't like the barrel I can easily change it up or build several of them to have on hand depending on the type of ground I am playing in and size of probable gold that would be found.

 

[N-Lionberger]

I am in the process of building a trommel, I went with drilling the holes in the barrel as it seems to me it will hold up better over the years of winter weather up at the mine, I'm going to make it a permenant setup that I will pipe the slurry down to using a hydraulic elevator, a little bit different than what you're suggesting. I have looked at a lot of designs for trommels and if I was going to make one for packing around I would make the barrel with large openings that can be covered in a sleeve of punch plate or expanded that can be clamped on, the best method I have seen is welding angle iron strips on the ends of the rolled expanded to hold bolts for tightening er down. That way you can change it out based on the fineness of gold at different locations.

 

[akflyer]

That gives me something to think about for sure. Just change out the screens not the barrel! I dig it

 

[akflyer]

I got a decent start on the trommel this hitch home. Frame is built and motor is mounted. I have about 1/3 of the holes drilled in the barrel. It goes pretty quick using the drill press but its still a ton of holes to drill. I used 8" X .125" pipe for the barrel and am drilling 1/2" holes in it. If I don't like how it runs I will cut some slots in the barrel and wrap it with expanded metal. All that will play out probably next summer now as the ground should be frozen by the time I get back home again.

The frame is 3/4" tubing with the top section of the legs being 1.25" tubing. The lower legs will be 1" tubing that will be able to slide for height and leveling.

I will have 2 sluice runs under it using gold hog matting. It should end up being a pretty cool little tool that I can break down easy to put in the wheeler or plane to et out and play in some remote areas and see if I can find something worth building bugger stuff for. I could have probably just bought one for the time I will have into this but I enjoy fabricating stuff and time spent in the garage keeps me out of other trouble.

I purchased a 96 tooth sprocket and took it to the local waterjet guy to have him cut the center out to slip on the 8" barrel.... then he cut the hole 1/2" off center. Slight set back on that one.

I am pretty excited to get this lil bugger up and running and I can see a larger one in the future.

I also picked up a Kobelco SS1 micro excavator to play with. The bucket is not much bigger than a shovel but its easy on the back and I can put a beer holder on it as well. If I am going to play I may as well have fun doing it and not work too hard if I can help it right?? haha

 

[Mine Shaft]

Are you putting 1/2" holes in the pipe through out the pipe ? How many holes ?

 

[akflyer]

I have drilled about 1/3 of the holes now. Yes they are half inch and the drilled section is 14" long. Should end up with around 1300 holes. I didn't lay them out I just blocked the pipe onto the drill press and started going to town with a pretty tight pattern ~ 1/8-3/16" between holes and staggering the rows. Actually goes pretty fast on the drill press. I used 2 chunks of 2x4 clamped to the table on the press so the pipe doesn't roll and I slide it on down the line till I hit the end of the row then give it a slight turn and slide it back down as I go. Works pretty slick and it keep the bit centered. No need for pilot holes, just the 1/2" bit.

 

[Mine Shaft]

The reason i asked was if you thought about 1/8" "Perf" sheet, boy that would save a lot of drilling and not to mention if you got to clean up the burs on the inside lol. Good luck looks good.

 

[akflyer]

The reason i asked was if you thought about 1/8" "Perf" sheet, boy that would save a lot of drilling and not to mention if you got to clean up the burs on the inside lol. Good luck looks good.

I thought about perf sheet but no one local had it and getting some shipped in was cost prohibitive. One of the few drawbacks to living in AK. Air tools will make quick work of deburring the inside of the holes. I tend to enjoy fabricating as much as possible just to say yep, I did it. Not to mention that the cost of "prototyping" various tools and products for a home based fabrication business is a nice write off. These days you gotta do all you can to beat the system and put more $ back in your own pocket.

I had actually laid it out in cad to have the local waterjet guy cut out the holes in a sheet and was going to roll it for the barrel but when he could not figure out how to square the plate on the table and cut the sprocket 1/2" off center I cut my losses and went this route.

 

[N-Lionberger]

Why would you need to deburr the holes? They're going to get sanded on pretty hard by all the rocks.

 

[Mine Shaft]

Why would you need to deburr the holes? They're going to get sanded on pretty hard by all the rocks.

The size of burs that a 1/2" drill bit going through 1/8" steel are large and will mushroom after time and could interfere with the flow and trap gold under the bur.

 

[N-Lionberger]

I drilled half inch holes in my trommel barrel, approximately 2600 of them lol I straddled it like a horse and went at it with the drill. The size of the burrs isn't substantial I really cant picture them being an issue especially after a couple hundred yards of gravel wearing it smooth. Also the amount of gold that may get caught by burrs really can't be that much to worry about. The part I worry about is how the growsers are welded in I can picture flat nuggets getting stuck in some of those nooks and crannies.

 

[akflyer]

I drilled half inch holes in my trommel barrel, approximately 2600 of them lol I straddled it like a horse and went at it with the drill. The size of the burrs isn't substantial I really cant picture them being an issue especially after a couple hundred yards of gravel wearing it smooth. Also the amount of gold that may get caught by burrs really can't be that much to worry about. The part I worry about is how the growsers are welded in I can picture flat nuggets getting stuck in some of those nooks and crannies.

2600 with a drill?? sounds like a not so good of time to me! LOL

I have thought about that. I can reach in there and weld them out however, I have been thinking about drilling and tapping them so I can bolt them in for relatively easy removal should I decided to change size or orientation etc. A bead of 5200 would seal them up completely so nothing could be trapped by them. A couple bolts or screws on each one with the 5200 and I don't think they would come out unless I wanted them to. Thoughts??

 

[arizau]

This is kind of after the fact(?) so maybe another time.

I've never seen this before for trommels but the idea should/may work and be somewhat self cleaning at the same time! What about spiral cutting parallel slits all the way around the drum?* Reinforce the drum, if necessary, by welding a few rods along the outside. With drum rotation, the feed would tend to track in the slits with the fines falling through and stubborn, hung up, rocks maybe being popped out or forced through with the action since only two sides of the rocks contact the slits compared to full circumference with round holes.

OOPS, here I go thinking outside the box again. Good luck.

*Cut parallel, diagonal slits between the edges of plate steel then finish cutting the slits when the plate is formed and welded to drum shape..or not(?).

 

[akflyer]

I thought about slits instead of holes, but the flat rocks were getting through the 3/8 grizzlys on my highbanker so I went with the holes hoping to keep the flat rocks out of the sluice.

 

[N-Lionberger]

How are you going to drive this beast? I have stagnated in my trommel project over this, I originally planned on casters and use a dc motor with a flat belt but have become interested in utilizing a pelton wheel to drive a set of powered rollers much like a big rock tumbler, I was looking at the steel tires from wagon wheels as a source of steel rings to affix to my barrel to make rails so I can use old ore cart wheels as my rollers.

 

[akflyer]

I am using a 12V motor and chain drive. I also added in a PWM speed controller so I can dial in RPM depending on the material. Extended family healthy issues prevented me from getting dirt through the barrel but its only about 1 day away from being able to run dirt now. Hopefully next hitch home I can find some ground that is not yet frozen and give her a test run.

 

[N-Lionberger]

Looking good! I just realized the size based on your welding gloves, looks burly.

 

[dredgernaut]

looks good and stout. it probably will out last all of us.