good angle for rock separator

[lfreng]

So I am looking at building a rock separator for getting some decent fill. Some of the details: Land I will be digging is primarily sandy loam with glacial boulders (fist sized to 12" angular boulders most likely, the larger stuff I can sort out with the bucket). Southern Boundary Waters area in MN. I am thinking of 3" separation in slats. This is just personal use for building some small atv roads, septic top cover and general fill in of low spots around the cabin so it wont be used heavily like a commercial operation. More hobby in nature. I will be dumping with a 16" mini ex bucket. I tried googling for a good angle on this type of rig and didn't come up with much. Does anyone have any recommendations as to a start point. I might work in some adjustability for fine tuning when it is fabricated but not sure where exactly to make a start point to go +/- off of. Attached is an initial concept. If you have any recommendations as to design improvements would like to hear them. (side note: I do not want vibratory, keeping it simple)

 

[Scrub Puller]

Yair . . . Ifreng. The ones I have seen scalping the big stuff off run of the ridge gravel were pretty steep . . . at a guess forty five degrees or so.

Four inch box with about a 3/8" wall mounted diamond wise seemed to work pretty good.

The more dwell time you can give it the better to get the separation as it passes down the slats.

I am sure Grandpa or some of the other quarry blokes will set you right.

Cheers.

 

[JDOFMEMI]

I very nearly agree with Scrub. The ones I have used are pretty steep, but I think a bit less than 45 degrees. I would build in some adjustability on the front side of the legs, and give it a range from about 30 degrees to maybe 40 degrees, 45 if it does not get too tall to be stable.

My reasoning is that the angle of repose, or the angle that material stacks at, is on average about 1.3H to 1V, or about 33 degrees. hardly anything except very sticky soil will stack at 45 degrees, or a 1:1 slope.
You want the dirt to move slowly enough to fall through, while the rock needs to roll or slide off with out hanging up. Get it too steep and much of the dirt will be in the rockpile, while too flat and the rock will hang up and plug the thing.

I suggest the adjustments so you can find a happy medium in your material. You could also shoot for the middle of the range and then change the slope by putting the front legs on a pile or in a hole to accomplish the same thing and keep it simple.

 

[wrangler]

When I enter images on google for stationary grizzly the photos I see are a lot steeper than your drawing.More in the range of 45 degrees or steeper.

 

[grandpa]

So if your going to feed it with a mini,,, what are you going to remove the material with?

You can get by with a flatter grizzly feeding with an excavator vs a wheel loader. Like JDOFMEMI stated you can adjust the angle by putting piles under the front or back legs. How long are your bars going to be? What thickness of bars are you contemplating?

If your after the fill and not the rock, then your mini could push the rocks across the face thus getting by with a flatter deck.

 

[Silveroddo]

For the effort and time involved for the amount of material your probably talking about, you might be ahead of the game to get some material trucked in..... Just a suggestion, unless you need the rock for something else.