Setting a sluice box
 

I ended up going with the Keene A52 (big one). I took it out for the first time last week, and it was frustrating trying to get it set correctly. The stream was running with strong volume, and I had a hard time getting is set high enough in the stream. Here are some questions:

1. Should the entire box be "full" of water? (At least within an inch of the top)

2. I've heard people say "15 seconds is too fast, and 45 seconds is too long". Are they talking about the amount of time for a scoop of 4 mesh classified material to wash INTO the box (from the initial pile) or OUT OF the box (until blond sands are washed completely away)?

I tried the rule of thumb (one inch descent for every foot of length), but this seemed to be way to fast -- especially because the A52 has a broad "intake" (this generates quite a bit of velocity).

Any tips would be greatly appreciated!

Re: Setting a sluice box
 

An A52 is more difficult to set up compared with (say) and A51 type or shorter box. This is because of the length of the A52. Rule: The longer the box the more difficult it is to set up. That said, they're not too hard.

you want at least a 2" depth of water running through the box. A deeper depth will not be problematic. The rule of thumb 1" drop for every 1' of box length is fine under usual conditions... i.e. not too high or two low a water velocity, and sufficient water entering the head of the box.

If the water flowing through the box has too much velocity then the smaller colors don't have a chance to settle out; they will "blow out" the foot of the box with all the lighter materials. Too little velocity and sands & gravels will "load" (pile) up in the box and defeat the riffles. As a result, colors will wash over the top and out the foot of the box.

One ofthe things a prospector needs to do if s/he is going to set up a sluice box, is become and engineer and alter the site. I don't think I've ever had a set up that I didn't have to do a little construction work to get the proper amount of water flowing and at the right velocity. The water and materials dribbled into the head of the box will tell you when the velocity of the water is "right". After some seconds, the water will steadly move the materials down over the riffles and out of the foot. Drop a twig into the head of the box. It should take maybe 4-5 seconds to move through and out the foot...but the movement or non movement of the light sands & gravels will ultimately tell you.

If you have too fast a velocity of water you need to divert some of the water with what we call a "wing dam".... set rocks in a "V" formation with the open legs of the "V" about 12-15 inches upstream from the head of the box, and make the legs of the "V" make the vortex (of the "V") upstream from the end of the open legs. i.e. If there is too little water then build the dam with the legs wider up stream and narrowing (coming towards each other but not touching) so at the head of the box they are the same width as the sides of the box.

Carry some plastic trash bags for this work; set the rocks on the edge of bags so the rest of the bag is sticking up above the water on the upstream side of the rocks. The plastic will keep you from losing water between the rocks.

Sometimes you can just set a couple of big rocks near the head of the box and they will divert water you don't want to enter the box.

Clear as mud probably...but don't get discouraged. A guy virtually ALWAYS has to do some constructing at the spot he wants to set up a box...usually as close as possible to the area he is getting materials to wash.

Re: Setting a sluice box
 

1. Should the entire box be "full" of water? (At least within an inch of the top)

No way, thats completely unnecessary. The right setting is a combination of drop and water flow. more drop and you need less flow, more flow and you need less drop. The material you put in should move along at a reasonable speed. It should not just blow throught the sluice in a couple seconds, but it should not just sit there and do nothing either.

2. I've heard people say "15 seconds is too fast, and 45 seconds is too long". Are they talking about the amount of time for a scoop of 4 mesh classified material to wash INTO the box (from the initial pile) or OUT OF the box (until blond sands are washed completely away)?

15 to 30 seconds to clear out is good. Slower than that and I'd try to direct more water into the sluice.

Good luck with your digging!

Here is a shot of a sluice from my website:

http://nevada-outback-gems.com/basic...uice_river.jpg


Chris