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Author Topic: Throw Screen  (Read 3962 times)

tinker

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Throw Screen
« on: May 05, 2013, 11:08:33 AM »
Again for Rumble, I copied Jimmyjerry's idea that he has posted and this is the result, I made it from left overs I found around my house and at the local tip (again).  The only things I paid for were the two wing nuts that attach to legs to the main frame. 8)

colza

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Re: Throw Screen
« Reply #1 on: May 05, 2013, 12:19:49 PM »
Hi tinker. Wanted to ask you the throw screen is used. Haven't seen one before, but it looks like something I could put together. Thanks.
Cheers,
colza
I dig it.

tinker

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Re: Throw Screen
« Reply #2 on: May 05, 2013, 05:44:11 PM »
Colza, its used when your fossicking and saves you taking home a lot of waste.  I usually throw the gravel onto it and it seperates it into three grades.

 There is usually a bit of channel iron diagonally across the top screen, which gets rid of the large rocks, I then have a half inch screen with a funnel at the bottom that feeds those rocks into a bucket and then finally have a quarter inch screen at the back with a bag under it to catch the smaller stuff, where the gem bits and pieces are.  It works fine for me saves a lot of time sorting by hand.  Is simple to make and you can have it any size you want and make your screens any size as well, at the moment I find the screens I use are adequate for the materials I'm looking for.

colza

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Re: Throw Screen
« Reply #3 on: May 06, 2013, 06:51:38 AM »
Thanks tinker. That makes a lot of sense.
Cheers,
colza
I dig it.

Bluey Zarzoff

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Re: Throw Screen
« Reply #4 on: May 06, 2013, 08:00:06 PM »
Also seen a throw screen used by inverting the bucket on the large mesh and rubbed up and down to break up the clumps. Works well if the dirt is a bit tight.
I started out with nothing
And still have most of it left.

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Lefty

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Re: Throw Screen
« Reply #5 on: August 15, 2013, 04:40:54 AM »
There's some interesting looking ideas in this sub-forum.

Shortly, we're going out to the Rubyvale gemfields to peg a couple of claims. We had a couple at Russian gully near Rubyvale around 30 years ago when I was just knee-high. After a couple of years, Dad got himself a trommel and pulsator (both of which were sold many years ago) but I remember that everyone did all the hand work using sheer grunt. While I am the picture of health and vitality  :P ;D, Dad and father-in-law would appreciate anything that would make the work lighter until such a time as we can acquire and use mechanised equipment again.

A willoughby would surely save your back a bit and I particularly like the idea of the sieve "shaker table" that Fullerton has in his photo. I suppose the rails in the bottom have to be made of/covered with a smooth, softish material so that the rails and the sieve don't wear each other out?

Lefty

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Re: Throw Screen
« Reply #6 on: November 03, 2013, 07:07:59 PM »
Made my first throw sieve today. Already had a large rectangular sieve about the same size as your typical throw sieve so I really only needed to add to it. It had extremely shallow sides so I deepened it with lengths of old channel iron bolted to the existing steel frame. I placed a sheet of 1-inch square mesh over top and then - fearing I would lose stuff over the sides - added another run of channel iron sides, sandwiching the larger mesh between the two runs of iron and creating sides of decent depth for the larger mesh layer.

Gave it a test run behind the shed. First half a dozen shovels and it seemed to be working great. But very quickly, the larger stones stopped running down the diagonal chute and material began to build up and spill over the front. Hmm - angle of the chute too shallow? Looks close to the angle of all the others I have seen. Closer examination revealed what is likely the problem. The larger mesh is not particularly high-tensile stuff. It's solid enough but is somewhat lacking in rigidity. It is attatched at the top and sides but the diagonal chute running across it is only attached to the sides of the frame. As more material goes on, the weight creates a belly in the top mesh, causing a gap to open between the chute and the mesh and the ends of some of the larger stones get jammed under the side of the chute instead of falling into it. More material slides down and gets jammed on them, and so on.

Just need to affix the chute tightly to the mesh along it's length so the mesh can't pull away and hopefully that will do the trick. I still expect to have to pull the shovel along the chute to free stuff up from time to time at least.

The angle that the sieve is propped up on seems important as well. Too steep and some material will fly off the front of the sieve. Too shallow and the larger stones wont shed away properly.

I suppose the friability of your wash will be a factor too. Luckily, my stuff is fairly loose and breaks up into sievable dirt easily.

I see that most of them are fairly low to the ground and run the sieved gravel to be washed into a bucket underneath. I had the idea of extending the legs so that the thing sits higher in the air. Where the desirable stuff comes out, feeding that into a piece of 100mm sewer pipe or something such with an elbow and another piece of pipe coming out of that and feeding straight down into a large wiloughby. I have another large rectangular sieve the same size with nice deep sides that we hang from a big tripod. I was thinking that could sit that in a large, low rectangular tub on wheels and feed the pipe straight into that. When full enough, scrub the stuff by hand then lift the whole thing out of the tub (it has handles) and straight onto a table to be sorted.

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