Re: portable sifting screen

From: Tedd Jacobs (Jacobs_at_mail.boisestate.edu)
Date: 03/17/05 

Date: Wed, 16 Mar 2005 23:13:17 -0700

(apologies for the self post)

"Tedd Jacobs" wrote...
>
> "Eric Stevens" wrote...
>> On Wed, 16 Mar 2005 14:54:32 -0700, "Tedd Jacobs"
>> <Jacobs@mail.boisestate.edu> wrote:
>>
>>>trying to find a manufacturer or supplier of a sifting screen that breaks
>>>down and is easily portable. i've checked the ones from foresters supply
>>>and a couple of others on-line, but they either 1.) are too small, 2.)
>>>dont
>>>compact, or 3.) are an "assemble when needed & discard". most of which
>>>have no self support with the exception of a "backpackers" rocker screen,
>>>which would require one person to pack on their back with little or no
>>>room
>>>for other equipment.
>>>
>>>what we are looking for is a portable screen that is compactable enough
>>>to
>>>be hiked in and out of a canyon site, has some type of support (either
>>>suspended or rocker), and is large enough to be of actual use (at minimum
>>>24" x 24") with 1/8" mesh.
>>>
>>>if a suitable one cannot be found we'll have to start fabricating our own
>>>which means we'd need to come up with a design. either wood, alluminum,
>>>a
>>>composite of both, or some other design entirely.
>>>
>>>any help finding or ideas designing are greatly appreciated.
>>>
>> How rugged do you want this to be? Are you trying to sift out
>> head-sized stones, stones like coffee cups, or merely fine dirt from
>> finer dirt?
>
> multipurpose: rocks- anything smaller than a golfball can easily be
> handled
>
>
>>
>> How big a volume do you want to sift? 1 cu.ft., 1 cu.yard, or what?
>
> normally we use buckets to transport the dirt from the unit to the screen,
> in a situation like this however we'll more than likely be shoveling
> straight into the screen or using dustpans. if we're not getting alot it
> is not uncommon to have the screen going while the shoveler continues to
> toss the dirt on in. so three to four shovel fulls need to be able to be
> handled, roughly 1- 1.5 cu ft.
>
>>
>> Are you sifting dry soil or wet and gluggy?
>
> varies. the soils are always changing depending on conditions. becase
> the unit floors are "shaved" the sediments are generally broken up rather
> well, but depending on moisture content they can ball right back up given
> the motion.
>
>>
>> How durable do you need it to be? 1 hour, one day or the rest of your
>> life?
>
> the rest of our life, also needs to be bulletproof, invisible and able to
> walk on water on it's own.
>
>>
>> Do you need a metal mesh or can you use fabric e.g. shade cloth?
>
> hmm... usually we always use 1/8th inch wire mesh screening. bcloth
> worries me, wouldnt take much for a lithic to cut right through it,
> especially when its being rocked back and forth. having to stop for
> repairs like this can really piss off the PI. ;-)
>
>>
>> Do want it to stand on legs or can you hang it from a tree?
>
> legged or "rocking" screens are usually the norm (for an visual example
> see: http://www.stoneyknoll.com/ ) another type is to have a suspended
> box using either a three- or four-legged stand from which the screening
> box hangs under. better not to attempt to rely on having a tree or other
> natural formation to hang it from.

one method we've considered for support is three telescoping aluminum legs,
it would have to be able to extend to at least a 6-7 feet overall height
with a 5-6 base width. and still support the weight and movement. all the
ones i have seen like this use 2x4s and are about 8 feet tall. smaller in
this case does not work better. you dont want to spend a day hunched over a
screen that's 2 feet off the ground or with one that has no room to be moved
(shaken).

>
>>
>> Are you going to use it in an arid desert with no life, will trees be
>> in the vicinity or will you be in deep jungle? (i.e. what
>> opportunities will you have to construct temporary bits and pieces
>> from the local flora with a machette?)
>
> none. better off to not rely on what might or might not be there.
>

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