# Home Made Filter Press



## kurt (Nov 27, 2011)

OK – its nothing fancy, but for the “small” time home refiner its cheap – easy to make & it works.

The tube is a piece of 4 inch PVC drain pipe (the thick wall type) 8 inch’s long with a 4 inch PVC cap with ½ inch holes drilled in it. I then cut a piece of fine mesh stainless steel screen to the O. D. of the drain pipe to fit in the bottom of the drain pipe cap with 3 coffee filters cut to the same size. The purpose of the stainless screen is to keep the coffee filters from tearing &/or braking through when applying pressure with the plunger in the press. The plunger is made from a cottage cheese container lid cut to the I. D. of the drain pipe (to make a good seal) with a stainless steel backing plate cut from the housing of an old microwave I scraped. The stainless backing plate is cut just a bit smaller then the I.D. of the drain pipe so that it doesn’t hang up & drag on the side of the tube when pushing the plunger down.

First test run was done with a batch of silver cement. After it was done dripping from gravity filtration I put the plunger to work & squeezed out right at another 4 oz. of solution (copper nitrate) with the end result being a very nice – very firm – silver cement cake.

Took me about an hour & a half to make & the only thing I had to buy was the end cap. Everything else was scrap. I should add that I had to take my dramel with a sanding drum (coarse grit) & hone the inside walls of the end cap just a bit so the drain pipe would seat all the way to the bottom but still fit snug so that the end cap still needs just a bit of tapping to remove.

Kurt


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## kurt (Nov 27, 2011)

Hmmm - for some reson the bottom of the pics got cut off. --- so here is another try with just a pic of the filter

Kurt


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## Joeforbes (Nov 27, 2011)

Kurt,

The pictures look like they got cut off, but there is a scroll bar on the right of each one. The pictures are there in full.

I love the press. Anyone doing this as a hobby could greatly benefit from using one.

One question though - There is still a good amount of Copper Nitrate still left in the Silver cake, how do you plan to remove the Copper before melting? 

I just got in a larger sized filter press made by ErtelAlsop in Kingston New York (I would definitely recommend them to anyone looking to make the investment for a good filter press, but they are expensive. Mine is capable of filtering 8 gallons per minute with a maximum cake capacity of about 3/4 of a cubic foot. Additional plates can be added to it so that it can hold up to three of the 3/4 cubic foot cakes at a time. It cost about $7000 shipped though, the additional plates cost about $700 a set).

But it cleans residue away from the cake by pumping through distilled water, and then uses an air compressor to increase the inside pressure to about 120PSI, which forces out any liquid that might be remaining.

It seems to be that you could also attached an air compressor to this unit pretty easily (obviously the pvc couldn't withstand 120PSI, but it could withstand something.)

Also, the compressed air it's self can be used to power the press, like a reverse vacuum filter. That's how mine works at least. The "press" is just to keep it a closed system that can withstand pressure that high, it doesn't actually press the liquid through by closing.


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## philddreamer (Nov 27, 2011)

Interesting, thanks for sharing, Kurt! 8) 

Phil


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## skeeter629 (Nov 27, 2011)

You should wash the silver with hot distilled water until no copper nitrate comes off in the wash.


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## kurt (Nov 28, 2011)

Hey Joeforbes – I see your from Wisconsin also – if your any where around the central part of Wi maybe we could get together sometime?

Anyway – you wrote – “One question though - There is still a good amount of Copper Nitrate still left in the Silver cake, how do you plan to remove the Copper before melting?

I figured someone was going to ask that question. --- That was just the first press & I was so happy with the results I wanted to get it posted before I got busy with some other things I needed to do yesterday.

So this is what I did to finish the process. – I put the cake back into one of my gallon jars & added just enough water to brake it back up (used a stainless kitchen whip to stir & beat it a bit) let it settle about 15 minutes (just enough time to let the heavier courser silver settle) Then siphoned off that water (that’s the water/copper nitrate in the ½ gallon mason jar) which still contains a fair amount of ultra fine silver which I will let settle as a ongoing ultra fine settling stock pot. – I then put the heavier cement back in the press & poured some more water through it till it looked like it was running fairly clear (the gallon jar in the middle) placed the filter over the end gallon jar, poured in a little more water to make sure it was running clear & pressed it for a second & final press.

All in all –it only took about an hour & a half (maybe 2) to do both presses & only about 2/3 (maybe ¾) of a gallon of water to end up with a nice clean silver cake that should take much less dry time now that most of the water is squeezed out. (that means less time on the hot plate which means less electricity used)

Before – when depending on gravity filtration - it would take the better part of a day (if not all day) because filters would plug up & slow down to a drip so it would take multiple washings through multiple filters with multiple gallons of water with more ultra fine silver (from rinsing multiple filters) & more dry time to get rid of the excess water.

I am a real happy camper at this point considering I only have an hour & a half time invested in making the filter & $8 cash to buy the PVC end cap as an experiment. Next thing to do is to see if its going to work as well on things like squeezing the solution out of things like ash from incinerated IC chips & ceramic slug from boiled ceramic caps etc. etc.

But first I need to finish with some more silver I am currently working with, as well as getting my fume hood installed (now that the weather is getting to cold to work outside) in the new lab I have been building. Oh ya - & then I have to get the deer I got hunting this last week skinned & cut up (the one good thing about the cold is that can still hang for a couple more days being as how it was the end of the week I got it)

Kurt


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## kurt (Nov 28, 2011)

Oooops - forgot to post the pics of the second filter run,  so here they are as explained in the previous post


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## samuel-a (Nov 28, 2011)

That's very inovative kurt.

I like the idea of using plain pvc pipe.


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## HAuCl4 (Nov 28, 2011)

I like it!. I used a similar device once, but used fiberglass cloth instead of the stainless mesh screen. 8)


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## Joeforbes (Nov 28, 2011)

skeeter629 said:


> You should wash the silver with hot distilled water until no copper nitrate comes off in the wash.



I tend to over think things  .. haha

Kurt, I'm in Southwest Wisconsin. I'd love to meet up sometime though, I've been looking for other small time refiners in Wisconsin for a while now. Where are you located?


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## gmiller (Feb 3, 2012)

Hi all,

I like it for its simplicity and low cost. I just have one question. How did you seal the plunger? I don't eat cottage cheese but have cut a butter tub lid to a very close fit.

Thanks,

Gary


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## lazersteve (Feb 9, 2012)

Kurt,

I like it so much I'm going to build one too.

I'm going to use polypropylene (PP) cloth for the filter backing/plate material and would like you to email me for a free piece to use in yours for submitting this great post. The cloth is highly acid resistant, very strong, and provides a good firm surface for your papers to push against.

I'm going to nix all the stainless stuff and use solid PP or teflon for the plunger and disc pieces. 

I try to keep _*all*_ metal (spoon, filters, screens, stir rods, etc.) away from my solutions whenever possible.

I look forward to your email so I can mail out your sample of cloth for your project.

Steve


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## butcher (Feb 10, 2012)

A stand, and arm handle like an old pump, like a cheese press.
I like the teflon disk Idea and poly screen.
I also have been collecting some materials to make one.


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## samuel-a (Feb 10, 2012)

butcher said:


> I also have been collecting some materials to make one.



Same here.

Though i'm tinkering with the idea of using a porous ceramic plates insted of filter paper or cloth.
I'm thinking that matching one to an on the shelf PTFE tube may not be so easy or cheap.... we'll see how this develops on this end.


Edit: An after thought, would you think a Quartz frit disk hold this kind of direct pressure forces, even when supported?


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## Geo (Feb 10, 2012)

NoIdea says he makes his own filters. im thinking about using a piece of silk and making filter material using nylon fibers or something other than wood.


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## DONNZ (Feb 10, 2012)

Pic's no problem if you have a left / right button mouse.

Right click on pic will get a drop down.

View Image 

Things you already know but don't use.

Tap the delete button to go backwards or right click and get the drop down. 

I'm on a Mac, this may work dif on yours.

"Keyboard Shortcuts"


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## rusty (Feb 21, 2012)

This type of filter has been on my plate for sometime now, a year ago I purchased this solid round to cut into shorter pieces then machine them down to size to fit a plastic pipe. The piston once finished will have a grove machined in to accept an O-Ring to make a perfect seal.


From my observations, looking inside PVC plastic pipe the extruded finish is far from perfect with ripples and would require machining to clean this up to make a better fit to the piston.

Using the PVC as it ships raw, would be like running a gasoline engine with a badly scored cylinder you would have excess blow by in the case of a filter press excessive leakage of liquids by-passing the piston. 

Using a filter press with a poorly fitting piston would allow liquids to pass by to collect onto the top of the piston as it is pushed to the bottom of the cylinder wrecking havoc with liquid which has now transfered to the top side of the piston to spill over when completely withdrawn.

I also plan to incorporate a vacuum break into the finished piston to permit easy withdrawal.


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## etack (Feb 21, 2012)

you could buy a plastic coffee press.

http://aerobie.com/products/aeropress.htm

http://aerobie.com/Products/Details/AeroPressMaterialsDescription.htm

just a thought might be easier for some less handy people

Eric

fixed the links


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## rusty (Feb 21, 2012)

etack said:


> you could buy a plastic coffee press.
> 
> http://aerobie.com/products/aeropress.html
> 
> ...



Eric grand idea, Try this link http://aerobie.com/products/aeropress.htm


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## etack (Feb 21, 2012)

thanks I'm not sure what happened with the link.

That's the one though it's all plastic. The other link was the materials that are used in the press. It was the third bullet down after made in USA.

Eric


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