Plastic HDPE racks + Voran - update

[Ray Blockley]

Quick update on how the HDPE racks are running with my Voran 100 P1.

 

Apart from the obvious dead easy cleaning of the racks (quick rinse at the end of the day), the most noticeable positive aspect is that the cloths come out very clean when emptying the press. With the wide mix of dessert fruit (often very ripe) that makes the bulk of my pressing, I've always been used to clogged cloths - especially where the cloth is forced into the gaps in the slats of the wooden racks. However, even running the Voran up to the "red line" as a test, produced very clean cloths with no hint of clogging. This has saved me a lot of time as I was having to shake out the cloths at the end of each pressing.

 

Likewise, the problem of fine pulp oozing out from the cloths and clogging the central gaps in the slats of the wooden racks is of course no more.

 

I also see that the 8mm thickness I purchased deforms much more readily than the wooden racks under pressure and so I suspect is more able to press into pockets of juicier pomace?

 

Negatives?

The smooth surface of the HDPE means some realignment of the frame is necessary after the cloth is folded up, as it can slip a little when filling the frame. A few shallow grooves of a millimetre or two would stop this, but I'm loath to do so at the moment.

 

Very ripe dessert pears can lead to some spurting out of fine pulpy juice under pressure along the outer edge of the cheese. However, I've invested in some fine-mesh pressing cloth from Vigo which should better suit the fruit I press and so hopefully stop this minor problem.

 

Cheers, Ray

[DaveK]

That is timely for me, Ray.  In a couple of weeks time we are going to be pressing cider apples using a borrowed hydraulic press with a 1 metre square bed, 1 metre height to the ram, and a ram that came from a JCB.  An amazing bit of kit conjured up by a local farmer, and driven off a tractor.  It's probably a 20 tonne.press or thereabouts.  Last year we used a Vigo rack & cloth screw press and a small basket press to make 900 litres, this year we hope we can do 2000 litres without the aching muscles.

 

I have co-incidentally just purchased some (also) 8mm thick sheets of food grade High Density Polyethylene to cut into 664mm x 498mm racks next week. I also was thinking of cutting some shallow grooves, too, but to reduce the potential for 'slip' during the actual pressing.  How much do your 'racks' slide about under compression, how much does the cheese distort? 

 

If I were to put in some grooves, I would not want to have them more than 0.5 to 1 mm deep to avoid damaging the integrity of the boards, just enough to provide some lateral grip because polyethylene (and polypropylene come to that) is incredibly slippery. If I did it, I would do one set of grooves on top (saw has a 3mm wide blade) , and another set at right angles on the underside of each board.  A bit worrying, though, to reduce the minimum thickness to 6-7mm and encourage more flexing.  Any thoughts from you or anyone who has actually grooved PE or PP boards and used them would be most interesting.  For example, groove spacing?  Or what about lightly sanding the PE with coarse sandpaper to provide more 'grip' without the structural weakening caused by grooving?

 

I do have some plastics industry background, and decided on HDPE rather than PP because it is a bit more flexible and also withstands lower temperatures.  8mm seemed to be a reasonable compromise between strength & price.  From memory, homopolymer PP has a propensity to get brittle below about 4 deg C, and copolymer is not much better, you have to let them warm up a bit if they've been near freezing (if they are dropped at near-freezing temperatures they can shatter/split) whereas HDPE is usually ok.

 

Thanks, Dave

(First post here)

[Good...@aol.com]

Hello Dave,

       A few years ago I made press sheets out of HDPE for use in a modified shop press with a 12 ton jack.

I used a router to groove my sheets. Sheets were about 14 inches wide by 22 inches long and 1/4" thick. The bottoms I put 3 grooves lengthwise, the tops also 3 grooves lengthwise and 6 grooves across. The grooves I cut 1/8" wide and about 1/16 inch deep and they seem to work ok. The only thing I didn't like was trying to get all the plastic shreds off that were still hanging on. Used various knives and scrapers to get the most of them off and a gas torch to burn off the tiny stuff and smooth things better so I didn't have tiny bits of plastic going into the juice. Maybe you can come up with something better. One nice feature about the shop press I use are the heavy springs that pull the ram back into the jack. This was the smallest shop press sold by Northern Tool and now I wish I had purchased a much larger one. I make 5 2" cheeses to fill it up and get 5-6 gallons of juice per press.

 

Darrel    

 

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[Rich Everett]

I thought the a Voran was a belt press so why does it need these?

I asked earlier for any input on the belt presses vs the traditional rack and cloth presses of similar sizes? 

We will be purchasing a new press and trying to figure out weather to go hydrolic rack or belt

We only press about one ton per hour

Sent from my iPhone

[nfcider]

Rich,
Voran also produce a range of rack and cloth press as well as different size belt press depending on throughput volume.
Barry

[Ray Blockley]

Hi Dave & Darrel,

Dave:
I first used HDPE about 8 or so years ago in my "Ray Press" - and made
the mistake of cutting grooves (with a circular saw) at 90 degrees on
opposite sides as you are suggesting? Don't. The boards will warp in
two planes due to the release of tension. (See attached photos with a
12 tonne hydraulic press being used - the HDPE here is 12mm, way too
thick IMO).

If you must cut grooves, keep them very shallow and to a minimum - 3
equally spaced should be plenty; or 2 centrally and perpendicular each
side in a "plus sign" formation? - and ensure they run in the same
parallel direction on both sides of the sheet. I think your concept of
0.5 - 1.0mm deep is ideal - you are only adding some "purchase" to
prevent movement during loading the press; soon as the pressure
builds, it ain't going anywhere...

Sanding is adding lots of cervices for bacteria and nasties to thrive
/ survive maybe? Just guessing here, but I wouldn't do it.

Incidentally, I passed these original racks onto someone who has an
identical press (they *paid* for the plans on ebay!) and he is still
using them.

With the Voran and the plain new HDPE racks, I have not experienced
any slippage yet; the racks haven't slid at all - at least to any
noticeable degree and certainly no more than I've had with the
supplied original wooden racks. As explained, the only slight snag is
the frame and cloth sliding when filling the frame, but a quick
realignment before lifting off the frame is all that's required.

Will take some photos of my pressing this weekend to show how the
racks are coping and post them up here.

Darrel:
I used a small Block Plane to clean up the grooves - it worked a treat
and left a nice clean 45 degree chamfer on the edges of the grooves.
See: http://tiny.cc/7xak5w

I also used the same Block Plane to clean up the sides of my new HDPE
sheets and to put a radius on the edges and corners. The low bed-angle
of the Block Plane makes them great for working plastics (and
aluminium!).

Cheers, Ray.

[DaveK]

Thanks for the suggestions Ray & Darrel.  We'll try to press without putting grooves in the boards, and see what happens.

 

Good point about the potential for bacteria living more easily in sanded boards. I wouldn't have thought, though, that it's any worse than with acacia racks and rivets etc.  I had in mind just creating an abraded matt finish similar to that found after moulding in an unpolished (injection) mould, and pressure wash/sanitise afterwards.  The extruded sheets are very shiny because they are calendared between rollers just after extrusion.

 

Is your Voran a 14 tonnes or 24 tonnes one, Ray, and what board (rack) size are you using?  Will be interesting to see your pressing pics.

 

cheers, Dave

[Ray Blockley]

Hi Dave,

500mm square. Will email you the spec off-list as it's a big PDF.

As to sanding, as I said it was just a thought - comes from working
with my incredibly picky EHO... I was chatting to the owners of our
local micro-pub last night who were moaning about the OTT stuff their
EHO was trying to force them to do; turns out it's the same woman.

Cheers, Ray

[DaveK]

On Sunday, October 27, 2013 9:28:27 AM UTC, Ray wrote:

Hi Dave,

500mm square. Will email you the spec off-list as it's a big PDF.

 

Thanks Ray, that's handy. 

24.7 tonnes onto 50 x 50 cm for your Voran.  Nice long 17" stroke.  Converted garage presses all seem to be 8" stroke or so.

 

I'll try to identify what the ram is on our press when it's been dropped off.  It was used previously on rackless cheeses 24" x 24" and apparently worked well, so in the absence of a spec, we've kept within that area.

 

cheers

Dave

 

[Good...@aol.com]

Thank's Ray!

 

       Will keep this info handy in case I make a bigger press vs. buying one in the near future.

 

Darrel 

 

[Ray Blockley]

OK - I've put a few images of a bit of pressing (taken yesterday) onto the web to hopefully show the new HDPE racks in use.

 

If I've sorted it correctly, one of the following links should work:

 

http://tiny.cc/sz4n5w

 

or:

https://picasaweb.google.com/114377646991688595722/Pressing_Oct2013?authuser=0&feat=directlink

 

Cheers, Ray

[richard marlborough]

hi ray

what was the weight (very roughly) of the apples b4 milling in the pics & what % roughly did you yeild? how much roughly did that press cost? how many gallons/litres per 8 hour day do you recon you could get out of it?

cheers

rich

rich

[DaveK]

On Monday, 28 October 2013 14:26:59 UTC, Ray wrote:

OK - I've put a few images of a bit of pressing (taken yesterday) onto the web to hopefully show the new HDPE racks in use.

 

If I've sorted it correctly, one of the following links should work:

 

http://tiny.cc/sz4n5w

 

or:

https://picasaweb.google.com/114377646991688595722/Pressing_Oct2013?authuser=0&feat=directlink

 

Cheers, Ray

 

Thanks Ray, that's great, gives me some confidence about using ungrooved HDPE racks.  Really nice square compressed cheese.  We pressed some perry today on a screw press but couldn't do a test with our 8mm HDPE racks because we would have lost too much juice over the edge of the larger HDPE racks sticking out too much - now I'm confident we can go straight onto the big hydraulic press with apples week after next without too much difficulty.  Thanks.

cheer, Dave