Conversion of a press

[David Pickering]

I’m seeking help in the modification/conversion of my cider press.

It was built with the pressing power coming from two manually operated high-lift jacks (now both Jackall, Canada) and my proposed change is to hydraulic. Note that the press operates by pressing “upwards” and I’d like to retain that action.

Images are attached of the stack of cheeses being built on a separate trolley and then of the pressing operation.

Each of the high-lift jacks is rated at 3000kg so because the two jacks operate independently it’s an interesting question as to whether the press should be rated at 3 tonnes or 6 tonnes…..

The distance from the bottom (moveable) pressing plate to the top fixed plate is 830mm. A substantial amount of that distance is obviously occupied by the non-compressible racks. At present the stack of cheeses compress to approx 400-300mm depending on effort applied and pomace characteristics. So the hydraulic rams would need to have a travel of perhaps 500-600mm. Ideally they would be double acting so as to keep cycling time to a minimum. And mounted to have maximum power contracting and the lesser power to open the press.

If I’m going hydraulic it’s probably a one-off opportunity so my thought is to aim for a rating in the range of 10-15 tonnes. Obviously there would need to be two rams, presumably they need to be able to be operated independently and it seems to make sense to operate with some form of mains voltage power pack so that there doesn't need to be a tractor sitting somewhere close.

Can somebody help with this conversion as regards things I haven’t considered and how much money I would be letting myself in for? On-list or off-list as the moderators consider appropriate.

An aside. Does anyone have any thoughts on measuring pressing pressure? Invariably pomace pressing pressure is deemed to be total pressure divided by area pressed. I can’t think how in a semi-fluid pomace pressing environment any form of compressing sensor would be feasible.

Cheers - David

David Pickering - Huntley Road, ORANGE NSW 2800

http://www.cideroz.com/
http://www.cideraustralia.org.au/
dav...@cideroz.com

[Claude Jolicoeur]

David,

At looking at the photos, your present setup looks fine to me.

My first question would be: what do you want to improve?

Is it the pressing yield by increase of the pressure?

Or is it to reduce the effort by having hydraulic rams that would be fed by a pump?
I am wondering however if you could possibly get away installing only one in the center.

For sure, you would be into substantial modifications to the frame of the press in order to install this or those hydraulic piston(s), as presently, you don't have a piece of frame to support the base of the cylinder(s) from under...

Claude

Le lundi 11 mars 2019 06:24:09 UTC-4, David Pickering a écrit :

I’m seeking help in the modification/conversion of my cider press.

It was built with the pressing power coming from two manually operated high-lift jacks (now both Jackall, Canada) and my proposed change is to hydraulic. Note that the press operates by pressing “upwards” and I’d like to retain that action.

[Colin Feather]

Dear David,

Interested in what and where you sourced your press boards and pressing bags?

Thanks,

Colin (Tawonga, Victoria, Australia)

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[David Pickering]

Claude,

I’m aiming to improve several aspects:

1. The yield of juice through increased pressure being applied

2. Definitely reducing the manual effort involved

3. In association with #2, reducing the WHS/OHS risks involved in operating the press. This comes from two sources. Firstly the risk of tilting the whole setup through over-enthusiastic assistants hanging off the handle as twosomes on each side. And secondly the potential for the pin system to not spring home and hence run the risk of the handle bouncing up or the press dropping down one or more notches

You’ve put a thought into my head though.

I think it would be feasible to modify the existing setup to have two Jackall jacks on each side:

…..Each of the high-lift jacks is rated at 3000kg so because the two jacks operate independently it’s an interesting question as to whether the press should be rated at 3 tonnes or 6 tonnes…..

Then I guess the question is, “would I have a press rated at 3 tonnes or 12 tonnes?”.

If it doesn’t already look like a Heath Robinson system, going to four jacks might just push it into the category……. 

Cheers - David

David Pickering - "Linden Lea" 681 Huntley Road, ORANGE NSW 2800

http://www.cideroz.com/
http://www.cideraustralia.org.au/

[David Pickering]

Colin,

The press boards are polypropylene and were sourced from a catering equipment supplier - bread boards, cutting boards etc etc.
The surface of the boards has a very slightly raised pattern which helps reduce slippage.
I’ve grooved channels into the boards with a router to enable better egress of juice from the inner areas of the cheeses. Note that the amount of “snow” from the routing process has to be seen to be believed so get organised before you begin. Routing also affects the boards structural integrity so I settled for shallow grooves, E-W on one side and N-S on the other.

The material enclosing the pomace to form the cheeses is woven weed mat, again in polypropylene. Being woven from flat filament it is readily cleaned either with hose or pressure cleaner.
I use rectangles of fabric rather than bags, large enough to fold over the top of the pomace. The edges of the fabric can be melted with a hot air gun to prevent unravelling of the weave. Bags would be feasible but cleaning might be more problematic.

[Colin Feather]

Dear David,

Thanks. I will give these a try.


Colin (Tawonga, Victoria, Australia)

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[Dick Dunn]

About sealing the edges of polypropylene fabric - David mentions a heat
gun; it can also be done with a special plastics tip on a soldering iron
or gun, which you draw along the edge of the fabric.
My guess is that the soldering gun tip would be more accurate (melting only
what you want) but it can be messy.

On Mon, Mar 18, 2019 at 04:52:56PM +1100, David Pickering wrote:
...

> The material enclosing the pomace to form the cheeses is woven weed mat, again in polypropylene. Being woven from flat filament it is readily cleaned either with hose or pressure cleaner.
> I use rectangles of fabric rather than bags, large enough to fold over the top of the pomace. The edges of the fabric can be melted with a hot air gun to prevent unravelling of the weave. Bags would be feasible but cleaning might be more problematic.
>
> Cheers - David
>
> David Pickering - "Linden Lea" 681 Huntley Road, ORANGE NSW 2800

--
Dick Dunn rc...@talisman.com Hygiene, Colorado USA

[Claude Jolicoeur]

David,

The fact that your present jacks are "rated" to 3 tons doesn't mean 3 tons are actually applied - it means the jack can support 3 tons without collapsing...

To get the true load applied, you would have to estimate the lever effect you get:

For example, if the travel of the lever is, say, 50cm, and if this travel causes a rise of the jack by 1 cm, then the lever effect is 50:1 (your actual numbers may vary). Then, knowing this number, if you apply say 50 kg on the handle, you would get 50 times more or 2500 kg.

You then multiply this by 2 to obtain the load provided by the 2 jacks to obtain your present actual load, and you divide by the area of the compressed cheese to obtain the pressure. See my book page 123.

From there on, you may see how much load you need for your new setup. You should aim for about 80 psi or 550 kPa for a good extraction. More than that isn't really necessary for a hobbyist's press.

Claude

[Max Nowell ( Steilhead Cider)]

I’m certainly no engineer, but I reckon the repeated application and release of 15 tonnes could be a bit much for that frame.

[David Pickering]

Thanks Dick,

Yes that does sound like a good alternative. I’ll see if I can "find a friend” with one of these to give it a try.
In retrospect the other approach to reduce the fraying problem would be to cut my cloths at something of an angle rather than square to the warp and weft. This will be more wasteful of fabric but will probably produce a cloth more resistant to fraying from wear and tear.

[David Pickering]

Thanks Claude,

I’ll give these sort of calculations a try when we start pressing in the next few weeks .
There’ll need to be some estimates since you’ve generally got two hands on the lever when the pressure has built up so the actual distance from point of application (the hands) to the mechanism working the pins will be a bit open to interpretation. At least, even if I’m conservative on my assumptions and the result has a bit of a margin of error, I’ll be well on the way to putting a number on the pressure.

And I’m pleased I can use that factor of 2!

Cheers - David

David Pickering - "Linden Lea" 681 Huntley Road, ORANGE NSW 2800

http://www.cideroz.com/
http://www.cideraustralia.org.au/

dav...@cideroz.com
mobile: 0427 271 477
home: 02 6365 5275

[David Pickering]

Hi Max,

It’s perhaps a bit difficult to get the concept of the press which is why there’s the mention in my first posting.

Note that the press operates by pressing “upwards”

The Jackalls are actually lifting the baseplate, tray, cheeses etc

If you look at the last (fourth) image where the pressing operation is virtually finished you’ll see that there is nothing pushing from below, all the pressure is created by the jacks. The frame is only carrying the weight of the baseplate, tray, cheeses etc and in fact the weight involved reduces as the juice is pressed out of the cheeses. The pressing pressure is confined to the jacks and there are no forces trying to push the press apart.

But perhaps that does raise the question (Claude and anyone else?) … The backbone of each Jackall is the black perforated rod. In four-wheel driving use that rod is under compression between the ground and the bogged vehicle. In this apple pressing operation the forces acting on the rods are extension. In an engineering or physics sense would this be any better or worse than compression? At least compared to the bogged vehicle scenario there would be minimal sideways forces when pressing.

[Claude Jolicoeur]

Le mercredi 20 mars 2019 18:04:38 UTC-4, David Pickering a écrit :

But perhaps that does raise the question (Claude and anyone else?) … The backbone of each Jackall is the black perforated rod. In four-wheel driving use that rod is under compression between the ground and the bogged vehicle. In this apple pressing operation the forces acting on the rods are extension. In an engineering or physics sense would this be any better or worse than compression?

David, the stress in the rod is the same in tension or in compression. However a long rod submitted to compression is susceptible to a type of instability called buckling. This is explained in my book page 145. Hence, you are safer with the rod in tension!

Claude

 

[Max Nowell ( Steilhead Cider)]

Ah, yes, I see that now.