Wooden rack and cloth press design concept

[Courtney Meier]

Hello all -

Having arrived at a point of severe infatuation with craft cider, I have found my current equipment does not allow for enough capacity when it comes to learning more about the process (and then tasting the results). To that end, my next task is to build a suitable rack and cloth press in order to reduce juice preparation times at the hobbyist scale. After reading Claude's book and studying the photos he's posted online of a potential design for a press, I created the attached drawing as a variation on the theme that I'd like to build. I have switched the posts from 3/4" diameter metal rod to wood, due to: 

a) The fact that I've always enjoyed working with wood, and

b) My reading here in forum posts from a few years back suggest that the metal rods can deflect under load if the cheeses are not perfectly centered. I think the wood would be more resistant to deflection, but am not sure.

Before I purchase materials, I wanted to get people's feedback with regard to overall design, and in particular, the design of the posts. Looking at the side-view drawing on the right, will the 1" of hard maple post between the two mortises be sufficient to withstand the vertical force of a 6-ton bottle jack? In this conceptualization, the posts are made from hard maple 1x4s, glued together with Titebond (or equivalent), then notched with a saw and chisel to hold the beams. There are other designs that involve two posts per side used to sandwich the beam, and while I think this '4-post' design can undoubtedly be made stronger, it would also be more expensive. Taking it all together, if people think the design in the attached drawing will suffice, I'll go with it since it means making half as many posts.

Thanks in advance for any and all thoughts!

Cheers,
Courtney

Courtney Meier | Plant Ecologist | Cider Hobbyist | Boulder, CO

[Claude Jolicoeur]

Le mardi 12 février 2019 23:17:11 UTC-5, Courtney Meier a écrit :

will the 1" of hard maple post between the two mortises be sufficient to withstand the vertical force of a 6-ton bottle jack?

This is obviously the weaker point of your design.

You have there a section of wood that will be 1" x 5 planks each 3/4" thick if I interpret correctly your drawing. That is 3.75 square inches that will have to resist to half of the load, or 3 tons, 6000 lbs. This makes a stress of 1600 lbs per square inch or 1600 psi. According to the table on page 137 of my book, hard wood allowable stress is 4000 psi. However, you will be in a situation of stress concentration due to the abrupt change of section, which makes it more risky.

If it was mine, I would try to improve on this.

And you are right about the bending of a single rod upright, and if I rewrite a second edition of this book, I will rather suggest a design with 2 rods on each side, something like what you see on page 142, but with a wooden crossbeam.

Claude

[Martin Thoburn]

Hi Courtney,

I've just finished building a rack and clock press from Claude's book and also made my uprights out of wood.  However, I used two upright supports with the cross beams in the middle.  Used a 1/2" notch on each side.  I started with rough sawn lumber and then glue laminated all my hardwood together for a single thick beam,  I calculated 11 Tons of support, since my cross beams were a little thinner then I hoped after I squared the board, so I went with a 10-ton jack.  I've attached screenshots of my design and I also included the original SketchUp design file if you want to download the free 3D software to view the model.

https://www.sketchup.com/

[Josh Kellermann]

Several of my antique presses incorporate a metal rod alongside wooden uprights. The rod provides vertical strength while the wooden posts both provide vertical strength and prevent twisting. The metal rods are typically routed into the side of the post so they don’t take up any more space than they need to.
Good luck!
Josh in the Catskills

[luis.ga...@gmail.com]

Hi Courtney,

I built a similar model of wood press 3 years ago. I also opted for the wood post for the same reason as you did (a friend of mine had built one with metal rods and things were clearly hard to manage.... It ended up breaking after 2-3 days of pressing).

I'll take pictures and show them to you. For this model of press, I think that the beams should be bigger than the posts. My press has 3,5 x 5 in. beams and 2x4 posts (in maple hardwood). These dimensions are somehow similar tou yours. If I had to do it again, I'd probably use 1,5x2,5 posts instead (it would be enough as these just handel some deflection, no real pressure). I'd also switch for 4x8 beams to have an overkill beast (I wasn't able to find bigger wood at that time).

Also, for my press, I've squeezed my beams into my post instead of the opposite. It isn't a big difference but it allows you to increase you beams size and decrease your post size.

Louis

Le mardi 12 février 2019 23:17:11 UTC-5, Courtney Meier a écrit :

[luis.ga...@gmail.com]

I've just seen Martin's post.

My model is actually about the same as his.

Martin : you're a great carpenter, you press is a very nice piece of art! congrat!

Louis

[Dan Samek]

Just this season I have remade my old basket press into a rack/cloth version. I have used M20 threaded rods (8,8 zinc plated) and put a 22/1mm stainless steel tube over those to protect the rods from the acid juice and allow for easier cleaning. The rods seem to withstand a 5ton bottle jack with ease.

Dne středa 13. února 2019 5:17:11 UTC+1 Courtney Meier napsal(a):

[Courtney Meier]

Martin - thanks for sharing your drawings! The design you've sketched out is pretty much exactly the '4-post' design I referenced in my original text, and I agree it has a number of things going for it compared to my drawings. For me, the two drawbacks to the 4-post setup are greater cost and more glue jobs since I only seem to be able to find 1x4s or 1x3s in oak or maple to make the posts. I think I'll draw up both versions and price out each one. 

[Courtney Meier]

Claude, your insight is much appreciated, thank you. I was looking at the table on p. 137 when I was making the drawings, and the stress data you provide are very helpful. Thinking about my proposed posts, I assumed based on the hardwood stress data that the narrow middle part of each post could withstand up to 4000 psi, and as your calculations show the maximum stress from a 6-ton bottle jack would be 1,600 psi. 

To clarify your comment, when you say that "... you will be in a situation of stress concentration due to the abrupt change of section..." do you mean that the 3.75 in^2 of post between the mortise notches may not be able to withstand 4000 psi due to the fact that the posts would be made by glueing planks together, rather than being one continuous piece of wood? If glueing multiple pieces together makes a weaker post, I can see perhaps needing to switch to a design such as Martin used in order to ensure sufficient strength.

On Tuesday, February 12, 2019 at 9:56:00 PM UTC-7, Claude Jolicoeur wrote:

Le mardi 12 février 2019 23:17:11 UTC-5, Courtney Meier a écrit :

will the 1" of hard maple post between the two mortises be sufficient to withstand the vertical force of a 6-ton bottle jack?

This is obviously the weaker point of your design.

You have there a section of wood that will be 1" x 5 planks each 3/4" thick if I interpret correctly your drawing. That is 3.75 square inches that will have to resist to half of the load, or 3 tons, 6000 lbs. This makes a stress of 1600 lbs per square inch or 1600 psi. According to the table on page 137 of my book, hard wood allowable stress is 4000 psi. However, you will be in a situation of stress concentration due to the abrupt change of section, which makes it more risky.

Claude

[Claude Jolicoeur]

Le mercredi 13 février 2019 15:07:49 UTC-5, Courtney Meier a écrit :

To clarify your comment, when you say that "... you will be in a situation of stress concentration due to the abrupt change of section..." do you mean that the 3.75 in^2 of post between the mortise notches may not be able to withstand 4000 psi due to the fact that the posts would be made by glueing planks together, rather than being one continuous piece of wood? If glueing multiple pieces together makes a weaker post, I can see perhaps needing to switch to a design such as Martin used in order to ensure sufficient strength.

The concept of stress concentration is a bit advanced to discuss in a cider forum like this...

You may read this: https://en.wikipedia.org/wiki/Stress_concentration

The risk is at the corner of the notch, where the stress increases suddently. You have to see that just below the notch (for the top crossbeam), the stress is evenly distributed on the full section of the upright (i.e. 5 x 3/4 x 3.5 = 13 square inches). Then at the notch, the section suddently decreases to 3.75 square inches. This locally provoques a much higher stress just at the corner, which may induce a crack even if the average stress in the section is less than what is allowable.

A stress concentration factor of 2 or 3 (which effectively doubles or triples the local effective stress) is quite plausible in a case like yours (but this would have to be checked by some advanced techniques).

In engineering we always try to smoothen section changes in critical parts in order to avoid such stress concentration points.

Add to that the possibility of having a bending stress that could add to the axial stress if the alignment is not perfect, and the situation becomes risky...

Claude

[Courtney Meier]

Claude, makes perfect sense actually, thanks. I was just not familiar with the terminology! Given the concentration of stress due to the mortices of a factor of 2-3, it seems that one might want to keep the stress due to the jack < 1000 psi in order to have a safe buffer for the assumed hardwood tolerance of 4000 psi. These considerations make me think that a '4-post' design like that used by Martin and Louis is a more conservative and better idea.

Martin and Louis - thanks again for sharing your detailed drawings.

Cheers,
Courtney

[Courtney Meier]

Josh, I hadn't thought about integrating the rods into the wood - that's an interesting idea and I assume allows for some relatively svelte and strong uprights. Certainly food for thought.

[Peter Eveleigh]

On Wednesday, February 13, 2019 at 4:17:11 AM UTC, Courtney Meier wrote:

Hi Courtney; my sixpenny-worth on your design thoughts - based on the fact that I am also a "woodie"!

1. Whilst completely accepting the fundamental "box" design as a workable solution, if you have a potential storage problem when the gear is not in use, (or want to take the press to the orchard!) you look for different answers - this drove me towards an A frame structure to support the top & bottom rails, all held together with 6 oak wedges. I've made 30 litre (pomace) barrel / hand screw presses; & 50 / 100 litre pack presses using 8 or 20 tonne bottle jacks - Horses for courses depending on what and how many apples you have and just highlighting an alternative if you have such considerations! By way of example, I've loaded 2 presses, Mill (after Claude's design) plus paraphanalia into a standard estate car! to go pressing!

2. Claude suggests a nominal pressure onto the cheese of around 80psi to which I agree - particularly if time is on your side. I rate my presses to 100psi to take account of the fact that the cheeses flatten out (particularly if your form height is 2.75") by up to an inch (ish) all round. When you factor this into your calcs, your pressures get a bit marginal. Also this may impact the overall size of your racks - to take the cheese's spreading into account. As you plan to use a 6 ton (presuming 2000 lb / ton) bottle jack, you have some options: a) reduce the former size by 1 inch / reduce its height to under 2"; b) Increase the rack sizes - which could lead to increasing the base tray size - which may require re-calculating the mechanics related to the beam lengths.

3. I have found that the base tray needs to be at east 1 inch all round (internal dimension) larger than the rack dimensions (& more for th 100 Ltr press) in order to cater for a bit of lateral movement in the racks - plus catch all the juice!

4. lastly, your steel (top) pressure plate; can I suggest you build in a recess to take the top of the jack. If the pack moves slightly the angle will change and it could "ping" off the plate. also, if you make it a bit longer along the rail, you will improve the rail's strength somewhat!

Pictorial info attached; good luck with the build and do feel free to contact if you want any further info. - what are you doing for the scratter / mill?

Best wishes, Peter

[Courtney Meier]

Hi Peter - thanks for sharing your thoughts and drawings. Your A-frame model is a beauty, and I think your joinery skills handily surpass mine! You are correct that a 6-ton jack will generate < 80 psi with racks that are 12.75" x 12.75" (74 psi, to be precise). I could use an 8-ton jack and re-size the beam and posts accordingly... or shrink the racks a little as you suggest.

When it comes to the size of the juice tray relative to the racks, I just borrowed the dimensions that Claude provided, which allow for 0.75" of tray space around the racks. I could either make a little smaller rack, or slightly larger space between the beams to allow for a larger tray. Taken with the point above, making the racks a little smaller would appear to create two efficiencies at once.

I also like the idea of of a recess for the top of the jack. Something tells me you may be speaking from experience regarding undesirable 'ping' sounds!

For the scratter, I currently have a garbage disposal that I mounted in a plywood box with a cooling fan. It's slow compared to most other options, but my current press is even slower, so the press project comes before the new scratter project ;-) 

Cheers, Courtney

[Cynthia Frunzi]

Hello. 

Does anyone have a good resource for Apple's in NJ?  I realize I'll probably have to ship them however we are in search of a few places we can use regularly with great variety and price. 

Thank you all, 

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[Courtney Meier]

Hello again - reviving this thread after receiving some excellent suggestions and studying the drawings several of you thoughtfully provided. I've attached a modified 2-post design, and a 4-post design similar to the one Martin provided drawings for above. I've also attached some stress calculations for each press. Based on the numbers, I'm leaning toward building the 4-post press since it looks like the slightly shorter beam is advantageous, and the posts don't have grooves cut as deeply, thus reducing stress concentration compared to the 2-post design. 

For both presses, I've also:

• Made the press racks smaller so as to achieve 1" of tray all around the racks. 
• The form has also been shrunk slightly, and the height shortened by 1/2" to reduce the risk that the cheese will extend past the edge of the racks under pressure. The smaller rack size of 12.25" x 12.25" also increases the pressure to 80 psi, which should aid in juice extraction.
• Added a circular ring of metal to the steel plate on the top beam, to prevent the jack from slipping suddenly if the load accidentally becomes unbalanced.

Thanks in advance for your thoughts and critiques!

Cheers, Courtney

Courtney Meier | Plant Ecologist | Cider Hobbyist | Boulder, CO

[Claude Jolicoeur]

Courtney,

Your 2 designs look plenty solid.

There are 2 things that I see:

- if you have 16.5" free width between the vertical members, why do you make your tray at 15.75"? I think you should use the maximum width you can and make your tray at 16.4" wide. As long as it fits between the uprights you'll be OK.

- if you go to the trouble of making such a nice and well built press, why don't you make it a big bigger? 12" racks make a pretty small cake (you don't want to make it higher than the width) and if you have a good amoung of apples, you'll probably soon wish you would have made it a bit larger. With the desing you have, you could probably extend it to 20" free width quite easily, make the tray at 19.9", and racks at 16.5" - this would more than double the capacity of the press.

Claude

[Peter Eveleigh]

Courtney Hi,

First - I go along with Claude's comments - particularly on making it a bit larger! As well as doing this, having reduced your former height by 1/2 ", you have effectively "lost" 2 1/2" of pomace height which can be resolved by adding another layer to make a 5 rack / 6 cheese press.

On the "critique side", your top plate thickness @ 18mm could be a bit flimsy to transmit the force evenly over the pack. ( I use a 2" thick slab of oak) so you might want to consider gluing up 2 ? 3 "layers" of  the birch ply, or make up a slab of solid hardwood. depending on the height of your jack, you should have sufficient internal height to do this.

Peter

On Monday, February 25, 2019 at 6:00:59 AM UTC, Courtney Meier wrote:

Hello again -

[Courtney Meier]

Peter and Claude - thank you both for the additional review and suggestions. I agree a wider, taller press makes sense if I am going to go to the trouble of buying a good deal of hardwood! Should also be no trouble to make the top plate a bit thicker by glueing together several layers of the birch ply. 

Back to the drawing board and spreadsheet!

Cheers,

Courtney

[woodcarver]

I would humbly suggest making your press tray long enough to be able to build a stack of cheeses while you’re pressing another. It won’t change any of your stress calculations and it will allow you to be more patient with your press and/or make better advantage of anyone who is helping you.

[Courtney Meier]

woodcarver - that is a very intriguing idea!

[Jeffrey Lewis]

I second woodcarver's suggestion.

I built two removable shelves and supports out of 2x4s, one on either side of the press tray.  They allow me to build a stack of cheeses while pressing another, and then slide the pressed cheese off the other side so I can disassemble it at my leisure while the fresh cheese is in the press. 

It saves a lot of time.  The shelves need to be sturdy, though.  My cheeses are nearly 100 kg.  I also put som low friction plastic on the shelves and press tray to make it easier to slide them around.

/Jeff

[Courtney Meier]

For posterity, I wanted to post the final press design and cutting plan that emerged after all of the helpful feedback provided here. For the present time, I didn't end up constructing a system to allow the pressing of one cheese while another is being built. While I've recently remodeled the basement to expand capacity, I am still pretty cramped for space and I wanted to keep the footprint small. That said, I think it's an excellent suggestion and I figure I can modify and add the required space and support for an attachable cheese-building station when the time finally arrives.

Hope these discussions have been helpful for others getting started as well! I've definitely benefited from the group's collective knowledge.

Cheers,

Courtney

Courtney Meier | Plant Ecologist | Cider Hobbyist | Boulder, CO

[Peter Eveleigh]

On Friday, March 22, 2019 at 3:48:27 AM UTC, Courtney Meier wrote:

For posterity, I wanted to post the final press design and cutting plan that emerged after all of the helpful feedback provided here.

Hi Courtney, that looks great! - just 2 fabrication thoughts:-

1. I'm intrigued by your decision to use laminated posts (and beams). Accepting they will be marginally stronger than solid, unless you have access to a planer / thicknesser machine, your labour (costs) will outweigh the material cost - according to your price list. And gluing up can get interesting! For your information I use Titebond 3 for the glue.

2. Wrt the base tray, I see you are using ply throughout. I discovered that after a while you can get some seepage through the joints & to overcome this I "tenonned" the side walls to the base; dry jointed with a silicon seal along the inside of the tenon, and screwed from both the bottom and sides onto the base ply ( @ 4" interval). The attached sketch uses an 18mm base with 1" / 25mm x 3" / 75mm beechwood side walls. I then routed a 45 degree cove along the inside edge of the wall tops. No more seepage & you can take apart should you need to!

Just another tuppence worth. Peterr

[Courtney Meier]

Hi Peter - I appreciate the tuppence!

The decision to construct laminated posts and beams was really not one I wanted to make since I'm not exactly looking forward to all the gluing! That said, I did not really have an alternative since I have not been able to source larger widths of hardwood where I live. It may be that someone sells bigger chunks of oak or maple, but I haven't been able to find any.

As for the base tray, attaching the sides with a tenon or biscuit joiner would make sense. My initial plan was to use Titebond 3 and screws every 4" (similar to you), and then coat everything in 3 layers of polyurethane to prevent seepage. I won't have to buy any additional tools this way. That said, I'll see if a friend has a biscuit joiner I can borrow because I think the joint would be stronger the way you've described it.

Cheers, 

Courtney

[Eric Tyira]

Just FYI, I believe biscuits are used more for alignment.  They don't really add to the strength as they are not inherently strong themselves.  If you are gluing two very long pieces together and don't have the bench space, biscuits allow the two boards to align for easier clamping.

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[luis.ga...@gmail.com]

Your design is very nice,I think it will make a great  apple press.

Louis

[Courtney Meier]

After many months of fitting in a few hours here and there, the wooden rack and cloth press build is finally complete! A sincere thanks to everyone who helped refine the design with their valuable suggestions. Photos of the process can be found here for anyone interested in trying something like this themselves:

https://drive.google.com/open?id=1JEX-a_ovIBpKmj50nt0LbUtRv1pef66A

Happy to address any questions!

[Ray Blockley]

Hi Courtney.

That looks great! Really nice job.
Are you happy for the link to your work to be shared more widely? In
other cider groups? The number of folk asking for help / tips / ideas
/ designs for a homebuilt press seems unending!

Cheers, Ray

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[Courtney Meier]

Hi Ray,

No problem to share more widely with other cider groups, and thanks for checking!

Cheers,
Courtney

On Thursday, August 29, 2019 at 12:05:27 PM UTC-6, Ray wrote:

Hi Courtney.

That looks great! Really nice job.
Are you happy for the link to your work to be shared more widely? In
other cider groups? The number of folk asking for help / tips / ideas
/ designs for a homebuilt press seems unending!

Cheers, Ray

On Thu, Aug 29, 2019 at 6:58 PM Courtney Meier <cmei...@gmail.com> wrote:
>
> After many months of fitting in a few hours here and there, the wooden rack and cloth press build is finally complete! A sincere thanks to everyone who helped refine the design with their valuable suggestions. Photos of the process can be found here for anyone interested in trying something like this themselves:
>
> https://drive.google.com/open?id=1JEX-a_ovIBpKmj50nt0LbUtRv1pef66A
>
> Happy to address any questions!
>
> Cheers,
> Courtney
>
>>
>> Courtney Meier | Plant Ecologist | Cider Hobbyist | Boulder, CO
>
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[Ray Blockley]

Awesome! Thank you! ☺

Cheers, Ray. 

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