I have been interested timber framing for ages and i'm ready for my first project. It will be an introduction to the techniques involved but more importantly an introduction to the engineering of timber frames.

To this end I want to build a timber frame press. My friends and I have over the last three years made around 600L of cider. This year I don't just wasn't to do cider but also to pasture some juice so that we can have juice throughout the year. This means that the equipment that we have been using is a little undersized.

The current press is a shop press run by a 20t (20, 000kg) bottle jack and, with the current arrangement we can do about 30L of pomace per pressing. The plan is to build a press capable of handling 200L of pomace in one pressing run by the bottle jack from the existing press. The footprint of the pomace cheese stack will be about 9 times bigger and this will mean that the pressure that the pomace will be subjected to will be about a ninth of what we have previously done. Based on our observations of the existing press I believe (hope) that this will not effect the yeild too much.

I want to hew all the main members (posts, beams, braces) but the alll the bits involved in the press floor and ceiling will be sawn. I have access to reasonable quantities monterey pine and monterey cypress but they can be prone to large numbers of knots (in particular the pine) as they are generally from windbreaks on farms or from around houses. I can also get occasional logs from a range of australian natives but these are harder to source.

Naturally there are a number of members that need to be sized appropriately. The first being the top and bottom beams to contain the load grom the jack.

I'm new to all this but.....

The press frame consists of two posts joined by two beams one above the other. The bottom beam will support the press floor, while the top beam will contain the bottle jack. The top beam will be subjected to a point load from the bottle jack.When the press is loaded it must be able to handle the load fron the bottle jack of 20t or 44,000lbs.

The beam has a free span of 1.2m or 47.25" therefore w=931lbs/inch.

As a starting point i'll consider a beam 8" by 10" in pine(P. radiata, E=1,146,000psi), cypress (C. macrocapa, E=1,146,000) and yellow box (Eucalyptus melliodora, E=1,600,000).

Deflection =5wL^4/(384EI)

Pine and cypress deflection is 0.08".
Box deflection is 0.06".

To this point I havn't had any problems. Its when looking at shear that I'm out of my depth.

Actually reviewing my working through "sizing rough sawn joists and beams" by ed levin, I notice that it is at bending that I get lost.

I can calculate the extreme fiber stress, 3897psi, but what do I check that against? The example has 1500psi for red oak but I don't know where that value came from. I'm guessing that it comes from a table which means that at a guess that a 8x10 beam is not going to be big enough even in box. The E of green yellow box (11mpa) is 28% greater than green american white oak (8.6mpa I don't have a figure for red oak). Therefore if I add 28% to 1500psi gives me a figure of 1918psi. Is this reasonable?

That would then mean i'd need a box beam 12"x12" (f=1804psi). Yes?

Or in softwood (f<1343) 12" x 14".

Sorry I can't help with the numbers. But I would be interested in how it is all fitted together, joinery, bolts, steal? In the end the timber will be large enough but what about the joining members? Do you have a sketch or pictures?

I'll be doing sketches shortly as it gets too complicated to explain. I figured every one could get their heads around simple beams.

The engineering on the post/beam joint is next as that will be needed in order to size the post.

Article goes on to say to check for shear (h).

h=3V/2bd

V=wL/2=931 x 47.25 / 2 = 21,994lbs

h=3 x 21994 / (2 x 12 x 14) = 196psi

Which is way over the recommended value of 125psi for red oak. For EW Pine the Fv value is meant to be less than 65psi. If P. Radiata is comparable then the beam would need to be 23" square giving, h=62.4psi!

Green that sucker is going to way around 500kg!

My conclusions are that either:

- I'm doing something wrong;
- the safety factors, are overly conservative ie there is no need for a continous loading safety factor or wet service safety factor;
- traditonal screw presses, ie pre industrial revolution, didn't develop any where near 20t of force.

Where are you located?

Are you using wood that you can find the Fv Fb and E values for?

I'm in Victoria, Australia about an hour wnw of Melbourne.

I have the E values for a large number of species but my values for Fb and Fv come from approximations from the F grades or from the "Timber frame joinery and design workbook". The latter source doesn't have values for any of the Australian species (naturally) and the pine that I have access to is P. radiata and I don't know where that fits in the species groupings. The only values I have for the cypress I can get is from a web site that sells f5 and f7 grade cypress of the same species, ie C. macrocapa.

Shoot, I was going to tell you if you lived nearby me, to come and view an interesting cider press.
About an hour from me in the town of Berne, Indiana, is the world's largest cider press. It was built by a Swiss immigrant in the 1800's who decided upon coming to America to be a cider producer. He built this press entirely from memory of presses back home.
But I doubt you'd want to come so far for that...

I'd love photos though, website?

http://www.swissheritage.org/SHV/Cider_Press.html

and while you're at it go ahead and take a gander at the old church
http://www.swissheritage.org/SHV/Church.html

OMG.

Thats a bit bigger than I was planning.

http://m.youtube.com/#/watch?desktop_uri=%2Fwatch%3Fv%3DGIsKYXS2bgQ&v=GIsKYXS2bgQ&gl=AU

yes, but the macro-engineering can help to illustrate things that are harder to see on more 'normal' examples

Hi DLB,

Have you thought about holding your Swiss framing teachathon at the Swiss Heritage Museum in Indiana? This type of venue would generally welcome an event like you are proposng.

Jack Sobon and Dave carlon hold similar Shaker style events at Hancock Shaker Village and Joe Thompson runs English scribe classes at The Weald & Downland Open Air Museum.

Regards

Ken Hume

Great video, thanks for posting.

Searching for wine press instead of cider press I found this great set of links:

http://larsdatter.com/winepresses.htm

There are two styles that I'm interested in. One is the two screw style that I'm familiar with from 18th century pictures and the screw and lever style that is the same design as depicted in the video posted several posts ago.

My original design was of a single screw press and while I have found some early pictures of them the two screw presses and screw and lever presses seem to be more suitable for the period which I'm interested in, 14th-16th century.

The problem I'm having with the design is not the rupture of members or excessive bending it is the shear at the joints which is dictating huge timbers.

It may be that I'm just trying for too much pressure. Something I have learnt from experience is that the press does NOT get the juice out of the apple. The mill gets the juice out of the apple. The press gets the juice out of the pomace (pulp). Given that I'm thinking that the pressures I'm after may be excessive. Also if I'm developing my pressure from one or two wooden screws (instead of cheating with a hydraulic jack) then it is likely that the screws will bind before the press members break if I size them based on what looks right from my eye and the pictures.

Still comes back to shear though. Bending and rupture I feel I have my head around. Shear is still hazy.

I have though about another way of approaching this hole deal.

Different types of screw can take different amounts of force before they bind or die. Sqaure thread can take more than triangualar thread. Ball threads much more than square threads. Engineering supplies list different types of screws and the forces that they can cope with.

So how are these limits calculated and can we make the same calculations with wood threads. The problem for me is that I suspect that the calculations will come down to shear again.

So I've decided that I want to build the lever style of press that was posted in the video earlier as I have found pictures of them from as early as 12th century.

I reckon that the member that is going to have the most force on it is going to be the lever itself. Everything would then be sized around that.

Here is a simplified version:

http://i1222.photobucket.com/albums/dd481/Weaverofduart/pressbeam.jpg

I'm not concerned about deflection but I obviously don't want it to break so everything else is important. Unfortunately I'm at a bit of a loss to calculate everything except deflection.

Personally, I would eliminate the mid-span fulcrum, having the pivot all the way at the far end. The pivot end could then be secured quite simply between two timbers or a notch in a wall timber or so.

You could use a screw mechanism like shown in the video, or more simply just use a block and tackle. Although with a screw on the end you can gain more force.

As for dating press types, there are examples of the remains of screw-type presses, the type with a screw that pushes directly down on the fruit, to be found in the walls of Roman ruins.

Both screw and beam presses are very ancient, with the screw principle known well among ancient Greeks, and the beam principle very simple and straightforward.

I learned a simple trick from Swiss cheese makers and their presses -they call them Schwarpressen. If your beam by itself is not heavy enough, set a big boulder out toward the end of it.

The mid span pivot is actually the top of the press stack. As the fruit pulp compresses it begins to resist the beam making everything past the stack a cantilever beam. I'm not worried about the forces involved in the center span pivot as seen in the video because if the beam can handle the loads when used on the end pivot it will be fine when used on the mid pivot.

This picture really simplifies things:

http://2.bp.blogspot.com/-0AXOSJ1OcK8/ToX3fkUGaiI/AAAAAAAAAO4/KCYdx7XJu5Q/s1600/Lever+Press.jpg

All the examples that try and explain shear horizontal talk about lying a number of planks on top of each other and then subjecting them to a load and watching how they slide past each other.

I need a member/s to resist 17700lbs in a point load. If the member is a 16"(depth) by 8" then it seems to be fine from my new found understanding of shear but what about 2 8"x8" on top of each other?

In Timber Framing see

Miller, Joe and Ben Brungraber
Mechanically Laminated Beams, 93:14

I found lots of stuff of mechanically laminated beams which was interesting but not very useful at the moment.

I did find a formula for Fb for a two layer non laminated beam which basically seemed to deliver the same required Fb rating for two 8x8s stacked on top as each other as for one 8 (width) x 16 (depth). Which is odd but maybe not too surprising.

Would failure due to horizontal shear be less of a factor given that the two members in the stacked beam are free to slide past each other?

Today i comeback this community and i would like to ask something relating to your topic which is that I'm struggling like many others to get on the property ladder.......... I know as other know that timber frame houses are far cheaper, but I don't know how you go about finding a plot and building one which is one of best, do I need planning permission?what you think...?