Author Topic: New compact, compound-lever, selectable MA press  (Read 38061 times)

cbenner33

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Re: New compact, compound-lever, selectable MA press
« Reply #60 on: December 12, 2016, 04:23:49 PM »
Sorry for the late update, but I have successfully held 49lbs on the end of the new press I made. This gives me a theoretical 686 lbs of force.

I have since glued the press together, doweled the main vertical supports and rounded most of the edges. I also added the hooks on the end for the weights.

Here is the final pics of my new press.

I also added a pic of the first cheese I pressed, Piora (3.89lbs) straight from the press

Chris




Offline awakephd

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Re: New compact, compound-lever, selectable MA press
« Reply #61 on: December 12, 2016, 09:54:03 PM »
Great work -- imPRESSive! :)
-- Andy

Offline Danbo

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Re: New compact, compound-lever, selectable MA press
« Reply #62 on: December 13, 2016, 06:26:03 AM »
Nice little beast...

Duntov

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Re: New compact, compound-lever, selectable MA press
« Reply #63 on: December 13, 2016, 07:40:55 PM »
Yes, it would be a handy way to adjust. The only thing I would caution is to be sure of the crush strength of the pin - this sort of pin is actually hollow, to accommodate the release mechanism. As long as the walls aren't too thin, the pin should be able to tolerate more than enough pressure ... I think ... but worth checking to be sure.

They do make these for quick-release wheel chair wheels so some of them should be rated fairly high.

cbenner33

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Re: New compact, compound-lever, selectable MA press
« Reply #64 on: December 16, 2016, 02:39:51 PM »
Yes, it would be a handy way to adjust. The only thing I would caution is to be sure of the crush strength of the pin - this sort of pin is actually hollow, to accommodate the release mechanism. As long as the walls aren't too thin, the pin should be able to tolerate more than enough pressure ... I think ... but worth checking to be sure.

They do make these for quick-release wheel chair wheels so some of them should be rated fairly high.

I plan on using 3" Clevis Pins for quick changing the ram and the adjustable slots for MA changes.

gstone

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Re: New compact, compound-lever, selectable MA press
« Reply #65 on: April 30, 2017, 02:21:31 AM »
Andy, this is a gorgeous press!  Was it by chance inspired by this one?   I go away for a mere five years and compound lever presses become all the rage!

I've often considered ways of compacting "my" design*, but ended up getting distracted from cheese-making before I got the chance.  I've grabbed your plans and look forward to making some sawdust this season.  It's good to see another woodworker here, too.

Cheers!



*Not my design, but as soon as I saw it I knew it was a great idea for a cheese press.

Offline awakephd

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Re: New compact, compound-lever, selectable MA press
« Reply #66 on: April 30, 2017, 05:37:15 PM »
Hi NW, and thanks for the compliment. No, not inspired by that press, but rather by an old-fashioned press that looks like it was made of cast iron. That said, I have looked many times at the press you linked to (and looks like you made), and there are a couple of big pluses and a couple of possible minuses that I see. The big pluses are 1) ease of construction / simplicity of design - far simpler than mine, and 2) potentially infinite adjustment of the MA. I have thought long and hard about whether I could make a press along these lines, with a built-in weight, that could be adjusted from, say, 10 to 1000 pounds by moving the weight, the points of attachment between the levers, and the point of attachment for the ram. In theory, I think something like this could be accomplished.

But here's the possible minus - the design as shown puts a pretty significant limit on the amount of travel for the lower lever, even when the MA is low. This in turn could mean needing to use either an adjustable ram (which the current design does not lend itself to) or shim blocks as the cheese settles. One way to resolve this might be to offset the levers so that they can pass by each other, rather than one directly over the top of the other.

The other possible minus, at least with the designs I've kicked around in my head, would be how to simplify the setting up a particular desired weight. There are three variables that would control the force applied: The placement of the weight along the top lever (perhaps dropping into pre-set slots); the placement of the connection between the levers; and the placement of the ram on the lower level. Might have to have a chart to show where to set each part to get the desired outcome, but it starts to feel rather complicated ...

One of these days, I hope to come up with something that will "do it all" with a single weight, but so far I'm still pondering!
-- Andy

gstone

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Re: New compact, compound-lever, selectable MA press
« Reply #67 on: April 30, 2017, 07:42:24 PM »
It is a bit of a challenge to find that sweet spot between simplicity and effectiveness.  My addition to the original design includes an two-way-adjustable piston that increases variability, but I never put it in because simply changing weights, adding followers, and moving the cheese horizontally has given me everything I need fairly conveniently. Adding notches to move the weight would increase variability even more.  But my goal is to get the thing smaller for easy storage, and your plans do that admirably.

I'd love to see the cast iron press if you have a link.  I have an antique French cast iron corker that's beautiful, and I was actually thinking of designing an "antique look" cheese press, based on its design.

Offline awakephd

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Re: New compact, compound-lever, selectable MA press
« Reply #68 on: May 01, 2017, 01:27:56 AM »
Actually, the picture that inspired my design is in the very first post in this thread. :)
-- Andy

gstone

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Re: New compact, compound-lever, selectable MA press
« Reply #69 on: May 01, 2017, 02:25:20 AM »
Too easy.   ;)

gstone

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Re: New compact, compound-lever, selectable MA press
« Reply #70 on: May 01, 2017, 02:45:18 AM »
Found photos of a similar antique. This is beautiful!

5ittingduck

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Re: New compact, compound-lever, selectable MA press
« Reply #71 on: May 01, 2017, 05:14:15 AM »
That's a very fine piece of machinery.
Parts of me are fizzing......

Offline awakephd

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Re: New compact, compound-lever, selectable MA press
« Reply #72 on: May 01, 2017, 01:27:27 PM »
Very sexy, indeed. But there is a catch (isn't there always?) - the press shown in the picture has a fixed and extremely high mechanical advantage (MA). As best I can tell, measuring from the picture, the upper lever has an MA of around 11. The lower lever has an MA of around 4. And the pulley will add an MA of 2. Multiplied together, and you get an MA of 88x - and again, this would be fixed, not adjustable. This has some very important implications:

On the positive side, it would be simple to put a great deal of force of weight on the cheese - 5 lbs applied to the end of the chain would produce 440 lbs of force.

On the negative side, it would be much more fiddly to put small amounts of weights on the cheese To follow a regimen of, say, 5, 10, 20, 40 lbs of pressing for an alpine style, you will need weights of .059, .11, .23, and .45 lbs. No, not too hard for a machinist to make, but not something you can easily do with a jug of water. To put this in perspective, with an 88x mechanical advantage, a change in just about 5 grams applied - a teaspoon of water - would produce a change in force of 1 lb. (Yes, I know - mixing my measurements - but for the metric folks, the relationship is easier to understand, and most of us who use pounds and pints still have some sense of what 5 grams "feels" like.) You may be thinking, "no problem - just hang a jug and put in a teaspoon of water for every pound desired." Yes, but first you need to weight the jug, very precisely, and factor that in, and you need to make sure you are using exactly a teaspoon of water each time, and above all, even after you've done all of this, you need to take into account the friction in the mechanism, which will throw all of your calculations out the window. IOW, you'll need to do some very careful calibration ...

But here's the real negative: with a fixed 88x MA, your weight on the pulley will have to move 88" in order for the cheese to compress by 1" - even when you are only pressing lightly. Since the first pressing of a cheese can easily compress by 2-3", that means a LOT of adjusting with the screw mechanism, every few minutes, to keep the weight from hitting the floor. Even once the cheese begins to compact, a movement of only .10" on the ram will require nearly 9" of movement on the weight - so even at the end of the process, you may be having to watch out that your mechanism has not "bottomed out."

All of the above is why I wanted a design that had adjustable MA, so that I could use high MA only when I really need a lot of force, and lower MA when I need more control.
« Last Edit: May 01, 2017, 01:42:51 PM by awakephd »
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Re: New compact, compound-lever, selectable MA press
« Reply #73 on: May 01, 2017, 02:55:53 PM »
AMEN!

Offline OzzieCheese

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Re: New compact, compound-lever, selectable MA press
« Reply #74 on: May 04, 2017, 03:34:43 AM »
I love the mechanical aspect of the old one and the obvious workmanship gone into the castings. That said I've tried several designs
1. Screw press with a spring
2. Basic dutch press
3. smolt1s collapsible and
4. Andy dual pivot - wooden version

While they all pressed cheese to one degree or another my all time fav is the dual pivot design. I have put some awful pressures on the cheese in this press and it just keeps on cranking out cheese. I don't think I've even considered making another - I'm not even sure I could break this one (under cheese pressing conditions). I've even considered making an extra ram with cupped adapter to press apples (for Cider making) - its just that good.

just my 10 cents worth.

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