I was kicking around how to easily calculate the wieghts/pressures needed for a given mold size and desired psi.
So I made a couple of tools.
The first is for a Dutch lever press.
Download the attached files or
Copy the stuff between the lines into a notpad on your PC, then save as LeverFromage.hta
Once you've done that double click and the rest is self explanitory.
Let me know if you find any errors
(i have attached the complete files at the bottom)
Thanks
<HTML>
<HEAD>
<TITLE>
Lever Fromage Du Fatman
</TITLE>
<SCRIPT LANGUAGE="vbscript">
OPTION EXPLICIT
Dim dblPrices(2)
dblPrices(0) = 12.56
dblPrices(1) = 28.26
dblPrices(2) = 50.24
Sub cmdCalc_OnClick
Dim intSelected, intSelected1, dblcyl0, dblcyl01
Dim dblTotal, dblcyl, dblcyl1, txtcyl
Dim dblTot, dblTot1, dblTot2, dblTot3
intSelected = frmForm1.cboProducts.SelectedIndex
dblTot = dblPrices(intSelected) * frmForm1.txtQty.Value
dblTot = dblTot
dblTot1 = dblTot * 2
dblTot2 = dblTot * 3
dblTot3 = dblTot * 4
dblcyl0 = CInt(frmForm1.txtwght.Value)
dblcyl01 = CInt(frmForm1.txtPiv.Value)
dblcyl = (dblcyl0 dblcyl01) / dblcyl01
dblcyl1 = dblPrices(intSelected)
frmForm1.txtTotal.Value = " " & dblTot
frmForm1.txtTotal1.Value = " " & dblTot1
frmForm1.txtTotal2.Value = " " & dblTot2
frmForm1.txtTotal3.Value = " " & dblTot3
frmForm1.txtTotal4.Value = " " & dblTot / dblcyl
frmForm1.txtTotal5.Value = " " & (dblTot / dblcyl) * 2
frmForm1.txtTotal6.Value = " " & (dblTot / dblcyl) * 3
frmForm1.txtTotal7.Value = " " & (dblTot / dblcyl) * 4
frmForm1.txtTotal8.Value = " " & dblTot / dblcyl
frmForm1.txtTotal9.Value = " " & dblcyl
End Sub
</SCRIPT>
</HEAD>
<BODY BGCOLOR="white">
<FONT FACE="arial" SIZE=2><B>
<CENTER>
<H3>Mold Pressure Calculator</H3>
<P>
Select the Mold Size you require from the list, then
simply enter the Desired internal mold psi,</P>
and click the Calculate
button to see the LBS of force needed.
</P>
<FORM NAME="frmForm1">
<SELECT NAME="cboProducts">
<OPTION>Mold Size 4"
<OPTION>Mold Size 6"
<OPTION>Mold Size 8"
</SELECT>
Target PSI
<INPUT TYPE="text" NAME="txtQty" SIZE=10>
</P>
Please enter your Measurment from pivot to fulcrum in inches
<INPUT TYPE="text" NAME="txtPiv" SIZE=10 value="1">
</P>
Please enter your Measurment from fulcrum to wieght point in inches
<INPUT TYPE="text" NAME="txtwght" SIZE=10 value="1">
<P>
<INPUT TYPE="button" NAME="cmdCalc" VALUE="Calculate">
<P>
This is the force in pounds needed on your Side by side molds.
</P>
<INPUT TYPE="text" NAME="txtTotal">
Two Molds <INPUT TYPE="text" NAME="txtTotal1">
Three Molds <INPUT TYPE="text" NAME="txtTotal2">
Four Molds <INPUT TYPE="text" NAME="txtTotal3">
</P>
This is the Prdicted necesarry Wieghts in pounds needed on your Lever.
</P><INPUT TYPE="text" NAME="txtTotal4">
Two Molds <INPUT TYPE="text" NAME="txtTotal5">
Three Molds <INPUT TYPE="text" NAME="txtTotal6">
Four Molds <INPUT TYPE="text" NAME="txtTotal7">
</P>
</P>
Amount of simulated wieght. (used for proofing Multiply sim wieght By Advantage Factor)
</P><INPUT TYPE="text" NAME="txtTotal8"> Your Mech Adv Factor <INPUT TYPE="text" NAME="txtTotal9">
</FORM>
</BODY>
</HTML>
This second section is for a pnuematic press, same instructions as before except the name changes to fromage.hta
<HTML>
<HEAD>
<TITLE>
Fromage Du Fatman
</TITLE>
<SCRIPT LANGUAGE="vbscript">
OPTION EXPLICIT
Dim dblPrices(2)
dblPrices(0) = 12.56
dblPrices(1) = 28.26
dblPrices(2) = 50.24
Sub cmdCalc_OnClick
Dim intSelected, intSelected1
Dim dblTotal, dblcyl, dblcyl1, txtcyl
Dim dblTot, dblTot1, dblTot2, dblTot3
intSelected = frmForm1.cboProducts.SelectedIndex
dblTot = dblPrices(intSelected) * frmForm1.txtQty.Value
dblTot = dblTot
dblTot1 = dblTot * 2
dblTot2 = dblTot * 3
dblTot3 = dblTot * 4
dblCyl = frmForm1.txtcyl.Value / 2
dblcyl1 = dblcyl * dblcyl * 3.14
frmForm1.txtTotal.Value = " " & dblTot
frmForm1.txtTotal1.Value = " " & dblTot1
frmForm1.txtTotal2.Value = " " & dblTot2
frmForm1.txtTotal3.Value = " " & dblTot3
frmForm1.txtTotal4.Value = " " & dblTot / dblcyl1
frmForm1.txtTotal5.Value = " " & dblTot1 / dblcyl1
frmForm1.txtTotal6.Value = " " & dblTot2 / dblcyl1
frmForm1.txtTotal7.Value = " " & dblTot3 / dblcyl1
End Sub
</SCRIPT>
</HEAD>
<BODY BGCOLOR="white">
<FONT FACE="arial" SIZE=2><B>
<CENTER>
<H3>Mold Pressure Calculator</H3>
<P>
Select the Mold Size you require from the list, then
simply enter the Desired internal mold psi,</P>
and click the Calculate
button to see the LBS of force needed.
</P>
<FORM NAME="frmForm1">
<SELECT NAME="cboProducts">
<OPTION>Mold Size 4"
<OPTION>Mold Size 6"
<OPTION>Mold Size 8"
</SELECT>
Target PSI
<INPUT TYPE="text" NAME="txtQty" SIZE=10>
</P>
Please enter your Cylinder Size in inches
<INPUT TYPE="text" NAME="txtCyl" SIZE=10>
<P>
<INPUT TYPE="button" NAME="cmdCalc" VALUE="Calculate">
<P>
This is the force in pounds needed on your Side by side molds.
</P>
<INPUT TYPE="text" NAME="txtTotal">
Two Molds <INPUT TYPE="text" NAME="txtTotal1">
Three Molds <INPUT TYPE="text" NAME="txtTotal2">
Four Molds <INPUT TYPE="text" NAME="txtTotal3">
</P>
This is the Prdicted necesarry psi in your pnuematic cylinder.
</P><INPUT TYPE="text" NAME="txtTotal4">
Two Molds <INPUT TYPE="text" NAME="txtTotal5">
Three Molds <INPUT TYPE="text" NAME="txtTotal6">
Four Molds <INPUT TYPE="text" NAME="txtTotal7">
</FORM>
</BODY>
</HTML>
Line 29
dblcyl = (dblcyl0 dblcyl01) / dblcyl01
Is missing something
Second part Line 22
dblTot = dblTot dblShipping
is missing something.
Probably copy paste converted signs to nothing. Was it a plus sign?
Quote from: Gürkan Yeniçeri on July 20, 2011, 05:32:19 AM
Line 29
dblcyl = (dblcyl0 dblcyl01) / dblcyl01
Is missing something
Second part Line 22
dblTot = dblTot dblShipping
is missing something.
Probably copy paste converted signs to nothing. Was it a plus sign?
Your absolutely right it striped out a + sign.
It should read dblcyl = ( dblcyl0 + dblcyl1) / dbcyl
This is the lever arm measurement calc..
The second part the variable dblshipping can be deleted it crept in from something else I was doing.
I will edit the original post to fix these error good catch thanks..
p.s yep the forum software doesn't appreciate html code dumped directly into its posts, my bad.
The original post is fixed.
Attached are the complete files.
Thanks
Here is what they look like.
(http://lever.jpg)
(http://pnuem.jpg)
How about a metric version? :P
I'm not familiar with common metric size molds.
If you want to post say the five most common sizes I can see how hard it would be to convert.
Also is the pressures expressed in psi or kpa?
How about a format that can work on a Mac?
Sorry I don't have access to a Mac, so I have no way to program for it.
Though most of the code is HTML, so likely someone with Javascript knowledge could convert it to run on Mac/Linux etc...
Well, thanks anyway. :)
Your welcome, I'm playing with an update that does any mold size inches or metric.
as well as psi or metric pressures and weights..
Probably a week or two though for that to be finished.
Fatman, you only have one more miracle left for the saintsip...
Thanks for these tools.
As they are html pages, may be John can include them somewhere on the cheeseforum.org and after that it will work on any OS anywhere.
He is certainly welcome to do so. The other tool on the back burner is a two mold size stack configuration..
I.e. A 4" on top of a 6" or 8" mold what would the respective pressures be.
I thought of this as I bet it's common for folks to make a cheese and have enough curds for a puck.
So what finagling would it take to pull off a successful double header of non equal sizes..
I know how just need the time to write it.
As you can see I'm still playing but this shows how you can mix and match metric and English values.
I did this as we Americans buy E.U. molds and need to be able to figure them out.
And our European cousins just might buy air cylinders or American made presses with English gauges.
Click the links below to download. (Sorry only works on PC's)
And please, let me know if there are errors.
Thanks
Fatman
Metric pressure calculation is off :P
Can you elaborate?
I used the canned formula so when you say it's off what do you mean?
Too high, too low, wrong expression?
Are you referring to as an example at 4psi it comes to 27.4Kpa rather than 27.5Kpa?
That is due to rounding I limited it to two decimal places to keep the numbers shorter.
But if that degree of accuracy is needed I can bump it up.
I figured +or- .1% was close enough.
My problem is not being educated in a metric system I don't know what's expected.
http://www.asknumbers.com/psi-to-kilopascal.aspx (http://www.asknumbers.com/psi-to-kilopascal.aspx)This is where I got the numbers.
Also I'm working on a web based version so I can use it on my iPad/android or macs.
The problem is the buttons don't work the same in all browsers..
www.netnut.us/fromage (http://www.netnut.us/fromage) for the pneumatic one.
and www.netnut.us/leverfromage (http://www.netnut.us/leverfromage)for the lever based one.
By extending the pi constant out to approx eight decimal places.
I can get it to within .003 of the exact Kpa, but then that requires a similar accuracy of input.
nobody I know will for instance put 102.3mm they will simply put 102mm
And if the recipe calls for 50lbs in a four inch mold that's not quite 4psi, but nobody will put "place 50.25lbs" on your cheese.
I think the old addages "close enough for government work" or "close enough for horse shoe's and hand grenades"
Comes to mind.
I will keep looking at it, but don't see a profound reason to chase it with these fractions that equate to grams, when kilo's are called for.
I'm not even sure any pressure regulators are accurate enough for it to matter.
0.12m=12cm diameter with 40kg gives 5028511.21 psi
Thats a bit of an overshoot.... :)
It should give 0.47411096 psi.
I think I see where we are off base.
My tool only knows mm, not m or cm.
So your example of 0.12m would need to be bumped to 120mm.
Just enter the numbers and select metric don't put mm.
so 120/2 = 60 give us our radius in mm
60/25.4 to convert to inches = 2.36"
2.36 X 2.36 X 3.14 for the area = 17.52"
Then we take 40Kg x 2.204 to convert to pounds = 88.16
weight / area = psi, so 88.16/17.52 = 5.03 psi
we can the multiply 5.03 by 6.89475729 to convert to Kpa which is 34.69
Probably should make a note on the tool to use only mm, Kg, Kpa, psi, lbs, inches
The only drifting I've found is due to pi not being a whole number so the decimal place comes into play for rounding.
This is exactly why I was asking for input from my Metric friends.
I do not know what the preferred method of entry or the expected output.
All of our Metric molds are listed in mm so I assumed that was the expression of choice.
Oh I see.... that makes sense.
Thanks.
Aside from clarifying some of the verbage in the tool.
So as to make entry clear so predicted outcomes are as expected.
I do plan another add on.
a resistance/tare weight factor.
Every press has a certain amount of resistance to overcome which must be subtracted from it applied force, and likewise the assorted resting weight of the lever or other bits weight must be added to the force.
All of this will effect the predicted weight/pressure needed.
If you have any ideas let me know, and I will see how it can be added.
The formula for the Arm weight is: ARMWEIGHT=(PRESSINGWEIGHT-TAREWEIGHT)/MECHANICALADVANTAGE.
Figuring the friction is not easy for a wooden lever press because it changes at different weights. Also the coefficient of starting friction is much different from the moving coefficient of friction especially if there is any ware on the wood at the fulcrum. Some presses can be modified to overcome most of the friction problems by fitting a plastic or metal plate at the fulcrum.
Hope this helps.
Yep, not to mention moisture causing wood to swell, and not slip against other parts well.
And pneumatic cylinders have a minimum operating pressure which drops off quick once it starts moving.
then comes on again at rest.
This is going to be one of the close, but not perfect issues.
The static resting weight should be easy and will be the starting place.
The cylinders issue I will need to do some real world testing, and an engineer buddy of mine
is advising me a bit on the friction issue.
But I just want the predicted weights and pressures necessary for a good press to be as close as possible.
I figure most recipes are ballpark figures anyway.
Even in the retail presses that use pressure springs there's a huge variance.
Temp, and mold to follower tightness, spring age, spring rate, etc...
I dare say 50lbs is not really 50lbs.
At least with a lever press or a pneumatic you can throw a scale under your pressing board zero it out.
and get a nearly 100% accurate weight of press.
Unfortunately they generally only go up to 350-400lbs, after that it's all math based calcs.
Hmmmmmm, Perhaps I should intigrate a load cell into my press.
Quote from: Fatman on August 01, 2011, 03:54:01 PM
Yep, not to mention moisture causing wood to swell, and not slip against other parts well.
And pneumatic cylinders have a minimum operating pressure which drops off quick once it starts moving.
then comes on again at rest.
This is going to be one of the close, but not perfect issues.
The static resting weight should be easy and will be the starting place.
The cylinders issue I will need to do some real world testing, and an engineer buddy of mine
is advising me a bit on the friction issue.
But I just want the predicted weights and pressures necessary for a good press to be as close as possible.
I figure most recipes are ballpark figures anyway.
Even in the retail presses that use pressure springs there's a huge variance.
Temp, and mold to follower tightness, spring age, spring rate, etc...
I dare say 50lbs is not really 50lbs.
At least with a lever press or a pneumatic you can throw a scale under your pressing board zero it out.
and get a nearly 100% accurate weight of press.
Unfortunately they generally only go up to 350-400lbs, after that it's all math based calcs.
Hmmmmmm, Perhaps I should intigrate a load cell into my press.
HAhahaha, just picked up a 3000lbs load cell.
If I can figure out how to use it, I will have the worlds first cheese press with intigrated scale.
You might ask why on earth 3000lbs!
I have two 8.5" mold I got from Ullmers dairy.
Pressing them side by side @ 20psi ~ cheddar pressure takes over a TON approx 2300lbs.