Control Design Features Using Fractions in Variables

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Hello everybody and welcome to this quick demonstration about how Fraction work inside Shapr3D when working with variables. What you see here is a small smartphone holder. I have one simple sketch and then multiple modeling steps to build my individual parts, the bottom plate, the hinges and the top one. And with

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Fractions, I would like now to perfect my design. For example, this bottom padding, I always want to be one-tenth of the material thickness of this bottom part. My hitches, I would like to be always one-third of the maximum width. And this opening here at the tip, that I would like to be always 50%

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of this maximum width. So I have to create some variables and then I can use fractions inside expressions. So let's do this with this bottom part. So that actually, this one millimeter should be one 10th of this overall material thickness. If I go into the sketch and here,

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I have my dimension for the material thickness, 2.5 millimeters. This I have to first convert into a variable. I can click on this plus icon and say, create length 1. There we are. This variable I will rename and I call this one empty material thickness. Because now with this number I have in here,

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is driving the sketch.

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So if I go back to the sketch, see here, it says Fx 2.5 millimeters that comes from this variable. Beautiful. Now, if I select my padding face, it presorts all the commands. Here's my extrusion command and this one millimeter, I would like now always to show one 10th of this 2.5 millimeters or actually the variable empty.

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To do this, I will make a reference and say empty the variable and that I multiply and here comes a trick to work with expressions in brackets 1 10th. There we are. See now this actually is 0.25. If I change this to 3 millimeters, this will be 0.3.

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Let's work on how we can make this opening here to be exactly 50% of the maximum width. First, have to explain that this extrusion is using the symmetric function and it uses 30 millimeters. So this is half of the diameter. So we'll create two more variables.

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This is actually also a good moment to show you the order in which you create the variables is very important. I would like to find the total width. So first I will write a variable called width of, and that is 30 millimeters. And then I will make a new variable, which is just width.

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And then here I say with half, I could write it. I can also click on this icon and then select the variable and with half multiply by two and click create. So you see here, this is with half. This is this one and that is actually the total because I just multiplied.

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To be accurate, I can adjust this one. So the 30, I overwrite with the variable I created. And then here I have a center cut. See this actually states 10. So this is actually that creates the opening. In here, what I have to write now, that is actually

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the following. So we'll take the material.

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total, and that I would like to multiply by one third. I have to put everything into brackets because this is not a result, because that result I divide by two. The reason why I do this is simply because we have a symmetric extrusion with a single value, not to a total width.

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and press Return. And there you say 10 millimeters. Now that is perfect. If I now go ahead and change this to 40, you see how this actually adjusted. So this line is 26, 26. And when I select the inside, that is 26. So everything is perfectly one third.

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This did not update yet because here I would have to need to copy in exactly the same. So I can do this one more time.

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the width, I multiply in brackets by one third. I put everything into brackets and then I divide this by two. There we are. You see, this is actually really elegant and easy to set up. There we are. So if we now take a look at how we could adjust this opening to be

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50%. A simple calculation would be the opening has to be 60 divided by 2 and that we divide by 2, but we want to work with fractions. And it's exactly the same process.

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So I have here this top cut. There we are. There we will go ahead and say one more time. So the width, we multiply in brackets by one half, put this into brackets and divide it by two.

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There we are. So if we select this and there, that is now 30 and 30 is exactly half of 60, the total. And that is actually everything that is important to know how you can write fractions inside expressions when working with variables inside a parametric environment.

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One last note, what you also can do is mix different unit systems. That's actually very easy to explain. Here, I just draw a line and then this line, I would like to be a mix of different unit systems, for example, meters and centimeters. I just do this only

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on purpose, so you see also how fractions and units work. So I would like this to be 1 20th of a meter.

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plus in brackets, one third. You also see in case something is wrong, there is a warning sign, one third of a centimeter. And you can also mix this with feet and inches or metric in imperial. But you see, this is kind of like the way how you have to write it. When I press Enter, there it is, 50.

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And that's it. That's everything to know about how to work with fractions and units in Shapr3D.