CAD modeling of Beta type Stirling Engine’s crank shaft

Crank shaft is a key part of the engine that is used to transmit power from piston to to the fly wheel or the load. Here we will be focused only the CAD modeling rather than the complete design consideration. Our final CAD model of this tutorial will looks like as shown in the fig below.

CAD model of crank-shaft


To start with this CAD design, first select the front plane and click at the sketch icon to enter into sketching window. There draw three circles of diameter 1.00, 0.7, 0.8 units according to arrangement as shown in fig. All the circles have their centers at a distance of 0.5 from each axis.

Figure 1


Now use tangent line to draw tangents on these three circles and use delete segment tool to remove extra curves to make our sketch looks like in the fig below. After this click at green “right (ok) “ sign.

figure 2


Now extrude this sketch up to the 0.5 units. I suggest you not to change the view by rotating the part. In the proceeding tutorial I will call it as “Crank Curve”.

figure 3


Before moving forward, first make sure that your part view is the same as it was oriented in fig (2).

After this select the front surface and click at sketch icon. In sketching window make a circle of diameter 0.5  as shown in the following fig 4(a) and click ok. In main window extrude this circle into rod of length 1.20 units see fig4 (b) below.

figure 4 (a & b)

After this select the same surface as you did for last sketch. Now we need to draw a datum plane that is 0.6 units away from the surface.see the fig 5.

figure 5


Now we are going to mirror our first crank curve . so select the extrude 1 or crank curve  from the model tree and then click at the mirror button. This will ask you to select the reference plane. For this just select the datume plane that you have just created and click ok. This will make your CAD model look like as shown in fig 6.

figure 6

Now select the front surface of second crank curve and create the sketch as shown in the fig (a) after creating it make it extrude upto the length 4.45 units as shown in fig (b)

figure 7


We are now just 2 steps away from creating the whole crank shaft. We need to make a central rod connection and after that we will use mirror again to create the second section of our CAD model.So make a short cylindrical rod at the other  crank curve with diameter up to 0.4 and length is again 1.2 units.

figure 8

Now select this surface again and create a datum plane which is 0.6 units away from the surface. Shown in fig below

figure 9

Now select the whole CAD model except the pin that have created in last and make a mirror of whole part using datum plane, which you created in the preceding step, as reference plane. This will complete our desired CAD model of Crank shaft. Don’t forget to save it as we will use in later tutorials.

figure 10



  1. can i see your existing design of beta stirling engine with dimensions like the piston and displacer length and those spaces with the crankshaft big thanks in advance email me


  2. hi :
    my final project in this year is about : design a prototype for beta type stirling engine , can you help me , to choose materials , & sketch the engine on autocad


    1. baraa’ hamad alliemoon use contact me page and tell me detail about your project so i can know if i can help you or not. with autocad. But in case of first two ( material and sketch) i can help you


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