There are several things wrong with your comparison. Let's do it right...
1. Each of the three calculators take a different input for lead/leg length:
- Steam engine takes the
total leg length (of both ends), measured from the
center of the coil to the screws.
- MC Pro takes a
single leg length (one end), measured from the
center of the coil to the screws.
- Coil Genius takes a a
single leg length (one end), measured from the
edge of the coil to the screws.
Therefore, 5mm total leg length in Steam Engine correspond to
- 2.5mm in MC Pro (5mm/2)
- 1.0mm in Coil Genius (5mm/2 - 1.5mm)
2. We want each candidate to do its calculation based on the same data. Now, Coil Genius uses a slightly different resistivity for grade 1 titanium: 0.49Ωmm²/m instead of 0.47Ωmm²/m, which is used by Steam Engine and MC Pro. As there are different kinds of grade 1, both values are reasonable. So, I defined a new wire with resistivity 0.47Ωmm²/m in Coil Genius for this comparison.
Results:
Here is the Steam Engine build (26g, 6 wraps around 3mm, 5mm total leg length):
View attachment 499608
Now, here are the results of the apps with equivalent inputs:
View attachment 499599 View attachment 499602
As you can see, the results from Coil Genius are exactly the same as those from Steam Engine. On the other hand, MC Pro calculates a different wire length for the coil, which leads to different resistance, and so on. In this example, the length (and therefore the resistance) is about 6% less than what Steam Engine and Coil Genius report.
The different results produced by MC Pro are not a matter of different data (e.g. specific resistivity for a particular wire) used by the app. Rather, they come from different calculations of the wire length. In other words, MC Pro uses less wire to make 6 wraps than Steam Engine and Coil Genius do! The difference even grows with thicker wire: with 24g around 3mm it is almost 10%.
Edit: MC Pro also gets the coil width wrong.
. I would hire it done but it keeps me in shape.
