I had this topics up before and has been try get a solution.

It's no real need to has a equal sided triangle as Plop do the math, but its more easy do them equal ( even in CAD/CNC machine ) and centre is correct located so balance is perfect.

If I take my cell for a example.

457 mm in diameter. ( 18" )

1829 mm FL ( f/4 )

33 mm edge thickness.

Quartz.

18 pt cell.

Automatic cell get's me a nm RMS at 9.2e07.

That gets me the 2 radius at ;

0.804606.

0.399088.

Now I did a even radius to 0.8 and 0.4 and run the program.

The side # 2-3 got me a number.

The #1 side got me a shorter number.

To get this equal one has to add +15.47% on that shorter number, and then the triangles is equal.

In program I let the radius 0.8 be there but I must adjust the radius 0.4 some.

The number was instead 0.414111, so one add 3.525 %.

The readings in Plop now show a hair more at 1.15e06 now, so it's a 'price' to pay.

A note here.

One could try adjust the 0.8 radius to get it more equal, so then the nm RMS readings might be little better, or clooser to the automatic number.

.

**Edited by hakann, 11 May 2019 - 01:28 PM.**