# [Gmsh] using gmsh for pin pattern generation

Stein, Alexander stein at berlinerglas.de
Mon Jun 20 11:00:58 CEST 2016

Hello,
i'm using GMSH for 2D mesh generation since a while (at beginners level - just create geometry or import dxf via dxf2geo and then press mesh).

I'd like to use GMSH also to generate an evenly spaced pin pattern (node position = pin position). I try to use this pattern as support for a plate to have less contact area. The spacing between the pins needs to be very equal to not have unflatness of the plate due to heavy sagg while vacuum clamping. The problem is: the geometry can be complex (e.g. circle with off-center circles inside).

Therefore I tried a simple test: A Circle inside of square. My iam is to fill the box with a pin pattern (=nodes) with spacing of 0.5mm (+/-0.2mm => 0.48mm till 0.52mm is okay). I need to force gmsh to do so.

//Circle
Point(1) = {0, 0, 0, 1};
Point(2) = {-2, 0, 0, 1};
Point(3) = {2, 0, 0, 1};
Point(4) = {0, -2, 0, 1};
Point(5) = {0, 2, 0, 1};

//Square
Point(6) = {7, 7, 0, 1};
Point(7) = {-7, 7, 0, 1};
Point(8) = {-7, -7, 0, 1};
Point(9) = {7, -7, 0, 1};

Line(1) = {9, 6};
Line(2) = {6, 7};
Line(3) = {7, 8};
Line(4) = {8, 9};
Circle(5) = {3, 1, 5};
Circle(6) = {5, 1, 2};
Circle(7) = {2, 1, 4};
Circle(8) = {4, 1, 3};
Line Loop(9) = {2, 3, 4, 1};
Line Loop(10) = {6, 7, 8, 5};
Plane Surface(11) = {9, 10};

But at this point in time (with only setting "Min/Max element size" to 0.48 and 0.52) it doesn't work.

What can I do to ? I very much appreciate any help.