(I think this might require JMP17 and hopefully this gets better in JMP18) Use Properties button to open properties for your graph, select axisbox and modify the width
jthi_0-1704187743130.png
jthi_2-1704187918750.png
This does seem to be a bit buggy though, what I did was to disable stretching, set the line width to 20, press enter and re-enable stretching. JMP is able to capture this as a script BUT I would consider that it hasn't been yet implemented properly in JMP17.2 as there is no proper documentation in Scripting Index
jthi_3-1704188022649.png
Graph Builder(
Size(541, 908),
Show Control Panel(0),
Variables(X(:weight), Y(:height)),
Elements(Points(X, Y, Legend(3)), Smoother(X, Y, Legend(4))),
SendToReport(
Dispatch({}, "weight", ScaleBox, {Label Row(Line Width(20))}),
Dispatch({}, "height", ScaleBox, {Label Row(Line Width(50))})
)
)
Other options could be reference line OR using graphic script
-Jarmo