Maximum number of gridlines?

[Instantaneo]

I'm building a diagram of trains running in Excel 2010 for my masters degree, which is a scatter plot with 24 hours a day on the horizontal axis and the line length (in this case 310 km) on the vertical axis.


Once that I need extreme precision, I'd like my chart to have in the horizontal axis major gridlines from 10 to 10 minutes and minor gridlines every minute. On the vertical axis, I'd want to put the 310 km in 0.1 km intervals.


However, when I'm splitting to obtain the horizontal axis gridlines, I do (as shown below):


Major Unit: 1 / (60 x 24/10)

Minor Unit: 1 / (60 x 24)


http://i49.tinypic.com/2j5mhz7.jpg


Instead of staying with a constant division between major gridlines, I get the following:


http://i50.tinypic.com/5fiyxh.jpg


Strangely, if I toggle between logarithmic scale and back off, all series disappear, although apparently and logically the data does not change. However, the divisions already appear correct!


http://i47.tinypic.com/rs4t95.jpg


Another thing I noticed is that if I change the plot range between 0 and 0.25 (ie 6 hours instead of 24 hours, between 0 and 1), the divisions already appear correct! When I start to increase the range of the graph starts the irregularity. However, I need to make one single diagram for 24 hours!...


Something similar happens in the vertical axis...


So, I wonder why if Excel has a limit of divisions in the charts...


Thank you in advance for your help!

 

[Luke M]

This is more of a guess than known fact, so take with grain of salt. My guess is that there's some limit due to number of pixels that can be displayed. Checking my computer's resolution settings, the highest I can get in horizontal is 1366. However, to plot a line for every minute in 24 period is 24 * 60 = 1440. That chart would just be a black box of grid lines.


One possible work around would be to create a dynamic chart with a scrolling horizontal axis. So, all the data is being calculated, but you're only showing a fraction at a time (since the user can only see so much as a time, I don't think this should be a problem.