Scaling Y Axis

Hi,

Is there a way to scale Y axis to start at a certain value and then increment by another. I have an issue where  in Chart 1, there is no lower grid line.  However in chart 2 of same size the chart starts at 0.  I dont have a min/max range value set on either chart. 

I tested adding 0 to the min range value chart 3 , but then the upper value for May is now nearly off the visual.  There is typically only a smal deviation in the values, so need to be abe to just show values without using min/,max

Any guidance on how to format appreciated. 

thanks