How to locate features

Do you have 2015?

You could utilise the 3d sketch option while creating holes. And then you can position them accordingly either with x,y and z coordinates or dimension. 

Hi Kingsley,

I ask the question do you have 2015, because I believe that you will need to do this using the variable pattern.  I do not have 2015 so I cannot do this (I don't know how to do a pattern like this without using a variable pattern in Solidworks.

However, there are a couple things:

First, I would never worry about cluttering up the drawing (it's actually called the "model" once you go 3D ) as you can hide the features.  A lot of work is however something to try to prevent when constructing something like this.

In ProE (I'm telling you this because there will be someone who reads this post and will say "well if it can be done in ProE, I can do it in Solidworks...), I can create a model like this in less than minute.

This pattern is varying, the angular dimension/the diameter/the position along the cylinder axis all at the same time.

In Solidworks, you can create a hole on the outside of the cylinder.  This would be considered a radial hole.  The nice thing is when you go to create that radial hole in SW it creates it so that the hole axis is perpendicular with the cylinder.  However, you can't dimension a 30 degree angle like I've shown in the above picture without some other construction geometry.  So, with that said,  I believe you will want to have the variable pattern functionality to be able to pattern it effectively.

But I would think there is some other way I am not aware of in 2014 and earlier to do the above, but my complaint has been that I have not found a way or how been shown how to do so.

So I would consider:

-A revolved cut that is on a plane that is off one side of the cylinder and then at any angle you like, then you can use the variable pattern to pattern the angular dimension/the diameter/the position along the cylinder axis (The base feature would be Cut-Revolve1 in the attached part)

-Create an angled plane and then place a radial hole placed the hole tool, patterning the same attributes above using the variable pattern.  (This is Hole1 in the attached model)

In both cases I believe the new variable pattern can be employed to give you what can be accomplished as I have shown in the picture above.

You start off with inserting the hole using the hole wizard (Insert -> Features -> Hole -> Wizard...), select the hole type, size, etc.  Click on the "Positions" tab at the top.  It will give you an option to click on 3D sketch, but you don't need to in this instance, since the pipe surface is not planar, it will automatically give you a 3D sketch when you click on the pipe (cylinder) surface.

Place the point somewhere on the cylinder and hit the Esc. button to exist the point command, but still remain in the hole wizard "positions" tab.

Now you can add a centerline as construction geometry.  To get a continuous sketch without having to start and stop the segments, I would suggest that you start by hovering over the point that you've inserted and click there to start (don't hold the mouse button down, just a click).  Then go straight down and click on the outer, bottom edge of the cylinder (you will notice that the line wants to snap to vertical - make sure it's vertical).  From there, click on the origin, and then move the mouse horizontally and click somewhere outside the cylinder (make sure that it's snapped to a horizontal).  If it will not snap in the horizontal, hit the tab button to change directions.

Now you can dimension the height and angle.  Model is attached, study it...