I need to cut holes in a dome to fit some cylinders into so that

Use a drill? Not sure what you're getting at

>>1063569
The answer depends on various factors. What materials are the dome and cylinder made of? Will the cylinder penetrate into the dome, or stop at the surface? How will you be joining them? What are the tolerances? What tools do you have available? Have you completed high school geometry?

Making some assumptions, an option would be to eyeball it, cut the cylinder at an angle, put it against the dome where you want it, mark where the cylinder has to be trimmed to fit, trim it, then put it back and trace around it on the dome to mark where to cut the dome.

>>1063569
just use the intersect tool in sketchup for exactly this purpose

>>1063569
You want it to be elongated. What material? Is it soft? Forster bit is the best bet. Build a mount and drill it on a drill press, or hand drill it. If you hand drill, maybe make a sliding dolly for the drill.

>>1063569
How big is the dome?

http://www.blocklayer.com/pipe-angle.aspx

First thing I found. Although it is for going through a flat surface it should get you close. Not sure what sizes you are dealing with though.

The simplest way I can think of doing it although It will take a while is find the position on the dome that you want the pipe to enter. By eye, line the pipe up at the correct angle to the outer radius.

If you have a band saw, I'd remove bits of the pipe away, providing you have a scrap piece, until it sits flush to the outside at the position you want it to enter.

Draw around the outside of the pipe and cut the hole out.

Depending on how accurate you are by eye though, you could avoid all of that and just go for the trial and error method.

The trouble with the link someone posted, pipe-angle, is that pitched roofs are normally flat with a run off, a dome is a radius curve, this will not account for that.

>>1063569
For tube joints we used to use cardboard tubes, trim by hand with scissors to fit, then use it as a template.

If you're talking about small tubes, use paper towel/toilet paper tubes.
For larger you can buy cardboard tubes used for concrete forms at like home depot/Lowes.

Or just make your own tubes of the correct size.

Fix the cylinder in the position you want(like the op pic)

use a strait edge along the cylinder to extend to the dome to mark the dome cutout.

To layout the cylinder, basically do the same thing but measure off the dome a fixed distance, as you go around the cylinder.


Mathmatically, divide the cylinder into equal parts, say 22.5 degrees(depends on the diameter and precision needed), then do the following for each point:

1)calculate the height(Z) on the pipe for the given angle
2)calculate the diameter of the dome at that height.
3)using the strait end of the pipe as a 0 point reference, calculate the line distance to the circle.

Once you've calculated the the distance for each pipe angle, wrap a piece of paper or posterboard around it to mark the circumference(calculating it doesn't work as well). Divide the circumference on the paper into the same equal parts(angles) , and mark the calculated distances on it. Cut it out and rewrap the template to mark the pipe.


What are you making? How big is it? What materials?

>>1063569
depends on the size.
I just fixed a tube where it should be then used a pencil to trace out the shape. Thought this case I was building a piece to fit a dashboard..
Straight edge an marks on the tube should get you close.