For those of you that have done the things I'll be describing many times, please be patient. This process and the processes in the following posts might be something new for many just starting out in the hobby.
The shoulder for the upscaled nose cone is going to made out of a coupler for a 3 inch body tube. The width of a body tube is also known as the "caliber" of the tube, a little factoid for those that didn't know. With a small square laid over both edges of the coupler, tic marks were placed at the .5 caliber meauserment (1 1/2inches) at several locations. See picture #1.
A plain 'ol piece of printer paper is wraped around the coupler. The paper is snuged up around the coupler and the edges of the paper are aligned with themselves and the tic marks at the 1 1/2 inch measurement. A pencil line was drawn around the coupler using the paper as a guide. This gives you a straight line to cut on.
Why did I choose 1 1/2 inches as the length for the nose cone shoulder? I'll explain why when I get to the part where the explanation will fit in better. See picture #2.
When I cut a coupler or tube, I like to place the middle of the blade on the line so the tip of the blade is off the tube. Then I PUSH the knife AWAY from me along the line on the coupler. Because the tip is off the tube it can't dig into the tube. Because you can see the tip and where it needs to go, you can steer the tip. Were ever the tip goes, the rest of the knife has to follow. Kinda like steering a car.
Go all he way around the tube a couple of times so there's a groove for the blade to follow.
Lift the knife up so the tip of the blade is in the groove, then PULL the knife TOWARDS you. You'll feel the tip starting to cut into the tube. The tip of the knife will follow the groove all the way around the tube. DO NOT try to cut thru the tube all at once. Use a light but firm pressure. Go around the tube several times or more and you'll get a clean, straight cut. See picture #3.
How come the two pieces of coupler have a differant shade of brown?
Thinking about taking pictures and starting a thread didn't cross my mind until after the piece was already cut, soaked with CA and sanded to fit on the mandrel. The pictures are recreations.
The inside of the shoulder was sanded down until a smooth friction fit was felt on the coupler bulkhead on the 3/8ths aluminum rod (mandrel) and the shoulder. See picture #4.
The outside of the shoulder was sanded smooth until a section of 3 inch body tube could be slid over the body tube bulkhead (that's glued to the other end of the 3/8 ths aluminum rod) and the shoulder with a smooth friction fit on the mandrel. See picture #5.
The mandrel is being reused from The Logo Rocket project. A good picture of how the mandrel is set up can be found in: The Scratch Built section, "Homemade Logo Rocket, Post #6, 3rd picture (
www.rocketryforum.com/showthread.php?t=10709). The mandrel will be used in the same way with the ASM nose cone, chucked up and spun up in a drill press.
So, there's alot going on with these pieces already, and it's not done yet.