High Strength Casing

From PyroGuide

High strength Home made casings

Required

• manilla folders
• pva glue
• roller and paint brush
• dowel with o.d. same as casing i.d. you want.
• clothes iron
• knife thin and sharp.I use victorinox like paring knife but has concave blade
• wood lathe and or cordless drill
• marker and rule

Method

This method is for high strength rocket casing. Mix a 1:1 PVA and water mix in the roller tray. Roll or paint glue solution onto one side of manila folder. When dry enough to invert paint the other side, then allow to dry throughly. The folder when dry will make an amplified sound to the touch, but if wet sound will be dull. Dryness important to stop stretch.

Lay dried folder on bench top (marble or another hard surface good) with folder spine pointing away. use a 25mm O.D. dowel in this example but down to 12mm works well but are harder to make. Take dowel place on folder perpendicular to spine and roll with with good pressure away from you. A couple of false starts and rollings will help to make it tight before heat is applied setting glue. Hold middle of rolled folder to prevent uncoiling. Place clothes iron upright on bench in front of you. Now with paper and dowel, slowly roll it down face of clothes iron in same rolling direction using your gut to apply pressure to iron. The folders I use are foolscap size about 46cm across and need the iron to be reposition several times, lift off to move clothes iron across, do not slide across is this can cause skewing. The heat will remelt glue allowing it to stick. For 25mm dowel use three manila folders sequentially not simultaneously as heat will not penetrate and glue more than one at a time. When it cools, remove dowel and tap the casing checking for a wood like sound.

If you have a problem with dowel adhesion, coat the dowel with wax from a candle.

A simpler but weaker case is made from unglued folders by applying glue after first wrap of paper is around the dowel and then gluing and ironing between layers.

Marks are then placed on folders at required lengths the dowel and rolled folders placed in wood lathe chopped with knife whilst rotating. If casing slips on dowel use masking tape to join both together. For smaller casing id a cordless drill can be used.

An exception to the 12mm minimum is 6mm dowel with 10cm strip of manila (may need moistening to bend this sharply) to make jumping cracker cases.

Can also be scaled down to use paper not manila.