THE HOBBYIST'S GUIDE TO CASTING METAL ND 2 EDITION BEN BAKER This work is licensed under the Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/3.0/us/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA. To view a free online version of this work, visit http://prometheus.vndv.com/tutorial.html. Acknowledgments Thanks to the members of the BackyardMetalcasting.com forums, without which this book would never have existed. i Disclaimer Many of the activities described in this book are very dangerous. I make an attempt to point out some specific safety precautions as they come up, but there is no way I can point out every conceivable danger. I'm not a professional foundryman, scientist, or engineer, just a hobbyist—so there may be dangers that I don't even know about. For that matter, any advice I give could be wrong or even dangerous in certain situations. I can't be held responsible for any harm that comes to person or property as a result of following my advice or using any of the information in this book. Remember, the extremely high temperatures that liquid metal can reach are more than enough to send you to the hospital or kill you, or to set fire to anything nearby (like your house). Other activities, like welding or machining, present their own very serious dangers. iii TABLE OF CONTENTS Table of Contents Introduction...........................................................................................................................1 Utility of Metalcasting.......................................................................................................1 The Basics..........................................................................................................................2 Personal History.................................................................................................................3 Section I: Safety....................................................................................................................5 Safety Gear.........................................................................................................................5 Clothing.........................................................................................................................5 Eye Protection...............................................................................................................6 Respiratory Protection...................................................................................................7 Special Precautions............................................................................................................8 Lead...............................................................................................................................8 Zinc................................................................................................................................8 Magnesium....................................................................................................................9 High-Temperature Metals.............................................................................................9 Safe Foundry Practice......................................................................................................10 Steam Explosions........................................................................................................10 Crucible Care...............................................................................................................11 General Safety Rules...................................................................................................12 Section II: Melting and Casting Practices........................................................................13 Judging Temperature........................................................................................................13 Temperature by Color.................................................................................................13 Optical Pyrometry.......................................................................................................14 Pyrometric Cones........................................................................................................14 Casting Processes.............................................................................................................15 Sandcasting..................................................................................................................15 Greensand...............................................................................................................15 Oil-Bonded Sand....................................................................................................15 Resin-Bonded Sand................................................................................................16 Lost Foam....................................................................................................................16 Lost Wax.....................................................................................................................16 Investment Casting.................................................................................................17 Ceramic Shell Casting............................................................................................17 Permanent Mold Casting.............................................................................................17 Identifying Scrap..............................................................................................................17 v THE HOBBYIST'S GUIDE TO CASTING METAL Melting Procedures for Common Metals.........................................................................19 Aluminum....................................................................................................................19 Copper and Copper Alloys..........................................................................................20 Iron..............................................................................................................................22 Zinc and Potmetal........................................................................................................23 Lead and Tin................................................................................................................23 Metalcasting on a Budget.................................................................................................24 Safety...........................................................................................................................24 Metal Sources..............................................................................................................25 Equipment...................................................................................................................25 Furnaces.......................................................................................................................26 Fuel.........................................................................................................................26 Refractory...............................................................................................................26 Mold Making...............................................................................................................28 Section III: Sand Molding..................................................................................................30 Sand..................................................................................................................................30 Mulling........................................................................................................................31 Pattern Making.................................................................................................................33 Molding Tools..................................................................................................................34 Flasks...........................................................................................................................34 Rammers......................................................................................................................36 Other Tools..................................................................................................................37 Mold Design.....................................................................................................................37 Molding Practice..............................................................................................................43 Section IV: Furnaces, Crucibles, and Fuel.......................................................................46 Furnaces...........................................................................................................................46 Refractoriness..............................................................................................................46 Insulative Ability.........................................................................................................47 Thermal Mass..............................................................................................................47 Hotfaces.......................................................................................................................48