Casting for Woodturning. By David Bell

Transcription

1 Casting for Woodturning By David Bell

2 Biography Reside in the beautiful scenic town of Elora, which is home to the Tooth of Time on the Grand river. Belong to the AAW, the Thames Valley Woodturners Guild and the Grey Bruce Woodturners Guild, which I am currently the elected President. Some of my passions for woodturning include, pens, bowls, goblets, vases and many other projects.

3 Introduction to Casting Safety Casting Principles Mold Design Casting Resins, Pigments, Dyes and Paints Casting Materials and Preparation Casting Tools Post Casting Projects Casting Process

4 Safety Latex Gloves Safety Glasses Safety Shields Respiratory Protection Gloves Safety Boots Hearing Protection Apron GFCI

5 Casting Principles What is casting? (Wiki definition) Casting is a manufacturing process by which a liquid material is usually poured into a mold, which contains a hollow cavity of the desired shape, and then allowed to solidify. The solidified part is also known as a casting, which is ejected or broken out of the mold to complete the process. Casting materials are usually metals or various cold setting materials that cure after mixing two or more components together; examples are epoxy, concrete, plaster and

6 Casting Principles clay. Casting is most often used for making complex shapes that would be otherwise difficult or uneconomical to make by other methods. Casting is a 6000 year old process. The oldest surviving casting is a copper frog from 3200 BC.

7 Mold Design Parts of the mold. 1. Cope Upper Mold half 2. Drag Lower Mold half 3. Riser provides liquid due to shrinkage. 4. Sprue passage for the liquid to flow. 5. Core The cavity that will be filled. 6. Pouring Cup Where the liquid is poured into.

8 Sand Cast Mold

9 Mold Form and Design Solid Form The core material is solid and held in place by means of an adhesive or a bridge material. The casting resin fills all of the voids. Simplest form of mold design. Cored or Hollow Form The mold consists of two or more pieces that follow the contour of the core material. The basic shape of the mold is similar to the shape of the core material. The casting resin flows through the mold to fill open voids. This is the most complicated mold form design and requires the most time to build. Loose Form The core material is allowed to float or remain suspended in the casting resin. Usually requires some sort of cap to prevent overflow of the resin. Simple mold form design.

10 Mold Form and Design Solid Form

11 Mold Form and Design Solid Form

12 Mold Form and Design Solid Form

13 Mold Form and Design Solid Form

14 Mold Form and Design Solid Form

15 Mold Form and Design Cored or Hollowed Forms

16 Mold Form and Design Cored or Hollowed Forms

17 Mold Form and Design Loose Forms

18 Mold Form and Design Loose Forms

19 Mold Form and Design Loose Forms

20 Mold Form and Design Loose Forms

21 Mold design con t Mold Materials Silicone Hardboard Pine PVC UHMW Delrin Rubber Plastic pails Plastic cups

22 Resins or Casting Mediums Alumilite Alumilite Corporation Epoxy West System Polyester Resin Clear Casting Resin

23 Casting Dyes and Pigments Dyes are an additive that colour the resins. Pigments are additives that give the colours a pearlescent reflection of light depending their platelets that are reflected. Oil base paints provide a colour effect similar to dyes, except they do no cause bleeding.

24 Casting Materials Wood Paper Pine Cones Chola Cactus Corn Cobs Coffee Beans Rice Pasta Brass Aluminum Sparkles Just about anything

25 Material Preparation Drying 200 F max. Cleaning wire brush Stabilizing Cactus Juice 0% moisture Material Sizing depending on the project, everything from the mold size, resin quantity and pressure pot size need to be taken into account.

26 Casting Tools Pressure Pot Toaster Oven Wire Brush Mold Chuck/Faceplate Mixing Paddle Pigment Spoon Measuring Spoons Cordless Drill Bandsaw/Tablesaw Wax Paper Masking tape Oven Thermometer Timer Air Compressor CA Glue Accelerator Tape Measure/Rule

27 Casting Tools Pencil Compass Mixing Cups Paper Towels Latex Gloves Turning Tools Sanding Medium Log Book Drop Sheet Acetone Aluminum Foil Level

28 Post Casting Cleaning as soon as your cast is under pressure, wipe down the mixing paddle or spoon. Check your work area to make sure that no resin spillage remains. Dispose of the latex gloves, paper towels and mixing container. Acetone will help remove any resin that is spilled. Wear appropriate gloves, a respirator and safety glasses.

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48 Lets Cast a Project

49 Casting Process 1. Prepare and dry the core material. 0% moisture is optimum. 2. Does the core material require stabilization? 3. Prepare the mold for the core material to be cast and determine what mold design will be used. 4. Determine the amount of resin that will be required to perform the cast. 5. Determine what resin will be used, what dyes, pigments and/or paint will be used. 6. Which recipe will be used to cast the resin? New or old? 7. Is your Casting Log Book filled out? 8. Place the core into the mold and secure it. Place into pressure pot and level mold. 9. Prepare the pressure pot for casting. Is the pressure pot level? Is the Pressure regulator set to the proper pressure? Is the baffle plate ready? Is there any pressurized air in the compressor and is there enough to charge the pressure pot? 10. Prepare the resin for casting. Which resin will be used? Are both parts A & B on hand? Is the dye on hand? Is the pigment on hand? Is the oil based paint on hand? Is the cordless drill ready and fully charged with a spare battery? Is the spoon and paddle ready? Is the digital scale ready and set to grams? Latex gloves ready? Paper towels ready? Is a disposable work surface laid out to mix the resin upon? 11. Pour equal parts by weight (grams) A & B into the mixing cup. Mix resins until they are clear. Add dye/paint and mix until uniform throughout. Add pigment and mix until uniform throughout. 12. Pour resin mixture into mold cavity slowly and uniformly.

50 Casting Process 13. Place baffle plate into pressure pot without disturbing the mold from being level. 14. Place lid onto pressure pot and secure immediately. 15. Pressurize the regulator side of the system. Slowly open the valve and charge the pressure pot to psi. 16. Close the valve when the pressure pot regulator reaches the desired pressure. Disconnect the air line from the pressure pot. 17. Set the timer for 60 minutes. 18. Clean the mixing paddle and spoons free of resin and pigment. 19. Record your casting information in the Cast Log Book. 20. Go for Coffee.

51 Resources Alumilite Plastic World - * Some hobby shops will carry this. Epoxy Lee Valley - Artistic Wood and Tool Supply - Polyester Resin Plastic World - Michaels - Pigments Wyndham Art Supplies - Art and Craft Stores Paints Oil Based Hardware Stores