Introduction: Casting Rings - From Startup to Finish

Who has the budget for a customized, unique engagement ring? I certainly don't, especially being a college student. Heck, I had no idea how rings were even made. It wasn't until a friend of mine told me about how he designed his own engagement ring for his wife. This really intrigued me and so I started doing some research on how this process is done. Pretty soon I discovered how relatively easy it is to make your own ring (or any other small metal part) using materials from the hardware store, jewelry supply shops, and a few online vendors. So here I've put together a comprehensive step-by-step Instructable on how to put together all the tools necessary (and quite inexpensively) for casting rings.

I am not a professional jeweler, nor am I going to school to be one. I am a mechanical engineering student, which gives me many benefits and insights into building the tools necessary to make successful castings; however, no part of this process requires you to have an engineering degree, or any prior knowledge in making jewelry.

A FEW WORDS OF CAUTION:

1) SAFETY FIRST! There are a few steps involved in this project that can be dangerous, so use caution and common sense! I assume no responsibility for anyone injured by following my Instructable.

2) The material cost of all parts and consumables used in this project will be approximately the same as a decent engagement ring. However, you will then have all the tools needed to make more rings - so in the long run you will be ahead!

3) As I said, I am not a jeweler. I have not had training or much experience with jewelry making until beginning this project. There are many ways to go about making jewelry that I do not discuss in this Instructable. If you know of a better way to do something, feel free to deviate and experiment (but make sure to let me know how it works!).

Step 1: Some Background and Overview

The method that I have used is called the Lost Wax Investment Casting process and is probably the most common way that professional jewelry is made today. This process has 5 basic steps that are followed:

  1. Create a version of the part using a melting/burning material (such as wax or certain plastics).
  2. Place the part into a heat-resistant cementing material using sprue channels.
  3. Heat up the cemented mold such that the part melts/burns out through the sprue channel.
  4. Melt down the metal to be used and force the molten metal into the mold through the sprue opening.
  5. Cool the part down and clean as appropriate.

There are different ways and materials that can be used to perform each step; I will only be showing what is called the Centrifugal method (another popular method is the Vacuum method). This involves using a centrifuge to force the molten metal into the mold via centrifugal/centripetal (lets just call it centrifᵫtal to make everyone happy) forces.

Step 2: Making the Kiln, Part 1: Gathering Materials

The kiln that I built is based off of another Instructable by Wolfgar77. However, my kiln has a PID temperature controller which is used to regulate the temperature, allowing me to walk away and do other things while it is running.

Materials used:

  • Soft fire bricks, 9"x4.5"x3", 2600 degrees C (K26) (x7)
    • NOTE: these will make a chamber that has a cavity of 3"x4.5"x6". These dimensions can be adjusted to your needs by either slicing the bricks or by finding other sized bricks. Adjust the steps accordingly.
  • Angle iron (~10 ft.)
  • 5/16 coarse threaded rods (~12 ft.)
  • 5/16 coarse nuts (x18)
  • PID temperature controller
  • Type K thermocouple
  • Kanthal A1 heating coil (> 15" long)
  • Zinc plated or Aluminum sheet (x2, at least 9"x9" each)
  • Steel coat hanger
  • Steel "staples" or paperclips
  • Kaowool ceramic fire wool (1" thick, 6"x6", optional)
  • Small hinge (x2, optional)
  • Screws (optional)
  • Small deadbolt (optional)
  • Variable speed controller (optional)

Tools used:

  • A band saw, skill saw, miter saw, hack saw, etc. (whatever you have lying around)
  • Screwdriver
  • Wire cutters
  • Wire strippers
  • Hand router (a knife will work too, though a little messy)
  • Tin snips
  • String
  • Face mask

Step 3: Making the Kiln, Part 2: Heating Chamber

Steps to making the heating chamber:

  1. Take one of the fire bricks and cut it in 1/3. This will be used for the back. Caution: I am unsure about the health effects of breathing in particulates from these bricks. I know that they are asbestos free, but I would strongly recommend using a breath mask when cutting them.
  2. Take the Kanthal heating element and stretch it slightly so that the coils are not touching each other (see image). For a kiln of this size, you will want approximately 720 watt heater. To figure out the amount of coil needed, use Ohm's law for power: P = V*I = V^2/R, thus R = V^2/P. Since V = 120V (from a standard outlet) and P = 750W, R should be around 20 ohms. As a check, make sure that the current doesn't exceed the wall outlet's maximum (typically 10 amps). So, using Ohm's law again: V = I*R, thus I = V/R = 120/20 = 6 amps. This is perfectly fine.
  3. Take a multimeter and check the resistance from one end of the wire until you read just above 20 ohms. Cut the coil at this spot.
  4. Take the coat hanger and cut 2 sections that are about as long as the thickness of the back of the kiln. Take the rods and rap one in each end of the coil so that they are tight - these will be used to prevent the coil from overheating and breaking near the tips.
  5. Lay out the firebricks that make up the 2 sides and the back of the kiln. Take pieces of string and lie them down on the bricks in the approximate pattern that you want the heating coils to make. Be sure to include a groove in the sides that allow the coils to pop out the back. Pencil in the outline on the bricks and then use the router with a 1/4" bit (or just using a knife), cut out a groove following those lines to a depth of 1/4".
  6. Take the string that you used and lie them end on end. Stretch the heating coil so that it is about an inch longer than the total length of the string.
  7. Cut the angle iron into 4 sections 14" long and 2 sections 9" long. Also, cut the threaded rods into 8 10" long sections.
  8. Set the long angle iron on end to make 4 corners, then insert the 4 threaded rods apply nuts to hold the base together. Also, set the smaller angle iron pieces on opposite ends to make a base for setting the firebricks.
  9. Start placing the firebricks onto the stand. Put in the heating coil into the grooves.
  10. Take some steel paperclips and cut them in 2 so that they make 2 "U" shaped pins each. Use these to pin the heating element in place.
  11. Place the top firebricks on and insert the final 4 rods into the angle iron, nutting them in place.

Optional door:

  1. Take a 9"x9" piece of sheet metal and cut out the 1.5"x1.5" corners. Draw lines at 1/2" and 1" from the edges on the tabs (see images) - these will be your bending points.
  2. Bend along the lines with your fingers and a table edge until you have 2x 90degree bends on each side. Snip off a little bit if necessary to allow the edges to mesh better.
  3. Figure out the alignment of the door with respect to the kiln; make marks on the metal leg and on the door where the hinge screws should go. Remove the leg and drill holes at those points.
  4. Screw the hinges in using long wood screws for the kiln side, and use nuts and bolts to hold in the door side.
  5. Take the 1" thick, 6"x6" piece of Kaowool and insert it inside the door
  6. If you are making the bolt lock, then go ahead and screw it into the fire brick in the desired location. Then, drill a hole in the door where the bolt will go, making sure to keep it a tight fit.

Step 4: Making the Kiln, Part 3: Electronic Control

At this point, you will be working with wall voltages and decent currents, so make sure you consult someone with enough electronics know-how to be safe. For the most part, you will need to consult the electrical schematic for all the wiring steps. I've included a few pictures of the circuit that I made.

  1. Drill a hole in the back of the kiln just large enough to fit the thermocouple - angle it slightly downward and located near the top of the kiln. Slide the thermocouple in and check that it protrudes enough inside the kiln.
  2. Take the other piece of sheet metal and fold it as shown in the image above. You want the flat parts to be just wide enough to fit the PID controller when fully bent in place. Only bend half way at this point.
  3. At the flat section that will become the bottom, screw in the Solid State Relay. Make sure the the "+" & "-" terminals and not the "~" terminals are facing toward the location that the PID controller will be.
  4. Use the wire strippers and cut the power cord receptor end off. Cut off an additional 15" of the cord and completely strip this section. Strip only the end of the remaining cord.
  5. Using the schematic above, wire up all the wires. I found that the Green, White, and Black wires corresponded to "Ground", "Hot" and "Neutral" respectively on the prongs.
  6. Connect the thermocouple. At this point fold the sheet metal all the way to make a shell for the electronics and a fin that attaches to the kiln.
  7. After drilling holes into the sheet, mount it onto 2 of the protruding threaded rods on the kiln body. Fasten with additional nuts.
  8. Caution: Before testing the kiln, use a multimeter to check for any short circuits on the kiln.
  9. Plug in and test the temperature settings.

If there is no door on the kiln, a small block of fire brick can be used to block the chamber. Make sure to test the maximum temperature you are using before leaving to do other things. My kiln can easily get over 800 degrees Celsius!

Step 5: Making the Vacuum Chamber

Materials used:

  • 1/64th" thick steel plate, 8"x8"
  • Rubbergasket, 6"x6"
  • 1/2" thick block of wood, 8"x8"
  • 1/4" ID plastic tubing
  • 1/4" male NPT to 1/4" MIP 90 degree elbow
  • 1/4" FIP to 1/4" OD barb
  • 3/8" MIP to 1/4" OD barb
  • Vacuum pump (cheaper substitute: hydro aspirator)
  • Rubber cement
  • Hose clamps (x2)
  • Screws (x4)
  • Glass bell-jar (a sturdy Tupperware container could work too)
  • Gas sealant

Tools used:

  • Saw, skill saw, band saw, etc (whatever you have lying around)
  • Drill, drill bits, and screw driver
  • Caulk gun

Steps:

  1. Drill a hole about 1.5" from one edge of the steel plate large enough to be able to thread the elbow joint into.
  2. Thread the 90 degree elbow into the hole, using the National Pipe Thread (NPT) side until it protrudes less than the thickness of the wooden board. Attach the female barb to the other end.
  3. Caulk around the hole with the gas sealant. Rub with finger or object to get into the crevasses.
  4. Cut a rectangular notch into the wood to accept the barbed part. Set the plate onto the wood as shown.
  5. Cut a hole into the rubber gasket so that it lines up with the protruding threaded pipe on the top of the plate. Take rubber cement and apply it to the rubber gasket and then press the gasket onto the steel plate (keep pressure on it until it dries; it will want to curl). CAUTION: Rubber cement produces fumes that are not good to inhale - use proper ventilation when using it.
  6. Attach the MIP barb to the vacuum pump (or use a hydro aspirator) and then attach the plastic tubing to the barb on both the pump/aspirator and use the hose clamps to tighten the seal.
  7. Wet the edge of the bell-jar and set it onto the rubber gasket. Turn on the pump (or the water spigot for the hydro aspirator) and admire your new vacuum chamber! This chamber gets around 25 in Hg of vacuum depending on how well it is sealed.

Step 6: Creating Your Ring - 3D Print or Hand Carve?

There are really 2 different ways that you can make rings for casting:

  1. Wax working - The process of taking a wax blank and subtracting and/or adding wax to make the shape of the ring by hand. This is the traditional way and takes many years of experience to perfect.
  2. 3D Printing - With the revolution of the 3D printer, printing a ring is a great way to integrate complex geometries without too much effort or skill, as long as you are somewhat familiar with CAD (Computer Aided Design) software.

Because I am a mechanical engineering student and have access to both quality CAD software and 3D printers, and because I really suck at hand carving geometries more complicated than a simple band, I chose to go the second route. For those who are not engineers and are familiar with CAD, DON'T STRESS! You can still go this route if you are willing to spend a little time learning a new program. Also, with the rise of online 3D printing vendors, you just have to send them a digital file and they will send you a completed part.

For a CAD program, I ended up using Creo (formerly known as Pro/ENGINEER). Solidworks is another high-end program. If you are really into making rings with CAD, I've heard that Rhino has an add-on specifically for jewelers. If you are looking for some free software, try either DesignSpark Mechanical, Google SketchUp, or FreeCAD.

I had school access to a Stratasys Objet260 Connex (think big, expensive, high resolution printer). The resolution on this sucker is plenty for making nice, smooth geometries. However, because the resin used in this printer is not designed to be able to cleanly "burn-out" (more about this process later), this is not the ideal way to make a plastic ring. A great printer to get fantastic resolution AND compatible resin would be the Formlabs Form 1+ printer. This printer eliminates a difficult step in the casting process, making things much more streamlined. Plus, it is within the price range of hobbyists!

Designing and creating a ring is not what this Instructables is about (you can find plenty of resources online for help with this) so I've thrown a few images of how I've made some rings just to give an idea of the process.

Step 7: Optional Rubber Mold and Wax Injection (for Saving Your Design)

This is an optional step that can be done to save and assembly-line the process of making multiple copies. The reason why I used this step in my process was because I did not have easy access to a lost wax-compatible printer; all the rings I printed were of a material that had dirty burn-outs and didn't turn out so well. By converting to wax, I could get cleaner burn-outs. The ideal fix for me would be to get a 3D printer (like the Form 1+) which has compatible resin thus saving me from needing to do this step which is difficult for complex parts.

For traditional carvings, this is a pretty useful step since it helps to save your design in case you mess up later with the casting.

Materials needed:

  • 2-part liquid silicone (I found that Castaldo LiquiFast ICE worked well)
  • Aluminum bar (for the frame)
  • C-clamp
  • Acrylic (or metal, plastic) sheet (x2)
  • Wax
  • Heat source (ie: propane torch)
  • Metal air piston (for injector)
  • Barb attachment for injector (1/4" MIP)
  • Metal funnel
  • Container (for mixing and vacuuming)
  • Piece of rubber (such as from an eraser)
  • Baby powder

Tools used:

  • Lamp/light source
  • Table vice
  • Spoon
  • Vacuum chamber
  • Metal bender or vice
  • Spoon
  • Metal bottle opener
  • Scalpel

Steps:

  1. Using a metal bender or vice, take the aluminum bar and bend 2x 90 degree bends in it so that it forms a flattened "U" shape approximately wide and tall enough to fit the ring and sprue with some space (don't make it too tall or wide so that you don't waste a lot of liquid silicone). Glue a small block of rubber to the bottom inside of the bar.
  2. Take the ring and add a sprue in an acceptable location on the ring. Attach the other side of the sprue to the top of the rubber such that the sprue is vertical.
  3. Clamp the 2 sheets of acrylic to the open sides of the metal U using the C-clamp.
  4. Using the 2-part liquid silicone, mix equal parts into the mixing container (measure out the amount that you need to properly cover the ring but not so much that you will waste). There is about a 15 minute working time - I spent about 7 minutes stirring and 6 minutes getting the air bubbles out with the vacuum chamber. The rest of the time is needed to pour the liquid silicone into the mold casing. Do this by letting it run down the side of the container and not onto the ring. It may take a little while because of the viscosity of the silicone.
  5. Allow to sit for a few hours until it is properly cured. At that point you can remove it from the mold case.
  6. Clamp the metal bottle opener to a table so that it can be used as a 3rd hand for prying the mold open. With plenty of light, take the scalpel and start opening the mold by cutting around the edge in a way that will allow you to pull out the ring without damaging either the ring or the mold. There are a few online videos that show the basic process of opening the silicone mold.

Once the ring has been removed, setup the injection system. There are commercial versions of wax injectors that run hundreds of dollars, and other ways of making decent injection systems. However, I wanted to be minimalistic here, so I simply took an air cylinder from my local surplus store and used it as an injector:

  1. Invert the air piston onto the vice. With the barbed tip removed, place the metal funnel with scrap wax over the injection hole. Heat up the funnel and piston so that the wax melts and flows into the piston. Caution: This type of wax is not good for you to breath in - well ventilate the area and use a mask.
  2. While heating the piston, screw on the the barbed tip. This will act as the injector nozzle.
  3. Use a very small amount of baby powder on the inside surfaces of the rubber mold. This will help remove the wax part.
  4. Once the wax inside the piston is warm enough to flow easily, take the 2 sheets of acrylic that you used earlier and place the closed mold in between them. Using your fingers to keep the mold together, place the hole over the injector nozzle. With a fair amount of force, push the piston so that the wax flows into the mold. Do this for about 4 seconds. Then allow the mold to cool for about 30 seconds.
  5. Remove the wax part carefully and check for defects. Inject again if necessary.

Step 8: Investing Your Ring

Now it is time to begin turning your wax ring into metal! What you will need:

  • Flame/heat source (such as an alcohol lamp)
  • Flask (I use a 2.5" diameter steel flask)
  • Rubber sprue bottom (sized to flask)
  • Fine metal tool
  • Dish soap (for debubbleizer)
  • Hydrogen Peroxide (for debubbleizer)
  • Cotton Swab
  • Balance/scale
  • Investment compound
  • Gas mask
  • Spoon
  • Timer
  • Water
  • Measuring cup
  • Vacuum chamber
  • Tape
  • Mixing cup

Steps:

  1. Attach a small sprue to your ring. Do this by taking a small rod of wax and fusing it onto the ring in a non-critical location. Use multiple sprues if necessary for larger and more complex parts.
  2. Measure the mass of the wax and sprue. Record this number down somewhere for future reference. You will need to measure out your metal based on this quantity.
  3. Affix the sprue and ring to the rubber sprue base. Keep the sprue as straight up and down as possible.
  4. Using a 50/50 mixture of Hydrogen Peroxide and Dish soap, apply generously to the wax ring (cotton swab is useful here). Allow to dry for about 10 minutes. This is the "debubbleizer" which prevents air bubbles from forming in the investment compound and ruining the part. After it drys, dunk in water to remove excess residue and to check for any bubble formation. Repeat as necessary until bubbles no longer form on part.
  5. Attach the sprue base to the flask. Apply a ring of tape to the top edge of the flask to prevent spilling.
  6. Using a measuring cup, measure out the amount of water you will need for mixing with the investment. Do this based on the manufacturer specifications of the powder you use. For my powder and flask size, I needed 100 ml of water with 150 g of investment. Keep a little bit of water on the side for fine tuning the mixture.
  7. Put on your mask! At this point you will be working with investment, which contains silica. You REALLY don't want to breath this in (it would be like sanding down your lungs and destroying them over time!).
  8. Using a balance, measure out the amount of investment you need into the mixing cup.
  9. Add the water to the investment and start the timer. There is an 8 minute working window - don't go over. Here is the suggested process for the powder I use:
    • 3.5 minutes mixing by hand in the cup. You want the mixture to be thin enough to be able to pour into the flask and surround the details of the ring, but not too thin. Fine-tune by adding bits of water or investment.
    • 1.5 minutes degassing the investment (in the cup) under vacuum. This will help remove air trapped in the investment. Shaking/vibrating the chamber a little can be done to improve results.
    • Pour the investment into the flask, running it down the inside and not over the ring (you don't want to knock it out of alignment).
    • Remaining time is used degassing the investment (in the flask) under vacuum. Shaking/vibrating the chamber a little can improve results.
    • At the 8 minute mark, put the flask in a convenient location to sit for 2 hours and harden.

Step 9: Casting of the Ring

Materials needed:

  • Centrifugal caster
  • Centrifuge crucible
  • Slab of wood
  • Large cardboard box
  • Dual-gas torch - combines oxygen and MAP/propane
  • Oxygen canister
  • MAP/propane canister
  • Tongs
  • Borax
  • Carbon rod
  • Metal to cast (Zinc, Silver, Gold, etc)
  • Balance/scale
  • Bucket of water
  • Kiln
  • Fire resistant gloves
  • Screws

Tools used:

  • Drill with screwdriver
  • Cinder blocks (optional)
  • Safety glasses

Steps:

  1. To prepare the centrifuge and keep it safe to use, take the wood sheet and screw the centrifuge to the center. Use the cardboard box to create a barrier around the centrifuge to block any flying objects from escaping without impeding the centrifuge motion (the more enclosed it is, the safer). Affix with glue/caulk.
  2. Measure out the amount of metal you need. For converting from wax, take the mass of the wax and multiply by ratio of densities between the wax and the metal (for Sterling, the ratio is about 10.4) then add a little extra to make sure there is enough (some might fly off, not go into the mold, burn off, etc).
  3. Balance the centrifuge out with the metal and flask (without rubber base) in place. This will help prevent molten metal from flying everywhere (as I incidentally found out) and give a better cast.
  4. Take the flask and place it into the kiln so that the hole is facing down. Turn on the kiln and begin the burnout process. Based on my experience, the investment I use, and the suggestions by bcyrjewelry, this is what I do:
    • 1 hour at 150 degrees C
    • 1 hour at 370 degrees C
    • 2 hours at 700 degrees C
    • 1 hour at casting temp (550 degrees C for Sterling)

    What this does is both allow the wax to "burn-out"/melt-out of the flask and also heat treats the investment so that it is much stronger. Once you are about ready to pull it out of the kiln, begin setting up the centrifuge.

  5. Wind up the centrifuge to its maximum number of turns. Use the locking mechanism (mine had a pin) to keep it wound.
  6. Start heating up the centrifuge crucible without any metal inside - this will help significantly with melting. Caution: Oxygen + Propane flame is HOT! Using MAP + Oxygen is REALLY HOT! Use common sense and get help if needed when using the torch. Be safe (tip: never start the flame with the oxygen on). You want a relatively "reducing" flame (one that is oxygen deficient) when working.
  7. Once the crucible is warmed up, add your metal. Heat up until the metal starts to glow red (such as for Sterling) then add a small pinch of borax powder. This will help prevent too much oxidation of the metal. Keep heating the metal and stir with the carbon rod to distribute heat. Note: for Sterling, any green flame is Copper being burned away - try to avoid too much of this.
  8. Hopefully the kiln is near by and you can quickly grab the flask and put it into the centrifuge while still heating up the metal. Use help if needed.
  9. Once the metal melts down, keep heating for about 30 more seconds. Then, release the mechanism and let it spin! Caution: Be safe at this point - expect metal to fly off, so wear safety glasses and make sure your barrier is in place to stop flying objects.
  10. Allow the centrifuge to slow down to a relative stop. Pull out the flask without inverting it. Let it cool until you can no longer see any red glow from the protruding metal, then take the flask and dunk it in the bucket of water, shaking back and forth. The ring will fall out to the bottom. Once cooled, go ahead and pick out the ring and flask and clean them off. A dark grey oxidation layer is common and can be removed easily in the next section.

Step 10: Cleaning and Finishing

Materials needed:

  • Mini Crock-Pot
  • Sparex
  • Ultrasonic cleaner
  • Water
  • Plastic fork
  • Small metal pick
  • Mini grinder with flex shaft
  • Disk cutter for flex shaft
  • Buffing compound
  • Buffing wheel/brushes for grinder and flex shaft
  • Tumbler (optional)
  • Dish soap (optional)
  • Burnishing compound (optional)
  • Metal shot (optional)

The first thing you need to do after casting is to clean off the excess investment from the ring. Start by using a small pick to get chunks out. Then, run the ring through an ultrasonic cleaner to get the finer chunks removed. After that, take the Crock-Pot and heat up some water, adding a small amount of Sparex. Don't touch the sparex or solution with your bare hands. This creates a "pickling" solution which helps to remove oxidation from the surface of the ring. Allow the ring to sit in the solution for a couple hours to remove any final oxidation. When you pull it out, use a plastic (not metal) fork. At this point you should have a white coating over the ring that can be removed by using a coarse brush attachment on the mini grinder. Once you get all the white compound off you can begin to use the buffing compounds and buffing wheels to polish the metal to the desired luster.

As an optional step the rings can be burnished (a type of polishing) using either a homemade tumbler, or one that was purchased. The burnishing process is performed by pieces of metal shot rolling over the piece of jewelry and therefore both work hardening and removing many of the minor defects.

  1. Fill the container with shot until the bottom is just covered.
  2. Fill the container with water until the shot is just covered.
  3. Add either a pinch of burnishing compound or a single drop of dish soap.
  4. Place the rings in the container and close it up.
  5. Run for somewhere between 2 hours and overnight (depending on how much is needed) making sure to replace the water every 2 hours

Do any final polishing at this point.

For the engagement ring I made, I ended up going to a professional jeweler and having them set the amethysts and diamond - I didn't feel comfortable with my skill level making sure the diamond didn't fall out. However, for less expensive stones, I could certainly set them myself. This is a whole art in of itself.

Step 11: Tips and Tricks

Helpful suggestions:

  • Clean and dry the flask right away after quenching - it will be easier and you will prevent rust from forming
  • Balance the centrifuge before putting the flask in the oven. Use the metal that you will be melting down as well.
  • Oxygen tanks will run out quickly (around 20 minutes of use) - keep a few stockpiled
  • Start off using Zinc - it is much cheaper and easier to melt than silver. Zinc is the primary metal in newer pennies
  • Only add a little bit of Sparex to the hot water for pickling (not the whole container)
  • Make thicker and longer stone setting prongs than what you think you need - they can always be cut down and filed

Things I would do different/add:

  • Add a handle to the kiln door that won't be hot to the touch
  • Make the safety shield around the centrifuge a little taller
  • Add a relief valve to the vacuum pump to quickly remove the lid
  • Use a 3D printer with compatible resin for lost wax casting - this removes the need to convert to wax and the risk of dirty casting
  • Purchase a better quality torch

Cheap-scape substitutes:

  • Instead of using a centrifuge, you could make a sling that you place the flask in and attach it to a long piece of string/cable. Melt down the metal over the hole of the flask and then swing the flask around really fast to get the centrifugal force
  • I've occasionally cut the kiln time from 5 hours to 3.5 hours total and had some decent castings
  • Use Zinc instead of Silver or Gold
  • For the Tumbler, you can take a plastic bottle, cut a hole in the bottom, glue a screw through it, and attach it to a drill in a vice to get the tumbling motion.
  • You can use propane instead of MAP - lasts, like, forever, but doesn't burn as hot

Let me know if you have any suggestions, tips, questions, answers, or if you made any rings yourself. Good luck!

Oh, and she said YES!!!

Comments

author
ErginM1 made it!(author)2017-04-24

You can use Load3D.com for silver and gold 3D printing from STL file, it is possible to calculate the price online.

author
bchas made it!(author)2017-01-08

Hi-thanks for the great instructable!

Im assuming I can use your electronics setup to control my present kiln- it seems by wiring the heating element to #2 as in your diagram. Would this be correct?

Thanks

author
jandyk made it!(author)2016-05-13

Hi Sure Hacksalot, I flatter you and Wolfgar77 by copying your kiln nearly identically, with help from Dudley of Joppa Glass-except I can't get my MYPIN TA controller to set higher than 1200 deg. Any tips? A smarter guy than me might hack into it. I want 2000 deg.for the satin cast investment, and other stuff. I really dig your inspirational instructable-it's been a fun challenge, 1 more hurdle.

author
der1311 made it!(author)2016-10-22

I have the same PID. To change the temp limit hold down the up and down arrows at the same time for 5 seconds. This will get you to another menu beside the regular set menu. Push set to get to USP and hit the m button to change from 1200 to whatever temp you want(I set my limit to 2500F). Hold set for 3 seconds and you're good to go.

author
Sure+Hacksalot made it!(author)2016-05-18

Hi jandyk,

I am so glad that you found our instructables useful! I took a quick peek at the MYPIN TA controller you are talking about and it looks like the upper limit is the 1200 you mentioned. The main reason why most controllers only go up to 1200 degrees F is because typical heating elements cannot go much higher without burning up.

The first thing I would suggest is make sure that your heating element can handle the temperature you are looking for. If not, then try to find one OR you may need to use a different method of heating (such as using a furnace/forge). If all you need to do is reach 2000 degrees without much concern for stability, long duration, or "ramping" the temp, then I might suggest using a fuel source (charcoal, propane, etc) with a simple high temperature gauge near your work piece and keep an eye on it.

Hope that helps!

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PhoebeJ made it!(author)2016-01-18

hi! do you know of any way to build a full vacuum casting unit? the vacuum chamber is great but I'm looking for a way to make the suction portion of a vacuum castor. any help would be much appreciated!

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Sure+Hacksalot made it!(author)2016-01-24

Hi. I have actually considered going this route for future projects. I think you could take the vacuum chamber and place the cast over the suction hole. Give that a try.

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zkaminski1 made it!(author)2016-01-14

This instructable is incredible. The level of detail and documentation is fantastic. I'm also an engineer and hope to try it someday! :)

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JarcelynD made it!(author)2016-01-08

Hi

I am in the process of building this type of kiln. I am only stuck at the wiring. I have a Ta4 RNR nor SSR. Would this even matter??!?!?!

here is the exact one i have: http://www.ebay.com/itm/New-Digital-PID-Temperatu...

Im trying to figure out how to hook up the heat element.

Currently I have the power cord hooked to the PID terminals 1 and 2

The TC is hooked to PID terminals 7 and 8 and i have the SSR hooked to PID terminals 3 and 4.

The SSR i have is the SSR-25AA:

http://www.amazon.com/Temperature-Contoller-Termin...

Hopeufully you still check this please help!!

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Sure+Hacksalot made it!(author)2016-01-08

Hi Jarcelyn! I'm very glad you've found this useful - I'll see if I can help answer your question. The PID controller and the SSR look nearly identical to what I have, and from what you described it sounds like everything's hooked up correctly so far. The most helpful part of this instructable for you will be the electrical sketch I put together in the 3rd kiln section. Basically, the SSR is just a bit "switch" which can handle a lot of current and be controlled by the PID. So, imagine that you want to use a light switch to turn on and off the kiln coils. What you would do is connect the wires across the switch such that when the switch is on, then current flows through the switch and heating coils, and vice versa. The SSR is the switch, so wire the circuit across that.
I hope that helps!

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JarcelynD made it!(author)2016-01-09

Hi thank you for your response!!! Where is this 3rd kiln section?!?! are you talking about the steps?!?! I have a SSR 25AA would this matter?!?! I see a lot of ppl have SSR 25 DA. this is my main hang up in moving foward. So the element wire should connect to SSR terminals 1 and 2?? Please point me in the direction of this 3rd kiln section thank you!!

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Sure+Hacksalot made it!(author)2016-01-10

Hey again. The section I'm reffering to is page 4 titled "Making the Kiln, part 3: electronic controls". There is a picture of the electronics. As for your SSR, it sounds like it would be fine, but make sure to read the spec sheet.

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JarcelynD made it!(author)2016-01-12

oh WWOOOOWWWW! I didn't know there was more pictures (a lot more matter of fact Im new to instructables) BUT THANK YOU THANK if this dont work i think the ssr is bust and im just going to buy another one thanx

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Rimwulf made it!(author)2015-11-21

I saw this years ago, how are two doing now?

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Sure+Hacksalot made it!(author)2016-01-08

Hi! Sorry for not responding sooner, life has been very busy these last few months. We are doing great! We were able to get married in July, and I was able to make both of our wedding rings (I`ll try to upload some pics). Within a month of the wedding I graduated school, we moved to a different state, got our first house, I started a new job, she started grad school and a new job...yeah, crazy! Thanks for asking!

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Sure+Hacksalot made it!(author)2016-01-08

Hi! Sorry for not responding sooner, life has been very busy these last few months. We are doing great! We were able to get married in July, and I was able to make both of our wedding rings (I`ll try to upload some pics). Within a month of the wedding I graduated school, we moved to a different state, got our first house, I started a new job, she started grad school and a new job...yeah, crazy! Thanks for asking!

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Sure+Hacksalot made it!(author)2016-01-08

Hi! Sorry for not responding sooner, life has been very busy these last few months. We are doing great! We were able to get married in July, and I was able to make both of our wedding rings (I`ll try to upload some pics). Within a month of the wedding I graduated school, we moved to a different state, got our first house, I started a new job, she started grad school and a new job...yeah, crazy! Thanks for asking!

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verticalvic made it!(author)2015-07-01

Whats the rating for your thermocouple?

Thanks

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Sure+Hacksalot made it!(author)2015-08-25

Hi. My thermocouple is a type K (rated up to 1350 C).

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snipperdoodle made it!(author)2015-03-17

So glad I found this. I've been doing this same (nearly) exact thing over the past year. I successfully cast an engagement ring (she said yes!) and now I'm about to work on the wedding bands.

The thing I'm having the most trouble with is melting the metal (copper for now). I didn't get into the whole "dual gas torch" thing because playing around with oxygen and propane seemed pretty dangerous for someone who knows very little about how to use both. So instead of that, I made a mini forge out of a big coffee can and Kaowool and used a propane torch to heat it up. The only problem with this is that it takes 10-20 minutes for it to get hot enough to melt and sometimes (and I haven't figured out why yet) it just doesn't get hot enough and I can't cast. I've thought about just remaking the whole forge but I see that you didn't seem to have an issue with melting the metal. Maybe that's because you've just been using zinc but if there's a chance I could bypass the forge, that would be great.

SO, what torch would you suggest when using a dual gas system? Or do you have any suggestions?

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cheG1 made it!(author)2015-05-02

A before O or up you go. don't fear the process, respect it. If you use oxygen you can achieve a higher temperature. The better your insulation, the less your heat loss, the higher the temperature - however some work space are just not practical. Thermal mass - the amount of material you are trying to melt. If your insulated space is inefficient and/or your heat source this equates to the time it takes to melt a smaller piece versus the nearly exhausting time for a larger amount. This too is equatable to the mass/density to melting point of material. (you'll melt more copper easier than gold but you evaporate gold leaf before you come near melting a copper nail)

covalent bonds - Propane has one it only gets so hot 1,995 C(3,623 °F) because of this, added pure oxygen 2,820 °C(5,110 °F) or not. Acetylene has three covalent bonds it can get very very hot(3160 °C, 6200 °F) especially in an oxygen enriched environment . mapp gas is only slightly hotter than propane 2,020 °C (3,670 °F) and 2925 °C (5300 °F) in pure oxygen remember light the acetylene(or any other fuel/gas) first then turn on the oxygen. I know twentyfive degrees doesn't seem like much but these numbers are their top ranges under optional condition and 25 degrees can be the tipping point. and often you don't want an oxygen rich environment.

Propane performs very poorly in reduction. (all fuels do) The mixture of gases in Mapp allows it an advantage over propane in reduction and of course Acetylene performs even better

fluxes - why on earth would you not use them??! Borax 20 mule team in your local shopping store for no more than $7 in north america you get 2 kg and all you need is one table spoon to change your world. How much money are you wasting on fuel? There are many many fluxes, Borax does duel duty here as mention in the original post. use it. research other fluxes as needed they are your friends, and when they play well together they form an eutectic which makes all the difference.

hope this helps.

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JuliaS4 made it!(author)2015-03-16

Very nice instructable!

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meat_chris made it!(author)2015-03-15

Hi, I've bought all the parts you listed, but in part 4 step 3, you mention a solid state relay. It's not listed elsewhere. Is it the optional variable speed controller you mention the materials list?

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Sure+Hacksalot made it!(author)2015-01-28

Thanks for all the votes and views! I made it as a finalist into one of the 3D printer contests!

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kattje made it!(author)2015-01-04

One thing I would like to caution everyone on: Wear a mask while cutting the brick as well! Most firebricks, to my knowledge, also contain silica, which it something you really don't want to breathe in. Look up silicosis if you want to know the worst case scenario. In any case, you really don't want to be breathing in the particulate.

Do it outside or in a workshop with PLENTY of strong ventilation, and if possible, vacuum up the dust with a HEPA vacuum, as to avoid spraying the dust throughout your work area. If you don't have a HEPA vacuum, simply sweep up and throw in the bin! :)

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Apolo8 made it!(author)2014-12-24

Great instructable
Voted, Of course

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brianhunt made it!(author)2014-12-21

This is an excellent instructable. I have been making Jewelry as a hobby and doing my own castings since College in the 80's. I love the fact you included plans for a small kiln. I have also seen plans in a book I have for making your own centrifuge out of a 2x4, a shaft and a spring that you use with a store bought crucible. A vacuum chamber is a really nice way to get all of the bubbles out of your casting but you can also go with a vibratory unit as well which is what I use since I have not invested in a vacuum pump. The only thing you might have missed on this would be cutting your own stones. Really nice job. :)

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OceanLady made it!(author)2014-12-16

You really should edit that title to somehow include "DIY kiln and debubbler". I think you'll get a lot more views.

I'm a jeweller, so I clicked on your link mostly out of curiosity and to see if I could offer any tips, because I've done a lot of casting myself, but now I'm sharing this with everyone I think might find it useful just for the kiln and debubbler instructions.

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TobiasL made it!(author)2014-12-13

Hello :) What is the AWG/Gauge of the Kanthal wire?

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Sure+Hacksalot made it!(author)2014-12-13

The description doesn't say (I would estimate about 22 gauge). If you get a similar coil, all you need to do is go through the resistance calculations that I used to determine the length you need. Here's the one I bought.

Kanthal.PNG
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TobiasL made it!(author)2014-12-13

Thank you :)

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rick.pihl.3 made it!(author)2014-12-12

Sure Hacksalot - I know someone at Crossroads who works for or owns a 3D printing company in Hastings. You may know him. We'll talk soon I'm sure.

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ThirdDimensionJ made it!(author)2014-12-11

While I especially admire someone learning how to do this (and on a budget, at that) might it not have been simpler to draw the design you had in mind, find someone to 3D model it (plenty of people out there) and get it 3D Printed? Next take it to a jeweller and choose your stones to insert... Just a thought, but well done, anyway.

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Sure+Hacksalot made it!(author)2014-12-11

That is exactly what I did! I guess great minds think alike. As a mechanical engineer I have some know-how in CAD, so after drawing it up on paper (with the stone sizes I wanted) I went to Creo and modeled it up. Since my school has some really nice 3D printers, I was able to print it there. After that, it was to the casting machine. As I said in the 'ible, I did have a jeweler set the stones since I didn't want to worry about the diamond falling out.

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Porda made it!(author)2014-12-11

Great instructable! I've been looking into casting from 3D printed parts, and this has given me some great insight.

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Sure+Hacksalot made it!(author)2014-12-11

Glad to hear that you'll use it! Depending on the final quality you want, you can just use the PLA you print instead of the wax - I wanted a cleaner burn-out so I did the extra step of converting to wax.

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emilyvanleemput made it!(author)2014-12-11

It turned out absolutely gorgeous!!

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Antzy+Carmasaic made it!(author)2014-12-09

A very detailed and informative instructable. I recently had the opportunity to tour the workshop of a big jewellery company and your process was pretty much the same except it's all done with kickass self made tools.

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Sure+Hacksalot made it!(author)2014-12-10

Glad you liked it! I tried to keep things similar but on a smaller, cheaper scale to that of industry.

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LeadDreamer made it!(author)2014-12-09

FYI - the "white coating" after pickling isn't really a coating - it's the raised silver grain, which tends to make it look white - when jewelers use a brass brush, they are actually burnishing - rubbing down the grain, not removing it. Same effect with the tumbler - it's burnishing the metal.

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Sure+Hacksalot made it!(author)2014-12-09

Great to know! Thanks. I'll have to look a little closer once I pickle my next ring.

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LeadDreamer made it!(author)2014-12-09

FYI, burnishing tools can be as simple as the back of a small spoon...

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Sure+Hacksalot made it!(author)2014-12-09

Neat thought! Much cheaper than the $25+ burnishing tool at the store.

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Perspective+Image made it!(author)2014-12-09

This a really thorough and well thought out instructable! Great job and really good instruction about all the steps involved with lost wax casting. Thanks for being so diligent and sharing this!

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katwerre made it!(author)2014-12-08

This is excellent! I love how organized and meticulous you are. Since you are so handy, I agree with dangerous dan that you could make a table to use vacuum assisted which has less potential flying metal and works very well. If you want more info on how we made ours, I would be happy to share.

You did a fantastic job and I hope you win the printer!

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Sure+Hacksalot made it!(author)2014-12-09

I actually am curious what you ended up doing to keep the flask from burning/melting the rubber of the vacuum chamber - did you use a special rubber, have some sort of metal stand, or some other technique to keep a good seal on the flask?

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Sure+Hacksalot made it!(author)2014-12-08

Thanks! I really appreciated your 'ible on the pendant. Really clean and well made!

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ByDesign808 made it!(author)2014-12-08

The Form 1 or +, does not have the resolution to meet the demands of serious jewelry manufacturing. 300 microns X/Y, is not accurate enough. The X/Y resolution, needs to be 60 microns or less (under 40 microns preferably). Nice Ring, all the same...

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jproffer made it!(author)2014-12-08

what are you talking about? Form1 can do 25 microns.

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Sure+Hacksalot made it!(author)2014-12-09

The Form 1+ has a 25 micron Z-axis resolution (vertically) but only a 300 micron X- & Y-axis resolution (laterally and horizontally).

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Bio: I'm a Mechanical Engineering masters student at the University of Minnesota who loves anything DIY.
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