Day 25 Casting Defects Pits and Porosity

If you haven’t casted your own jewelry, or sent waxes (or CAD Files) off to someone to cast them for you, here is a tip and a quick check to save you cleanup time in the metal. There is nothing more frustration than finishing a casted piece and finding pits and porosity that you have to either solder to fill pits, or have them laser-filled. There are many types of porosity, from bad sprue/gate design or placement, shrinkage porosity, gas porosity, etc. but the easiest to avoid we will cover today. (A sprue or gate is the way the metal gets into the piece of jewelry during casting.)

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The easiest way to avoid casting defects is to pay attention to the sprueing or gating of your piece in wax or the model. Sprueing/Gating can be a complicated subject, and can take a long time to get a grasp on the technical end of it, but I will give you a couple of quick tips to get you understanding why it is important.

First, if you are adding a sprue to a piece that you are molding, or a wax you are casting, add the sprue to the thickest part of the piece and use a sprue that, as a rule of thumb, is 1.5 times thicker the area you are adding the sprue to. (For example, if you are adding a sprue to a ring, and the ring has a shank that is 2mm thick and 4mm wide, use a sprue that is approx. 3mm thick (2mm x 1.5)

Now for the easiest way to avoid a defect in the casting. Pay special attention to the joint, or union of the sprue, and the piece of jewelry. If there is not a good complete union, like a pit or a sharp edge, in the solder or wax joint, this will cause pits in your castings. Let me show you how:

Bad Wax 01 Bad tree

Bad gate 02 Bad gate 01

In the casting process, the wax is surrounded by investment, similar to Plaster of Paris, for the “burnout” or elimination of the wax. If there is a divot, pit, or sharp edge in either the union of either the sprue-to-jewelry, or the piece to the casting base, (tree) then during the casting process, when there is molten metal flowing through the casting flask, the metal flowing at a high speed and pressure will hit the little investment defect and break it off, and the piece of investment will float around in the metal and end up as a void or defect in the metal, resulting in a pit.

porosity 02 porosity 01

A little care and attention to the union of the wax to the tree, or sprue to the wax will prevent these kind of defects in your castings. I know this is kind of complicated, but I hope I explained it in a way that makes it understandable. I also hope the images help to explain. If it is still unclear, go ahead and post a comment and I will try to answer your questions.

Also if you have a subject you would like me to cover, comment here or on Facebook (JewelryMonk).

Take Care and have a great day! Now go make something shiny!

Doug

Day 24 Aluminum Sanding Sticks

Making tools again today. To get a nice flat surface or a clean edge, a sanding stick works really well. I have used wooden sanding sticks and plastic sanding sticks before, but truthfully, I like a good aluminum one because it just feels a little more substantial in my hand, it remains flat and true, doesn’t bend like a plastic one, and it doesn’t “grove” like wooden ones can. Today I will show you how to make your own aluminum sanding sticks that will last you forever.

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All you will need is a trip to the hardware store, (or online) buy Aluminum Flat Bar that is 1/8″ x 3/4″ in a length that will be long enough to make as many sticks as you want. I have 2 of them for 2 different grits of sandpaper. The sticks are 12″ long (1 foot). You will also want to buy some sheets of Wetordry Sandpaper. I use 400 Grit and 600 Grit, but you can use the grit you want. I have used 320 grit and 1000 grit as well, but found out I didn’t use them very much. The 320 grit was similar to my #4 Flat Hand File, and the 1000 was a bit too fine, and I found I could polish after the 600 grit sandpaper.

Sanding Stick (1)

Place the sandpaper face down and place the aluminum stick along the edge and “score” or scratch a line along the edge, just hard enough to leave a mark in the paper but not all the way through the paper. After you score the line, bend the paper over to make the scored line nice and sharp. Fold over and continue. You could do this if you like your edges sharp, or you could just wrap the sandpaper around the aluminum stick. I make about 3 complete wraps, then trim off the excess with a Surgical Blade in a  Scalpel Handle.

Sanding Stick (2) Sanding Stick (3)

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After I trim the sandpaper, I wrap the end with Masking Tape to hold it in place and write the number of the sandpaper on the tape, so I can identify it quickly. (4 = 400, 6 = 600)

Sanding Stick (5)

Again, the reason I like the aluminum is because it is light weight, inexpensive to make, long-lasting, won’t mark, grove or bend, and substantial feeling in my hand.

Sanding Stick (6) Sanding Stick (7)

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Thanks for stopping by today, I hope my tool “Geekiness” is not boring you.

Enjoy your day and go make something outrageously beautiful!

Doug

Day 24 Aluminum Sanding Sticks

Making tools again today. To get a nice flat surface or a clean edge, a sanding stick works really well. I have used wooden sanding sticks and plastic sanding sticks before, but truthfully, I like a good aluminum one because it just feels a little more substantial in my hand, it remains flat and true, doesn’t bend like a plastic one, and it doesn’t “grove” like wooden ones can. Today I will show you how to make your own aluminum sanding sticks that will last you forever.

Sanding Sticks Header

All you will need is a trip to the hardware store, (or online) buy Aluminum Flat Bar that is 1/8″ x 3/4″ in a length that will be long enough to make as many sticks as you want. I have 2 of them for 2 different grits of sandpaper. The sticks are 12″ long (1 foot). You will also want to buy some sheets of Wetordry Sandpaper. I use 400 Grit and 600 Grit, but you can use the grit you want. I have used 320 grit and 1000 grit as well, but found out I didn’t use them very much. The 320 grit was similar to my #4 Flat Hand File, and the 1000 was a bit too fine, and I found I could polish after the 600 grit sandpaper.

Sanding Stick (1)

Place the sandpaper face down and place the aluminum stick along the edge and “score” or scratch a line along the edge, just hard enough to leave a mark in the paper but not all the way through the paper. After you score the line, bend the paper over to make the scored line nice and sharp. Fold over and continue. You could do this if you like your edges sharp, or you could just wrap the sandpaper around the aluminum stick. I make about 3 complete wraps, then trim off the excess with a Surgical Blade in a  Scalpel Handle.

Sanding Stick (2) Sanding Stick (3)

Sanding Stick (4)

After I trim the sandpaper, I wrap the end with Masking Tape to hold it in place and write the number of the sandpaper on the tape, so I can identify it quickly. (4 = 400, 6 = 600)

Sanding Stick (5)

Again, the reason I like the aluminum is because it is light weight, inexpensive to make, long-lasting, won’t mark, grove or bend, and substantial feeling in my hand.

Sanding Stick (6) Sanding Stick (7)

Sanding Stick (8)

Thanks for stopping by today, I hope my tool “Geekiness” is not boring you.

Enjoy your day and go make something outrageously beautiful!

Doug

Day 23 Contrasting Jewelry Textures (part 2)

Day 23…. I mentioned yesterday that I really like contrasting textures, and I do. For some reason, contrasts really appeal to me, whether it is textures, colors, metals,….. even in nature I am attracted to things that have a strong contrasting edge. I showed you yesterday how I use my Electric Vibratory Engraver. It works wonderful at giving a matte or satin finish, and is quick. A good contrasting finish is sometimes better than a good shiny polish.

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Today I will add a twist to the Electric Vibratory Engraver by adding a diamond bit. On Day 13 of this journey, I showed you how to bezel set or tube set a stone and now we will do something similar, just with a twist, we will be setting it upside down. What WHAT??? Yes, upside down.

I use a piece of brass rod (2.35 mm), I file it flat and drill a pilot hole in the end with a bit about 1.4mm. In this instance I am using a stone that is 1.75mm. You can use different sized stones if you like, this is just one I had that was chipped on the girdle. (a good use for chipped stones) Any size diamond will work as long as the “culet” or bottom point of the stone is in good shape.

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Use a 1.70mm Hart Bur to cut the seat for the stone, and use a Cylinder Bur (1.40mm or so) to clean the bezel walls and flatten the bottom of the seat so it makes good flat contact with the stone after it is set upside down. Place the stone in the setting, top side down and make sure that the top of the bezel is just barely over the girdle. You want the stone to be exposed as much as possible, if the bezel is too tall, just file it down a bit. Set the stone by pressing the bezel over with a Flat, Square Prong Pusher.

Texturing (14) Texturing (15)

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Now that the stone is set into the brass rod, trim the brass to approximately one inch total length, (trim to how ever you feel comfortable 3/4″ to 1″) use a small flat screw driver to remove the screw that holds the bit that is in the engraver and insert the piece you just made. The new tool is smaller in diameter than the hole it fits into, but once the screw is tightened, it holds firmly.

Now just turn on the engraver and rub over the area that you want textured. I try to keep the back and forth motion going in the same direction to make the look of the texture uniform. Be careful though since the movement of the engraver is an up and down motion, (like a small jackhammer) and if you touch an area that you do not want textured, it will leave small little divots or pits. The texture from the diamond bit tool is much shinier and brighter than the steel tool. It will reflect the light like a diamond wheeled surface and catch the light and look like itty bitty diamonds are set in the surface of the metal. The images I took do not do justice to the actual look of the piece.

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Texturing (2) Texturing Finished

Thanks for stopping by. I hope to see some of your contrasting textures.

Until Tomorrow……

Doug

Day 22 Jewelry Texturing (part 1)

Day 22…. I know, I know, I am a little late posting this one, but I got it under the wire, still on schedule with this crazy 90 in a row kick-off to the JewelryMonk Blog.  I took a road trip this weekend and didn’t have any lessons in the bag, so I had to “whip one up” when I got home, so let’s get on with it.

One of the things I really enjoy about finishing jewelry is trying different contrasting textures. Sometimes just polishing doesn’t “do it” for me.

Texturing (2)

Today and tomorrow I will cover a very quick and very easy way of getting a good texture. The first thing you will need is an Electric Vibratory Engraver. Luckily these are pretty inexpensive and readily available. These come with a carbide steel engraving point, but truthfully, this is the first thing I replace. I have mentioned before that I reuse and retool many of my burs, and this is exactly what I do here. Even though the carbine bit that comes with the engraver is a lot harder, it is a little big to my liking. I make mine sharper and thinner to get into tight spots without marking the walls of the pieces. I just use a small used up ball bur and sharpen it with a Snap-on Disc. The tip can be sharpened, rounded, polished, flattened, etc. to give you different looks, you will have to experiment with this.

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Now just turn it on and rub over the area that you want textured. I try to keep the back and forth motion going in the same direction to make the look of the texture uniform. Be careful though since the movement of the engraver is an up and down motion, (like a small jackhammer) and if you touch an area that you do not want textured, it will leave small little divots or pits.

Texturing (6) Texturing (7)

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Great look if you like contrasting textures and super easy and quick.

Give it a try. Tomorrow I will demonstrate another tip that is amazing in this tool.

Cheers!

Doug