Improvements To My Vibrating Tumbler Design

     Buyers of my book know that the vibrating tumbler design is a good one, and can be easily and cheaply made, even though it took me years to get right.  I have built another tumbler just recently, to handle larger loads, and wanted to add some improvements I made for the users of my instructions. 

     First thing:  When using hose clamps to fasten the motor in place in its sling, consider replacing at least one of the hose clamps sets with one of those cheap ratchet straps that you can buy for very little money, just about anywhere even the dollar store.   You trim off the excess strap, and then hook the ends together and you have an adjustable clamping strap that is cheap and can be reused or adjusted when needed.  This is best to tie around the motor and the suspension strap.  In the picture it is the red strap down around the motor, holding it together with the suspension strap -- the ratchet is in back of the motor.  Remember to get it very tight when you do it, but it works well.

     Second:  I left one of the tire tubs whole, instead of cutting in half, and was able to then secure it better by putting a strap across the entire top of the tire, fastening at the top of both posts.  In the picture the strap is not fastened yet, i just nailed it into the top of the posts before I used it, and I then move the strap itself  back and forth to remove the tub.  I also made a very tight fit for the tire between the posts, please notice that as well.    You will have to make some adjustments, but a whole tire seems much better than a half tire for several reasons.  It saves the labor of cutting the tire in half, it can be used to secure the tub better, and also it keeps edge splash down.

     Finally, instead of using a small fan to cool the motor, I bought a used high powered hair dryer which really puts out the airstream, choose the cold setting of course.  It keeps the motor cool a lot better than regular fans, especially when directed through the motors windings. 

Making Saw Blade Shaft Adaptors

One thing everyone has had to come to grips with are saw blade adaptors, now that the majority of the diamond tooling we buy is made in China.  There have been problems with consistency and other things, things like arbitrary shaft hole sizes in the same lot, et al.   Sometimes, even most of the time, a Chinese item will work ok, as long as you fix it first.  Remember that natural law, rocky-san.

When you put your new sawblade up to the shaft of your saw, and the hole in the blade is too big for the shaft, you are in need of a shaft adaptor.  There are some commercial adaptors available and if you can find those that work (Good Luck!) stick with them.  Otherwise, fashion your own from thin cut cross sections of pvc pipe, sanded and/or filed and/or cut down; or punched out of leather or plastic with round punches of varying sizes.  That last I have been recently successful with.  Tape your adaptor into the blades hole from one or both sides of the blade.  Lighters can come in handy during these operations as well.

You want the blade to rotate without wobble, so it has to be centered on the shaft pretty closely.  It can be done, perhaps not easily, but correctly.  When doing these make 4-6, use the best one.

Cost Savings

I happened to pick up a catalog from the most well known manufacturer of lapidary equipment here in the states, and it was driven home to me once again the value of this book I sell, and I am glad to do it.  When I first began cutting rocks, it was long before the net, and there were no alternatives to buying the equipment as it was manufactured, usually used, though I have bought a new machine or two in my life, and they were not worth the money.  Some of the old timers built their own machines, and I owned a few of them over time too.  Mostly though, I began experimenting early with my own devices.  It was because of things like I saw in this catalog I picked up:  6" trim saw with arbor $270.00+ (see the photo-plans in this blog where you make one of those for about ten dollars),  10 pound capacity vibrating tumblers start around $500.00, Bench Lathe Electric Arbor Systems $700.00 and up,and even a flat lap near 2 grand!  Some people might think the 50 bux for the plan sets/lesson plans/how-to book is steep, it is not.  It will get you working stone quickly and cheaply, and perhaps even inspire you.  That is the wished for result.

Apache Mine Gems In Cast Silver

Your Guerilla Gem Shop

Gemstones have always been a viable currency. A million dollars in gold weighs quite a lot, it is cumbersome to carry....the right gemstones can be worth a million dollars and easily fit into a pocket.


Here are some things I have learned about working gemstones that will help anyone who likes to work with stone or is thinking about working with stone. You can get a lot more information from my book HOW TO BUILD BETTER LAPIDARY EQUIPMENT, but this is actually what I have evolved to on my bench, to do the lions share of my work, having gone through the entire smorgasbord of manufactured equipment and home made equipment, several times.

My specialty tumblers and grinders and saws, in HOW TO BUILD BETTER LAPIDARY EQUIPMENT are very viable machinery: they will be even more viable and useful, I am sure, as more people become aware and are educated in how to change stones into money.

Rule #1

I have found that most gem operations can be done on miniaturized equipment with diamond grinding burrs of various sorts, and small diamond blades.

To see the type of tooling I am speaking of, visit:


http://www.lopacki.com

I have gone from massive bench top machines to small motors on movable wood bases which are supremely flexible in their uses and attributes. You get much better at finish and creative work very quickly, employing the smaller bench lathe type machines detailed below, which can easily be built for 20$ or less.


Rule #2

Durability. Build your equipment to last. This is not hard to do at all. Pretty is not important. In fact, you may come to redefine pretty, as you gain respect and even awe through witnessing long term and flawless mechanical operation. Teslas motors still run as they always have, and they are a marvel for you to ponder as you use them.



Rule #3

Safety.  A lot of safety is working wet and working outdoors. Your guerrilla shop will make it easy for you to be safe. By being mobile, you can employ the outdoors to your needs. Dust masks are good, but working wet is best, so that no powders ever become airborn. Rinse the work area regularly and well, so powders do not build up.


Your best water source for grinding operations up close is a simple spray bottle used by barbers and gardeners, housewives and window cleaners. Spray the wheels to keep them wet, refill the bottles when necessary. You can make shields for all your grinding operations from plastic milk jug or 2 liter bottoms, as explained below. They are a good idea in some situations.


Try to never work metal chain, wire, or rod on high speed or powerful motors.  Thats how fingers and eyes are lost.


There are attachments that can be bought for most motor shafts, which convert a motor into a useful bench machine, like a grinder, or polishing unit, or what have you, with the turn of a couple of allen screws.


The attachment I speak of actually fits over the motors shaft, and is available from 1/4" to 3/4" sizes, to fit those size shafts, and even larger.  Harbor Freight sometimes has these, or shop the Foredom company for a more high quality product. Once fastened to the motor shaft this attachment provides a threaded shaft for mounting a grinding wheel, or sanding drum, or flat lap disc.


There are some motor shaft attachments which are pointed and threaded to receive muslin wheels or other cloth polishing wheels.


Places like harbor freight call these motor shaft attachments: arbors. Other search terms: mandrels, chucks. I recommend Foredom motor shaft attachments whenever possible.


Be aware of right and left handed issues with these motor shaft attachments; will the shaft be facing right or left when mounted? The threading on the shaft will be different for different applications. They are sometimes labeled RH or LH.  You want the wheel turning toward you, not away from you, for several reasons, the most important being safety, but also because if it rotates away from you, versus toward you, it will most likely loosen itself through use and be a real pain. If you keep your motors nice and portable you can always just turn it around on the bench top if it is turning the wrong way.  Also, sometimes you can change the wiring at the motor and get a reverse spin to what you have, check the diagram on the motor if it has one.


The larger motors, like washing machine and dryers motors (1725 rpm 1/3 or 1/2 HP), can be dangerous and are actually overkill in most lapidary situations.


The best motor set up I have is a 1/20th hp motor with a 1/4" shaft, out of an IBM selectric typewriter. Attached to its shaft is a 1/4" mandrell/chuck. Into this chuck I can insert hundreds of different types of grinding bits and wheels. I can even make my own attachments with leather wheels, or silicon carbide cloth, and small diameter nuts and bolts. On this set up I can easily take a stone from rough shape to polish.

 Stones can be rough shaped, prior to grinding, with diamond blades and larger grinders. They can also be flaked/knapped, and broken in other shearing ways, to good effect. Think tile snapping. Also nipping with pliers is effective to trim a rock without specialised equipment. Finally, shields for all wheels can be made from milk jug bottoms or 2-liter bottoms. Just cut the bottle as long as needed, then melt a hole in its bottom for the shaft of the motor to pass through before the wheel or whatver is attached to the motor shaft. Attach to bench or work table with a tack or small flat headed nail.

OK. Motors should always be considered portable. Once you have an attachment on the shaft of your portable motor, so that it can accept grinding and sanding wheels, or diamond grinding bits or whatever, then use quick clamps to fasten the motors where needed on the benches you use. Sometimes spacer wood will be necessary in this clamping operation, to get the wheel off the bench. You can mount motors to permanent spacers easily enough with hose clamps or other things, then just clamp the whole show to the bench. thats how I do it. 

If you wish to make a motor semi-permanent in its application, and there are no readily available mounting features on the thing, you can wedge it at the bottom on two opposing sides, and use metal strapping with drywall screws to fasten it in place on a board, and there are other strapping configurations that work well too. Some motors have mounting features, but are out of synch with our particular needs. This is where the ability to fasten a motor in place using readily available materials is a good advantage to have.

I have many motors mounted in esoteric ways, most have been surprising in their longevity. Don't be skeered. Finally -- Never forget to look at old floor scrubbers and other equipment for sale at most thrift stores and flea markets. Some old floor scrubbers make excellent flat laps when reconfigured, and there are many other things that lend parts to educated entrepeneurship.

An important thing to know about motors is this: fans always prolong the life of electrical motors, when situated to dissipate heat. That means you should have the fan blowing on the electric motor in order to cool it, and it will run better for lots longer. Computer fans, I think they are also called biscuit fans, work very well and can be easily wired and configured to turn on when the motor is turned on. Also: when motors get old and carry a good load, sometimes they need to be hand started after the power is turned on, by spinning the pulley by hand.  Don't get your fingers in the belt/pulley interface, you will be very sorry if you do.

If a motor hums but does not move, try hand starting, it usually works. Other motors require capacitors to get going, but sometimes they too can be hand started when their capacitors go kaput, and are bypassed.

Some trix at the guerrilla gem bench: Old abrasives can be reused for lesser but more refined operations. Collect the slurries and other detritus of abrasive actions, and retain. Can be sorted by washing, or dry sifting, too.

Glue stix are a true innovation. They can be used for many things, not least of which is easily dopping stones for working. This gives the operator something to hold onto. Melt the end of a stix with a lighter and apply to the bottom of stone, then after it cools, the glue stix itself can be used to hold the rock when grinding, which saves fingernails and skin.  Wood dop sticks with dop wax are best, and small pieces of bamboo branches seem ready made for that operation.

Some very interesting pedal power machines are manifesting around, and pedal power is good. It is not too hard to do.

Diamond blades are going toward the miniature as well, and some can be bought less than an inch across! Many of these cut just fine when sprayed with water, or are otherwise lubricated. Some people make tile saws work for preforming rocks, and thats a good idea I think. Once the stone is down to grinding size though, a small bench-lathe will do all the rest of the work, all in one place, with a minimum of hassle, angst, and expense. Is that not nice?

Drilling stones definitely requires specialised equipment, and the 2 things that need to be remembered when drilling stone with a diamond bit is that slower is generally better, and the item being drilled with a diamond burr should be submerged in water, so that the drilling itself is also submerged. Clear the drilled hole often as you do it, which means: the deeper the hole goes, the more you should pull the bit up, actually exiting the hole, so that mud from the operation does not overheat the bit and cause the diamond plating to separate from the bit. Some neo-experimenters use bow drills and even galvanized pipes to drill holes larger than normal, or out of the ordinary, and I think anything a person can do to accomplish what they are able to conceive is a good thing, and the way its supposed to be.  Keep an open open mind.

Large stone or glass drilling is done with an abrasive slurry that is steadily drip-fed to the point of contact between stone and a piece of heavier sized pipe. Very time consuming, but ways can be improvised to speed it up, if thought is given and time is taken. The native Americans had some novel drilling units, most notably a pump type drill that is easy to duplicate and is the most efficient non-electrical drill I have ever seen.

Hand Grinders should be employed whenever possible because they are good efficient tools for the stone sculptor. They are made from small motors modified by attaching a pistol grip, usually by means of a couple of hose clamps around the motor, and through a perforation on the pistol grip handle. Put a chuck on the motor shaft and you can easily utilize all the available diamond grinding bits and burrs to carve large sized sculptures. These also make good hand-sanding units. Cut discs of sandpaper 3-6" across and attach to a mandrel with a washer on either side of paper. This will flex if it has no backing to it, and thats fine because the flexing of the sandpaper disc will allow you better control at contours and in other hard to sand places.

About rocks. They must have good eye appeal, bright, colors, chatoyance, opalaescence, irridesence -- this is where pretty matters, pretty is all. It takes as long to make a strand of dull grey limestone beads as it does a strand of bright green serpentine beads. Always strive for bright colors, clear and clean material free of pits and undercutting, and the nicest polish you can get. If you have a stone people look at and go Wow, thats a good one.  Remember though that the dust from some stones is poisonous or hazardous, and with the softer materials it is definitely something to guard against.



Bill Gallagher

Light Happens.

How To Make Flap Wheel Sanding Discs For Bench Lathe

The best way to make flap wheels for the bench lathe: cut a circle out of sanding cloth, punch a hole in the middle, put it on a mandrel with two washers, either side, and then make four equal and equilateral cuts at four places on the outside of this disc. Cuts are at 12 oclock, 3, 6, 9 oclock, and come in only about 1/4 " or so. 

They deform spherically and uniform every time, make nice inexpensive and easily replacable sanding tools. I use 100, 220 grit belts mostly, I cut the worn ones up for this, or if I need real aggressive action I use new sanding cloth in those grits. 400 and 600 work too. 

 One must be forceful to get the propellor shape to manifest, and this should happen as the disc begins to wear some, so that you get max cutting power from the new cloth. Once the propellor shape happens you will get a true flap wheel effect and it will be harder to use the center of the disc. The tool will take a lot of hard wear before it wears out. It can be used inside hollows, and works well for that, just watch that metal from the tool does not hit the stone.

Increasing the number of cuts at the outside of the disc can create some interesting effects, and by making the cuts deeper at the edge of the disc you can actually get a flapwheel effect. Finally, if no cuts are made, the wheel wears and forms in certain predictable ways too, giving you a real nice spectrum of variability in your sanding work.

 

How To Solder With A Blowpipe

The use of blowpipes to increase heat to the point where soldering and/or fusing of some metals is possible is a well known technique throughout the world. The traditional fuel in many areas has always been charcoal, although bunsen type burners, alcohol lamps, or even candles are preferred because of the readily available flame.

An air-jet is produced by the restriction of the blowpipe. When directed through a flame, will produce a super hot sideways flame, or jet, which is easy to manipulate. The oilcan blowpipe illustrated here is also more efficient because it does not conduct heat to the lips, and is flexible so that the head and face do not need to be positioned uncomfortably or unnaturally to accomplish the work.

This oilcan blow pipe as illustrated here also serves as a collector of moisture, which is a byproduct of breath, and can cause problems if not addressed. Obtain an oilcan with a very small hole at the end of the spout. Variation in flame size then can be had by altering the flow of your breath. The nipple that the rubber tubing is hooked to can even be hard plastic. Rubber tubing is cheap at all auto parts stores, ask for vacuum tube or even fuel line.

This type of blowpipe is used for soldering of jewelry, small machine parts, the fusing of some metals such as gold, and also for certain mining assay tests for fusability of ores. Silver soldering is a breeze.

Beginners must learn to position the work and the heat source correctly, and tweezers come in very handy. The work must be positioned to accept this pinpoint heat produced with the blowpipe. This entails some getting used to and do not feel bad if you find yourself wishing for a few more hands -- everybody does.

Little alligator clips on extendable antennae rigs, tweezers of various sizes, hemostats, or those little shop helper benchtop tools with arms and clips -- all come in handy -- even jewelers vises of various types -- can be used to make this operation work better. Like anything: practice will make perfect, for your particular needs, do not fear.

Through experimentation you can see which part of your burner flame yields which kind of needle flame, and this is the way you can vary temperature by eye -- get used to the various flame colors you produce when you send the blowpipe-jet through the alcohol lamps flame.

How To Draw Wire and Small Tubing. Make Custom Wire Sizes and Shapes In The Home Shop.

                                 A Wire Drawing Plate for round wire.



The ability to draw custom wire sizes and shapes is valuable to the mechanic, craftsman, and artist. The wire drawing plate is clamped upright in a vise, and the existing large stock wire is ground to a point on one end, inserted in the smallest hole that will snugly accept it, then pulled with a pair of pliers, or vise grips, through successively smaller holes, until the correct diameter is reached. This removes all local kinks and creates great uniformity, as well.

The metal will harden after a few pulls and must be annealed by coiling, heating to red, then let cool to room temperature without quenching. The pulling of the wire itself should be smooth and in one motion, no stopping. Soap can help this process along. Pull the wire across a cake of soap, or a soap coated cloth. It is sometimes difficult to get the wire started, but once it starts its very easy to keep pulling. You will gain length as you draw the wire, so keep that in mind.

How To Achieve Forge Black Iron Rustproofing and Metal Finish

This metal finish is known among afficianadoes of forged iron metal work as FORGE BLACK, and it derives from a technique dating back over a thousand years. This method is an attractive finish and a very early method for the rust proofing of iron.
The metal is first meticulously cleaned with 00 emery cloth or steel wool, then washed with denatured alcohol, shellac grade. This is to remove all grease and dirt. Do this with clean cloth or paper gloves on so that further grease from handling is not deposited.
As soon as this is dry, coat with linseed oil by wiping, brushing or spraying. Immediately heat over the forge with air flow applied. This adds free carbon to the burning oil, and an enamel like finish will eventually result, once the oil is all burned off. Do not heat above black. When the piece stops smoking, remove, cool, and wipe with a cloth to remove free soot. This leaves a good black finish and has been used for ages as an initial treatment for iron, with defeat of rust as its main ideal.      ------------------------------------------    

One of the best places for metal stock and parts is used lawnmower shops.  Of course the local junk/salvage car lot is a veritable smorgasbord of free and cheap materials and parts.  If you are a true owlhooter and look real carefully for anything of value, you never know what you will find stashed in little boxes, or in trunks of cars.  It definitely pays to look carefully.

Shop Tip: Metal can be cleaned very easily by immersion in salt water while applying battery power.  Run a wire from the negative side of a D sized Duracell battery to the item being cleaned, and the positive side of the battery wire up to a salvaged piece of stainless steel like a one piece butterknife marked stainless.  Immerse them together but NOT touching, in the salt water, and watch the corrosion or encrustation "Bubble Away" through this electrolytic process.  No smoking as the gas given off here is hydrogen, flammable.  Do it outside, and get rid of the wastes by dehydrating the electrolyte (Evaporation),  then dispose of as solid.  Rinse the cleaned object well and treat with light heat to dry thoroughly. 

email me: luxefaire@gmail.com

How To Cut Fine Designs From Sheet Metals With Acid

The cutting of extremely detailed parts from brass, copper, and steel sheet metals, with no rough or bent edges, is generally considered to be a job for massive machinery which can cleanly punch out products by the thousands. This process below is simple, and does a fine job on all the metals mentioned, with the exception of Stainless steels. This method works so well it can be used to make metal parts for art, models, and even some machine and electronic parts. Fine engraving is also possible. Read on.

The advantage to this recipe and system of work is that it utilizes easily available but somewhat specialized materials, and the original author and inventor was well acquainted with chemicals and their reactions. For instance, one of the accepted ways to accomplish this has always been with nitric based acid baths -- and this is only partially true: Nitric acid baths generally create a FOAMING in most reactions with metals , and this disrupts the integrity of the wax shield at the edges, causing roughness, and unevenness.


The acid for this method is made like so:
3 Ounces potassium bichromate dissolved in 32 ounces of water, then 3 ounces of concentrated sulphuric acid is added. That mix there is also known as Photographers CHROMIC-ACID TRAY CLEANER. If you can get that premixed that saves time. Next an emulsifying oil is added to this mix, and that is a key to making this all work, as it gives the solution greater wetting power, and allows it to soak into the finest of lines scribed through the wax coating. A few drops ONLY of any emulsifying oil will make this a very efficient acid bath for the purpose of cutting out finely detailed parts. Rust inhibitor for car radiators works well, and liquid detergents will work too.

If aluminum is to be cut, add half ounce or so of hydrochloric acid to the above mentioned acid bath. When any metal but copper is cut, stir the bath frequently during the operation, to defeat any encrustations which may result, and slow down the etching. Preserve this mix after use by straining and storing for future use. Dispose of, when spent, by evaporation in an outdoor shed.

The metal to be used can be very thin sheet metals, and up to 1/16th inch thick or even thicker. The time required to cut the part is dependent on temperature (80 F optimum), and the thickness and type of metal. Experiment on scrap or practice pieces before tackling bigger jobs. Fine acid engraving can be accomplished with this process too, by allowing the metal to soak for only half the time, or less, which was required to cut the metal. That is very handy information indeed. Anything can be traced onto the wax, then scribed down to the metal so that the acid is allowed access: even photographic images can be engraved or cut out!

The wax coating is also very important to this process, and has to be of syncera or ceresin wax. Regular crayons usually work fine. Heat the metal slightly and dip in molten wax so good UNIFORM and TOTAL coating results. Let drain and dry by hanging until wax gets hard and everything is room temp. This coating will be what you draw your design through. It can be etched with a scribe or any sharp tool. You can trace a design easily on the wax, then go back after, with an exacto knife or something like it, and cut through the wax to expose the metal surface which will be cut by the acid. A template or tracing design can be held to the waxed metal with a dab or two of contact cement. Remember: where ever metal is exposed, the acid will cut.

Finally, it is very important that your metal be 100% finished before coating with wax, and cutting in the acid bath, because trying to polish a finely cut piece of sheet metal is ludicrous. Also, this polishing beforehand must entail total cleaning of the metal, because grease of any type will resist the acid bath and cause problems. Benzene works well as a final cleaner right before the wax coating. Remember your skin has oils too, so handle at that stage with rubber gloves if possible. You cannot be too careful. After the etching process, clean it all up with gasoline. If the type of wax you used does not come off with gas, use low heat in an oven until all the wax drains off.

For safety wear a good rubber apron, goggles or safety glasses, and gloves at all times, when handling chemicals such as explained above. Perform this job outside and don't breathe the fumes at all.

Build A Charcoal Fueled Metal Casting Furnace

email me: luxefaire @ gmail.com


Build A Charcoal Fueled Metal Casting Furnace

This project is easily accomplished by anyone with at least an average mechanical aptitude. The actions of the author are protrayal of tested knowledge. The actions of anyone else, whether aware of this knowledge in whole or in part, or not, are in No Way to be construed as actions of the author.    

It is very simple to build a metal smelting furnace powered with regular store-bought charcoal briquets. Temperatures in excess of 2500 degrees fahrenheit can consistently be reached, and sometimes a good bit higher. The apparatus can be as simple as a coffee can buried partially in the ground, with a pipe and blow dryer for the air source, or as extravagant as a galvanized trash can utilizing firebrick, fireproof mortar (refractory mix), stainless steel, and a heavy duty air blower, as can be found on many high output electric and gas heaters or air conditioners.
Care must be taken to measure and understand the air input to your furnace though, because many times too little is ok, and will work, whereas too much air, too much pressure, will blow cinders out of the fire and even dampen the heat. I use a blow dryer on low, and can melt silver easily, with high settings used only at the end of a brass melt. Below are a few pictures of the furnace I am currently using. It is nice and portable, and I have melted 5 pounds of silver in one crucible load with this furnace.

The main thing one needs to be concerned about when melting metal (Or doing ANY shop work, for that matter) is SAFETY. Say it: Say---ffffff---TEE. Molten metal will go off like a bomb if mishandled, or if impurities are introduced into the crucible during a melt, and the shrapnel of course is molten and will burn through most things, you included, before you even know it is happening. Not cool at all. This I know from experience. Molten metal blowing up is one of the ugliest things I have ever witnessed.

Notice in these pictures of my furnace that there are two compartments, a lower, and an upper. The lower is nothing more than a large coffee can with top and bottom cut out. A piece of screen separates the top and bottom compartments, resting on the lower cans opening. The lower can has a hole in the side also, just big enough to allow the air pipe in, and it sits on some filler, clay. The top compartment is another coffee can, bottom down, with the bottom left intact, but punched full of larger sized (three quarter inch) holes, to allow the airflow good access to the fuel charge, the charcoal. Make a lot of holes, dont skimp. You want plenty of airflow through the two compartments.

Firebrick and common clay from the ground is what I use to contain the heat, and hold the cans in place. I usually clean and refill around the cans each time I use the furnace. The pipe for the airflow goes into the bottom compartment, through the wall of the little galvanized trash can, and through the fire brick and coffee can. It enters the lower compartment at about the halfway point, and closer to the bottom is better. The lower compartment allows a bit of pressure to be built up, to jet up through the top compartment, where the fuel and crucible live. The charcoal goes in the top can, and you need to light the charcoal first, using a propane torch, or lighter fluid. If you use lighter fluid use just a small amount and let it soak in for a full 120 seconds before lighting. Once lit, and once some of the briquets get ashed over a little, like at the corners, turn on your air supply and away she goes.

After turning on the air supply, put the loaded crucible on the coals once they are totally ashed over, and continue to feed the fire with charcoal until your metal puddles. You have to feed the fire by placing briquets around the edges of the crucible with tongs. Let the crucible fall a little into the upper compartment, after the fire gets going good, so that hot coals surround it. The crucible will get red hot quickly. I use either a fused silica crucible or a graphite. You can gently shake, or tap the crucible occasionally, agitating the metal, which may induce melting. I use kingsford charcoal and it is by far the best for this purpose. I also use powdered charcoal as a flux, and there are many other things that work as flux too, like borax and the like. Powdered charcoal is free, and can be collected from the bottom of the bag you buy. It covers the metal and keeps it from oxidizing as it heats. You can be liberal with it, like a few tablespoons per load of metal, if you are using a five pound crucible.

If the metal is having trouble melting, sometimes addition of a little flux will remedy the problem. The Complete Metal Smith by Tim McCreight is a great book to have around whenever working with metal.     A swirling motion on the surface of the molten metal usually means it is ready to pour. Never look directly over a crucible. Wear gloves, a hat, safety glasses, leather shoes and a long sleeved shirt when smelting metals. I use crucible tongs which are just a long set of plier-like things I got at a flea market. I grab the lip of the crucible firmly, then quickly and smoothly move the crucible to my mold and pour in one fluid motion

I use my metal casting furnace in conjunction with the delft casting method, a unique and extremely easy to use molding system that will produce highly detailed and consistent parts with little or no fuss. Search for Swest Jewelers supply, Indian Jewelers Supply, or Rio Grande Jewelers Supply online, they all carry the kit. It is around 100 bux, and comes complete with a video, casting sand, and a small mold. Once you see the system you can make bigger molds easily, and it is well worth your time to get into this if you have a need to reproduce small to medium sized parts from original models of high detail and uniformity.  
As in any sandcasting, undercut models are not feasible, but many many other things can be reproduced easily and efficiently with sand casting. There are cheaper sands, and different mold set ups and if you are after a lesser uniformity, or the pieces do not require great detail, then other types of sandcasting should be looked into by you too.