Building a diamond saw for cutting rocks is very easy and inexpensive. With a washing machine motor (115VAC, 1725 RPM) and a few salvaged parts, you can make a saw that will handle from 6” blades up to 10” blades, without a problem. These plans can be adapted and modified even further, to incorporate larger blades and capabilities. Here is all the information you need to get into lapidary work on a professional basis, or to upgrade your shop, for pennies on the dollar.
You will need a base for your machine, and I recommend 3/4 inch plywood of marine quality if possible. Other types of plywood work fine, although eventually moisture will get the wood, causing it to weaken and rot, and there is a lot of moisture in lapidary work. A good coat of heavy oil-based paint on both sides of regular plywood, and along the edges, will waterproof well too. Even cheap plywood uncoated will many times go for years, so do not go out of your way to buy a sheet of marine plywood for this project, because that would be purposeless and expensive. Once you realize how easy it is to build equipment for yourself, you will probably replace your first saw with a better one before even the crummiest plywood would go away. Try to salvage the wood you need, and everything else. Its fun, like a treasure hunt, and everyone knows there is a plethora of junk lying around all over the planet, and maybe by building stuff out of it we will actually do the planet a service. Wouldn’t that be nice? I'm sure.
Always talk up salvage possibilities, make friends at boatyards and construction areas, thrift stores and dumps. You will be glad you did. The most important part about the plywood is the thickness; it must be stout. 3/4” is good. It should be on the order of 24” by 24”, and if you like you can assemble all your parts, then lay them out as they will fit on this plywood base, then the plywood can be trimmed to the size and shape that will work best.
The next thing you will need is a housing for the saw itself. Because the lubricant for diamond tooling is water, this housing needs to be waterproof, and it is good if a pluggable drain is incorporated at trddddd3rhe bottom of this housing, whether through aquarium fixtures, small plumbing or auto parts---it doesn't matter, but a drain will make life a LOT easier down the road. The housing should be metal, and as strong as possible without overdoing it. You Don't need 1/4" steel for this.
It is also possible to construct a wooden housing as a form for fiberglass resin and cloth, but that is excess effort for most people, and not as strong or easy to obtain as a metal box. The metal of the box must be sturdy enough to handle the force of a large motor-run bearing, but should also be workable with hand tools, like hacksaws, hand drills, and the like. Some fixture boxes used in the electrical industry lend themselves well to saw applications, but besides those pre-made terminal boxes made to hold electrical wiring, the best and RECOMMENDED housing for your saw is an ammunition box, of metal, that can be obtained from army surplus stores. They measure small, medium, large, for the most part, with the smaller being around 6” wide by 12” long by 8” deep. Some of the larger ones are truly gargantuan, and only good for making really big saws, like ones that hold 24”+ blades. The small ones, good for 6” or 10” saws, run anywhere from $5 to 10.00 apiece, but look around, you may just find one languishing somewhere.
To test a metal housing for leaks with your vision, hold the box up to the sunlight, looking into it, and see what you see. Light shining through anywhere within the bottom part of the box means leaks, and leaks are bad. Remember to judge the size of the housing-box you obtain by using a blade as a measuring guide. If you don’t have a blade cut one out of cardboard, 6” or 10” across the circle. You are going to want nearly one half of the blade protruding above the cutting table, so its important to judge the size of the box correctly, and position the blade correctly in reference to the box.
This pertains to the bearing assembly, as well, which the blade is affixed to. You want the blade to come within 2” of the BOTTOM of the housing box (The closer to the bottom of the box the better) without sacrificing blade height on the cutting table. This is because the lower the blade sits in the box, the less water you will have to add to the box to get the blade continuously running through it. And thats why the box must needs be waterproof, because it is going to hold the water which the blade HAS to run through in order to keep it cool, and to lubricate the steel/diamond composition on its edge.
Once you have your base and housing, the next part you will need, and perhaps the most critical of all the parts in this project, is a salvage item that can be had at any used lawnmower shop. They can be purchased new or used, and many times the used parts are just given away. These marvels of technology are called a "Spindle Assembly", and are the actual bearings used on lawnmowers which the lawnmower blade is attached to. I have been given many, free, just for the pulling. When pulling them make sure there is little or no play in the bearing, and pull them from the HOUSINGS of Front-Cutting Rider Lawnmowers, if at all possible. Most rider lawnmowers do not have direct drive from the motor to the blade, but a transmission and series of pulleys which redirects the rotational energy from the motor to the blades. Many times on these rigs there will also be a permanent pulley attached to the stationary shaft (Spindle) running through the bearing (A NICE THING!) and occasionally you get to salvage a few belts as well as the bearing/spindle assembly. Good pre-work inspection of the bearing is a MUST, because there is a gnarly bit of work involved in getting the spindle assemblies loose, not least of which is removal of the lawnmowing blade. Once the blade is off there are some bolts and nuts where the mounting plate of the bearing is bolted to the blade housing, so bring some adjustable wrenches of several sizes, a couple screwdrivers, maybe a chisel, a hammer, and some gloves with you to get the parts. I like vise-grips and liquid-wrench-in-a-can a lot too. They always come in handy. Do not damage a good bearing in removal. Get all the fastening hardware off, and the blade, and if it is frozen on the hood/housing strike the bearings mounting plate lightly with hammer and chisel to break loose the assembly from the rust or grime or both holding it in place. Save ALL the hardware from this operation, whether you think you will need it or not. If you throw it away you WILL need it. Most especially, save the mounting hardware that holds the blade onto the spindle shaft. There may be a couple nuts, washers, a bolt running down the center of the spindle, etc., etc..
Here is a diagram of the Lawnmower Bearing/Spindle Assembly as viewed from the side, with the lower grooved portion representing the pulley:
It is very important to get this basic type of pulley bearing/spindle assembly. The whole construction of the diamond saw revolves around this. It is an advantage employed whereby one type of equipment is introduced into an area it was not necessarily created for, but achieves greater efficiency than present art. These are the type of advantages everyone can use, and the possibilities are limitless. For now just be glad this is available so that you can make a BETTER diamond saw than can be bought on the market, for a lot cheaper price. Later you can think of other ways to employ this spindle-assembly bearing set up to your advantage, and there is even another machine in this book which relies on the advantage of the stationary-shaft lawnmower bearing/spindle assembly.
Finally, you can buy a new spindle assembly to suit your needs, and STILL save a lot of money in constructing a diamond saw, but that means you are going to have to part with a good little chunk of dough, and also deal with the guy at the counter. Your choice. I myself prefer the lawnmower graveyard and only the birds tweet-tweet-tweeting as my wrenches rattle and dance.
MOTORS
Now, a word or two about motors, because they are all important, and because this is the first chapter of this book. In order to avoid redundancy, we shall get it it over with right here. The very best motors for lapidary work are the older, heavy duty, cast-iron encased Alternating Current (AC)1725 RPM (Rotations Per Minute) motors from a variety of equipment. I say the older ones are better because they were made better, beefier, more heavy duty, last a lot longer. But even the 1725 motors made today have to possess a certain sturdiness, because of their applications, and they are most commonly found in washing machines and clothes dryers.
When a washing machine or dryer breaks, it is usually NOT the motor. It is usually a weak point in design or workmanship within the mechanical automata of the machine, which govern the feeds, draining, agitation, and so on of the machine. A lot of the older washer and dryer machines are junked because its time to upgrade anyway, or its easier or less expensive (Than repair) to buy a new one, so these motors are ALWAYS available. You can buy them at fleamarkets sometimes, pulled, for as little as 5.00 each. New motors of the same type cost a couple hundred or so. Use an electric cord with a plug on one end and bare wires on the other to test motors. Hook the bare wires to the wires of the motor, twist on some wire nuts, or electrical tape, and plug it in. Make sure to keep any bare wire from these two connections from touching each other, or you will see some sparks. If the motors windings are shorted it might fizzle and smoke a little bit, but hardly ever does that happen; usually a capacitor goes bad and the older motors don’t even use capacitors for starting up, which is another reason the old ones are desirable.
If the capacitor on a newer motor is shot, the motor will likely just sit there once power is applied. Many times there are more than two wires coming from the motor itself, and it pays to test some of the various combinations by applying ac current with your cord to them, because sometimes different connections create different speeds within the motor. You cannot mess up polaritys testing these motors because they utilize Alternating Current, which means the current alternates from positive to negative continuously as it moves sideways through time/space, and in the case of America, at 60 times a second! Thanks Nikola Tesla! You are not forgotten! When obtaining AC motors to build machines, always try to remember how you are laying the machine out, and what mounting configurations will be easiest, strongest; most advantageous. There are many different configurations of motor mounts, just remember that if you do not get a motor with a mount on it, you will have to mount it in ways that take a lot more time and effort. Once the motor is tested, do not forget to mark the direction the shaft turns. Put it somewhere easy to see, and make it indelible.
Onward. Once you have obtained the most necessary four parts -- wooden base, housing box, electric motor, and bearing assembly, all you will need is a pulley and and a pulley belt, some woodscrews and metal screws, a few nuts and bolts, and some strips of galvanized metal such as flashing from a roof job. Also line up a small plastic serving tray like you see in some restaurants, and some thicker sheet plastic such as 1/8” lexan or acrylic or even nylon if its around. Plastic is EVERYWHERE, so you should not have any trouble finding it. The other stuff can be salvaged or purchased cheaply. And of course you will need a diamond blade too. See the suppliers list at the back of the book for information concerning where to get the best deal on quality diamond tooling.
You will want the speed of your diamond blade a little less than 1725 RPM, around 1500 RPM, so make sure the pulley you get for the motor shaft, which DRIVES the belt/bearing/blade, is slightly smaller than the pulley on the spindle/bearing assembly. Of course if you wanted to speed the blade up you would do exactly the opposite, the pulley at the motor would be Larger than the pulley at the load. This is how you adjust machine speeds by varying sizes of pulleys.
The speed of the blade does not have to be exact, so don’t sweat over it, 1500-1800 will do the job well, but the faster it goes, the more water it will sling, and the greater the damage when a rock jams in the blade.
Assembling The Saw
Now we put it together. As stated above, the optimum situation is where you assemble all the parts first, before trying to assemble the machine. This way you can lay it all out in very close resemblance to the way it will look when its done, and make any necessary adjustments while it is easy to do. Believe me. I learned this the very hardest way possible, and though there are advantages to freeform assembly if you are into design and engineering heavily (Sometimes Mistakes Work Good!!), the learning process dictates that durability and efficiency are based on a firm foundation in construction. That fancy little bit of wording there simply means IF YOU DO NOT SET IT ALL UP FIRST, BEFORE FASTENING BEGINS, YOU’LL BE SORRY. Rasta say: “Measure Twice, Cut Once”. Thats Good Advice.
Lay out the parts, and configure them so the pulleys of the bearing and the motor line up. The motor goes behind the housing box. And the blade needs to turn TOWARD you. You may have to flop the motors position around to get that right, but it is VERY IMPORTANT. Mark your board by outlining the pre-positioned parts, and get to work on mounting the lawnmower bearing on the housing box.
This is probably the hardest part, other than obtaining the lawnmower bearing. Its pretty much up to you how the blade housing box is mounted to your wooden board platform, just remember punctures are not good, and should be minimized. The housing box can be strapped to the board with good effect (See diagram below), or certain waterproof fasteners are available where you drill the bottom of the box and the screws tighten up a rubber grommet sealing the surfaces. Unless you are familiar with that type of fastening, I do not recommend it. When strapping the box to the wood, remember to keep any holes well above the future waterline of the box. That means about 3 inches above where the bottom of the blade will be, at least.
To mount the spindle assembly you are going to have to cut the housing box to fit whatever type of bearing you have. The bearings have a plate with bolt holes already pierced there, from where it was mounted on the lawnmower housing. You will want to utilize this of course, so keeping in mind the future water level of the box, as well as maximum clearance of the blade at the top edge of the box, position the bearing on the side of the housing box EXACTLY where it should go, and mark it. Do not let any part of the bearing or its pulley protrude ABOVE the edge of the box, because that will eventually be the base for your saw table, and it needs stay level. When I use an ammo box, I drill two holes in the side of the box, then cut down to those holes, bend the flap over, and use it to secure the box to the wood base. There are many different ways of doing it, but if you can make that happen for you, it will save a lot of time. See diagrams below.
If the bearing HAS to protrude for some reason above the edge of the box, said edge can be built up later by fastening one by twos around the edge, or what have you, so don’t get bent out of shape if that happens. ANYTHING CAN BE FIXED!! But fixing takes time, effort, and materials. I am trying to save you as much as possible concerning all that. Keep going, you will be cutting rocks in no time now.
As far as cutting the box goes, drilled holes will aid your layout of the cuts and just make life a lot easier all the way around. I usually hacksaw through the boxes side down to the holes. It is tedious but works and is pretty quick. Sawzall would work real well too.
If there is a grease fitting on the bearing from the lawnmower, position it before you mount the bearing, so you can easily grease it later. If there are any voids between the bearing and the housing when it is placed, you will either have to make a gasket for it, or caulk it with silicone before using the saw, else water will find its way out even the tiniest of holes.
Once the box is punctured correctly, and the bearing is mounted, mount the box to your board, attach the pulley belt to the motor and bearing, and mount the motor to the board. Keep the pulley belt as tight as possible during this operation, because it will loosen with time and wear anyway. You can actually place the pulley belt AFTER the motor is mounted, by putting it on one pulley, then getting it started on the other pulley, and turning it so it presses itself on. Measure twice, and then mount the motor and pulley belt. You are now very close to finishing this project!
Mount the blade on the bearing. This is where some custom work will probably come in, because each bearing is a little different. Use whatever combinations of nuts bolts washer etc on the shaft of the bearing to make the blade secure and running true. Over tightening sometimes warps blades so do not. Blades have different sized shaft (Arbor) holes, so you may even have to make or purchase a bushing. Most lawnmower bearings have a center bored shaft with a bolt...this is good, it makes your mounting project simply a matter of washers and bushings. Washers touching the blade should be as large as possible but fit the shaft bolt exactly. Any others used to space or shim can be smaller, but the two washers touching the blade must be uniform and at least an inch and a half across, or thereabouts. The diagram above will help you with this also.
Now make a cutting table from a raised-edge plastic serving tray and some plastic sheet. Use the mounted blade in the box to measure where you need to cut a slit in the serving tray JUST large enough for the blade to protrude through. Only make it as long and wide as it HAS to be, otherwise more water gets slung about. See diagrams.
You can either make the table socket to the box by attaching a lip underneath, or you can fasten by screwing the table itself to wooden fastening points attached to the side of the metal box for that purpose. Build good splash guards that do not restrict vision but keep most of the water in the saw. Gravity feeds and holding vises can be made for this machine, and it can be modified for larger applications with ease.
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