This little project took many moons to complete, but is well worth the time, and because it took me so long it will save You, the buyer of this information, a lot of effort and experimentation, things I had to work out the hard way. There are, as always, some adjustments you will have to make on your own, depending on what kind of materials you are able to procure for this project, but it is pretty cut and dried, and EASY. I will give you the best possible configuration, and you can go from there. Theres plenty of room for modification, so bear all this in mind and understand that you can make some improvements, or may have to compensate for the various project materials that differ from this design. All changes in the design or make-up of the machine will affect the way your tumbler works: this is important to know because as any machine works, it wears, and this in itself causes changes that you must be able to interpret and adjust.
This design has been protected by the way, which means anybody can build as many as they want, but if they try to restrict me from building by patenting it, they are in for a rude surprise. That said, I am sure you will find the plans here to be a true advantage. The innovation is a hanging vibratory platform, versus a supported platform. This changes EVERYTHING! Which is very good for us dear reader, and for the art in general.
The first thing you will need for your vibrating tumbler is a frame. This can be made from 4 pieces of two by four @ 14" each in length, bolted or nailed together on a plywood platform. Use waterproof epoxy, or wood glue if you don’t have the epoxy.
The threaded rod support across the bottom is essential to long term operation of this machine. Its easy and is the basis of your frame. It keeps everything tight over the long run, and can be further tightened later as need be. If you build a bigger tumbler, or smaller tumbler, than one using a 1/20th or 1/35th Horsepower Motor (Electric Typewriter), then adjust the size of the two by fours upward or downward by measuring it out first, by figuring what you need to have as far as clearance for your motor is concerned. You do not need excess clearance at the bottom for the motor shaft and counterweight to spin, but you definitely have to make sure the shaft/counterweight does not even have a chance of hitting anything.
After the frame is built you will need a strip of leather or seat belt material (Kevlar), to act as the support of the tub and tub platform. It needs to be long enough, wide enough (3” minimum), and strong enough to be affixed between the arms of the frame, hanging low in the middle with enough clearance between it and the bottom of the frame for the motor to hang. I use wood screws to permanently secure the strap on one end of the frame, and a c-clamp on the other for adjustability.
A platform will be hung on this strap, sitting on TOP of it, and that platform is where the motor and the tub will be mounted, so it needs to be stout enough to handle that, and also the vibration inherent in the polishing process. It is not hard to accomplish this, and anything from heavy plastic to plywood can be used for your platform, although the thinner the better (Without sacrificing strength) as far as the material for the platform itself is concerned. I use a small square of 1/4” or 3/8” plywood, about 9 inches by 9 inches, for my smaller machines, and that works just fine.
Overall, the platform and the tub are places you are going to have to be careful about. The tub must be a round bottom type: tupperware bowls, or rubberlike bowls like them work OK, and can be covered easily. A regular showercap with elastic band can be used as splash protector on top of most bowls, and really there are myriad ways to cover your bowls to keep gritty water from splashing out. The problem with bowls is they are constantly exposed to the vibration of this tumbler, which, in a word, is a MONSTER. They eventually wear through. The best tub I have discovered to date is a smaller tire cut in half crosswise, so it looks like a symmetrical half-moon, as can be seen in the drawing of the finished tumbler below. This is some work, cutting the tire like that, but the rubber is stout and two of these tubs can usually fit on one platform, thereby doubling a load. The best tires for this are from riding lawnmowers, go carts, or atv’s. Position the tire as is shown in the diagram.
I have also heard that some feed bowls for livestock, particularly water bowls for horses, are rubber, and may be another ticket for this, although I have not seen any of them yet.
Any tub is going to want to ride all over the platform though, and that spells spill. This can be fixed by using bungie cords across the bottom of the platform, that are then hooked to the sides of the tub at either side. Always keep some heavy duty clamps around too, as they are invaluable for adjusting the loaded tubs to optimum vibration, and for quick fastenings. Many times I clamp the tubs at one end, to one of the frame uprights, and that really gets her going good.
Once you have the set up where the tub is secure on the platform, you are in like Flynn. Many other ways can probably be cooked up to hold the bowl to the platform, but they must be secure, so the bowl does not walk around. Any movement by the bowl itself, you are wasting vibratory force, and thats a no-no. We want the vibratory force going into the rocks, not transmitted out into the quantum foam.
Onward.
The motor must be mounted at the center of the the platform, right below the center of the bottom of the tub, so that the shaft hangs downward, perpendicular to the platform. If you try to mount it so the shaft is parallel to the platform, you will get some vibration once the counterweight is added to the motor shaft, but it will be the wrong directional force, and the rox will not move as they should in the tub, and will not grind quickly.
I have used hose clamps, long bolts, and leather to mount motors, and the leather/kevlar strap method is easiest and works best. A 4" or larger strap with a hole punched in it goes over the motor shaft and motor front. Screw it into the bottom of the platform tightly, at either side of the motor, and trim off excess. See diagram above.
You may have to put a few screws into the platform around the motor where it butts up too the platform, to keep that end of the motor in place. But most motors have mounting screws and some fan motors are made to mount this way already. If the motor has a protrusion on the shaftless end (The bearing housing, like is on GE motors out of IBM selectric typewriters) it can actually be SOCKETED into the platform by drilling a hole to match, in the platform and supporting strap. Finally, if the small motor you get has shafts from both ends, cut the shortest piece flush to the motor with a hacksaw. You can make anything work, just take your time and do not get discouraged. Departure from the norm is a GOOD thing!
The motor and counterweight are very important parts of the overall project, you might say the most important parts. The motor cannot be too large, and it cannot be too small. It should be a heavy duty type, to be able to handle the vibration of the off-center force of the counterweight. I like fractional (1/20th) HP motors of GE type, and they can be gotten out of old IBM typewriters, which of course are now obsolete and can had for about 5 bux each or less. Speeds around 1000-1500 rpm are good.
The motor should also incorporate its own cooling fan if possible. Even with its own cooling fan though, auxiliary cooling is still necessary, with a small computer fan. This may necessitate the addition of a power strip to your setup, so that a fan and the motor can be plugged into it, then into one electrical socket, and the circuit breaker in the power strip is always a nice thing too. You need a 115vac computer fan on the side of your motor, within the frame, to keep the motor cool. This is necessary because the eccentric motion of the counterweighted shaft creates unaccounted-for stress in the design of the motor. The fans will increase the life of your motor exponentially, and are a bona-fide aspect of this particular design of mine.
BE CAREFUL with computer fans though, they cut meat when running. Computer fans are free or nominal in cost. Flea markets, computer repair shops, or out of large piles of obsolete computer equipment, laying around everywhere. NEWS FLASH! Try to position your cooling fan so the forced air goes into slots in the side of the motor, versus just against the housing. OR, instead of having a fan on the side of the motor, blowing on the motor to cool it, you can try putting one BELOW the motor, blowing upward. You'll need to set that one on spacers though, so it can draw air (which necessitates thinking about this when figuring motor clearance from bottom of frame). This works just as well if not better than two fans at either side.
VERY IMPORTANT! Finally, remember this: as your motors bearings wear from eccentricity caused by the counterweight (Unavoidable!), it may become necessary to start the motor by hand, by starting the spin. I have been hand starting mine now for a long time, over a year, and it still runs and runs and runs. If you turn on the motor and it doesn't run, just spin the counterweighted shaft to get it going. Do it FAST and keep your fingers out of the way. I use a stick most of the time to get mine going. And remember to mark the direction the motor shaft turns, on all motors you handle.
The counterweight for the motors shaft is something you build, and needs to be heavy enough to cause decent vibration on the motor once its mounted, but not too heavy to burn the motor up. Make it so you can adjust its weight. The best way I have found to make a counterweight is to get a sleeve of aluminum or brass that fits the shaft of the motor you are using, and can be locked onto the shaft by means of a set screw. An auto parts store can probably help with this, and a machine shop will definitely know what you are talking about.
Remember all this when you are salvaging a motor and get something that will work from the various parts at your disposal. Get two, in fact.
Drill a hole through one end, side to side so to speak, so a long, small diameter bolt, can be inserted. Load one side of the bolt (ONLY) up with washers and nuts until you have a decent off-center weight. You will want to go heavy at first, and if it is too much you can remove some excess weight. Most problems here occur because there is not enough weight to cause proper eccentricity on the motors spin, which is the vibration you are looking for.
Another diagram to give an idea on how to construct a good counterweight.
The counterweight goes on the motor shaft and tightened well; the motor is mounted hanging downward from the platform where the tub sits and this is all attached to the belt across the two arms of your frame, and made strong. Drywall screws and a cordless drill with phillips bit is a wonderful combination.
I sometimes mount my motor right over the leather which is between the platform and the motor, thereby securing the platform, motor, and strap all in one step. In fact, I have gotten to the point where my platform is actually TWO pieces of plywood cut alike, which then SANDWICH the supporting strap, and are screwed together when the motor is mounted to the hanging platform. Again, drywall Screws work great, and any excess out the other side of the wood can be snapped easily by bending twice with pliers.
After adding grit and water to the rox in your tub, turn the machine on and see if it worx. It should. Here is where you have to test your counterweight. If the bowl and platform “jump” at all, the weight is a little too heavy. And if you test it without a load of rox in it, expect it to act like a bucking bronco, which is not good. Please refrain. It should purr along with no up-and-down or side-to-side motion; all the vibrational energy going into the tub o’ rox. The rox need to move around the edge of the tub, and they will sink into the middle and come up at the edges. It is a toroid energy flow, like a donut rotating inward towards center, and round and round. Your grit will begin to break down almost immediately if all is well. Refer to the abrasion info included at the back of this book for information about that.
Chances are you will get a working unit going pretty quickly with these plans. If you like and have the time, it would be prudent to experiment then with larger or smaller counterweights, and remember that the counterweights position on the motor shaft will add or subtract from the vibration of the unit, depending on how far away from the motor housing the counterweight is. Out towards the end of the motor-shaft is good. Remember that if the counterweight or any of its components were to ever separate from the shaft while the motor was on, they could have projectile force for a short distance, so a barrier around your tumblers bottom is not a bad idea.
You can polish a full load of rox in a week or two using vibrating tumblers, versus 3-4 weex using rotary types. Also experiment with your load and find the optimum for rock movement and polishing action. Go light at first, start with a half-full tub and add a little more rock until it stops working in toroid form...take a little out and that is your best load weight. In this way you will soon be able to discern the capacity of your tumbler. If it seems you are not getting enough rocks working correctly, add weight to the counterweight, or another tub alongside the primary. Some vibrating tumblers use stackable tubs, and that works well too. Constantly adjust the position of the tub on the vibrating platform until you find the spot of optimum vibratory action.
No comments:
Post a Comment