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Hey Unabiker you still alive? Ya tease us with your beautiful work and then vanish. How about a nod or somethin'
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I would think a solid mounted frame would be best to avoid losing energy in a secondary non productive vibration. Mounting the machine to your floor would be fine with concrete anchors epoxied into holes (at least 3 inches deep) in the concrete to attach it with. We use a similar mounting system for rail where I work, and its suitable for passenger trains to travel over. I doubt your concrete would suffer with proper mounting hardware and dampening of the vibrator from the frame.Originally Posted by Fred Nerk
But if you are really concerned about it a seperate high strength concrete "plinth", an elevated concrete pad with rebar reinforcement could be poured onto a section of your floor (after the floor surface has been prepared by roughing it and priming it) to mount the machines frame to, and that would virtually guaranty structural soundness.
Hey Unabiker you still alive? Ya tease us with your beautiful work and then vanish. How about a nod or somethin'
Hey all,
Sorry it's been so long since the last update. Went through a nice busy stretch, which meant my web surfing time had to be translated into workin' time.
The shaker has been happily chuggin away for 6-10 hours a day, about every day.
I had some welds fail on the cradle a while back. The welds were on the ribs of the cradle, on the back side. Too much force going through a section that was not supported enough. I fixed it by welding it where it broke and added some more reinforcement to make the whole cradle more rigid.
At the same time, I added some thin plywood shims between the cradle and barrel. This was to make the fit between the two more snug. I could see where the cradle was not shaking at the same rate as the barrel in some places. This is lost energy to the media, more noise created, and also tough on the barrel as it tends to pull the barrel to cradle bolts through the plastic of the barrel.
I did both of these mods at the same time, since I had to take the barrel out to fix the cradle. The net effect made the machine a bit quieter and made the media more active.
I also changed the way I attach the weights to the axle. I was using 3 M6 bolts per weight that would thread into tapped holes in the axle. This resulted in a broken M6 or three about every 4 weeks. Its a real pain in the ass to take the axle out, then dig out a few broken bolt. The weights are .500" wall thickness aluminum tube. Pleny of meat to tap 10mm bolt holes. So now each weight is held in place by 3 10mm bolts that thread through the weight and clamp onto the axle. This makes the phase infintaley adjustable. Really a worthless feature in this application. I want the barrel and cradle to jump straight up and down. Any twisting in the jump only provides more wear on the guides, and less action in the media. It would be very easy to cut the weights in half, though, and allow adjustment to the amount of force the weights generate.
I've found the easiest way to affect the flow of the media through the tub is to restrict the movement of one side of the cradle. I've been using a ratchet strap for this. The media is wierd. Some days, it tumbles in a nice top to bottome circular fashion. Other days, it just kind of sits there. When it sits there, we change the tension on the strap. It doesn't seem to matter if you add or subtract tension...it just needs to be different.
The other major improvement is in the juice circulation department. After buring up several cheapo $10 pumps, I splurged on a $50 sump pump from Harbor Freight. This pump has a float switch, giving me control over the amount of juice in the barrel. The cheap pumps just could not handle the sediment. They would clog up, then burn up. The sump pump doen't seem to care about the sediment. I'm also using a router speed controller to slow the pump down.
I'm now using a 20 gallon keg tub (leftover from a kegger) as the resivoir, which allows enough room for the float to work. The juice gets changed every 2-3 days. So far, the best finish in the least time seems to come from plain old tap water. The soap only seems to add time to the finish, and if you get too much, it leaves chemical burn spots on the aluminum.
I'll try to get some pics the next time I have the sound-resistant box off of the shaker.
I'm thinking about building a similar tumbler. I'm thinking about using some extruded alu channel for the 4 guide tracks and lining them with some teflon or delrin or something. Vibrating "cart" would have a matching teflon / delrin / whatever piece.
I would think it'd make it a bit quieter then a loose metal on metal interface.
I'm thinking a little smaller scale so I might just cut a 5 gallon drinking water jug in half or maybe take 3/8" of it out or something. Also only planning on doing final polishing so I thikn the thin wall will still last because its a very fine abrasive.
I was looking at some commercial ones today and they seem to be much the same design anyways, at least for the large ones...
Any thoughts?
where are you guys getting the microbrite media ???
it it the same as ceramic balls ?
After over a year of shaking and learning, I've developed some ideas for improvement on my vibratory finisher. When the drive pulley on my axle came apart a week ago, I decided now was the time for some upgrades.
I would often use a ratchet strap to restrict the movement of one side of the tube to help get the media to move in a cylindrical tumbling fashion. With this in mind, I got rid of the springs along one side and replaced them with an axle and bearing setup.
I think this setup offers several advantages over the old style in that it gets rid of the guides (and the noise they created) that were used to keep the tub centered over the base, it makes emptying the media from the tub very easy, and it allows for easy access to the drive axle and weights.
On the original design, the drive axle was located just off of center on the bottom of the tub. I moved the drive axle further outboard to increase the effect that the spinning weights will have in creating up and down motion, and to create a bit more space for my drain upgrade. I also shifted the drive pulley over a bit, and relocated the motor, again to make space for the drain. The motor was relocated closer to the tub pivot axles in order to decrease the side loads on the motor created by the tub's up and down movement.
For drains in the original version, I had been using 3 brass fittings that are threaded on one end with barbs on the other with 1/2" ID vinyl tube running to the puke tub. When the media is new, these worked ok. But as the media wears and gets smaller, it would get down into the fittings and plug up the drains. Then you would have to remove the drain lines and unplug the drains with a punch. As you can see in the pics, this makes quite a mess.
To improve this, I switched to a bath tub style drain. This drain has a metal plate with lots of tiny holes that should prevent the line being clogged by media. The larger diameter of the tubing also helps keep things moving along nicely.
My original barrel had started wearing away at the contact points and I wanted to change the drains. Instead of patching the old one, I splurged and spent $15 on a new barrel. A lot of the noise on the old design came from various parts of the rack smacking into the barrel. To help this area, I cut several strips of 3/8" plywood to act as shims between the rack and the barrel. The strips were slid into place, with a bead of liquid nails securing each strip to the next. The barrel is bolted to the rack using stainless steel hardware. I lucked out and found some oak trim pieces that were just the right shape to act as spacers between the rack and barrel at the bolting areas.
Here she is sitting in the sound resistant box ready for action.
The above changes all have helped increase the effeciency of the machine, as well as reduce the noise output by half. The cycle time is 20-30 minutes, depending on the shape of the objects. This load had 8 pieces and ran for 30 minutes. The number of parts varies depending on the shape of the parts. Some of my larger guards can only be run 4 at a time. I make a lot of 5" long x 7/16" rods and run them through hundreds at a time.
I'm in the process of trying different size pulleys on the motor to vary the speed of the axle. I've done one change so far, and it tells me faster is better.
I need to take some shots of my stuff before and after finishing, and after they come back from anodizing so you'll have an idea of the finish quality I'm getting.
Bloody hell Unabiker, those are some serious counterweights you've got there. If you're getting any decent speed out of that motor your tub must just about be taking off! Then again, if it works and it works wel, way to go man!
What would you say your shaking frequency is at present?
The motor I'm using claims 1740 rpms at full boogie. Right now, I've got a 2.5" pulley on the motor and a 5.5" pulley on the axle. That should give me about 790 rpm at the axle shaft. Using the 3" pulley on the motor gives me about 950 rpm.
If it weren't securely bolted to the floor, it would walk around the shop at a fairly brisk pace.
Unabiker
What is the amplitude of your vibrations, say at the non-hinged end of the drum? I am busy working on plans for my model and had fairly small amplitude but high Hz (more like 2 KHz+) in mind. Is there anyone out there who have one of these on a varispeed drive and took it all the way up in the speed range?
Currently, the amplitude is about .200". You can affect the amplitude by changing the speed of the axle or by playing with the weights on the axle.
More RPM's on the axle will result in a smaller amplitude at higher frequency. Increasing the weight on the axle will increase amplitude....it will also put more stress on the machine.
Unabiker,
can you indicate to me as you are due to calculate the power of the means
excuse my English
Thanks
I think you are asking how I calculated the size of the motor used. That was easy, as I used a surplus motor that I had laying around my shop.
The power requirement could be easily figured if you knew how much the tub and media weighed, the size of the desired amplitude, and the frequency of the shake. Using the amplitude and frequency, you can figure the amount of accleration of the tub. Multiplying that by the mass of the tub and media would give you a required force.
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