Some background. I do some restoration work that requires cleaning up lots of small parts. I have been doing this by hand for a long time. Its gotten old, so I decided to solve my problem. Some research into polishing parts turned up 3 basic ways to do it. By hand - done that. Tumbling or Vibrating machines. I found several good sites and info on building a tumbler polisher. Not difficult or expensive but polishing time seemed to be long. I had a hard time finding info on Vibrating polishers. Seems nobody has a site on a small homemade bench top sized machine. I found that they could be had on Ebay for about $65 and new from several companies for around $100. But there was some concern about them handling much weight as most were advertised for polishing brass shells. The commercial machines were in the $200 plus range, not for me.
The goal - Build a vibrating polisher for less than $50 that works and can handle a couple pounds of steel or aluminum parts. I wanted to see if my junk (treasure) pile was up to the task.
You need 2 things to make this work. A bowl to put parts in that isn't affected by your polishing media and a way to make it vibrate. The vibrate part seemed easy enough just mount a weight off center to a motor shaft and watch it shake. I scrounged a motor and weight from a vibrating recliner (Lazy Boy). Now the bowl. Seems simple right? This is the part that stumped me for a while. The common materials used in commercial machines were some form of plastic or rubber. The shape of the bowl was the problem. We need nice gentle curves to encourage the media and parts to circulate both around the bowl and top to bottom. So a bucket was out because it has hard edges at the bottom and parts could get stuck. While moving a box of wheels one day, there it was. A single lonely tire with nice curves.
Click here for a basic drawing showing most of the parts. - Opens new window
The dimensions given here are based on the size tire I had and the motor. You should collect these 2 items and build accordingly. The tire measures about 11" diameter. I cut a piece of 1/2" plywood 12" square for a base. Knocked off the corners just for looks. Cut a 3" hole in the center for access to the motor shaft, weight and fan. 4 - 3/4" thick spacer blocks 2.5" x 4" were evenly spaced inside an 11" diameter circle glued and nailed to the base. A 1/4" diameter plywood disc was glued and nailed to the top of the spacers. I cut an 8" diameter hole in this disc so the motor could pass through..:
We need to have a way for the bowl to vibrate. Securing it directly to the base would make the whole thing dance. I used 4 lawn mower (5 hp) valve springs mounted to the base. Take a 1/4" washer slide it on top of the last coil and screw it down with a #10 x 1" wood screw. Make an 11" disc from 1/2" plywood sit it on top of the valve springs. I used 1/4" x 1" bolts through the disc with a 1/4" washer in the top coil of the spring. Locktite on the nuts so they don't vibrate loose :) There is a trick here to tighten the nuts. I'll tell you later.
Before you mount the top disc you need to mount your motor to the bottom of the disc. This will depend on the type of motor you have. Mine came with a flat steel bar attached. So I just bent the bar into a U shape around the motor and screwed the bracket to the disc. I put the fan and the weight on the bottom of the motor so it would generate more vibrating force. I found that it was better to have the fan closer to the motor and the weight on the end of the motor shaft. You will also need some way to mount the bowl to this top disc. I used a 3/8" x 16 tpi T nut. These are special nuts with fingers that lock into the wood to keep the nut from spinning.
Now the bowl. I cut 2- 3/4" thick plywood discs to cover the space where the wheel would be. One on the inside and 1 on the outside of the tire. Again a T nut was used on the outside disc. A piece of all thread through both discs and a washer and nut on the inside of the tire to squeeze it all together. I covered the inside disc with rubber roof material for protection. Used silicone around the edge to make a nice tight seal. The rod needs to stick out the bottom about 3/4" inch so it can thread onto the base section. It also needs to be about 1.5" longer on top for a knob to close the lid. I found that by cutting away part of the side of the tire on top made access much easier and did not effect the use. I am currently using a 1/4" piece of plywood for a lid. I will be changing that to something clear in the future.
Initial Testing - There seems to be a lot of choices for media. I had initially decided to use walnut shells from a pet store. They are used to line the bottom of bird cages. Calls to the local stores turned up only corn cob. This works for soft metals like brass and aluminum but does take longer and does nothing for steel. When I discovered a local source for polishing supplies I was told that steel should be cleaned with a medium sized plastic cone media and water. Then switch to walnut shells impregnated with polishing compound to get a nice polished finish. Some research showed that plain walnut shells with Flitz polishing compound would do the same thing. The local supplier agreed. Turns out that a 50lb bag is $32 from the supplier and the pet stores wanted $15 for a 10lb bag. It pays to look around and ask questions.
On the Left is a sample from the first test. The top handle has been cleaned with sand for about 5 hours. The middle handle was in for about 3 hours. The bottom is what they usually look like before cleaning. I hope to get the walnut soon and do some more testing. Stay tuned for updates.
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