Vibratory Tumblers - Media.

[luke]

[bofh]

I've used sand in my pinball tumbler, it's work OK. No where are as good as the walnut shells, and it was much slower.

But Sand is cheap.


Maybe if you get coarser sand that I, (I bought very fine sand for detail areas)

[luke]

I've used sand in my pinball tumbler, it's work OK. No where are as good as the walnut shells, and it was much slower.

But Sand is cheap.


Maybe if you get coarser sand that I, (I bought very fine sand for detail areas)

I've considered glass bead, and will probably try it. It will probably take something a little more aggressive though.

Walnut shells would work great, but they are pretty expensive after shipping, especially for as much as I need. I may have to break down and buy some.

[behemoth]

I've considered glass bead, and will probably try it. It will probably take something a little more aggressive though.

Walnut shells would work great, but they are pretty expensive after shipping, especially for as much as I need. I may have to break down and buy some.

go to the grocery store and buy walnuts.

You get to eat it, and then use it in your tumbler

[luke]

I would weigh 400 lbs by the time I had enough.

[CoolHand]

Walnut shells will polish, but not make the first cut. You can load them with rouge, or polishing compound, and help them out some, but they will never cut like ceramic will.

I'd say your best bet for cheapo first cut media would be bulk Novaculite.

You can buy it from McMaster Carr for ~$36 for 50 lbs, and it will certainly cut better than even rouge loaded walnut shell.

It needs to be run with a cutting fluid, or a detergent at the very least, to keep it from loading up with metal, but its very hard, and very long wearing.

Give that stuff a shot, or if you have a good local source for clean quartzite rock, you can just take a shovel and snag you some. Limestone won't cut, but quartzite or granite chips will. Unfortunatly, unless you live around an old gold mine, you aren't likely to find a big pile of quartzite just waiting to be pillaged. Lanscapers will have it, but they are likely to want as much for it as McMaster does (if its graded clean enough).

I would go for the first cut with the Novaculite, and then hit it with the rouge loaded walnut shells, then finish with dry corn cob for a hard core shine.

Good luck with it, and you know you have to post a pic when you get it built.

[luke]

Walnut shells will polish, but not make the first cut. You can load them with rouge, or polishing compound, and help them out some, but they will never cut like ceramic will.

I didn't know that, thanks.

Give that stuff a shot, or if you have a good local source for clean quartzite rock, you can just take a shovel and snag you some. Limestone won't cut, but quartzite or granite chips will. Unfortunatly, unless you live around an old gold mine, you aren't likely to find a big pile of quartzite just waiting to be pillaged. Lanscapers will have it, but they are likely to want as much for it as McMaster does (if its graded clean enough).

I would go for the first cut with the Novaculite, and then hit it with the rouge loaded walnut

Actually Cottonwood use to be a major mining town, they smelted all the ore though, I was curious if the slag from the smelting process would work, it's like glass. (?) And there are several acres 50' tall....

Landscaping granite is all over the place here, 9 out of 10 homes use it for landscaping.

[luke]

CoolHand,

I have several ideas for VT, but have never seen one first hand. I was wondering if you could explain the mechanical function of a standard VT, as in how the vibration created? With an off-set weight mounted to the shaft maybe?

[CoolHand]

CoolHand,

I have several ideas for VT, but have never seen one first hand. I was wondering if you could explain the mechanical function of a standard VT, as in how the vibration created? With an off-set weight mounted to the shaft maybe?

There are two basic types:

Round Bowl
Square Tank

Both are suspended on spings, and both are shook by a motor with an offset weight attached.

The round bowl type the motor is mouned underneith the bowl, and it spins the weight around a vertical axis, which when coupled with the sping suspension, creates a kind of wobble about a point down below the whole machine. This wobbling action goes along with the doughnut shaped bowl to create a circular stirring action inside the media. The parts stay put more or less in their position around the bowl radially speaking (when looking from the top), but will be run around in little circles inside the cross section of the doughnut (looking from the side).

The Square tank type has the motor mounted on the chassis at one end of the tank or the other, and spins the weight along a horizontal axis perpendicular to the long axis of the media tank. This arrangment produces a kind of lower case cursive "e" shaped path, over and over again, and promotes travel from one end of the tank to the other, as well as travel up and down through the media during the trip. Since this kind of tumbler forces movement along one axis more than another, it is perfectly suited for continuous processes. That is to say that the parts come in one end, make their trip through the tank, and come out the other end finished with their pass through that particular media (ready to go to another media, in another tumbler down the line), all without anyone being there to watch them. The residence time in the tank is controlled by the length of the tank, the length of the throw on the eccentric, and the RPM of the motor running the weight.

You can build either type, and either type can be used for batch tumbling (though you might have to stir or reposition parts in a short tank if a long tumble is needed).

The box type seems to me to be much easier to build, but since they are usually bigger, they are more expensive as well (bigger motor, more media, etc, etc).

The required shape of the bowl for a bowl type tumbler to work right makes creating them yourself a bit tougher. If you have a lot of sheet metal working skill, you can do it yourself, otherwise you are better off buying the bowl and building the rest.

OR if you don't need a huge one, you can buy bowl tumblers for reloading, or really serious rock polishing for about $2k new, or a bit less used (though a used tumbler will likely be ragged out).

Good luck, we tried a similar project ourselves, but found it to be cheaper in the long run to just stick with an anodizer who will do the surface prep themselves.

[luke]

[CoolHand]

Yeah, that will work just fine. Though you will need to take precautions to keep the parts from ricocheting around inside the container. The media needs to kinda groove on the part, not slam dance on it. Plus, if the parts start running into each other, they will dent and ding, and that is counter productive.

I'd say you'll need to decrease the size of the stroke to keep bounce in check though.

Other than that, it seems like a fairly sound plan.

[luke]

Yeah, that will work just fine. Though you will need to take precautions to keep the parts from ricocheting around inside the container. The media needs to kinda groove on the part, not slam dance on it. Plus, if the parts start running into each other, they will dent and ding, and that is counter productive.

Interesting, I was trying to create more "action" with the springs. It may work without mounting the container with springs.

I can easily set this up with smaller containers that hold only one part.

I'd say you'll need to decrease the size of the stroke to keep bounce in check though.

The hammer only has a stroke of 3/8", but that is easily designed around if necessary.

Other than that, it seems like a fairly sound plan.

I'm afraid my other design may be to aggressive, unless I used glass bead or something....

[CoolHand]

Interesting, I was trying to create more "action" with the springs. It may work without mounting the container with springs.

I can easily set this up with smaller containers that hold only one part.

The hammer only has a stroke of 3/8", but that is easily designed around if necessary.

I'm afraid my other design may be to aggressive, unless I used glass bead or something....

Well, you've got to understand that by adding more "action", you are actually just sand blasting with 3/8" clean aggregate, which will not polish, but shot peen, and that is not what you are after.

For this to work you need two things: 1) Media contact with the part. 2) Motion.

You just have to be careful that when getting #2, you don't reduce or eliminate #1. The media is grinding or scraping off tiny bits of metal, impact will not aid this, it will actually make the process slow down or stop alltogether.

Ideally, you want a stoke equal to the nominal size of the biggest media you will use. 3/8 of an inch sounds about right for first cut stuff. From the look of the thing, I thought it was gonna have a 2" stroke.

If you line the containers with some kind of deadening material (like rubber sheeting), and keep them nearly full (maybe an inch air gap at the top when fully loaded), and then lid that bad boy up, you should be good to go.

I'd sure give it a try at least. What's the worst that could happen? Some poorly finished parts? Eh. I say go for it.

Post some pics of the results if you do try it.

[luke]

I think we are close in our thinking(me guessing of course) with what will happen. I agree with keeping the container almost full.

I may just modify my hammer for a test run, just to see if the design will work. I can probably build something in a few hours; if it works I can build a complete machine with multiple containers...

[billybob_81067]

Cement mixer + sand