DIY Vibratory Tumbler

[mxtras]

As is my nature, I am interested in building a DIY vibratory deburring machine stricktly for deburring smallish aluminum parts. I have been reading and looking around for a few days but not much on the subject of DIY units exists - at least not from what I can find, so the search is on.

What is the desired motion for such a unit?

What frequency and what amplitude is typical?

Frequency is an easy thing to adjust on the fly, but not amplitude, so having information on what works seems like a decent starting point for building a DIY vibratory tumbler.

Unibiker's home built tumbler's axis of motion creates a vertical vibration and with his recent design alteration, I can see where the motion is now almost a rocking motion. The axis of motion is perpendicular to the tub. He states he has about .200" amplitude, and he gets results. His requirements differ greatly from mine - I have no need to deburr a small car! Here is his thread:

Home Brewed vibratory finisher

The commercially available tumbler's motion looks to be 90 degrees to what Unibiker created - most available units have the vibratory motion on the same plane as the tub - horizontal, not vertical like Unibiker's.

Take a peek at this site: http://www.massfinish.com

What's the prefered motion? Circular? Random? Vertical?

What's the min/max amplitude?

Scott

[mxtras]

Some useful stuff from recent researches:

Vibratory polishers and aluminum – thread on media and strategies

Frequency vs amplitude of the vibration for a polisher – thread on amplitude

http://www.kramerindustriesonline.co...ing-guides.htm - helpful site

http://www.rhodesmktg.com/products/bowls/benchtop.htm - bowl dimensions, other info

http://www.kramerindustriesonline.co...-finishers.htm - very good, not commonly found information.

"The most common finishing equipment design has a single weight mounted on a motor that is fastened under the bowl. The other drive available has a two-weight system where the second weight is on the top of the motor in the cone center hub.

The single-weight system produces a nice rolling action from the outer edge to the center, but very little spiral action. The two-weight finishing equipment system, which is usually more expensive, produces both the rolling action and the spiral movement around the bowl, which is the same action achieved in the large machines. The spiral action keeps the parts spread out around the bowl."

More info to follow as it is discovered.....

Scott

[mxtras]

So my current thinking is to use a single, vertical shaft in the center of a cone shaped bowl. The bowl could be built from steel sheet, welded and then coated with urethane or a spray in bed liner.

This shaft could have one eccentric at the base and one at the top of the cone to create a wobble in the tub. Each eccentric or counterweight could be adjustable - possibly on-the-fly if I can figure out how to accomplish that but on-the-fly adjustment is not necessarily a requirement.

I am also thinking about 3/8"-3/4" of total amplitude with variable speed. If I can adjust the speed and the amplitude, I could create the motion needed for each batch of parts. I like having flexibility - especially when I don't really know what the heck I am doing. I have even come up with a way to move the upper eccentric/weight up or down on the center shaft to alter the rocking action.

It also looks like this equipment supply market is a bit thinly populated (small, full feature equipment under $1500).

Thoughts?

Scott

[Stepper Monkey]

I have three pretty generic cheapo units that came with fixed weights, but quickly found the need to modify them by making adjustable weights for them
(a big cap screw tapped into the hub at 90 degrees to the shaft, two stainless nuts to run up and down the shaft and lock together). I also found adding cooling fans to the ends of the shafts very useful as they can get pretty hot after a few hours run time.

I can't see that an on-the-fly adjustable weight is necessary, but adjustable weights and speeds are definitely useful. Actually, most fine control seems to be best done by just adjusting the weight of the load, or just water level if its running wet. Between all those variables you can control amplitude and frequency which is nice to find the sweet spot for any material.

[Harryman]

I would suggest that if you want to make a concentric vibratory tumbler to buy the bowl. A metal one would be loud and I don't think you have much luck with any coating staying on. Between the abrasive media wear and it hammering away at the bowl, it'd be toast.

Figure on experimenting with frequency (shaft rpm) and amplitude (weight and offset) and design that in. The amount of parts, media and fluid you run will all effect the results as well.

A tub tumbler made with a plastic barrel or other container would be the easiest if you want to go from scratch.

[Stepper Monkey]

What he said. If you aren't going to modify an existing unit, at least buy a standard replacement bowl for an expensive commercial unit and build the rest from there. They are readily and cheaply available from all manufacturers as they are standard wear items.

I think a metal bowl would be a relatively bad idea as well. The commercial units (that type anyway) don't use them either, probably for good reason, which may only be the horrible noise or maybe more, I don't know. In any case no coating would stand up for long at all, that is a guarantee!

[Unabiker]

Sorry to be a bit late to the party.
I agree with the others that you would probably be ahead of the game going with a pre-existing plastic based tub instead of a metal one with a liner. Any sort of goo that you could spray in place will most likely come off too easily or leave marks on the stuff your de-burring. I went with the recycled plastic barrel, mainly due to the fact that they are nice and thick, and I can buy them localy for $5 each. You may want to take a look at a 5 gallon bucket.
Regardless of the tub used, you will want to make adequate accomodations for a drainage system. I started off using 1/2" hose with barb fittings on mine, and that pretty much sucked. It would clog easily with either media or the goo produced by shaking. I'm currently using a bathtub drain setup with good results.
I'm not sure how usefull on-the-fly adjustment of the weights would be. Once I got it pretty close, I left it alone. I haven't messed with the weights in over a year. I do all the adjustment on my machine via speed control, media load and juicing frequency.
Another thing I would reccomend to consider during the design phase would be some sort of sound proofing. I like my shop a lot better after the last shaker upgrade and big sound resisitant box.
Keep us posted.

[mxtras]

Well - I went out and purchased a very small tumbler from Horrible Freight. The little unit works pretty well but it is very small - too small for my liking. I bought it to use as a learning tool - I am a babe in the woods when it comes to mass finishing. For $38, I treat this tumbler as a research tool.

I bought several varieties of media. I doubt I have the right stuff and I doubt I have good quality media. Remember - I am wanting to deburr aluminum parts, not polish them. I want to create a small radius on all edges of milled parts.

Call me crazy, but the best results so far have come from using lava rocks with a small amount of water, even though the tumbler directions say not to use any liquids. The lava rocks are very light in weight so the action in the bowl is excellent and this "media" is rediculously cheap. The down side is the lava rocks leave the parts with a red hue - not an issue for me since I am not anodizing. A quick dip in welding-prep acid and the red is gone. The lava rocks also wear very quickly, but I get the desired results in less than 2 hours where it took over 7 hours with the much, much more expensive media to achieve similar results. Also - as the lava "media" wears, the results improve and the time required drops. The lava rock feels like pumice and that was the idea behind trying them. I am very pleasantly suprised. A big bag of lava rocks cost $2.50. I know, I know - I am a cheap SOB, but that's how I roll.

Still researching and looking. I need a larger capacity machine - this little POS research tumbler will only hold about 20 pcs at a time and I have several hundred pcs to deburr. My recent purchase is not the answer and I knew that before I bought it.

This is the machine I want: http://www.massfinish.com (video of it in action, too! WooHoo!) It's a bit out of my price range at the moment....maybe next year.

Thanks for chiming in, all! Feel free to flame......

Scott

[Harryman]

Hey, I'm all for cheap! I've made plenty of tumblers because I hate to spend money on something I can easily make.

The pumice is probably a good thing with the HF tumbler, as any significant weight would probably fry the thing ASAP. You could buy a bunch of them just for the bowls.

With a larger tumbler, you could use a coarse ceramic media if you want an agressive cut down and don't need a nice fine satin finish, it'll cut pretty fast. It's just like sanding, go to a finer grit in stages to whatever finish you need.

Always run wet, it'll keep the media clean which means it cuts faster. Set up a flow through system with a settling tank if you can.

No matter what you end up with, you'll have to experiment with media and water levels to get the best results.

[mxtras]

The use of lava rocks continues to appear to be a very good, economical, novel solution.

Last night, I was able to obtain a very uniform, 1/32" radius on all edges of 25 pieces in 2.5 hours in the extremely small Harbor Freight tumbler. This was using a small amount of water (maybe 1/2 cup) and about 1/2 of the tub full of previously used lava rocks with a small handful of new stones added.

The downsides to using the lava rocks are that the rocks wear pretty quickly (actually not necessarily a disadvantage) and the parts are left with a red tinge. The color is easily removed with acid, but that produces waste and might be a big problem - jury is still out on this aspect. Again - I am NOT anodizing, so surface contamination is not an issue for these parts. If they were going to be anodized, I would not use lava rocks for deburring!

The benefits are that the rocks are dirt cheap, very light in weight and work extremely fast.

Scott

[Harryman]

The red's got to be from iron oxide in the lava. Maybe vinegar or Lime Away instead of whatever acid you're using? Wouldn't have as much of a disposal situation then.

[Unabiker]

There's nothing wrong with cheap, especialy when it allows you to try a lot of different things. Even if you burn it up, you'll only be out $40.
You may want to try some ceramic media. It's not as light weight as lava rocks, but it could dramaticly cut down your cycle time. It would probably help you with the staining as well.
I wonder how pea gravel would work.
As you have seen, some sort of juice in the bowl helps with that, too. McMaster Carr sells media in 10lb bags. That may be a reasonable way to try out different medias. I also occasionaly see media variety packs on fleabay.