[mhackney]

This thread motivated me to do a little research on media between the pyramids and walnut shells and the posts above about ceramic ball media is right on track! I ordered 10 pounds of 3mm porcelain balls to give it a try and will report back in a week or so. I don't know why I didn't do that before, might have saved me a lot of time! Shor has some great information and options on their web site.

Sorry John, can't help with UK sources. Try googling "vibratory tumbler" and "vibratory tumbler media".

Cheers,
Michael

[RomanLini]

I don't use a tumbler but I did notice people suggesting dishwasher soap.

Generally dish soaps are quite acid or alkaline, which is designed to remove specific food residues. It's generally considered quite bad to use dish soap on metal as it is corrosive, and it is known for destroying non-stainless parts of a dishwasher.

On the other hand, soap and detergent designed for washing cars is designed to be PH neutral and will not cause metal corrosion. So a bottle of "liquid car wash" is probably a better choice of soap. I have some in the workshop for any time I need to wash sanded aluminium etc with soap.

[mhackney]

RomanLini, thanks for that, I never considered that. It turns out that the media suppliers all carry liquid polishing additives/soaps specific to different media like steel, plastic, ceramic and porcelain. I ordered some for the porcelain ball media I ordered yesterday.

It makes sense on the car soap being formulated for metal! And it is low suds usually.

cheers,
Michael

[pete from TN]

Hey man interested to hear how you get on with the new media. Thanks for looking into alternatives to the green stuff. Sounds like you have quite some experience with these tumblers and I for one would like to hear what you find....peace

Pete

[SCzEngrgGroup]

Keep in mind much, if not most, ceramic media is NOT abrasive. It is basically just a carrier for the abrasive, which must be added separately. I have a large vibratory finisher (about 24" diameter), with large ceramic media. If I put parts in there without abrasive, even for 24 hours, they'll come out looking just like they went in, with just a few more scratches. It's usually used with an abrasive slurry, or even dry abrasive, like rouge, pumice, etc.

Regards,
Ray L.

[BobWarfield]

Keep in mind much, if not most, ceramic media is NOT abrasive. It is basically just a carrier for the abrasive, which must be added separately.

Regards,
Ray L.

No, actually not true of most commercial ceramic media, though I can't vouch for the Asian imports.

Normally, when abrasives are added, it is only done occasionally to knock the glaze off the ceramic so it will cut again. The media itself should have abrasives bonded into the clay, and that's why you have to choose from several grades.

Here are some good resources for reference:

Vibra Finish has a good sized pdf from Cutting Tool Engineering (good mag, BTW): http://www.vibrafinish.com/pdf/white...icle1-full.pdf

Kramer Industries finishing guide has a shorter more introductory discussion:
Metal Vibratory Finishing Techniques, Vibratory Tumbling Process, Vibratory Finishing Information, Vibratory Finishing Tips, Vibratory Finishing Help

I use Raytech: Raytech Metal Finishing

Lots of products out there, lots of information. There is a lot of knowledge required to optimize these processes for best industrial efficacy, but you can get great results pretty quickly and save yourself a lot of work with just a little reading or advice from the been there done that gang.

Cheers,

BW

[mhackney]

Just a quick update. My ceramic ball media FINALLY came in so I can set up to do some tests. Meanwhile, I have a tweak to do to my flow through system and then I'll post photos etc. I am still VERY pleased with the large HF vibrator. I have it sitting on top of a 3 1/2 gal bucket that holds the water. A nice compact setup.

Here is something interesting. I used Simple Green in the water as per the advise above. After 3 hours in pyramids the aluminum and brass parts actually came out quite nice. Just for grins I left some parts in for another 10 hours (13 hrs total) and the brass parts just looked a little more polished but the aluminum parts picked up a dark grey coloration that is quite durable:



This is GREAT if it is reproducible! This grey aluminum patina looks fantastic on fly fishing reel part and I've been experimenting with various chemicals to get something I like. I suspect that the solution is basic and the color is the result of oxidation. I'm going to experiment to see if this is reproducible next.

I'll report back on the ceramic ball media too.

cheers,
Michael

[rwskinner]

Just curious, How many pounds of triangle media did you have in there?

Richard

[mhackney]

Richard, 15 pounds of the light green media. Could probably hold another 5 pounds. The water was a slow trickle through.

cheers,
Michael

[TXFred]

Michael,

I've been getting good results from my HF tumbler too. I rigged a flow through system as well, and it eliminated the grey aluminum. In my case, the water doesn't recirculate. I connected a garden hose to the upper port, and let water trickle in and then trickle out the drain. It then flows down my driveway and waters my lawn.

I've made another modification to the tumbler, which I suggest you do as well. The drain can be clogged by a single green pyramid. To fix this, I cut a couple of pieces of 1/8" welding rod and jammed them in the drain fitting to form an X across the drain's opening. This has prevented clogs, which is pretty important with my garden hose setup.

I'm still seeing tool marks after running for 4 hours in the pyramids. But any more time and my chamfers get eaten up. I'm making some tooling and programming changes to see if I can reduce the tool marks. I cut the feed in half for the finish passes, and used a stone to break the corners on my end mill, turning it into a bull mill with a corner radius of 0.01" The parts from that test are in the tumbler now, so I'll have results later today.

I'm looking forward to seeing how the ceramic media performs.

Frederic

[mhackney]

Hey Frederic, for short (2-3 hr) runs the parts do not turn grey at all, so I can control that. I am getting very good results after tweaking my CAM and tooling. I rough at .01" over and then finish pass. I actually go faster on my finish pass. I posted a video over the weekend on my milling process - it's on my X2 thread. 3 flute .125" end mill, 4300RPM 15IPM rough, 20IPM finish.

I discovered the plugging problem too! I just used a little piece of that nylon pot scrubber and stuck it in the plastic drain nipple fitting. It will work fine for the 1mm to 3mm porcelain balls I got too.

cheers,
Michael

[doorknob]

Meanwhile, I have a tweak to do to my flow through system and then I'll post photos etc. I am still VERY pleased with the large HF vibrator. I have it sitting on top of a 3 1/2 gal bucket that holds the water. A nice compact setup.

Just wondering whether you are at the point where you could post photos of your flow-through system.

I have the large HF tumbler, although I have only used it once, with the green pyramids and no flowing water, using dawn soap on 6061 aluminum. My parts were really too large for the tumbler (4" x 6" x 0.5"), or maybe I had too many parts in the tumbler at the same time. I had trouble with some of the parts rubbing against and putting deep gouges in the other parts, and I found that the media would get stuck in some of the drilled holes (X or Q drill sized holes, for example), and would be hard to dislodge.

I'd like to improve my system and technique, and so I'm interested in seeing how others are doing things. My goal is to remove machining marks from drilling holes in some brackets that I will be making of a similar size (but only 0.250" thick). I will not be doing further finishing to those parts (no anodizing, for example).

These brackets will be used outdoors, in the rain and snow and sunlight. What I've been wondering is whether using a somewhat basic cleaner (such as Simple Green) will end up causing more or less corrosion in the brackets when used outdoors. In the past I have used a sodium hydroxide bath (if I am remembering correctly) for something like twenty or thirty minutes to put a light/whitish finish on the otherwise plain aluminum mill finish, and I expect that Simple Green will do something similar, but I have never tried exposing those treated parts to the weather. Time for some experiments, I guess...

BTW, I noticed that your aluminum reels treated with Simple Green and ceramic media came out with a grayish finish after a few hours. Are you using 6061 or some other alloy?

Also, I vaguely remember reading about a variety of Simple Green that is not basic, and that is recommended for aluminum aircraft chassis use. (I don't remember where - maybe it is even mentioned earlier in this thread). I'll have to keep an eye out for that version and give it a try.

[mhackney]

I don't have time to shoot and process photos right now - I have a big workshop on Saturday and I am still making up kits! Basically, it's a 3 1/2 gallon bucket with a plywood disk screwed to the lid. The vibrator sits on the plywood on top of the bucket. 3 gallons of 2 water in the bucket with the hoses coming up through a hole in the lid/plywood. I have a 5 micron filter (McMaster) that the output water drips into back in the bucket. That's about it.

cheers,
Michael

[mhackney]

The 10# of 3mm porcelain balls is about 1/2 of what I need for the HF 17# vibrator. I ordered 10 pounds of mixed 1, 2, and 3 mm. The info I've read said that mixing the ball sizes is a good idea so the spaces between the large balls are filled in for more efficient polishing. I should get them this week or early next. I have some parts in the vibrator and balls now just for giggles. I did get the Burnishing Compound D to try with them too.

Within an hour, those grey parts I posted a photo of above were aluminum silver again. I'll let these run for a while. They are small parts and I am getting good turnover even with 1/2 the amount of media I should have.

regards,
Michael

[mhackney]

I did a test in the 3mm porcelain ball media with Compound D (a liquid additive for burnishing). Ran for 12 hours with a very slow drip of water/Compound D to keep things wet and remove grit. I also added a 3"D brass part to the mix to see how it would come out. Here is what I learned:

1. Using the proper amount of media is critical. The parts did not roll over as nicely with a 1/2 full bowl as they did with the proper amount of pyramids (20# in the HF 17# machine). I have another 10# of balls on order.
2. Don't mix aluminum and brass in the same run! The brass came out looking fantastic, almost polished. I was very impressed with that. The aluminum parts would have looked great too but they had a lot of little scratches - most likely from where they bumped into the brass part. That makes sense in retrospect.
3. A slow drip of solution is really all that is necessary. The bowl looked great inside when I opened it, no grit, no foam, just nice clean balls and parts.
4. So far, taking a part right off the mill into 2-3 hours of green pyramids and then 12 hours of porcelain balls should give a very nice surface that could easily be hand polished to shine. However, I do have 1 more vibratory step to experiment with - walnut shells with a compound. I have red rouge and ruby powder. I have tried rouge in the past and it seems to do a good job but left a red residue that was a bit of a pain to remove. I think the ruby will be a bit more aggressive and not leave a residue.

cheers,
Michael

[mrcodewiz]

My final step is Graves Tumble-Dry Green which does a good job. I have tried to make up my own Walnut shell mixture in the past by adding red rouge as well as green (different mixes) and neither ever did as good a job as the Graves stuff. I'm not sure why. Maybe they somehow bake the rouge onto the shell whereas i added the powder to the walnut shells and let them tumble for a couple days.

[mhackney]

I'd like to try that and maybe their red for brass too. I know the quality of the media can make a big difference. How much of the green media is needed for the 17# HF vibrator?

cheers,
Michael

[mrcodewiz]

I don't recall for sure. I know I didn't buy enough the first time around. I think I may have ended up getting 2 of the 5 pound bags. You really need to fill it up to the top. I will check tonight and see how much I ended up with.

[mhackney]

Great, thanks.

Michael

[TXFred]

I'm using corn cob and red rouge from Grainger. It was readily available, and seems similar to walnut shells.

They take aluminum and brass to a very nice shine, that is only marred by the pitting left by the pyramids.

I am eager to see how your walnut shells work in conjunction with the ceramic balls.

Where did you get the ceramic media? I suspect that I'm going to want some.

Frederic