http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96923

I have little experience with finishing so have read through this forum to try to learn. It seems most interest is in polishing.

I'm in need of removing tool marks from aluminum parts I'm milling. Polishing is not required, just a matte finish. Nothing is dimensionally critial either, no threaded holes. And the parts will be anodized. Will the above HF tumbler be cost effective? If so, what is a reasonable media and expected time for just removing machining lines? The little green plastic things? An aggressive media is ok with me.

Or am I better off just using a blast cabinet?

Thanks in advance.

One of the many problems with small bowl types is the bowl itself. Because of the curves the parts have to be fairly small. Of they will wedge in and just sit there. Also they don't have much power so they don't put much power into the part or media. Which means it might work for you but you might have to let it run for 48 hours or so.
Gary

I do have this tumbler. Just got it maybe a few weeks ago.
Tried the green plastic media for deburring 6061. Wasn't all that good at two hours. Went with some mild ceramic type media and the result is much better for me at 1 hour cycle time. Deburred all the parts but leaves a dull surface. I don't have tool marks as my parts are profiles, but they are smooth.
The parts get powdercoated so the surface finish is perfect. I do have to wash the parts.
I haven't yet tried it with the liquid dripped in, but will at some point.
For now, I'm impressed with this machine.

Thanks for the input. The parts I am considering this for are about .75" x 1.5" x 4.5" so I think they should fit decently inside the bowl of that 18lb HF unit. I do all the deburring on the mill already so I'm only chasing the surface finish issue at this point. A blast cabinet would be faster but requires more human attendance. The appeal of the tumbler is to drop the parts in and be free to go work on something else.

Leeway, what is the ceramic media you are using?

... Deburred all the parts but leaves a dull surface...

....The parts get powdercoated so the surface finish is perfect...

I suggest trying to get some samples before spending the money. We have a bigger version of this type of vibratory finisher and it is does deburr nicely and the parts are dull and we think they look horrible after anodizing. I can see it would work with powder coating and could even give some 'keying' on the surface for better adhesion, but for us it is the category of failed experiment because we anodize almost everything.

So far I get good results with the PCing. I do want to do a test of just wiped down or blown off versus rinsed of with water. I will also test when I start using the cleaners inside the bowl. That would keep the dust rinsed out of it. Just do soemthing like a few drops per minute.

I only used 10 pounds to start with, but feel I need a little more for my larger parts.
They are 5" by 1" by 3/8".


The ones I have tested are about 2" by 2.5" .063" sheet.

I get the media from Mcmaster Carr.
A little pricey, but should last quite some time. Not that costly when you consider the man hours it is actually saving me.
I am using the small 3/8" by 3/8" 60 degree triangular fine ceramic media.

http://www.mcmaster.com/#about-tumbling-media/=338hsh

I suggest trying to get some samples before spending the money. We have a bigger version of this type of vibratory finisher and it is does deburr nicely and the parts are dull and we think they look horrible after anodizing. I can see it would work with powder coating and could even give some 'keying' on the surface for better adhesion, but for us it is the category of failed experiment because we anodize almost everything.

Geof,

Can you elaborate on "horrible"? Do you have pictures for comparision perhaps? How do you finish your parts now?

Powder coating is not a viable option for these parts unfortunately.

I wouldn't really use it for anything but powdercoating.
I can do a decent job of deburring these parts by hand using about a 120 belt sander or even a ROS. I will try to get some pictures of my parts as soon as I can.
I'm now not so sure it will work that well to remove machining marks with the fine ceramics. I think you would need to use medium to coarse or a combination of those. These little drums aren't really designed for the rough stuff. The little manual actually warns against it citing premature drum wear.
The finer stuff may work for you, but take longer cycle times. I haven't ran mine more than an hour at a time. I have an electric timer that it plugs into.

I am building a larger one with coarse ceramics for my steel parts. No quite yet done with it. Actually my first iteration worked, but was a poor design. Few little changes should make it much better.

...Can you elaborate on "horrible"?....

...

Do you not like my technical terms? :D

Dull and mottled, not an even mat finish. Sorry I don't have any pictures.

We were trying to using tumbling for removing burrs not for finishing the surface but the surface effect was so negative we had to try a different approach. Normally we anodize parts with the as-machined finish.

Leeway,

I don't mind the cost of the media if it would do the job. How coarse do you think is "too" coarse for these bowls?

Do you not like my technical terms? :D



I am familiar with the technical terminology. However, I wasn't sure if you were using metric or English units of "horrible". :) Would I mulitply or divide by 25.4?

Here's what I'm making. There is one more operation to do yet. The part will be attached using bolts through the slots. If the part is powdercoated, the paint will chip off when the bolts are snugged down. Thus the anodizing.

When it comes off the mill, there are no sharp corners as all deburring happens on the machine but I was hoping to get rid of most of the machining marks prior to anodizing.

Should I just blast these instead?

......When it comes off the mill, there are no sharp corners as all deburring happens on the machine but I was hoping to get rid of most of the machining marks prior to anodizing.

Should I just blast these instead?

Why is it necessary to do anything? Maybe I am a bit quirky but I find nothing wrong with a smooth machined surface.


Incidentally your factor of 25.4 would probably work; if my horrible mottled blotchiness was scaledd down by this amount then it would probably translate into a nice even mat finish which would be okay. But I suppose the way to get this is with very fine glass bead blasting.

Why is it necessary to do anything? Maybe I am a bit quirky but I find nothing wrong with a smooth machined surface.


Incidentally your factor of 25.4 would probably work; if my horrible mottled blotchiness was scaledd down by this amount then it would probably translate into a nice even mat finish which would be okay. But I suppose the way to get this is with very fine glass bead blasting.

I am the same way about tool path evidence. However, the retail market disagrees and prefers no clues about manufacturing. Philistines and heretics they are. :D

A friend sometimes asks me to make things for him. He prefers maximum tool path lines be visible in the finished piece so that it is clear a CNC was used to produce the part. I am happy to oblige.

I make faceplates out of 16 ga 6061 ~1"X4". I tried a tumbler like the HF and found it to not work well. I bought a small plastic bowl cement mixer from Home Despot and use 5/8 ceramilite from Raytech mixed with silica sand and some dawn to cut the oil. I put in just enough water and mix for about 20 mins. I use an Alodine process tho to finish them. I have to agree with others tho. It looks like the as-machined finish is more gooder.

I'll try to run a few parts tomorrow and take a couple pics.

This will dull that finish big time. Not only dull it, but darken as well. Even more so than bead blasting. I actually liked the glass bead finish I used to get. Pretty time consuming though.

I did run some water through the drum this evening and cleaned out most of the dust. It is much quieter with a little water inside.

I didn't get any new parts ran as planned, but came across this thread that may be helpful.
http://www.cnczone.com/forums/showthread.php?t=67225

I guess I didn't stress properly in my last post the right amount of water is essential. Too much and it affects the finish - too little and it comes out black or dirty.
Use just enough Dawn soap to cut the oil and maybe a touch of TSP.

Here are the images of some of my parts. I vibrated these for an hour. Could have stood another. I had less than a pint of water and a few drops of liquid cascade. They came out ready to powder coat once rinsed. The milling marks on the ends are covered up by PC, so that is fine for my needs. For the other parts shown on here, I imagine it would take a few hours per cycle. Depending on what color the parts will become, it might work okay.

Leeway,

Thanks for the images. A few hours cycle would be acceptable if I could put a few hours worth of parts in. The parts I'm working on take about 10 minutes to complete. Might be worthwhile.

I'm going to the anodizer tomorrow so I will ask them some questions while there about tumbling. Maybe they can show examples of other parts that may shed more light on this.

Kimfab,

Is the water and soap a trial and error process? Or is there a general rule based on the amount of media being used?

I'm afraid the water and soap is trial and error. For my stuff I have the sand and media in the mixer and the water is just barely to the top of the mix. The soap is added till it just barely has foam. I add TSP to clear it up and once in a while add a little clay to make it clean up the oil some more. I use mobilmet gamma for my punching but occasionally have to use omega because of the alum, that's when the clay comes in

I wouldn't mind spending the few hundred bucks it would take if I knew I could get the intended results. I may just blast these first ones and see how they sell before investing too much. Or I may see if someone local will run them through their equipment for a reasonable price.

Thanks for the help so far.

Definitely a trial and error thing. This is why when you want to buy larger machines, the sellers will develop a specific process or recipe for your specific needs before you buy.
In my case, I started building a much larger machine for my steel parts and then stumbled upon this 18 pounder at HF. I had intended to build a smaller one about this size for my aluminum parts. Working out the recipe in this smaller one is a whole lot cheaper than it would have taken in the larger. I knew though that I needed the rough grade ceramics in the larger one, so bought those. I have 100 pounds in it now. Probably a little more than $150. The machine cost me maybe $200 in parts, but I had a lot of parts on hand. Most of the bought items won't even be used now with a newer simpler design.

By all means, if you can get someone to run a batch of your parts for you, that will save a good deal of money and frustration.
When this will work best for me is when production is ahead of my finished needs. Then I can just throw a dozen parts into the drum every time it quits. That would be about 60 parts a day in two hour cycles. That is about a weeks worth of shipping. for me. It will start to show it's labor savings pretty quickly I think. Free up a lot of time normally spent at the sander. It's a little safer than the sander as well. No dust with the tumbler.