Tumble polishing - where have you been all my life !

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David Santistevan

Well-Known Member
Joined
Aug 5, 2011
Messages
1,365
I wanted to take a moment and share some information about polishing props that I think many of you can benefit from. When I was in the hobby in the past I polished props the old fashion way with a Dremel Tool, sand paper and a lot of elbow grease. Much to my surprise when I recently got back into the hobby and bought my first set of props there was a large warning that grinding Beryllium/Copper could be hazardous to your health. After doing so research online I found that indeed breathing dust from the grinding of props can actually kill you.

So I began my quest of looking for a way to safely polish my props. One day while I was at Harbor Freight Tools I ran across a double drum rock tumbler. To me using a rock tumbler made a lot of sense for a number of reasons. First and foremost there would be no grinding, everything would be contained within the drum. Secondly it did not require a huge amount of work to polish the props and this appealed to me very much because of the number of props that I had to do. So I purchased the rock tumbler and so began my quest for a safe a relatively easy way to polish my props. The other major benefit of this process is that it allowed me to polish a number of props simultaneously with the same about of work.

I won’t bore you with the various iterations that I went through to get to a final solution. It suffices to say that it took a while to perfect the process but now I have it down cold and I would like to share it with those who are interested.

Some Background

The process of polishing props using a tumbler is a three phase process. This is where having multiple drums comes in handy. The first phase is the primary burnishing phase. This phase removes all of the major casting flanges and flaws. It has the added benefit of getting the balance fairly close through the natural tumbling effects (the heavy blade will get burnished more). In most cases depending on the size and number of props will take about three to five days in the tumbler.

The second phase of the process is the beginning of the finish process. This will smooth the entire surface and get you read y for final balancing and sharpening. The first part of phase two take again about three to five days. After the initial finishing you will remove the props and do a final sharpening and balance on the blades. You will be using WET 320 or 400 for your balancing and a file to sharpen. After you have completed balancing and sharpening the props you will return them again to the finishing media for two or three days more to complete the process.

The final phase is the polishing and this can take between two and five days depending on how high polish finish you want on your props. During the first two phases of the project you will be working with WET media so the risk of dust inhalation is minimized, however you must still wear appropriate masks. But you do not have to worry about immediately washing your clothes and shower as recommended. The final polishing phase is a dry phase so precautions to be taken when working around the media (especially after you have polished the props and there may be dust in the media).

What You Will Need

  1. A double drum rock tumbler. I bought mine at Harbor Freight Tools for around $50.
  2. You will need three type of tumbling media. A burnishing compound, a finish compound and a polishing compound. I buy these on-line from Rio Grande (http://www.riogrande.com/) . What you will need is for the burnishing compound is the Blue Pyramids, and for the Green Pyramids and for the polish you will need “Media Shell Shine Red”. This is a crushed Walnut shell encrusted polish. Each of these runs about $30.
  3. A strainer, I purchased mine from the local grocery store. A small unit with a handle works best.
  4. 320 and 400 wet sand paper
  5. A fine metal file
  6. A few drops of dishwashing liquid as a burnishing agent.


Phase 1

  1. Fill a drum a little more than half with the Blue Pyramid polishing media. You will also want to add a small amount of water. I would say about a 1/8 cup along with two drops of liquid dish soap. You will then add your props. The secret hear is not to overload the drum. If you are working large props you will probably only get two, maybe three. There must be room in the drum with the media and props for things to tumble. If you find that you are not getting the desired effect try fewer props.
  2. You will need to clean the props, drum and media at least every couple of days. This process consists of going to the sink, using the strainer pour the contents into the strainer and wash thoroughly. Make sure none of the polishing media goes down the drain or you will have another “honey do” keeping you from your boats. Then simply replace the media, props, water and soap and put it back on the tumbler. The props are finished when all of the major casting flanges and burrs are gone and the prop has a nice even texture.
  3. When finished you will need to once again clean out your drum and media. Your media is reusable so after cleaning it place it in a bucket to dry.

Phase Two

  1. Like before you will want to load your drum with the media, props and soap only this time you will be using the Green Pyramids. You will be running the props for three to five days depending again on the number of props and their sizes. During this time you will need to clean your media, props and drum daily. Otherwise your props will begin to turn a dingy brown and harder to polish.
  2. After your props have reached a consistent, smooth finish you are ready for balancing and sharpening. You will be using 320 and 400 sandpaper wet to minimize dust. Balance and sharpen the props according to your own technique.
  3. After you have completed balancing and sharpening the blade you will return them to the tumbler using the Green Pyramids for another couple of days paying a great deal of attention to keeping the media and drum clean. I would do it at the very least once a day.
  4. The props will be done when all of your balancing and sharping marks are gone from the prop and it again has a uniform smooth finish.
  5. Clean out your drum and media as before.


Phase Three (Payday!)

  1. This is the final phase and it is the easiest. All you have to do is once again load your drum with the Red Shell polishing media and props and put it to run. The longer they run the more polished they will become. You can achieve a beautiful gold finish in just a couple of days. This is a DRY mixture so you will not be adding any water or soap. Since you are now dealing with a dry mixture that is going to be taking very small amounts of metal off you must take care when handling this media especially after you are done polishing. I would recommend wearing a high quality dust mask and washing the media when you are through thoroughly.
  2. You do not have to concern yourself too much about balance after polishing as very little metal is actually removed. However with that said, polishing for a long period of time may change your balance slightly. Your blade will also lose some of their sharpness but a careful file along the edge and you are ready to go again.
  3. When finished removed your polished props and hand buff with a soft cloth.
  4. Once again clean out your drum and media.


Conclusion

This is a wonderful and safe way to polish your props. The major benefits are : 1) much safer than traditional sanding and grinding, 2) highly productive in that you can do a large number of props with the same small amount of work, 3) you end up with props that are the envy of everyone at the pond.

As always I would love to hear from anyone who can help me to improve the process or has had similar or differing results.

Happing Boating!

Dave
 
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Seems like a lot of time and money to invest for zero gain.Shiny props don't propel boats any better than dull ones. What happens to the razor sharp edges you sharpen your props to when you toss a few of them together in a tumbler for a few days?
 
Larry,

after the final polish I sharpen them again. The taper is still there but the edge is dulled. a quick run with 600 wet and a block on the edges and they are good to go. I know this isn't for everyone, there are some drag benefits but for the most part it is about the safety issue for me. I am not keen on the idea of grinding these based on the hazards. The aesthetics are always a nice touch.
 
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:) I agree with you about the health issues involved. I wear a respirator, while working on props and I don't use power tools while thinning and sharpening them.
 
I have been thinking about this.. It seams like the a small vibratory shaker may work faster. The polish phase may not be needed for some. Do you guys think that the heavy blades would fall and get more material removal, hence doing a cursory balance of the blade,.. at least getting real close... THen a final leading and trailing edge treatment and maybe a little balancing.. you could do your cupping and stuff, then put the props through this,.. cleaning up any marks and smoothing out gouges.. I could by 3-4 raw props,.. back cut, detounge etc,.. maybe cup,.. then toss them in for finishing and balancing,.. and have nice smooth props.. MR Allen told me I need to do my own... I suck at props,.. this could be my edge up!
 
LOL, I have a vibratory tumblers and it in fact does the polishing work much faster. These are part of the iterations I did not list on the final process I published. You could give it a try but you are right about the balancing aspect, It also does not seem to thin the blade as well. I am using the vibratory for final polish. Careful not to leave it in too long or you will lose your edge.

As I had mentioned it appears that the tumbling action is what I suspect ends up getting the blades so close in balance. Let me know your experience if you try this. I am looking for ways to improve it.

D
 
I use a 6" x 1/2" 2sfn wheel by 3M, it doesnt polish but leaves a matte finish, good enough for me and it takes about 45 minutes to cup balance and polish a prop. I used these wheels to polish the tarnish off stainless welds, they work really quick on bronze, and dont leave any scratches in the finish either.

A repirator is required as well..........
 
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One of my friends does a fine glass bead on one side . Makes it satin or mat on purpose.
 
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