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  1. #41
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    I've spent most of the last 40 years vibratory finishing. Obviously, I get involved in a lot different processes. The last time I did plastic it was clear plastic (sorry I can't remember the exact type) duck calls. They were machined and they wanted to get the machine marks out and make them clear again. We came up with a process, it worked perfect and he is a happy customer. Your situation is a little different because you want to do it dry. Vibratory finishing is most always done wet but dry is possible. I get a lot of people that ask me to do the impossible but I don't think your application is that bad.

    My suggestion is a mix of plastic media, it will do the deburring, and corn cob, it will take away the dirt. Maybe a 50/50 mix. There is a slight chance that it might turn into a 2 step process. Fast cut media to deburr the edges and then a pre-plate media to make them smooth, but I really think one step will work. Harbor Freight bowls don't have a lot of energy. It takes them a long time to do the job, but that's not a problem. Once you have a process developed you can run them overnight if that's what it takes. Call me anytime if you have more questions. (My son-in-law is a pick, maybe he would like one of yours.)

    Rick 800-643-5839
    Vibratory Finishing Mass Finishing Ball Burnishing Deburring Media Compound Equipment

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  3. #42
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    Sorry for the late reply, yes kerosene or any petroleum will be flammable. We keep the tumbler, kero, stones and such in an out building with the heat treat oven. Used kerosene for almost 25 years, not sure why it cuts so much faster than water based compounds. At my first machine shop job they had a centerless grinder in the building across the street, the old timer that ran it was busy all the time and he used kerosene in it. Must have promoted abrasive cutting more that water based coolants which were just becoming common then.
    Petroleum products have what is called a flash point, do not completely understand it but the higher number is less likely to catch fire. Orange oil (yes it comes from citrus peels) I understand is very volatile with a 100F flash point as an example. Honing oil would probably be safer is not that hard to get.
    A couple of points:
    Stone shape greatly affects your results, I am thinking V-cut cylinders may work for you.
    Amount of compound affects the tumbling speed and finish, add more compound to slow down the motion of the stones and get a finer finish.
    You can reduce a vibratory mills speed by changing to a lighter weight.

    The plastic polish I purchased from the plastic supply house is water based, but you probably can get jewelers rouge from a jewelry supply house that is wax based. You may be able to do your fine polishing on the edges with a buffing wheel. I would guess jeweler's rouge come in different grits if so keep each buffing wheel and source separate.

    Your abrasive stone supplier should be able to recommend the right stones. May not be able to process a sample with kerosene or honing oil as it is not commonly done. If you want to send me one piece to run with the next batch of tubing, I can do that and see if it helps as a start to your process. We do use V cut cylinders on the tubing.
    Send me a PM, if you want to try it.

  4. #43
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    Quote Originally Posted by tdmidget View Post
    Mineral spirits isn't flammable?
    If you soak a rag in mineral spirits, you can make it burn. But it is a very low VOC, which is why it is preferred by painters over turpentine.

    It's not like lacquer thinner. Put a pan of it out overnite, it's still there in the morning, lacquer thinner or acetone is all gone. If you read the MSDS, it has all the usual warnings- but the CPSC does not classify low VOC mineral spirits as flammable liquids.

    They will eventually gas off, but it takes a long time.

    Mineral oil can be had in all levels of purity all the way to the stuff they sell in the laxative aisle for human consumption. Baby oil is pure mineral oil.

    It wouldn't take much mineral spirits to thin down a pure mineral oil to nearly water-like viscosity. A few ounces per gallon. It would not be very volatile, certainly less so that say pure kerosene.

    You could get it to burn, but it would probably require holding a propane torch to it long enough to heat it up so the gases ignite. It's not going to just flash off.

    I use mineral oil to re-impregnate oilite bronze bushings. I put them in one of those home deep-fryers. Parts go in the basket and heat it to 300 degrees, let it soak. No special precautions necessary, just don't do it next to an open flame.

  5. #44
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    Quote Originally Posted by jancollc View Post
    If you soak a rag in mineral spirits, you can make it burn. But it is a very low VOC, which is why it is preferred by painters over turpentine.

    It's not like lacquer thinner. Put a pan of it out overnite, it's still there in the morning, lacquer thinner or acetone is all gone. If you read the MSDS, it has all the usual warnings- but the CPSC does not classify low VOC mineral spirits as flammable liquids.

    They will eventually gas off, but it takes a long time.

    Mineral oil can be had in all levels of purity all the way to the stuff they sell in the laxative aisle for human consumption. Baby oil is pure mineral oil.

    It wouldn't take much mineral spirits to thin down a pure mineral oil to nearly water-like viscosity. A few ounces per gallon. It would not be very volatile, certainly less so that say pure kerosene.

    You could get it to burn, but it would probably require holding a propane torch to it long enough to heat it up so the gases ignite. It's not going to just flash off.
    Never tried mineral spirits in the tumbler, thought it was designed to evaporate so the paint would dry. If it flushes the "honing debris" out of the stones and promotes cutting it could work also. I might buy a can just to try it.

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    Quote Originally Posted by FredC View Post
    Never tried mineral spirits in the tumbler, thought it was designed to evaporate so the paint would dry. If it flushes the "honing debris" out of the stones and promotes cutting it could work also. I might buy a can just to try it.
    It will evaporate, but it's very slow. If you buy mineral spirits that are labeled "low odor", you are getting a low VOC, high flash-point formulation.

    I have used Dawn dishwashing liquid to clean my tumbling stones, it works good if you don't mind the foam...

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    I was doing some (different) plastic many years ago. I think the best I was able to do was walnut shells with red rouse (powder form).
    Also you might be buying normal walnut shells locally, which are really small. I buy 4/6 by the pallet Ecoshell.com - Media Sizes

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    Where else in the World could you get this level of knowledge, insight, wisdom etc all given so freely ?

    I can't contribute much on this subject but well done to the guys who can and did.

    Makes you proud to be a member of the site.

    Regards Tyrone.

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    Folks, my sincerest apologies. As the OP here, I didn't realize I had to subscribe to my own threads to receive notification of new posts. Each forum is a little different. I've now subscribed and will do my best to stay more current. I'm slammed the next couple days in the shop, then the weekend will open up for me.

    As someone stated here, I am stunned at the generosity and feedback and expertise in this forum. It is truly a blessing for my business and I'm humbled by the attention. Can't thank you all enough.

    One quick question: I do have mineral oil, and that looks like it might be the first thing I'll try, in addition to running a batch dry as well. However, I went to a major hardware retailer here in Los Angeles today, and he said mineral spirits cannot be sold in CA for environmental or some such reason. Is there something else I can use to thin mineral oil? Would paint thinner or parts cleaner solvent work, and still not be flammable?

    Thanks again. I look forward to answering each one of you here individually in the next 24-48 hours.

    thanks so much,
    scott

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    That's California..... Paint thinner, mineral spirits, same thing, generally. Parts cleaner? maybe.... They are concerned with the "VOCs", the volatile organic compounds, because those affect the air quality, which is a hot button in LA. Basically, they are going to hate just about any solvent that evaporates.

    You might be back to kerosene. That does burn, but it is not very volatile.

    If you do not do the tumbling, you will not have the issue of solvents. I still like separating the edge rounding and the polishing. That lets you decide how much polishing getsdone, because you do not have to go until the edges are good.

    How much edge rounding do you need? I sorta visualized it as a full rounded edge, especially at the string contact end.

    Can the rounding be the same all around?

    Is it better if less rounded in the grip area?

    And is the 1mm the actual dimension?

    If you need less rounding, and/or the 1mm is thicker than you need, that could change the appropriate way to handle the problem.

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    Man California has sure went off the deep end. I have no idea how businesses stay there anymore
    Nothing a year long bird super flu wouldn't cure

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    Quote Originally Posted by educatedguess417 View Post
    Folks, my sincerest apologies. As the OP here, I didn't realize I had to subscribe to my own threads to receive notification of new posts. Each forum is a little different. I've now subscribed and will do my best to stay more current. I'm slammed the next couple days in the shop, then the weekend will open up for me.

    As someone stated here, I am stunned at the generosity and feedback and expertise in this forum. It is truly a blessing for my business and I'm humbled by the attention. Can't thank you all enough.

    One quick question: I do have mineral oil, and that looks like it might be the first thing I'll try, in addition to running a batch dry as well. However, I went to a major hardware retailer here in Los Angeles today, and he said mineral spirits cannot be sold in CA for environmental or some such reason. Is there something else I can use to thin mineral oil? Would paint thinner or parts cleaner solvent work, and still not be flammable?

    Thanks again. I look forward to answering each one of you here individually in the next 24-48 hours.

    thanks so much,
    scott
    Give yourself a little vacation. Head to Vegas for a couple days, and buy whatever nasty crap you want. Just don't tell Jerry.

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    Quote Originally Posted by educatedguess417 View Post
    ...However, I went to a major hardware retailer here in Los Angeles today, and he said mineral spirits cannot be sold in CA for environmental or some such reason. Is there something else I can use to thin mineral oil? Would paint thinner or parts cleaner solvent work, and still not be flammable?
    As mentioned, paint thinner is usually mineral spirits. Basically anything that can thin oil based enamels or varnishes should be fine. You are in kommiefornia, so anything other than a low VOC paint thinner probably isn't even on the shelves.

    Check the label on the can. I can't recall ever buying something labeled 'paint thinner' that wasn't mineral spirits.

    Not to be confused with lacquer thinner- do not use that! Lacquer thinner is a stripper- mostly MEK, acetone, and toluene, and it flashes off at very low temps. That's not what you are looking for.

    edit to add: I really think your solution is going to be a dry process. You said you were getting scratches left over, but that should really just be a matter of figuring out how long to soak in the different grits. Give the 400 less time, and the 800 more time, etc.

    Each step up in grit should remove all the scratches from the previous soak, and leave a finer bunch of scratches for the next one.

    I initially thought about ball burnishing, but I think your parts are just too fragile. A series of barrel tumblers setup with the different grits seems like the best answer. I vaguely recall an episode of "How It's Made" that had a plastics tumbling/polishing segment, IIRC they finished with talc for the final polish.

    I think you need to setup some controlled processes to get it dialed in. Use scrap material that you haven't sunk a bunch of time in, and keep track of the soak times in each grit and record the results. You may need progressively longer times as the media gets finer, but the coarser media (properly applied) should reduce the time required in the finer grits.

  16. #53
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    Just to switch gears, how about milling these to almost finished size, then dry tumbling as suggested with different grit media? I am thinking a vacuum plate on a CNC mill to get near net shapes. Take the near net pieces and fixture them twice and to do the full radius all the way around. I have attached some photos of plastic squares that we used to do on a vacuum plate, milled these almost all the way through then popped them out of the frame. The brass hot knife, we fixtured then milled the knife shape 3/4 of the way around with one set up. It would take 2 setups to do your picks.

    The 2 frames in the window have already had the small squares popped out, they were 31mm, the frames were 6 X 8 inches and we never had one move using an 1/8" cutter. The brass hot knives were profilled with a custom ground 80 degree cutter with an .008 radius instead of a sharp point, no reason a full radius could not be applied in .040 or .030 plastic.

    vacuumplate.jpgip-plastic.jpghotknives.jpg

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    Quote Originally Posted by FredC View Post
    Just to switch gears, how about milling these to almost finished size, then dry tumbling as suggested with different grit media? I am thinking a vacuum plate on a CNC mill to get near net shapes. Take the near net pieces and fixture them twice and to do the full radius all the way around. .....
    That is the best idea, I think. That way you separate the rounding operation from polishing, and can have each of them optimized. You polish all sides at once, and the operation is "just" polishing, no need to make it round edges as well, which was proposed as the original idea.

    Otherwise you may have to polish too long in order to get the rounding right. With a tumbler etc, the two are linked in a way that would seem to be inconvenient and hard to get right consistently.

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    I like the idea of a large vacuum fixture. machine profiles. then full corner round with something from Harvey off the shelf or AB custom. Then maybe grind in place with a grinding wheel made for your materials? At least it would take care of the flat facets. Then tumble/buff your edges. Hell you could maybe buff the flats in the mill too.

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    Folks, still slammed in shop, but promise to answer all these by Monday, at the latest. Wow, what a wealth of info you guys are.

    BTW, several of you PM'd me here and I responded, but now I look into the messaging center, including in the SENT folder, and see nothing. Any idea what I'm doing wrong? There seem to be some quirks with the interface for this forum that I have not encountered elsewhere.

    Anyway, I'm truly humbled and grateful for all the attention and responses. I like the idea of a vacuum scenario, with some kind of electric jig that cuts most of the edge, then smoothing the reminder by tumbling. The challenge is we want the edges rounded, like cut in angles. But it's all solvable.

    Will be back ASAP.

    thanks again,
    with gratitude,
    scott

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    Quote Originally Posted by educatedguess417 View Post
    ...but now I look into the messaging center, including in the SENT folder, and see nothing. Any idea what I'm doing wrong?
    The mailbox space is pretty limited. When you are on the compose message page, there is a check box down below that says "save a copy of this message in the sent items folder".

    It's unchecked by default.

  21. #58
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    Quote Originally Posted by educatedguess417 View Post
    Howdy:

    I'm not a regular visitor here, but could use your insights. There's so much knowledge in these pages.

    I own a guitar pick company that makes really expensive picks. Our cheapest model is $30. We are three years in business and doing extremely well.

    Here's our store: charmedlife | store

    Our main line of products is made from a strange bioplastic called CASEIN plastic. If you're familiar with casein nutritional supplement, it's made from the same stuff -- milk, plus the addition of an acid. We don't make the stuff ourselves but buy it overseas (it never caught on in the States). This particular material gives the tone and feel of genuine tortoise shell picks, which were outlawed in the seventies. It also is considered one of the most beautiful plastics in the history of mankind, and can be colored almost any color. To this day it is known as the "Queen of Plastics." Here's a snap of our most popular model. Pretty cool, huh?



    Okay, now the problem. This stuff is far and away the most difficult material in the world from which to make guitar picks. It's just brutal. It cannot be injection-molded, so you must but sheets about 4.0 mm thick (.160") and machine it from finished stock. And that's just the beginning of the fun.

    It does not like heat, and it HATES water. 15 minutes of exposure to water warps it and makes it unusable.

    Once the material is cut into a pick shape and ground down to, let say, .040" (1.0 mm), the edges must be fully radiused and the pick buffed and polished. It shows the tiniest micro-scratches and requires a lot of man hours. I'm looking for a way to automate.

    Sorry to drag this out. Has anyone ever tried vibratory tumbling with oil instead of water? This stuff is fine which all oils I've tried on it, but will the oil just negate any cutting and deburring because it increases lubrication?

    I'll stop here. Appreciate your insights. I'll figure it out, but just trying to reduce my trial-and-error, which has already cost me thousands of dollars and thousands of hours of experimentation.

    All the Best,
    Scott
    I have been playing for 58 years (everyday). What is the advantage of this material?

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    Quote Originally Posted by Wild West View Post
    I have been playing for 58 years (everyday). What is the advantage of this material?
    i

    In general forums discussions, I avoid sales pitches or marketing. Please PM or email me directly if interested to charmedlifepicks @ gmail.

    There's been a moderm revolution in the guitar pick that began about twenty years ago. There are a LOT of companies doing this. In fact one of the leaders, Blue Chip Picks, used DuPont Vespel. This whole movement began when genuine tortoise shell material was banned in more than 100 countries in the late 1970s under the international CITES agreement (which also banned Brazilian rosewood, ivory, and hundreds of other flora and fauna).

    The problem? You cannot use just any tortoise or turtle for their shell; there is only one in the world -- the hawksbill sea turtle -- that the source, and it has been hunted to close to extinction.

    That's the short version.

    sm

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    out of pure curiosity does the pick affect the sound or just how one plays? I assumed sound was sound, but I also can barely push the play button.


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