eliminating waviness altogether on small surface grinders - Page 2
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  1. #21
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    I've never heard of magnetic aluminum???? You called it "aluminum heat sink". I have seen similar marks on steel when the mag chuck was not holding and the part slide a little. I am assuming you have the part on the mag on an angle. It almost seems your playing a joke here. A year ago one member was doing that. He Made up a fake identity and asked dumb questions until we discovered what he was doing. I hope this is not the case.

  2. #22
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    The part I ground was the flat piece of steel lying down. Standing on the part you see fingers that look vaguely like a comb. Those "fingers" are part of an aluminum heat sink attached to some computer memory that happened to be sitting on my desk when I was taking the picture.

    I did not grind any aluminum.

    I put the heat sink on the ground part not to play some kind of joke but rather because vertical elements in an image cause the autofocus in a digital camera to focus right there. In other words, I was forcing the camera in my phone to focus where I wanted it.

    I am very sorry that I confused anyone and I PROMISE I'm not some troll. I may be a newbie on this particular subgroup, but I have been around a long time. Being ignorant can give the appearance of being stupid, but ignorance is curable and I'm not stupid.

    metalmagpie

  3. #23
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    I've spent a lot of years trying to cure my ignorance but I'm still a work in progress. Surface grinding, and probably most other forms of grinding, seem to be part science and part art form. Most people get results by trial and error, or were taught by somebody with more experience. The problem is that experience was achieved by... trial and error. I think grinding operations can be measured and analyzed. The profilometer tells you a lot, as do accelerometers on the machine. My experience is you can dress a wheel until the cows come home, but that won't make it balanced. What it does do is subtly shape the wheel to correspond to the vibration of the machine such that waviness is reduced. At least until something changes. What you really want is a round wheel running in balance and no vibrations. The lighter the machine, the fussier it is. IMO, you're on the right track.

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    I don't know if this might help, but Cutting Tool Engineering's YouTube channel has some detailed videos on dealing with grinding problems. Maybe there is something there.

    YouTube

    Bill

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    Trying slowing down on the last pass when dressing the wheel. It makes a big difference in the finish you end up with. Do let the part get any heat, if you can leave the part in a position so the air moved surface grinder wheel helps cool it.

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    Don't dress too slow or you'll end up with a closed wheel and burn marks, as well as more chatter. You kind of just have to arrive at the correct parameters via experience. There are lots of variables involved and you have to make adjustments to the relevant ones based on all of them.

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    I really dont understand the finish in poat #1, How does it feel running a ball point pen across in the cross direction. Can you feel that finish?
    What does a fresh dress wheel with just tickle grind with the full wheel and no cross Tavel,,so just dusting the part with full wheel..Take care to not get hot.

    What is the material that you are grinding?

  10. #28
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    Those Grinding Doc videos are really good and confirm what I've thought about balance and egg shaped wheels. I have no coolant system on my 612 and that's probably the next thing to investigate.

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    I have done a ton of grinding dry and with not balancing...It just takes more care and more time...But for something as big and important as a chuck wet is best...even a drip bucket or hand spray.

    Yes I have even ground a chuck dry...just took a lot of time..and many gauges in the millionths..

    My buddy Don worked in a major shop mostly running high presision form spade drill points. and form lathe cutters..and the shop owner refused to use/allow any coolant on any grinder...

  12. #30
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    Quote Originally Posted by michiganbuck View Post
    I really dont understand the finish in poat #1, How does it feel running a ball point pen across in the cross direction. Can you feel that finish?
    What does a fresh dress wheel with just tickle grind with the full wheel and no cross Tavel,,so just dusting the part with full wheel..Take care to not get hot.

    What is the material that you are grinding?
    Remember, that original image is magnified. No, I can't feel anything with a ballpoint pen or anything else. It feels way smooth. And it's a steel part.

    I can't do any more experiments for awhile because I'm tearing down my hydraulic unit. It gets too hot too fast. I'm expecting a very worn-out gear pump, and I'm hoping I can rebuild it.

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    Quote Originally Posted by majohnson View Post
    Try slowing down on the last pass when dressing the wheel
    Quote Originally Posted by eKretz View Post
    Don't dress too slow or you'll end up with a closed wheel and burn marks, as well as more chatter.
    SLOW DOWN! DON'T GO TOO SLOW! What's a newbie to think? :-)

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    Well, dress fast for an open wheel when roughing. Maybe 1/2 - 1 second to get across a 1/2" wheel. Slow the dress down to 2-3 seconds across a 1/2" wheel for a pretty good finish. These numbers are for a sharp diamond! If you have a dull diamond they will be different and you need to keep the diamond moving faster. You can dress even slower for a better finish but you'd better be dusting low-tenths or less or you'll regret it.

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    Watch this. YouTube

    YouTube

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  17. #34
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    Good demo. That's about the speed I dress a wheel. Single pass only. I know people balance wheels by removing material, but I just can't get comfortable with it. I also know static balancing is the rule, but it's not near as good as dynamic. IMO, the smaller the grinder, the fussier it is.

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    That is a good dress for finishing. Conrad how do you dynamically balance your grinding wheels?

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    on the spindle, maybe?

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    Not sure if this has been mentioned, but 'dull' diamond for dressing will leave poor results. Also, it can help to try a cluster diamond for dressing as well as a single point diamond.

    https://www.mscdirect.com/product/details/03502127

    https://www.mscdirect.com/product/details/03546454

  21. #38
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    Quote Originally Posted by eKretz View Post
    That is a good dress for finishing. Conrad how do you dynamically balance your grinding wheels?
    See my post #15 in the OP's previous question- grinding wheel nomenclature - how to you remember it?
    I use more sophisticated stuff than most people have, but any accelerometer that gives you a useful output will work. The 4-pass method doesn't require strobes or any worries about rotation, just that the thing runs at constant speed during the test. I suspect modern phones might even do it, with a suitable app, but have never tried it.

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  23. #39
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    Quote Originally Posted by Mike1974 View Post
    Not sure if this has been mentioned, but 'dull' diamond for dressing will leave poor results. Also, it can help to try a cluster diamond for dressing as well as a single point diamond.

    https://www.mscdirect.com/product/details/03502127

    https://www.mscdirect.com/product/details/03546454
    One of those grinding doc videos talked about clusters. Apparently they work well, but you have to traverse them extremely fast to get the desired results. Used like a single point diamond, they won't work right.

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    I don't understand how a cluster can work. Unless it is extremely accurately
    aligned, doesn't one diamond to all the cutting? The other diamonds are just too
    far away to cut.


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