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    Default Table stones

    Happy New Year to everyone!

    Expecting my first piece of new equipment (VF-2ssyt) at the end of Jan. What stones are you guys using on your mill table? Below is one I've always used on my Chinese mill w/ a healthy dose of WD-40. I've read some guys recommend silicon carbide stones, even the fine cores (300+) these cut pretty aggressive, correct?

    Link: Norton 614636855653 IB8 1-by-2-by-8-Inch Fine/Coarse India Combination Oilstone, Red: Sharpening Stones: Amazon.com: Industrial & Scientific

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    I prefer smaller stones, they give me better feedback when I encounter bumps. But more critically, minimize damage by using a sheet of plastic under a vise when placing it on the table , then carefully lever the vise up and slide the plastic out. Make sure all surfaces were clean to start with, of course.

    When you tighten studs and T-nuts, clean the T-slots first, especially the upper surface that will bear the clamp load. Ditto clean the T-nuts so they don't have chips or bumps on them. And don't go crazy tightening the studs or bolts, at some point you're just deforming the cast iron, not improving the actual clamping load.

    Good habits will minimize the need to stone the table, preserving accuracy and making setups easier.

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    I like bigger hones better. Larger surface area in contact at once means less pressure per square inch and in turn less unintentional material removal over time from the surface that is actually flat. I used a stoning at every setup for over a decade on a cherry HBM table and a .0005" graduated indicator needle doesn't even flutter when run across the table. 4" puck works excellent. Fine silicon carbide or fine India, either is good. I don't like WD-40, much prefer clean mineral spirits. Don't be stupid and hunker down with heavy pressure on the stone. Light pressure only (weight of the stone only) unless you hit a bump of displaced metal. If it's little, stone it down. If it's big, I use a cut-off piece of flat file with masking tape wrapped at the ends to knock it down closer first, then stone. Also look for the idiot who banged up the table and use a hammer to knock him down.

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    Quote Originally Posted by Djstorm100 View Post
    Happy New Year to everyone!

    Expecting my first piece of new equipment (VF-2ssyt) at the end of Jan. What stones are you guys using on your mill table? Below is one I've always used on my Chinese mill w/ a healthy dose of WD-40. I've read some guys recommend silicon carbide stones, even the fine cores (300+) these cut pretty aggressive, correct?

    Link: Norton 614636855653 IB8 1-by-2-by-8-Inch Fine/Coarse India Combination Oilstone, Red: Sharpening Stones: Amazon.com: Industrial & Scientific
    This is a job for precision stones. Those norton stones you reference made flat in a surface grinder using a diamond wheel. These are very flat and will only remove burrs and crud. You will need a set of two. The surface of the stones will load up with chips as you use them. Sliding the second stone across the loaded one will drive the chips into the surface and out of harms way. As you rub the stones together they will slide across each other as is they were made of glass.

    Sounds hokey but they are very effective and can be used on angle plates, parallels and just about anything. You will see where the burrs or high spots are on any surface with no damage to that surface.

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    I use a 1"x4" fine india stone that is quite glazed with no lubricant, I want it to stay glazed so it doesn't cut anything but burrs. The stone is just to find any burrs and to maybe remove the smallest ones on the table, vises, or 4th axis. On the rare occasion I find a burr bigger than this stone will handle then I flip it over and use a little lube to keep it from loading up so it cuts. This stone gets used for nothing else. Maintenance stoning is just to find burrs and nothing else so there shouldn't be any worry about overdoing it.

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    I have to absolutely agree with this. Precision ground stones are an important tool for any machine shop. I had a friend who used his surface grinder to go over a pair of inexpensive, hardware store stones that were far, far from flat. He ground both sides (coarse and fine) and the two edges. He left a shoulder on one edge so I could do corners.

    There is no real substitute. They are great. Before using them, they are rubbed together to remove any stray grit, dust, or metal from the burrs they have previously removed with one of them. After rubbing them together for two or three strokes, they slide across each other almost like an air bearing. Then you use one of them on the table or any other flat surface to remove any raised areas. It works like a charm. Other places where I have used them include: my squares and protractor heads, 1-2-3 and 2-4-6 blocks, milling vise surfaces, my better rulers, my rotaty table, etc. One place where I do not use them is on my shop blocks. There are stones made for that. I do not know what the difference is, but I do not want to introduce any wear or scratches on them.

    Previously I had a stone that I used on my mill's table that was fairly flat, but it was not ground. It did not do any noticible damage to my mill's table, but I kept it's use to a bare minimum. I do not have to do that with the precision ground stones. Even with moderately heavy pressure, they simply can not remove any of the table itself, just any high spots. I use them much more than I ever used that unground stone.

    If you must use an ordinary stone that is not ground flat, DO find one that does not rock when placed on a flat surface. And one with a fairly fine grit.



    Quote Originally Posted by Rickyb View Post
    This is a job for precision stones. Those norton stones you reference made flat in a surface grinder using a diamond wheel. These are very flat and will only remove burrs and crud. You will need a set of two. The surface of the stones will load up with chips as you use them. Sliding the second stone across the loaded one will drive the chips into the surface and out of harms way. As you rub the stones together they will slide across each other as is they were made of glass.

    Sounds hokey but they are very effective and can be used on angle plates, parallels and just about anything. You will see where the burrs or high spots are on any surface with no damage to that surface.

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    I want a hard table stone. That way you can feel the bruises. If a pass or two doesn't knock it down, cut it off with a scraper. The best table stones I ever used were broken segments of thread grinding wheels.

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    It IS important for the stone to be flat. This can be accomplished with the surface grinder method or simply rubbing the stone on a diamond plate until it's flat. The good thick steel-backed diamond plates (i.e. DMT) are guaranteed flat within a thou or so when new.

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    Quote Originally Posted by Djstorm100 View Post
    Happy New Year to everyone!

    Expecting my first piece of new equipment (VF-2ssyt) at the end of Jan. What stones are you guys using on your mill table? Below is one I've always used on my Chinese mill w/ a healthy dose of WD-40. I've read some guys recommend silicon carbide stones, even the fine cores (300+) these cut pretty aggressive, correct?

    Link: Norton 614636855653 IB8 1-by-2-by-8-Inch Fine/Coarse India Combination Oilstone, Red: Sharpening Stones: Amazon.com: Industrial & Scientific
    .
    1) normally you are not lapping the table, a precision ground steel block with adhesive backed Stikit sandpaper or plastic lapping film is better for lapping. comes in different grits and when worn takes a few seconds to replace. if you actually every sand .0001" off over larger surfaces it takes a considerable amount of effort and a lot of time even with 180 grit. with 600 grit you talking .00005" could take many many hours
    .
    2) stone normally for minor rust removal and as you move across you can feel rust or dings or burs if sticking up. its a push any dust into slots and feel for burr thing mostly. for that a fine stone works ok
    .
    3) heavy rust usually use alcohol soaked rags and nylon abrasive pad or a very coarse stone. obviously heavy buildup not going to come off with a fine stone. large fixtures over 10 square feet often use a hand held air sander with a nylon abrasive pad to remove the heavy rust buildup. ifs its been on over 6 months it can be very rusty. you would need weeks if using a fine stone to remove the rust

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    We are sort of segueing here, but for heavy rust, a scraper is what I use. Anything else I've tried (including all mentioned above) pales in comparison. Get a stiff steel putty knife/scraper and angle it so that it "cuts" the rust off the table. It will literally be removed and ready to start stoning in seconds, and doesn't remove metal. If there are low points, add a quick scrub with a wire brush. At that point mineral spirits and a stone will do the job right quick.


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