Cleaning & Stoning Bridgeport table
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    Default Cleaning & Stoning Bridgeport table

    I see a number of old timers stone their mill table and or mill vise jaws before starting a project. What type stone and what grit are they using in order not to damage the table over time? Also, what type of cleaner would one use to clean the table of all the old solidified cutting oil before stoning? Any part numbers would help. Thanks!

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    Quote Originally Posted by berol View Post
    I see a number of old timers stone their mill table and or mill vise jaws before starting a project. What type stone and what grit are they using in order not to damage the table over time? Also, what type of cleaner would one use to clean the table of all the old solidified cutting oil before stoning? Any part numbers would help. Thanks!
    .
    .
    i wipe table with alcohol soaked rag and stone to feel for burs and any coolant oil residue still there. if you ever stoned off .0002" on a large surface you realize it aint easy.
    .
    rusty fixture i stone with medium coarse stone. i am removing rust not metal. fine stone is all thats needed if just checking for burs sticking up or for the feel of coolant or oil still on table fixture. also rotary stone motion pushes dust into table tee slots.
    .
    you really ought to try stoning .0002" off a large surface. i wish it was that easy. it takes a extreme amount of work to remove even .0001". i usually use 60 or 80 grit if i was trying to remove .0001". common to use stikit sand paper on a flat block to remove mill marks off a part. if you use 180 grit it takes like 10x longer

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    If the table is flat and true with just a ding here and there, instead of stoning try a lathe tool bit. Lay it flat on the table after ensuring there are no burrs on the edges, and use it as a scraper to remove only high spots. A stone can cut everywhere it rubs the surface, but a lathe tool bit will only cut where it hits a high spot. Just make sure it stays laying flat on the table. If you let it tip up on edge it can cut all along that edge pressed into the surface of the table. Constantly rotate it around the high spot to change where it hits the high spot and keep the area of contact small, and soon the high spot will be gone without changing the flat surface around it.

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    i prefer a stone. it feels different when over a ding and when over coolant oil. often coolant will smear and i wipe with alcohol soaked rag and stone again feeling and looking for smears.
    .
    and of course it pushes dust into slots.
    .
    really you ought to try stoning a large part and see how long it takes to remove .0001". a fine stone will have trouble even removing surface rust or tarnished light rust oxidation.
    .
    i used to use 400 grit to remove .00001" thats 10 millionths. even that took time. had to measure bars with computer controlled capacitance gage that show irregularity in millionths. 600 grit you could be there a hour removing 10 millionth.
    .
    machine table will rust 10 millionths after a few weeks

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    I like to with a good name brand flat file file about the table to just remove all the bugs and bumps Often that is plenty enough for a mill. If wanting better then the Norton stone fine side with oil. *With both just get down to witness flat ..not to remove material..As if the table was blued you would get down to the blue.


    6" Long x 2" Wide x 1" Thick, Aluminum Oxide 513965 - MSC

    Then you put it back in the box so nobody sharpens knives with it.

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    Quote Originally Posted by DMF_TomB View Post
    i prefer a stone. it feels different when over a ding and when over coolant oil. often coolant will smear and i wipe with alcohol soaked rag and stone again feeling and looking for smears.
    .
    and of course it pushes dust into slots.
    .
    really you ought to try stoning a large part and see how long it takes to remove .0001". a fine stone will have trouble even removing surface rust or tarnished light rust oxidation.
    .
    i used to use 400 grit to remove .00001" thats 10 millionths. even that took time. had to measure bars with computer controlled capacitance gage that show irregularity in millionths. 600 grit you could be there a hour removing 10 millionth.
    .
    machine table will rust 10 millionths after a few weeks
    It's not that difficult to remove material. Look at a typical old BP table and the center will be dished out from people stoning it to death.
    --------------------

    Run something flat over the table and find the burs, then just debur the bur area.

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    You don't "stone" the table, you use a stone as a burr detector. A stone glided over a flat surface will detect the smallest raised metal and a little localized effort will bring the raised metal flush with the original surface. Theoretically stoning the table surface if done right causes it no wear but there's always a little. The more sensitive and skilled the stoning the less wear. I've seen Sip table still exhibiting their original scraping after 20 years of continuous use marked only by hundreds of tiny bull's eyes where the raised metal surrounding where a little piece of grit or a chip was driven into the table and silver streaks either side of a scratch was removed by skilled stone work.

    It's not a perfect world. You clean and wipe, taking great care but one in a while something gets past you,.forever marking what should remain pristine. It happens and when it does you glide a stone over it, cursing whoever raised the blemish including yourself.

    I've seen knuckleheads attack machine tool work clamping surfaces with files and for some reason nobody shot them, I don't know why. Monkey see monkey over-do, maybe. Some behavior merits a Darwinian award.

    The preferred stone for this kind of work is a "slip stone" or "abrasive file". You don't want to use grandpa's old bench stone on a machine table. I prefer a fine hard India stone from Norton. Usually these are orange to cinnamon colored stones that come is a variety of shapes and sizes. I prefer a 1 x 1 x 6 square. These are aggressive when new - too sharp for burr detection and a little off geometry.

    One of the stone's surfaces needs to be smoothed for table stoning - and only table stoning. Since the faces are seldom flat, I dress the concave side briefly on a DMT coarse diamond sharpening stone or 220 wet or dry just enough to dress it flat to slightly concave and blunt the surface abrasive. I do this under running water to control abrasive drift. WD-40 is nearly worthless as a preservative or lubricant but it is an excellent cleaner and stone oil. I foof a light film on the table, wipe it clean, foof again and glide the stone..

    There are many tricks, trivia, and picky details relating to machine shop activities. The good part is, it only takes a few years to pick up enough of them to become a tiresome bore, a source of unasked-for advice to noobs who, wishing to know only the time, have to listen to you lecture on how to build a clock.

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    Forest, would that be a fine india stone, is that how name & grit I would order it?

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    Quote Originally Posted by berol View Post
    Forest, would that be a fine india stone, is that how name & grit I would order it?

    Good plalce to start:

    fine india stone | eBay

    I might prefer one particular stone but your needs may be somewhat different. Think about it They are expensive so choose with care.

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    I also prefer the fine hard India stones that Forrest described. What's usually been available in various shops or a company provided perishable in the die/mold shops has been the round version that's half fine India(light brown) / half coarse carborundum (dark gray). They're often referred to in the shop as a "hockey puck" if you're from Chicago. Often kept in a coffee can with a little kerosene, they're always ready for a light skimming over the BP table. Grinder mag chucks or any delicate precision surface gets a gentle wipe down with a Soft Arkansas or Washita stone so it extends the life of the last time you made freshly ground chuck. Hard Arkansas (white or black), often called "slip stones" just don't do much other than identify the location of a raised ding IMHO so I don't use them for much except the final edge of wood chisels. I prefer to feel the Washita or Soft Arkansas as it bites into the surface with gentle finger pressure. That's just my opinion for my methods, YMMV.

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    IFYOU WANT IT TO LOOK GOOD
    Here is what I do.First use almost any stone to knock the burrs down,but carefully only stroke lengthwise.Second ,clamp a long 2x4 on the table and use a nice flat wood block with 120 grit sandpaper. Keep the side of your sanding block against the 2x4,Dont move the block sideways,only lengthwise.This will give the appearance of a surface ground table. Edwin Dirnbeck

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    Quote Originally Posted by edwin dirnbeck View Post
    IFYOU WANT IT TO LOOK GOOD
    Here is what I do.First use almost any stone to knock the burrs down,but carefully only stroke lengthwise.Second ,clamp a long 2x4 on the table and use a nice flat wood block with 120 grit sandpaper. Keep the side of your sanding block against the 2x4,Dont move the block sideways,only lengthwise.This will give the appearance of a surface ground table. Edwin Dirnbeck
    I think the OP was concerned about function more than creating the appearance of a surface ground trough.

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    Quote Originally Posted by tdmidget View Post
    I think the OP was concerned about function more than creating the appearance of a surface ground trough.
    Agree, this is about preservation of precision not appearance. A machine tool is intended for productive work. A machine tool is not fine furniture to be kept pristine for critical guests. The goal is maintenance of a precision reference surface not beautifying a coffee table or polishing a copper pot..

    If I was concerned about maintaining a uniform scratch pattern but wanted to minimize wear on a precision surface I'd suggest - not advocate - a flat planed wood bock faced with 400 to 1000 grit wet-or dry guided by a straight edge (wood?) to keep the scratch pattern on track. I'd do it no oftener than once a year.
    Last edited by Forrest Addy; 04-12-2017 at 04:30 AM.

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    Norton India Bench Stone 8" x 2" I buy the fine for stoning tables...

    Never could find theses at McMaster Carr.....

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    I started to use a aluminum oxide stone that I surface ground with a diamond wheel - That makes the stone rather dull and perfectly flat, with that stone it is pretty much impossible to scratch the table/fixture/tooling and removing metal from a flat surface is also not going to happen in an reasonable ammount of time. But it will make you able to feel and cut away trown up material from a ding in the surface. Keep the stone always clean, blow it and the table off with air before use, use a bit of something liquid to add a bit of lubrication - Pretty much anything works, water soluable cooleant, light cutting oil, WD40, whatever.

    (You can also buy those stones... Gf-5 Precision-Ground Flatstones | Professional Instruments Company )

    I cringe when I see people using a silicon carbide stone on a machines table or a fixture..the SiC stones cut cast iron so well, easy to dish out a table over time.

    Stefan

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    Stefan, did you look at the prices on those flatstones? $500 a pair? Maybe next paycheck.

    I have in the distant past, ground sharpening stones and India stones to remove embedded debris, flatten them etc. A toolmaker showed me a trick (toolmakers do have uses). He walked me to a vapor blaster (like a bead blaster that uses fine garnet, water coolant, and air in the blast nozzle.) It's adjustable from very gentle to very aggressive depending on the settings. He twiddled the controls and vapor blasted the half dozen stones I'd ground. Roughed them up perfectly so they would cut but not scratch. Maybe that would work on the blaster you have in your shed. Your 400 micron media is just about right but perhaps sharp garnet would be better

    Maybe mask the stone with a layer of window screen to erode an array of depressions leaving the masked grid proud. Maybe anoint the work with oil expressed from the scrotums of unborn white mice. There's certainly other possibilities we haven't considered.

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    Quote Originally Posted by edwin dirnbeck View Post
    IFYOU WANT IT TO LOOK GOOD
    Here is what I do.First use almost any stone to knock the burrs down,but carefully only stroke lengthwise.Second ,clamp a long 2x4 on the table and use a nice flat wood block with 120 grit sandpaper. Keep the side of your sanding block against the 2x4,Dont move the block sideways,only lengthwise.This will give the appearance of a surface ground table. Edwin Dirnbeck
    Is it just me? But every time I see Dimbeck. I associate that with dumb brick. Nice flat wood block & 120 sandpaper grit. Heaven help us.

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    I was lucky enough to have obtained a supply of " roll honing stones/bricks " from one place I worked. They were roughly 5" or 6" long by about 2-1/2" wide at the bottom and 2" wide at the top, they were about 2-1/2" to 3" high. They were just perfect for holding in the hand with the big side down. I had a selection of grits ranging from 150-200 grit up to 400 grit. They were perfect for the job and made rubbing a table down a pleasure and not a chore. Nothing else I've used came near to these stones.

    I'm pretty sure " Norton " made some of them but I've looked high and low on the Internet and I can't seem to find anyone who supplies them or an equivalent. Maybe they are no longer made.

    Regards Tyrone.

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    I use a 4" "HOCKEY PUCK" stone with rough on one side and fine on the other....it will take you 40 years of lightly rubbing that table with this and you might take off .001


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    Quote Originally Posted by edwin dirnbeck View Post
    IFYOU WANT IT TO LOOK GOOD
    Here is what I do.First use almost any stone to knock the burrs down,but carefully only stroke lengthwise.Second ,clamp a long 2x4 on the table and use a nice flat wood block with 120 grit sandpaper. Keep the side of your sanding block against the 2x4,Dont move the block sideways,only lengthwise.This will give the appearance of a surface ground table. Edwin Dirnbeck
    Are you talking about cleaning up a welding table? That would destroy the flatness of any table.


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