Stone the table??

hoytheld · Mar 24, 2020

Question:

Do any of you periodically hand stone the table of your machine to remove any potential high spots?

If so, what are you methods and what do you use? (part numbers of stones/equipment would be appreciated).

If not, what is your reason?

Thanks for your input!
jason

michiganbuck · Mar 24, 2020

Good to flat file off all the bugs just down to original surface, then with a good flat hone and oil make figure 8s evenly all over your table. if you have mapped it and found high and low then go over the low places twice. Turn the stone 180* about half way through the job. Never use your table stone for knife sharpening, burring or anything but tables. Put it back in its original box and treat it like gold.
Norton Combination India Stone

DavidScott · Mar 24, 2020

I use a 1/4"x 1"x4" Norton medium India stone that I dedicated to this use many years ago, and that is all it is used for. It is loaded up and doesn't cut worth a damn on one side, the side I check for any burrs with, and the other side will cut with a little lubricant. I rarely use the side that cuts, most of its use is just to make sure there are no burrs and since it doesn't cut it's safe on my table, vises, or anything else I care about.

Vancbiker · Mar 24, 2020

When I did field service, I settled on a Norton machine stone.....

Crystolon Machine Knife Stone | Norton Abrasives

coarse side for knocking down the big owies and a fine side for normal work. Easy to hang on to also.

CarbideBob · Mar 24, 2020

Often, like daily or more.
Bob

kustomizingkid · Mar 24, 2020

Everyone has been talking up their precision ground stones among the Instagram machinists. Anyone have any experience with this concept?

HOME | 26AcreMaker

WRL · Mar 24, 2020

I keep a 1/4 x 1 x 4 stone in my apron pocket.

I stone everything, parallels, vise bases, lathe tool holders, the parts I'm working on,...

My pocket knife is sharp also.

Stoning high spots is good practice.

TonyStark · Mar 25, 2020

I use the norton stone, but I prefer the 4” round version. I was always concerned the square ones would catch a corner and dig in. Spray a bunch of Gibbs on the table and stone, and figure 8’s as people have mentioned.

As far as how often- well that depends on how often you adjust your fixtures. I have 2 Orange vises and they only ever move for the very odd job once every 3-4 months. I take them off, stone the table and bottoms of the vises before I dial them back in.

Cole2534 · Mar 25, 2020

I don't use a stone, rather an unground lathe tool blank. It knocks off burrs etc, but being flat gtound steel it absolutely won't cut. I got the tip/idea ftom a thread here in the general section years ago.

Mtndew · Mar 25, 2020

Just get a 4" Norton round palm stone and use the fine side, circular swirl pattern with either oil or WD-40.

Mike RzMachine · Mar 25, 2020

I ground a pair of $20 common norton oil stones on my surface grinder and use them all the time in the shop. Touching up the table, the bottom of vises, fixtures, parallels, tool holder tapers, I use them constantly.

It's worth the effort to make a pair if you have a surface grinder. I bought a diamond grinding wheel from shars to grind these, and to relieve carbide end mills. If i didn't have a surface grinder, I'd probably buy some. Robin Renzetti has a video detailing the grinding process.

Regular stones are usually bowed and you could use the convex side on a table with very light pressure. They'll keep cutting if you keep pressing though.

Garwood · Mar 25, 2020

Vancbiker said:
When I did field service, I settled on a Norton machine stone.....

Crystolon Machine Knife Stone | Norton Abrasives

coarse side for knocking down the big owies and a fine side for normal work. Easy to hang on to also.

This is exactly what I have used for 15 years.

The coarse side will take dings down faster than a file and the fine side finishes.

I clean, stone and oil precision surfaces every time I'm using them. Bottoms of vises and fixtures, tables, etc.

Not uncommon to find a high spot I didn't know was there. Wouldn't have caught otherwise. Had a lot of bolt holes in fixtures where the bolt bottoms and bulges the bottom or even swarf stuck in a hole can do it.

TheBigLebowski · Mar 27, 2020

As everyone has already said, The Norton combination oilstones are the way to go, I use the 2 x 6 inch ones.

Clean the table extremely well and then use the fine side of the stone with no downward pressure. The way I explain it to new guys (and I am not saying you don't know this, I am just putting the info out there) is that it should feel almost exactly like using and air hockey table, the stone just floats across. As soon as you feel some resistance you have found a high spot, and you can apply some pressure to knock it down.

Cool Tip - if you are going to buy a stone, buy a pair. Once one stone starts to load up, liberally pour mineral oil over it, grab the other stone, then rub them together as you would if you were trying to warm up your hands. All of the contaminates will come to the surface and can then just be wiped off. They will come as clean as they were when new.

eKretz · Mar 28, 2020

These fellas have covered it pretty well. The only thing I do different is use mineral spirits as the lubricant.

BGL · Mar 28, 2020

I have only been in this craft for more than forty years and recall reeling in horror the first time seeing someone 'stone' a mill table.

I have watched a series of videos by a very experienced and skilled man I have great respect for (never meet in person) who practices this 'stoning' religiously.
I am vehemently opposed to this as a routine practice - No, I will not do it! It is for repair only.

I commented on a Haas video that is excellent except for the practice of stoning - should not need to be routine and should be a video in itself.

I completely dismiss the idea this is routine - sometimes you have no choice but most times a spritz of your favorite fluid or even the machines coolant. Steel wool or fine scotch brite is all that is needed, rinse again with your fluid and wipe dry with clean rag.

If ever I do stone tools such a parallels and the like it is to remove the nicks and burrs left by the dull and ignorant. And that is with a very fine and soft Arkansas stone, done carefully. Be mindful of your tools and surfaces and you will rarely if ever have to do it.

A few times I have used a large stone as described above to restore tooling and machine tables that had been neglected. A few times just the spot where a tool loading tragedy raised a divot.

Never ever lay steel tools on the machine surface. I don't mind squeaky chalk but that clink of a wrench gently set on a table I hear from across the shop over the din. That is my burden. I always have a rag, cardboard, or even a scrap of aluminum sheet to lay tools on.

All this being said - if you insist and are compelled to do this, read post #13. This is a skill, not just rubbing a rock.
You do what you feel is best for yourself and your tools.

Me, I am ever so kind to precision surfaces and they have served me very well.

BugRobotics · Mar 28, 2020

kustomizingkid said:
Everyone has been talking up their precision ground stones among the Instagram machinists. Anyone have any experience with this concept?

HOME | 26AcreMaker

Yep, made a set a few years ago after seeing Robin Renzetti mention them in a video and I use them every day in the shop. Like night and day when compared to an non-ground variant.

eKretz · Mar 28, 2020

Yes, the stones absolutely need to be flat. That can be accomplished on the surface grinder or by "lapping" them with a flat diamond plate. DMT plates were guaranteed flat within .001" when I bought mine. This distributes the weight of the stone and any pressure you apply over such a large area that the stone doesn't remove anything unless it hits a high spot. This is also why it's beneficial to use a larger stone with some surface area. A small stone will cut more readily and remove more steel than a large one with equally applied force on a flat surface.

The description above of trying to slide the stone like a puck on an air hockey table is very good, that's exactly how I do it. You'll know right away if and when the stone hits a high spot by the instant change in drag and feel.

I think it's okay to not do much stoning if you're the only one working in your shop - you know damn well instantly if you've done something to cause a nick, ding or metal displacement. However, if other people are using the same machines, you never know the condition they left the parallels or machine table in. In that case, I always check with the stone before setting parallels or other equipment on a table.

Garwood · Mar 28, 2020

BGL said:
I have only been in this craft for more than forty years and recall reeling in horror the first time seeing someone 'stone' a mill table.

I have watched a series of videos by a very experienced and skilled man I have great respect for (never meet in person) who practices this 'stoning' religiously.
I am vehemently opposed to this as a routine practice - No, I will not do it! It is for repair only.

I commented on a Haas video that is excellent except for the practice of stoning - should not need to be routine and should be a video in itself.

I completely dismiss the idea this is routine - sometimes you have no choice but most times a spritz of your favorite fluid or even the machines coolant. Steel wool or fine scotch brite is all that is needed, rinse again with your fluid and wipe dry with clean rag.

If ever I do stone tools such a parallels and the like it is to remove the nicks and burrs left by the dull and ignorant. And that is with a very fine and soft Arkansas stone, done carefully. Be mindful of your tools and surfaces and you will rarely if ever have to do it.

A few times I have used a large stone as described above to restore tooling and machine tables that had been neglected. A few times just the spot where a tool loading tragedy raised a divot.

Never ever lay steel tools on the machine surface. I don't mind squeaky chalk but that clink of a wrench gently set on a table I hear from across the shop over the din. That is my burden. I always have a rag, cardboard, or even a scrap of aluminum sheet to lay tools on.

All this being said - if you insist and are compelled to do this, read post #13. This is a skill, not just rubbing a rock.
You do what you feel is best for yourself and your tools.

Me, I am ever so kind to precision surfaces and they have served me very well.

All this precision junk we have is all going to be melted down someday. Every. Last. Bit. Of. It.

They are just tools. Make money with it then send it on.

I was really anal about things at one time. I realized life is way to short for that and my give a fuck for investing time into nonsense is pretty low.

I'm not a hack, I'm a realist. Stoning the damn table, or whatever else, won't amount to dick in any of our lifetimes, but will prevent problems.

CarbideBob · Mar 28, 2020

BGL said:
I have only been in this craft for more than forty years and recall reeling in horror the first time seeing someone 'stone' a mill table.

I have watched a series of videos by a very experienced and skilled man I have great respect for (never meet in person) who practices this 'stoning' religiously.
I am vehemently opposed to this as a routine practice - No, I will not do it! It is for repair only.
......

All this being said - if you insist and are compelled to do this, read post #13. This is a skill, not just rubbing a rock.
l.

The great thing on this site is a variety of views.
I wear out stones, they get .060 thick and break into bits. That takes a lot of use.
Like hand lapping a mirror it is a skill and you can create problems.
Never stone a spindle taper or even abrasive pad unless you really know what you are doing, have had to regrind many of these.
Stones can be your friend, can also be a big enemy if used hard or not rotated. A stone may be bought flat but it will not stay that way if abused.
A light stone across all with a fine grit picks up high spots or nicks in a feel in your hand during a pass. Here we get to touch.
Micron nicks are unavoidable in my world. Just placing your precision vise or fixture onto the mag chuck may leave these.
I have the same "reeling in horror" feel, you have to teach correct use and still the employees will scrap a table top, vise, spindle or other.
You want to slap them silly but I've messed up a few in my time.

Think a stone is bad turn somebody loose with a carbide scraper or side of a HSS tool bit to remove burrs or high spots.
Bob

M. Moore · Mar 29, 2020

michiganbuck said:
if you have mapped it and found high and low then go over the low places twice.
Norton Combination India Stone

Michigan,
Can you explain why you go over the low places twice? Do you want to make them lower?
Just wondering?

Stone the table??

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