Oil stone calculations...

Re: Oil stone calculations...

Joe Rogers, Northern Virginia

>I hereby nominate this post for an article. Much good information and examples to make it understandable.JR

Re: Oil stone calculations...

Tony Zaffuto

>How does it affect the stone if they have been subjected to a life of oiling without cleaning?

Re: Oil stone calculations...

Todd O. Cronkhite Maine Native now in Jax Fl.

>Tony,

A stone* that has never been cleaned will not cut properly. All the pores are filled with grime and swarf to the point of being useless. It is very inportant to at least wife a stone off from time to time WHILE using it, AND for sure when your thru with it. You don't want to leave that dirty oil just siiting on, and thereby soaking into the stone. Even with diligent wiping during and after use, the time will eventually come where you'll want to "freshen up" the surface by either rubbing it on some very fine grit sandpaper if it is a very fine stone, and perhaps a bit coarser grit for the softer stones. You certainly wouldn't want to use coarse grits on fine stones a potentialy scratch up the surface.

* I'm speaking of Natural Stones and not manmade ones as I really have no experince with manmade stones other than carborundums, which clogging is not a problem, but keeping them flat is. I a cemet block to re-flatten my carborundums.

Todd O.

Dang it Bryan,

Todd O. Cronkhite Maine Native now in Jax Fl.

>What you tryin' to do get me hooked into complex math*?

I apprecite the info, and have printed it out for further study.

* anything past basic addition, subtraction, mulipling and dividing is considered to be complex math by me. However, in my current Carpenty studies we have been dealing with complex math, and I've really enjoyed it.

Todd O.

The oil content question is a good one

Bill Houghton, sunny yahoo! in Sebastopol, CA

>Does a stone pick up weight if it's been repeatedly washed with oil, or does the oil not actually penetrate the stone?

Wifing the stone

Bill Houghton, sunny yahoo! in Sebastopol, CA

>I'm going to assume, Todd, either that you meant "wipe" or that you normally sleep in the garage, if you're prone to comments like that.

a better way , maybe

bill tindall

>To differentiate the differences you quote the size must be determined with better than 5% accuracy, a difficult task if the stone is rounded on edges, has chips, etc. Another way to determine volume is by displacment. Fill something with water , add the stone, catch water that overflows and weigh it. If near 70 degrees assume density of water is 1. Weigh stone. Weight stone divided by weight water is the density. There are other even better ways if one has the right kind of scale.

A few answers...

Bryan in Broad Ripple, IN

>I would expect that the more oil in the stone, the heavier the stone is and the higher the apparent specific gravity. I weighed my stones after they had been boiled for about 10 minutes and then allowed to air dry for several days. I boil them with a bit of Spic and Span, and this really seems to draw the oil out. However, the denser stones like translucents probably absord too little oil to really affect the calcs. They are that dense. Washitas, however, are fairly porous, and would be impacted more by the weight of the oil.

Bill Tindall is correct that directly measuring volume by measuring it's displacment would be more accurate in some circumstances. However, the stones I measured were near mint examples of vintage stones, and were Pike and Norton brand so their were straght, square, and true. So, measuring their dimensions was pretty easy. Besides, I did this late at night a few weeks ago, and didn't feel like going Archimedes at the time. :)

If your's is dished, or irregular, then measuring volume directly through displacment would undoubtedly be more accurate. For quick and dirty approximations, however, nothing beats just measuring the dimensions...it'll at least get you in the ball-park. Regardless of how you determine volume, the rest of the calcs apply.

-Bryan

Question

bill tindall

>To begin I don't know anything about these stones so this idea could be miles off track.........

If slight differences in density is what differentiates these stones, and this density difference is a result of porosity, then another way to determine their name would be by absorbing water or another liquid. Displace oil, bake dry , weigh, immerse in water with a bit of surfactant(soap) to aide absorption, wipe dry and weigh. Perhaps this direct measure of porosity would be relaible.

Re: A few answers...

Tony Zaffuto

>Actually I did not give a good description in my earlier post. I own a powder metal parts manufacturing business. As a normal quality control method density of molded products is checked routinely. There are a number of variables that can affect density/specific gravity. Our products are porous, as are most stones, both man-made and natural. To measure density/specific gravity in the most accurate way, the porosity needs "sealed off". We achive this in a number of different manners, which for the sake of brevity I will not get into.

In my earlier post, I should have stated that density and/or specific gravity can assist you in determining what a stone may be similar to, but it is affected by the environment it has previously been subjected to. Should anyone wish to email me "off list", please do so. My Quality Manager has a Phd. in metallurgy and chemistry and I'm sure he can offer an expanded set of criteria to guide anyone interested in this subject.

Personally, I have a wide array of sharpening items: waterstones of 200, 800, 4000 and 8000 grits; fine and medium India stones, Black Arkansas, Lilly White Washita, Translucent Arkansas plus stones if undetermined vintage and all kinds of "Scary Sharp" devices and several "tailed" devices. I like the medium India followed by Black Arkansas and then 1500-2000-2500 grit SiC paper. Quick and not too messy.

Re: Question

Bryan in Broad Ripple, IN

>I suppose this would work, in theory, if the stones were analogous to open cell expanded foam, where the cells interconnect with one another and can fully saturate....like a sponge. If they are similar to closed cell foam, like a styrofoam cup, where the cells do not connect, they would not saturate, and this would not work.

If the stone was "open cell" and you want to try measuring porosity, it's important to realize that in some cases (the very dense translucents), porosity is a very small fraction of total volume. Greater control over the measurements (they will be pretty small) would be required so you don't lose your resolution, so to speak, to erroneous "noise". It might require a level of accuracey and precision that a typical DYI'er just may not be capable of.

Regardless, it's kind of fun seeing where this is leading, as this was originally a 1:30 am, quicky, scrap paper calculation, done to satisfy my personal curiousity. That is to say, fun in a weird, over-analytical sort of way. ;)

-Bryan

Re: a better way , maybe

Phil Albany,NY

>Actually I think that the best way is somewhere between the two proposals. Don't let the water escape the top of the container. Rather fill the container with less water, measure the height of the water and then completely submerge the stone in the water of the container. Next accurately measure the height the water rose to after you submerged the stone. Take the difference between these two heights and compute the volume of the stone by using the following formula: Pie (3.141592 is good enough) * (the square of the diameter of the container) divided by 4 * the difference in height before and after the stone is submerged in the water. This will give a surprisingly accurate way to measure the volume of the stone. Make sure that the container has no taper though or you will get bad results. Don't worry about the miniscus where the water meets the side of the bucket, just be consistent with how you measure height. A good candidate for the container would be an empty paint can.

Good luck,

Phil

Re: A few answers...

Phil Albany,NY

>Oops. Sorry Bryan. Should have read the complete posting before replying above.

Phil