[meteorite-list] Lessons from the Saw - Cutting Meteorites for Newbies and Curious Onlookers

From: Matthew Martin <mmartin_at_meteoritecentral.com>
Date: Wed, 02 Jun 2010 18:30:37 -0500
Message-ID: <20100602183037.alqauzyr4skwg0c0_at_webmail.meteoritetreasures.com>

Mike,

That was very nice of you to share your very comprehensive list of
cutting experiences and lessons learned with the list. I enjoyed
reading it. Thank you.

Aloha,

Matt



Quoting Galactic Stone & Ironworks <meteoritemike at gmail.com>:

> Hi Listees, Listoids, and Lurkers!
>
> I just past my first anniversary of owning a lapidary saw and I am
> preparing to cut some unidentified NWA material that is likely a
> howardite or eucrite. Cutting material like a howardite is very
> different than cutting something harder like most H-chondrites. This
> got me to thinking - I often asked the List about various aspects of
> cutting and polishing, and rarely would I get any useful answers. A
> small handful of people did contact me in private to give me some
> pointers, and I would like to thank them again for sharing their
> wisdom with a rookie cutter. But, in public on the List, you could
> hear crickets and see tumbleweeds blowing by as I waited for answers.
> A long-time veteran collector and List member told me the reason is
> because the skills involved when cutting meteorites are learned
> through trial and error, and they are akin to "trade secrets" - no
> successful cutter is going to divulge these techniques because it
> amounts to helping out the competition.
>
> Well, a year later, I am a pretty good cutter - or so I am told by
> several people who have used my cutting and polishing services. I can
> make nice even cuts and I can produce a hard polish that is mirror
> smooth. Recently, I started shopping around my services as cutter to
> collectors and dealers who don't own saws. In the process of doing
> so, I had a lot of questions thrown at me - about cutting,
> preparation, blades, coolants, sanding, polishing, etc.
>
> This List has been very gracious to me over the 3 years I have been
> here, so I wanted to contribute some knowledge back into the List -
> for the benefit of the newbies, lurkers, and people who are
> considering whether or not to purchase a saw.
>
> First, I want to give a little background on my own cutting, so this
> will give some context to the tips and pointers I am going to offer
> below.
>
> I use a Lortone Rock Rascal 6-inch lapidary saw. I paid about $300
> for it. It is now discontinued by Lortone, but they are still
> available for purchase from some vendors as NOS - New Old Stock. It
> is the only rock saw I have personally used. I like this saw. I did
> some research before buying it and I considered several alternatives
> before deciding on this particular saw. I could have bought a bigger
> saw and budget was not a constraint - but I went with the 6-inch saw
> because I don't have much desire (or opportunity) to cut large
> specimens. The vast majority of the specimens I deal with are about
> the size of a golf ball, so a 6-inch saw was all I needed.
>
> I cut frequently and I have cut several types of material. I have cut
> some rocks, shells, and other non-meteorite materials, but I will
> limit my comments to cutting meteorites and tektites.
>
> Materials I have cut - every type of OC one can imagine, highly
> weathered materials, fresh materials, carbonaceous chondrites (several
> types), mesosiderites, howardites, eucrites, and indochinites.
>
> I don't cut irons. It's too labor intensive, time intensive, and it's
> hard on the equipment. So all of the advice below is geared towards
> cutting stony-type meteorites and some mesosiderites.
>
> DISCLAIMER : I am not claiming to be an expert and these remarks are
> intended as unsolicited advice for newbies who are curious about
> cutting or would like to learn more about cutting. I do not claim
> that my methods and equipment are the best choice on the market. I
> use what I have and it works for me. Your mileage may vary.
>
> SAW and CUTTING TIPS :
> -------------------------------
>
> 1) Bigger saws require bigger blades. Bigger saws make more noise and
> mess. Get a saw as big as you need - don't buy a saw that can cut a
> basketball-sized meteorite if you don't have access to such
> meteorites. Consider what you are going to need to cut and then
> decide what size saw to get. Keep in mind - half of the saw blade is
> under the table surface. So, a 6-inch saw has approx. 3 inches of
> useable cutting surface. This means the biggest meteorite you can
> properly cut in one pass on a 6-inch saw is about 3 inches in
> diameter. Replacement blades for larger saws are more expensive -
> another reason to get the proper size saw.
>
> 2) Avoid home improvement tile saws. I call these "Home Depot saws".
> Yes, they are cheap. And yes, they will cut meteorites. But, the
> blades are thick and are made for cutting materials like ceramic tile.
> Loss is not much of a consideration when cutting tiles for your
> shower surround. But, using that thick tile blade on a meteorite will
> result in a wide cutting swath of lost material and money. It's
> similar to swatting a fly with a baseball bat. If you want to lose
> half of every meteorite you cut, then buy a Home Depot saw. If you
> want a razor-thin cutting swath and minimal loss, get a true lapidary
> saw. Further proof of this is to take a look at any successful or
> experienced cutter - all of them use lapidary saws. (unless they cut
> irons, and then many use wire or band saws)
>
> 3) Don't use tap water as a coolant. Tap water contains chlorine,
> which will contaminate the material and result in an unstable
> specimen. Use distilled water only. Distilled water is cheap. You
> can buy it at Walmart for less than $1 a gallon. With a small 6" saw,
> a gallon goes a long way. It's well worth the investment. Your
> specimens will thank you and the people who end up owning those
> specimens will thank you.
>
> 4) A .012" kerf saw is plenty thin. Loss with a .012" blade is very
> minimal. There are thinner blades available, but some of them will
> not work with all saws. For example, there are ultra-thin blades that
> are .006" kerf. These blades are floppy and must be rotated at very
> high RPM's to maintain their rigidity during cutting. Always check
> your saw motor speeds and the size of your pulley before using one of
> these ultra-thin blades. I have tried both, and the .012" is plenty
> thin for me while still being rigid.
>
> 5) Everyone has their own ideas about what type of blade is best. I
> have tried the CBN blades (cubic boron nitride) that are supposedly
> designed for meteorites, and I didn't like them. I find that diamond
> blades cut much better than CBN blades. So, IMO, forget about CBN
> blades. I use the DiaLaser brand diamond-coated blades and they work
> very well for me. My next couple of blade purchases will be
> experimental and I am going to try a sintered Pro-Slicer blade. I
> will report back in the future about the performance of those blades.
>
> 6) You can dry cut a meteorite. I just don't recommend it for the
> majority of circumstances. If you have a very small and friable
> specimen that will not react well to getting wet, then you can dry
> cut. Keep in mind, dry cutting is hard on your blade and will result
> in a dull blade much faster than wet cutting. But, replacing a $30
> blade might be a worthwhile trade off if you are cutting something
> fragile like Orgueil or something very valuable like a lunar or
> martian. 99% of the time, I cut wet.
>
> 7) Don't be in a hurry. Cutting meteorites is not a race. The faster
> you feed the specimen into the saw, the more likely the blade is to
> wander, resulting in a crooked or wedged cut. Feed slowly,
> consistently, and evenly. Cutting in a hurry will only result in poor
> cuts that require more work later to clean up. It's better not to
> leave a deep saw mark in the first place, than to spend time sanding
> it out later - which also results in more loss of material.
>
> 8) Don't be afraid to hand cut specimens. I've hand cut hundreds of
> specimens and have yet to cut my hand or fingers. (*knock on wood*)
> There are a wide variety of options of available for clamping
> specimens into a vise or jig that will hold the specimen during
> cutting. These result in nice straight even cuts. But, all of them
> have tradeoffs. First, some specimens are odd shaped or small, and
> they are difficult (or impossible) to clamp into a vise or jig. If
> you don't have a vise or jig, don't let that stop you from slicing.
> With practice, it is possible to make straight even cuts by hand. I
> own a sliding vise for slicing, but I rarely use it. I find it much
> easier to just hold the specimen in my own hands and I get better
> feedback during cutting because I can feel the specimen during the
> cut. I'm not saying that hand cutting is the best way to cut, I'm
> just saying that it works for me in many situations. Ultimately, the
> specimen itself may dictate what method is used to cut it.
>
> 9) If you do cut by hand - cut slowly and evenly. Do not feed to hard
> or quickly. Do not force the cut. Let the blade do the work and
> watch the cutting swath closely, especially in relation to the blade.
> A thin blade can flex in subtle ways that is not readily apparent, and
> this can result in an uneven cut. When the blade wanders in this
> manner, you will end up with slices that have a taper or wedged
> profile. Also, don't try to cut slices less than 1mm by hand, unless
> you can live with some breakage. Perhaps I am not experienced enough
> yet, but when I try to cut super thin slices by hand, it rarely works
> out well - that is where a feeding mechanism like a vise or jig comes
> in handy.
>
> 10) I guess I shouldn't have to say this, but for the record - wear
> safety goggles or safety glasses while cutting. Even if you wear
> eyeglasses, be sure to wear some impact-rated eyewear over those. You
> will save your eyesight and you will prevent your eyeglasses from
> being damaged.
>
> 11) If your saw doesn't have a light on it, get a "clamp lamp" or
> similar light fixture and set it up to illuminating the cutting area -
> with a focus on the blade area. An adjustable desk lamp or shop lamp
> is good for this. If you want to safely make nice even cuts, you must
> be able to clearly see what you are cutting. Don't assume your garage
> that is sufficiently lit to cut plywood is bright enough to do detail
> cutting on small valuable meteorites - throw more light on the
> subject.
>
> 12) Keep a magnet handy. I have a magnet on the end of a pencil-sized
> wooden stick. I prop this up on the saw table during cutting and it
> helps prevent specimens from getting stuck to the blade or falling
> into the tank. It's also handy to collect crumbs and specks during
> cutting. If doing the latter, put a tiny ziploc bag over the end of
> the wand - to easily remove the crumbs later.
>
> 13) That little slot in the saw table that the blade passes through is
> too wide. Get a piece of thin, flat plastic and cut a small slit into
> it that will barely accomodate the cutting blade. Shape this piece of
> plastic to fit as a "template" that will drop onto the cutting table
> and can be removed easily. This will help prevent thin slices and
> pieces from dropping through the slot in the table and into the murky
> depths of the coolant tank. This little modification will pay for
> itself the first time is saves a thin slice of a rare fall from
> falling into the tank.
>
> 14) Let the stone dictate where to cut. The shape, composition, and
> size of the stone will usually determine where to make the first cut.
> Carefully examine the stone prior to cutting and have a plan in mind -
> don't just start cutting willy nilly. Take notice of any fractures in
> the stone which may effect the cutting - if you cut across or along a
> fracture, the specimen will often crumble or a slice may break. Take
> into account the weathering state of the specimen as this may also
> effect the cutting.
>
> 15) Often you will have two choices for cutting a specimen - cutting
> it in a way which will expose the most surface area on the slices, or
> cutting it in a way that will produce the most slices. An example is
> an elongated or thin (or flat) specimen - if you cut it lengthwise
> along the narrow profile, you will yield pieces with the most surface
> area, but you will get fewer pieces. If you cut it widthwise across
> the longest dimension, you will get a loaf of bread type of affair -
> many pieces, but with less surface area on each. Which route is best
> is determined by a variety of factors that the cutter decides.
>
> 16) Have your oven on at 225-240F in advance of cutting. After
> cutting, take the specimens and put them directly into the oven
> without delay. Bake for 4-6 hours minimum, to purge any moisture from
> cutting. Some people like to chase the water out with alcohol prior
> to baking, but I have had good results without using alcohol and now I
> rarely use it.
>
> 17) After you are finished cutting, empty the coolant tank
> immediately, and then spin the blade dry. Keep your saw clean and
> tidy and don't let gunk build up between cuttings.
>
> 18) Saw marks are difficult to avoid and can be laborious to remove.
> As I said above, cut slowly and evenly and you will avoid deep saw
> marks. If you do get saw marks, keep some sandpaper handy in various
> grits from 100-600 - these grits are easiest to find at Wally World or
> home improvement stores. Start at 100 for deep saw marks on robust
> specimens, start at 200 or 220 if you have a more friable specimen.
> Place the sandpaper on a hard, level, flat surface and then place the
> specimen "face down" onto the sandpaper - press firmly and sand the
> specimen in a circular motion. Don't press too hard or the specimen
> may break or chip.
>
> 19) If you don't own a lap polisher, keep additional sandpaper handy
> in grits from 600 to 1500. Jeweler's rouge is also good to keep
> around - to achieve those hard glassy polishes.
>
> 20) If you aren't in the mood, don't cut. If you don't cherish your
> cutting time and love what you are doing, it will show in the results.
>
> That's it for now. I am off to do some more cutting and polishing. :)
>
> Best regards and happy cutting!
>
> MikeG
>
> http://www.galactic-stone.com
>
>
> --
> ------------------------------------------------------------
> Mike Gilmer - Galactic Stone & Ironworks Meteorites
> http://www.galactic-stone.com
> http://www.facebook.com/galacticstone
> ------------------------------------------------------------
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Received on Wed 02 Jun 2010 07:30:37 PM PDT