BY WILL SHAW

Resurrecting a used slab saw.

Sold! Marvin's Monster before restoration begins.

There it was, printed in the monthly flyer from our rock and gem club — “18-inch Highland Park® Slab Saw for Sale” from a member family. Turned out later it was actually a classic old Frantom® 18", but by any name, a used slab saw is often the Holy Grail of a devout lapidary. Slab saws can be used for slicing everything from pietersite to petrified wood, preforming spheres and carvings, making clock faces, bookends, and of course, slabs — the preliminary shape for cutting gem cabochons. So when I saw that ad, a little thrill of anticipation ran up the back of my neck — only a true rockhound can understand that sort of slab-lust!

I'd missed out a couple years earlier at a lapidary's estate sale, when I was just too much of a novice to appreciate the use and value of such a tool. Besides, the saw was just slightly smaller than a Volkswagen, and I lived in a condo — where was I going to put a monster like that? I stood by and watched a friend buy the saw for a fraction of its value, and fix it in 20 minutes (it had a shorted power switch). These saws are usually built like tanks — in fact, they are basically tanks! — and are often passed down from club member to club member, in a sort of lapidary ritual where one generation inherits the tools from the last. And it's a natural fact that you'll find new friends when rockhounds discover you own a good slab saw!

As I saw the wonderful chyrsocollas, jaspers, petrified palm, and huge football-sized chunks of wonderful plasma agate that my fellow lapidaries were cutting into slabs, I began to regret not jumping on that classic slab saw when I had a chance. Some saw manufacturers are no longer in business — Beacon Star, Ducketts, Sears Craftsman, Highland Park — but others, like Raytech, Lortone, Covington, Barranca Diamond, and Diamond Pacific, are still making great products. And when I began to look around at auctions or on eBay for a used slab saw, I realized just how shortsighted I'd been — the least expensive 12" slab saws often sold for $700 or more, and larger 18"-24" saws regularly went up above $1,200. And shipping these 200-pound monsters, often in two parts, added at least $100 to the deal. And to purchase a new slab saw, King Midas might have to take out a loan — a new Covington or Diamond Pacific saw can cost $3,000-$7,000 or more. No wonder a relationship with a slab saw is often for life.

Hence, the tingle, the thrill of the chase I felt when I saw the ad in our club flyer!

I had known the saw's original owner well — I'd cabbed alongside Marvin for two years at our Searchers Rock and Gem Club workshop in Anaheim — and shared and swapped stones and stories with him, and well, learned from him, as we all do from our elder members. He was very popular with the kids in the club, too — on field trips he'd call the youngsters together at his big RV and host a “rocktail party,” where he'd talk about the origin and content of the local stones, and make geology a bit of “edutainment” around the campfire.

Imagine our sadness and loss, then, when we learned Marvin, who appeared strong and vibrant — ready to hike up any trail that had fire agate at the end of it — had died suddenly on vacation in Colorado, on the road, as he loved to be. We had a big empty space in our weekly workshops, and in our hearts.

Marvin and I had once talked about how gemstones, once cut, and barring loss, will probably last forever. They are passed to other hands when we are gone, but the beauty endures, irresistible. And so it should be with a good rockhound's tools — I felt a real obligation to honor Marvin's legacy, to resurrect his “monster” saw and put it back in service, revealing the natural beauty hidden in gemstones.

I called a few folks in my club to learn the sale particulars, and luckily, our workshop supervisor, who had restored and still owns similar saws, became my invaluable resource. He'd seen the saw and thought it was in pretty good shape, though it wasn't much to look at, cosmetically. In talking with him and others, I learned how to inspect a used slab saw, and evaluate its condition. (Many of these same tests and criteria may apply to other lapidary saws, as well.) In restoring the saw, I also learned some valuable tips and tricks that I hope can help you if you're lucky enough to find a used slab saw.

A trick to check alignment: mount a felt-tip marker in the vise and observe its contact with the blade.

To check that a blade is true, use a straightedge to look for gaps.

EVALUATING THE SLAB SAW.
I was first in line on the day of the lapidary sale, and there it was — Marvin's Monster — tucked in a corner behind the garage door. It was old, greasy, rugged, and roughed up a bit — could I turn this ugly duckling into a swan? I looked the saw over, quickly paid the asking price, and was proud to tell Marvin's daughters that I had known him well and felt honored to “inherit” his slab saw.

Appraising the condition of a used saw is critical, not only to determine the price, though obviously the condition of the saw — and especially the blade — are negotiating points. More important, though, these checks will help predict just how much work will be involved in restoring it, if parts and service are necessary. An 18" saw blade alone can cost over $200 as of this writing, and without it, or with a damaged blade, the saw can be worse than costly, it can be dangerous. I can suggest these general checks (noting that they are not comprehensive), but the fact is that used saws appear so rarely — and with the availability of blades, bearings, even entire carriage assemblies — they are almost always a bargain, even if some further restoration is necessary.

Examining a used saw in front of the owner can be awkward. If the owner is willing, there is probably no better evaluation than to simply slab a stone. But this often takes 10-20 minutes, and a quicker check may be more practical, especially if there are other buyers present, or the saw is up for auction preview only. If allowed, take several photographs of the belt positions on the pulleys, the motor wiring, switch wiring, or other sub-assemblies; if you end up purchasing the saw, these will become an invaluable reference in re-assembling or re-adjusting the saw.

Most often, used saws are snapped up so quickly, you'll be lucky to perform even a cursory inspection, but try to bring the Quick Check List on Page 58, and go through it, with the owner's permission. If the owner is open and willing to allow you to examine the saw in depth, and even possibly remove the blade for scrutiny, so much the better. More extensive checks follow below, if you gain permission for a fuller — and even private — inspection.

IN-DEPTH INSPECTION.
One strategy here might be to hire an expert — find a machinist or engineer friend who might be able to bring his dial-gauge micrometer, a square and straightedge, and other tools to use in a more thorough inspection. And if you're lucky enough to have a slab-saw owner as a friend, ask for his advice — users are a wealth of tips and resources.

But the following checks can be made if you have time and permission to spend an hour or so with the saw, and are allowed by the owner to remove the blade, or even disassemble some parts. See the "Quick Checklist" for other tips and checks.

• Blade-to-vise alignment
  A friend passed a neat trick along to me on a simple check of parallel alignment of the rock vise to the blade cutting plane. If the owner will allow it, take a disposable felt-tip marker and mount it in the vise so the marking end just barely contacts the blade at its outermost edge. Release the carriage clutch, and push the carriage slowly forward through its normal path. Watch the felt tip marker as it travels along the blade radius. Does the felt tip stay the same distance from the blade through the whole trip? Are there little stretches where the marker didn't contact the blade? If so, this might indicate a dished or bent blade, or a carriage that's not truly parallel to the blade.
  
  
• Blade check: new, true, or “dished?”
  Since a new saw blade may cost several hundred dollars, blade condition may be the biggest factor when deciding how much to offer on a used slab saw. A true blade with even 25 percent of its useful lifespan left may even be the reason to buy a saw that needs other repairs! Or, if the blade is irreparable, plan on spending well over a hundred dollars for a new blade. A saw without a working blade is a just a very large doorstop indeed!
  
  Before you remove the blade, use a felt tip marker to mark an arrow indicating the original direction of rotation. Although diamond blades should be reversed now and then to insure even wear and long life, the owner may wish you to “put it all back like it was.”
  
  Remove the lock nut and carefully spread the flange rings. A leather hammer can help break their grip on the blade if there is heavy sedimentation. Sometimes a little finger twisting can help release the flange if oil causes the flange to suction-lock. Remove the blade without bending it, clean it of excess oil, and lay it flat on a known-flat surface. Use a known-true straightedge — like a metal ruler — laid across the blade's diameter to see if it's flat surface is true — that is, truly flat and level, no bumps or high spots, warps or dips. If the blade is true, the straightedge will rest parallel along the diameter of the blade with no gaps between the blade and the flat surface. A “dished” blade is a blade where the inner part of the blade is pushed in or out from the outer edge. Imagine a new CD or DVD lying flat on the table — that's a true blade. Now imagine a saucer or a frisbee, slightly curved toward the edge — that's a dished blade.
  
  A blade that is “out of round” will pound the rock as it saws, wear itself out, and even damage the bearings. A good test of the roundness of the blade is to move the felt-tip marker in the vise until the tip is just off the blade about 1/8", and just in front of the blade. With the unit unplugged, turn the arbor and watch the blade in profile at the space between the rim edge of the blade and the marker. The blade should stay the same distance (1/8", in this case) from the marker as it rotates.
  
  

• Flanges should extend up into the radius of the blade for about 25 percent of the blade's diameter.

  To check the flanges, press them together and hold them up to the light. There shouldn't be any gaps.

  Flange check
  The flange is a clamp made of two rings that fit over the arbor shaft, and secures the blade on either side to the arbor with a locking nut. The flanges actually drive the blade, but they also support the blade and stiffen it as it cuts. The flanges should extend up into the radius of the blade for about 25 percent of the blade's diameter.
  
  If you're allowed, remove the blade and spread the flanges apart, checking for nicks or heavy gouges in the outer edges that might be evidence that a rock was allowed to feed into them during a careless cut. Check the flat flush edge of the flanges with a metal ruler or straightedge, same as you did for the blade. Press the flanges together and hold the flange “sandwich” up to a light — there shouldn't be any space between the rings to allow light to shine through. Flanges can be resurfaced at a machine shop, or if severely damaged, purchased new at the suppliers noted later in this article.
  
  
• Carriage drive mechanism
  The carriage drive is the long, threaded shaft under the rock vise and carriage that typically uses a smaller motor at the back of the saw to propel the carriage parallel to the blade as it cuts. The key word here is parallel. If the carriage is not moving parallel to the blade's cutting plane, the rock you cut may push into the blade at an angle, and actually wedge itself against the blade during the cut. This will not only dish the blade, it may cause the saw to jam, and seize up the arbor, which could cause a motor to burn out too.
  
  Again, the best practical test of parallel carriage travel with a used saw is simply to slab a stone — or examine a recently cut stone, if the owner objects to a drawn-out session. Stay with the saw through the entire cut. Listen for any pinching or binding noises that rise above the steady whir of the cutting blade — in fact, the more you slab, the more you realize how sound is one of your most important indicators of your saw's operation — especially as your visual scrutiny during slabbing is usually limited to a small plexiglass window with oil sprayed over it! Soon you'll become familiar with your saw's normal cutting sound — but this requires you to be present during the first 5-10 sessions or so. You may not have time to watch the saw cut for 10-15 minutes, but don't walk away to do the laundry or check your e-mail — listen! In fact, I'll go so far as to recommend that you always stay within earshot of your saw while it's cutting. Listen for sudden changes in the sound, such as a sudden screech or scraping sound, or a rhythmic tick . . . tick . . . tick that may indicate an obstruction. If you catch these symptoms early enough, you can usually avoid damage to your blade or motor.
  
  

• Listen for sudden changes in the sound, such as a sudden screech or scraping sound, or a rhythmic tick... tick... tick that may indicate an obstruction. If you catch these symptoms early enough, you can usually avoid damage to your blade or motor.

  Cross-feed travel
  The cross-feed is the perpendicular carriage adjustment made as you advance the rock into the saw blade. The cross-feed determines the thickness of the slabs you cut. With the saw unplugged, back off the cross-feed as if accomodating a very large rock in the vise. Then turn the cross-feed handle and watch the carriage advance. The feed should be smooth and regular. Watch for binding here, or seizing. A very thorough test would be to mount a ruler in the rock vise to measure the distance advanced for a specific number of turns — my saw took five turns to make a 1/4" exactly, yours might vary. Align the ruler on an even inch mark . . . e.g., 2" exactly. Then turn the cross-feed handle, counting the turns, until the ruler reads 2-1/4" (which would produce a cut 1/4" thick from the previous setting). If the 1/4" required six turns, for example, turn another six turns to assure that they result in another exact 1/4" advance, to exactly 2-1/2" on the ruler, in our example. Continue this process, making sure that six turns (or whatever your increment is) always results in a 1/4" advance through the entire range of the cut. Once you're cutting, slab thickness is often determined by turns of the cross-feed, rather than inches, so this standard becomes important.
  
  
• Auto shut-off
  When a cut is almost complete, the slab often breaks off as its weight cracks the last corner attached to the rock in the vise. Sometimes a little corner of the main rock protrudes, and may continue into the blade surface as the carriage drive advances. If this rock corner, or “spur,” pushes into the blade, it will bend or even dish the blade. In order to prevent this, many saws now feature an automatic power cut-off switch. A small pin or lever connected to an adjustable chain or link will switch off the power depending on the distance you set for the carriage advance. To check the operation of the auto shut-off switch, unplug the saw, back off the carriage to its start position, then attach the chain or link for a short travel — say, two inches. Re-engage the clutch, close the lid, and plug the saw back in. Start the saw, and wait a bit to see if it shuts down properly when the chain reaches its two-inch limit.
  
  
• See the "Quick Checklist" for other tips and checks.
  

A MONSTER RESTORATION.
The day after the sale found me armed with buckets, scrapers, scoops, funnels, and rags, ready to tackle the ugly muck that still filled the saw from years of cutting. The accumulated oil had made the saw extra heavy, too — the four or five gallons still in the saw probably added 80-100 pounds to the weight of the unit. I'd promised to remove the saw from the garage, and suddenly the transport became my first goal. Our club workshop leader gave me the best tip of all, and advised me to avoid all potentially explosive solvents, and simply get dirty and scrape the saw basin out manually. He had done this job several times, and he didn't really reveal how messy it would be — he knew if I figured out how many hours were involved it might seriously deplete my gumption level. Plan on simply discarding anything you wear to this party! Remember: take a photo before disassembly to have a record of belt positions, motor mount, wiring, etc.

The slab saw oil, through hundreds of slabs and perhaps years of use, really consisted of three or four layers of stuff, one lying on top of the other. The first layer was still usable saw oil, which, being lightest, floated on top of the rest, and could be skimmed off and re-used.

The second layer down consisted of a slurry of dirt and oil, with the consistency of a milkshake. This layer had to be removed and disposed of at an official county waste-disposal station. Finally, at the bottom, lay a thin but dense layer of bits of rock and compacted silt which was sticking to the bottom of the basin and doing a pretty good imitation of concrete! Carving away the long strips of this sticky clay required a good old paint scraper. I collected the clay in a large plastic milk jug with the top cut off. This mud layer is so thick that it will not even flow to drain out of the bottom of the saw, and in fact, usually covers the drain plug anyway, rendering it useless. My advice: remove your saw from the top.

First, I removed the blade to protect it from accidental impact, and to allow more elbow room inside the basin. Removing the hood is a good idea, too. The saw blade's lock nut was a standard thread, as most are, so it came off with a counterclockwise turn. These nuts are designed to tighten as the blade turns into the rock, so it's a safe bet that nearly all blade nuts are removed by turning counterclockwise. Be careful not to touch or hold the blade as you torque off the nut — a better idea is to have a helper secure and lock down the drive pulley as you wrench off the blade nut to avoid bending the blade.

Take a photo of the belt positions before disassembly!

When I discovered that the cost of the new saw oil was relatively inexpensive (about $25 for a five-gallon drum at this writing), I decided that skimming the oil to preserve an extra quart or so of the old oil was just wasting time — I had promised Marvin's family I'd have the saw off the premises by day's end. So, I devoted myself simply to emptying the saw of oil and mud and discarding it safely and legally. I had a variety of scoops and funnels and hoses, but nothing worked as well as a simple quart-sized plastic milk jug, cut off about an inch or two from the bottom. Our workshop leader showed me that if I replaced the cap and held the jug upside down, I had a perfect “square” scoop with a nice handle that could scoop right into the corners of the tank, and hold up to half a quart of goop at a time!

TRANSPORT.
Moving this monster around became a preliminary task to restoring it. I measured the saw as if the legs were removed, and found it would fit nicely inside my SUV. A friend with a pick-up truck can be very handy here too, but probably the best idea is to rent a small trailer with a ramp or lift. If you can't bring a strong friend, that ramp is critical.

I broke down the saw for easier transport by removing the legs. That required that I remove the motor and motor mount. Since I needed to transport further, I also rebuilt the wooden trolley underneath it with much larger wheels than Marvin had. In fact, if you are considering a big slab saw, this mobility is a major issue — make sure you can move the saw easily, as these monsters can easily weigh over 250 pounds when full of lubricant! Remember: take a photo before disassembly to have a record of belt positions, motor mount, wiring, etc.

MONSTER'S NEW HOME.
With the saw safely at my address, I began to give some thought as to how far to carry on the restoration.

The author had his saw professionally stripped.

My goal became not a complete blueprint job, not remachining bearing races or rechroming every nut and bolt, but preserving basic functionality. There are machine shops and engineers who might take this path, but it would clearly involve a great deal more time and money than I had budgeted. I wanted to clean the saw enough to insure that the arbor, carriage, and drive were working properly, and one other important thing: so the youngsters or beginners could see and appreciate the mechanism by which the saw worked, for example, so if I showed them the clutch lever and drive shaft, they could see the parts well enough to determine whether the clutch was engaged or not.

DEGREASING AND STRIPPING.
I gave the saw to a local “dip-and-strip” outfit to clean the saw drive mechanism and the housing, and remove most of the residual oil from the interior and exterior surfaces. These companies have a huge tank full of corrosive liquid that they can dip an entire auto body into at one time, though we decided against this with Marvin's Monster. If I had removed the bearings and pulleys and the vise and carriage from the saw, as well as the Plexiglas side windows and any other aluminum parts, I could have dipped the entire steel housing for a very comprehensive cleaning. But the parts were all working well together, and not wishing to disturb the calibration, seals, blade alignment, and general fit, I figured, “If it ain't broke, don't fix it!” We opted simply to paint on stripper fluid and grind the stubborn spots of paint or corrosion with all the hardware in place — with hindsight, I probably could have done this myself much less expensively, but it is amazingly time-consuming. The professional stripping — though not complete — did allow me to go to work on the vise and carriage without working through a layer of oil and muck over it all, so in that regard, it was worthwhile. Time is money here, too.

CLEANING CARRIAGE DRIVE.
I thought at first it might be possible to use some solvent that would remove the years of caked-on sediment that covered the carriage and vise, but everything I tried barely touched the hard thin concretized coating over everything. I finally resorted to a very hard metal flat file to use as a scraper, and simply chipped and scratched the stuff off. This is where you learn patience; and plan on clearing just a few square inches in a session. The file had a long, flat edge, and a sharper tip for crevices and crannies, and it worked well. A stiff steel-brush wheel mounted in a power drill is also good for clearing shaft threads and old paint. And my good ol' flex-shaft tool had a little wire-brush tip that was perfect for cleaning the stubborn sediment on the threads of the carriage advance.

To chip off the caked-on sediment, the author used a hard metal flat file as a scraper (left); for the threads of the carriage advance, he used a wire brush tip on his flex shaft (right).

This step took a lot of time — planning a full day is probably not enough. Better to devote an hour here and an hour there, until your gumption runs out. Remember, it took years to accumulate all that gunk, so you may not remove it all in one session. I don't even think you could pay someone to do this part of the job properly — this is where you've got to love your saw . . . or learn to love it!

A simple 110V two-position on/off switch was mounted in a plastic electrical junction box.

INSTALLATION OF AUTO SHUT-OFF SWITCH.
Since the original Frantom didn't include an auto shut-off switch, I thought I'd add this one modern makeover to the Monster. For those familiar with electrical, it's a simple, normally closed switch in series before the main power switch . . . but always consult an electrician or electrical expert before installation.

A local electronics store provided a simple 110V two-position on/off switch with a long switch lever. I mounted the switch in a plastic electrical junction box, easily found at a hardware store. I found some chain and some thick 12-gauge wire (those huge paper clips, bent into eye loops on each end, also work well) to link the switch through the tank to the carriage movement. I installed a small hook on one of the carriage cross-feed mount bolts on which to attach the adjusting chain. Only after careful consideration of where the chain would travel did I drill a hole through the tank, and three other holes to mount the switch. Again, if you try this, get an electrician to check it out. Here's a tip: if you do attach the adjustable chain to the carriage, try to position the links and the chain away from the clutch lever or any other moving part where they could get tangled up. Try a couple spots, move the carriage forward, and test the position before you drill any holes in the tank. Use the “Measure twice, cut once” strategy.

SANDING AND PREP FOR PAINTING.
I tried Naval Jelly® on what few corroded surfaces I could find to remove rust. But Rustoleum® stripper was a better product somehow — worked faster and more completely.

Left: On some stubborn paint spots, the author used sandpaper, as well as a wire-brush wheel on his flex shaft. Right: Once the metal was bare, a thin layer of oil was applied to prevent rust.

I learned to almost double the recommended stripping time before removing the stripper with water. Always use rubber gloves with paint stripper, and have plenty of ventilation — it's nasty to inhale! The stripper comes with a mesh pad for scraping, which seemed to work best after rinsing with water. On some of the stubborn old paint spots, I sanded with a 100-grit paper, then a 320-grit to get down to the metal surface. The wire-brush wheel on your flex-shaft tool is helpful here too. This is a big job — you may need days, so I broke down the project into areas about a foot square. When I got down to the bare metal, I would coat it with a thin layer of oil to prevent rust, until the entire surface was ready to paint.

PAINTING.
After resurfacing parts that had more rust — the legs were the worst — I used two coats of an automotive primer to coat the bare metal prior to final paint. I used lacquer thinner solvent to remove that protective layer of oil, then immediately primered the surface to seal it against rust. A neighbor recommended a painter who owned a spray booth, and painted the exterior of the saw for a nominal charge. If the saw is primed and masked off properly (windows, chrome, handles, etc.), many auto-body shops will spray-paint your saw when they're painting a car and already have a color mixed. You may want to leave the saw with them or schedule a convenient time to take advantage of a particular color run they already have scheduled for an automobile job.

CHECK THE OIL, PLEASE!
When it came time to fill ‘er up again, several slab-saw owners in our club tipped me to a great Shell product called Amber Light® Mineral Oil, which the label says is a “Hydrotreated Light Naphthenic Distillate 64742-53-6.” This oil is effectively odorless and very safe to handle — the Hazard rating label displayed a Fire Hazard rating of 1 (slightly hazardous, where 4 is the extreme), a Health Hazard of 1, and a Reactivity rating of 0, signifying “No significant” reaction hazard with other materials. This oil, and other products recommended for lapidary use, like Chevron's Superla #5®, Texaco's “Almag®,” Standard's “RPM Flushing Oil®,” Shell's “Pella 21®,” and Arco's “Calube SIOS® aren't found at the corner gas station, though — you've usually got to visit a manufacturer's distributor. Try the Yellow Pages under “Oil Products” or the Web by using “Oil products distributor” in your search.

LEGACY.
When I reassembled the saw, I was glad I'd taken those reference photographs — especially the one that showed the pulley belt configurations, and the motor mounted. There were some surprises, such as when the wood clamps in the vise jaws crumbled in my fingers when I tried to remove them. And the cost of a good spray paint job. And the rebuilding of the trolley below the saw, which I'd recommend as a first step next time.

But the saw worked great, and even better than saving all that money by choosing a used saw, I came to know my saw first hand as I resurrected Marvin's Monster. There's nothing like hands-on experience with such a tool . . . knowing every shaft and stop, belt and bearing, every whir and click. This was the real payoff — knowledge gained through the feel, the sounds, and the careful restoring of a tool that had outlived its master, but not his memory. I often talked to Marvin as I chipped away, and sanded, and scraped — sometimes grumbling (“Why didn't you replace those disintegrating wooden vise jaws?”), sometimes in relief (“Thanks for keeping that blade true!”), but always, I hope, in pursuit of our shared passion — the beauty revealed in Nature's treasures in stone.

Maybe someday someone may inherit Will's Monster — and be as grateful for the privilege as I am to Marvin.

The author owes special thanks to Dean Delahut of Barranca Diamond and Don Depue of Diamond Pacific for their technical guidance and advice. See the "Quick Checklist" for other tips and checks if you're considering buying and restoring your own slab saw monster.

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Will Shaw is a video- and multimedia-producer in civilian life. He has been a rockhound since he was nine, and enjoys slabbing & cabbing pietersite, Peruvian opal, and chrysoprase at the Searchers Gem and Mineral Society in Anaheim, CA. He also created the Web site for the Gem Art Center at www.gemartcenter.com. Will can be reached at info@digvisions.com, especially if you have any tips on polishing Yowah opal!