Stone Business…Is it Right for my Shop?
How hard is stone to work and what costs are involved in the fabrication of stone?
By Al Gerhart: Our shop, like many of those who read the FabNet, fabricates a variety of materials. We farmed out the stone and quartz, but loss of control and loss of jobs due to increased costs convinced me to get started in the fabrication end. Here is what I have learned, which is not intended to be an instruction manual, more like a description of the processes and pitfalls of starting out.
Stone Slab Costs
For the most common stones, figure approximately from $8.00 to $15.00 per square foot, up to $20 for some Absolute Black slabs. Most yards separate stones into price levels. The customer doesn't get pricing, just levels that they can use to stay in budget. The pricing can vary, from the mid $8.00 up to over $75.00 per foot.
Our first job, we paid around $800 for the slab, delivered. Santa Cecilia, level I, beveled edge, under mount stainless steel sink, with four bump outs.
Abaco slab clamps, $450 to $550, seem to be the most recommended. They are used on a short chain on the end of a boom that fits over the forklift forks. An average 3cm slab will weigh 1,000 pounds, easily handled by a 5,000 pound lift as long as the boom is not over 6 feet long. I tested ours by picking up one end of a truck, slowly to make sure the lift didn't tip.
We had the slab truck park parallel to our dock. Since we didn't have a slab clamp, we used truck straps, those 2" wide yellow straps used for tying down loads on trailers. Most big box stores sell them for under $20. A load strap has a 3,000 pound capacity when used for lifting. Since two are used as slings, there is adequate safety margin. Regardless, treat each lift as if it is going to fall, keep the men out of the way and train them to run at the first sign of trouble. We used the long ends of the straps as tag lines, keeping the men back eight to ten feet. Be sure to purchase slab clamp as soon as you can.
Our first attempt was done with a spreader bar that I had made, thinking that it would make it easier, it didn't. We chucked the spreader and just used the straps by feeding the ends under the slabs, making sure that when tightened up, they were equal distances from the end of the slab and the boom was close to the center of the slab. Make sure to place pads between the straps and the stone to avoid the granite slicing through the strap.
Once off the truck, we drove the forklift about a hundred yards through the shop, twisting the slab where needed to clear obstacles. Be sure to place the strap ratchets on the polished side to make for easy placement on the work table. We then positioned the slab on the tilt table, using the forklift and a chain to help tip the slab from vertical to flat.
We laid the template out, finding the best position for waste, grain, slab color and movement. Trace the shapes with a black sharpie or paint pen. Paint pens are better because they won’t wash off and some stones are stained with the use of a sharpie.
Diamond Skill saw blade, cost $69.00. We also bought a new worm drive Skill Saw for around $160.00. We used 1/4" icemaker tubing and ran a water line back to the countertop shop, using regular compressed air quick disconnects at the tool. A short section of tubing is used for the water spray at the blade. Very little water comes out, especially after running 100 feet through the small tubing. It might take five minutes to fill a two gallon bucket. Not much water is needed, so this works well. We also put small shut off valves where each tool water line is plugged in, giving us a way to shut off or slow down the water flow.
We made a 1/2" thick plywood sub base for the saw, covered with thin floor mat carpet from an auto parts store. Supposedly, speaker carpet is the best. Speaker carpet will let the saw glide over any quartz chips that can scratch the granite top. Be sure and make the carpet long, wrapping it over the front and back edges. Secure carpet with contact cement and a few screws in the end of the plywood base. One mistake we made was not making the slot for the blade big enough for the blade guard to pass through, had to notch it out later. Also, make sure you leave plenty of room by the blade so you can see the line to cut when you free hand cut.
A GFI plug completed our cutting rig. Make sure that goggles and good two strap dust masks are worn at all times. Have a lens cleaning station, some Windex and paper towels nearby because it is messy work. We do not have floor drains yet, so we had the helper mop up every hour or so. Floor drains can be as simple as scrap granite strips glued to the floor, with a sump pump at the low end, or just cut outside in the driveway.
We also bought steel toed rubber boots, under $20 at Wal-Mart for the workers, and Granite City sells a great long yellow apron for around $30.00 as well as some long rubber gloves that reach up to the elbows. They call them application gloves, but they keep the little tingles down from the electricity after the tool gets damp. The GFI will take care of any dangerous shocks, but the gloves help with the tiny voltages that will make your fingers tingle.
Cutting the slabs can be done in one or more passes. I found that running several passes isn't as perfect, it makes little ridges in the edge, but the edge is straighter and closer to square. Single passes are harder, you have to watch the angle of the saw and make sure you aren't tipping it. We used a wood straight edge clamped to the stone for straight cuts, then freehanded the bumpouts and inside corners where needed. The skill saw cuts amazingly fast, maybe three to four times slower than cutting solid surface.
After the slabs are roughed out, we used a coarse 4" diameter diamond cup wheel, $70.00, to square up the edges and grind the bump outs and inside corner. A Makita variable speed angle grinder, $166.00, was used for edge work. The diamond cup wheels cut fast, faster than a belt sander on oak. Clean up the edges much the same as solid surface, then switch to a fine cup wheel, $70.00, which takes only a few minutes. A “stone”, which is a small grinding wheel, $10.00, is used next or you can go directly to 50 grit diamond pads. We bought 46 grit and 80 grit stones from a local mobile tool salesman.
Once the edges are square and straight, we used a Whoopazz pad set, $96.00 for the set, to polish the edge. They fit on a backer pad, $18.00, that threads on a grinder, 5/8"-11 thread, the most common shaft size on grinders and polishers. There is a 50, 100, 200, 400, 800, 1500, and a 3000 grit Whoopazz pad, with a black buff pad for the final polish. It takes very little time, about the same as polishing solid surface edging, except you have more grits to go through. A Flex wet polisher, $289.00 was used for polishing. It didn't have variable speed, but has a water connection that runs through the center of the spindle. This process is messy but very fast.
I purchased a bevel bit for the Makita variable speed router (MVSR). I have yet to figure that one out. Without a base plate of some kind, it seems it would be difficult to keep the depth consistent. A better buy would be a profile bit that fits a 1/2" shank router. We will make a carrier base plate for the grinder to use the profile cutter in the future.
As it turns out, it is easier to run some masking tape along the top and face of the edge. Use a small combo square set to 3/8", you can just run a pencil down the edge, making a straight line, and grind it freehand. It is easier than it sounds, just keep an eye on the angle of the grinder to get a consistent edge.
After the edging was done, the top was flipped for the rodding process. We inserted 1/2" x 1/8" rod between the front edge and the sink opening and also along the back of the sink opening. Rodding won't guarantee the top won't break, but it will help and keep any pieces together so it can be patched if it breaks. Two rods, one vertical and one horizontal were used in the front and back. Some use threaded rod, fish tape or fiberglass rods, others insist on using stainless steel to prevent rod rusting which will eventually crack the stone. Some fabricators skip the rodding process and opt for a seam through the sink opening.
Rodding slots were cut with the skill saw, then ground out with the coarse diamond cup wheel, making sure the steel was below the surface. Knife grade epoxy, $18.75 a quart, was used to set the rod. A quart will do two cutouts or more. It cures quickly, maybe thirty minutes. Be sure the groove is very clean, alcohol the cut, and dry it with a heat gun or torch before adding epoxy. Rough up the steel bars with a grinder, using one of the cheap metal pads that come with the grinders.
After allowing it to cure overnight, the area was ground flat using a grinding wheel on the right angle grinder. We used the cheap wheels that come with the grinders. I think they are intended for metal, but they knocked it down fast and didn't clog the wheel. The top was flipped, the sink marked and cut with the diamond skill saw blade. We used a contour blade, $125.00, for cutting closer to the corners.
A contour blade fits the skill saw, and allows curved cuts. My stone worker claims you can cut a vanity sink with one, but I haven't seen it myself. The corners of the kitchen sink were pretty rough cut, several inches of stone left to grind out with the coarse diamond cup wheel, followed by the fine cup wheel.
Once squared up and ground to the layout line, coarse and fine stones are used, followed by Whoopazz polishing pads on the Flex wet grinder. It goes fast, probably 1 - 2 hours on a kitchen sink cutout, from layout to final polish. Getting the round inside corners smooth takes a steady hand, similar to doing solid surface. I found that if you took one of the stones and worked it into a curved edge, using a chunk of concrete block, it makes smoother corners. Or you can use the 2” x 3” stone to true up the inside corners. This stone is designed for grinding with the sides of the stone, not the bottom.
Faucet holes were drilled with a 1 3/8" diamond core bit and grinder. Use a spray bottle with water to keep the bit cool. The core bits could also be used with a Flex Polisher or a drill and adapter. Each hole takes only a minute or so.
The final step was dressing the seams with the coarse and fine stones with the Makita grinder, on slow speed. First, the edge was ground straight, the seam lined up and checked by laying the template on top, just as you would a solid surface top. The seam was back ground to one or two degree angle, leaving a slight gap in the backside of the seam, but stopping short of any edges. Pushing the seam together showed the high spots that were slowly ground off until the seam fit tight as possible.
My granite guy, with four years experience was freaking out at this point, having never seen a seam dressed. He was convinced I was going to ruin the seam. It took maybe an hour to get the seam near perfect. Test by clamping with a long bar clamp, then if a razor blade will stand up without dropping more than 1/16" down into the gap, you will have a very nice seam.
Use a new stone, or one with a pretty square edge, and watch that you don't put chips in the top edge of the material, which will show up after filling with glue, leaving little triangles of glue. When close to perfect, use a coarse diamond cup wheel to cut a keyway or groove in the center of the seam, which once filled with glue will act as a spline to keep the top aligned. After cutting the keyway, be careful grinding the edge as you are grinding a smaller surface and can easily cut a dip into the seam
I built a narrow install buggy, using some 1 ½” maple, bolts and four inflatable tire casters from Harbor Freight, $9.00 per wheel. We used a 4' x 8' plywood cart to transport the completed top, strapped down after being positioned on the trailer.
Four men lifted the big “L” top onto the install buggy, across the yard, through the narrow doors and into the kitchen. Handle the slab like a big solid surface counter. Keep it vertical till you can get one edge in contact with the cabinets, then lay it down and slide it in. Double check the seam, which in this case was near perfect, and glue it the same as you would a solid surface seam. I recommend using Integra E-stone adhesive, color matched to the particular stone.
We used Monument Toolworks Paraligns clamps, which worked well. For the next job we will be using the larger Gorilla Grip Clamps. Gorilla Grip Clamps are a bit stronger and more effective for stone counters.
After the glue cured twenty minutes, the seam was top polished, starting with 400 grit. Maybe ten to fifteen minutes to grind off the front edge, grind in the profile, and top polish the seam. The results were a perfectly flat seam. Nearly impossible to feel when you slid your hand across it and visible from three to four feet, if you knew where it was. Looked like a bad solid surface seam, but far better than the MIA standard 1/16" glue line with 1/16" bevels on both sides, with lippage up to 1/32".
In all, 49 square feet of top took one man 16 hours to fabricate, with a helper adding maybe two hours cleaning up and helping flip or move. Installation took four men, but we had cabinets to install, so the total time was maybe a half hour for each man to carry and install.
I find that it takes little time to work stone than a nice solid surface top, with built up edges, integral sink and back splashes. No laminating edges, and no substrate to install. It adds an hour to the cutout of material, and some extra labor handling, but still maybe five or six hours over what a solid surface top takes.
If you are still on the fence about fabricating your first stone counter, I hope this give you a little insight. Maybe this will push you over the fence and into the stone world. I would also like to thank Dave at Federal Saw and Tool. He was instrumental in providing all the proper tools.
About the Author:
Al Gerhart owns and operates The Carpenter Shop www.thecarpentershop.net
along with his wife Christina. Al has been doing woodworking since 1979, and working solid surface since 2001. Al and The Carpenter Shop were featured in Surface Fabrication Magazine in May of 2007. Al can be reached at email@example.com