Drill Presses in the Stone Shop: Precise Holes in Small Parts

Most holes in a stone shop are drilled where the stone lies: faucet holes on a countertop, anchor holes on a wall panel, sink cutouts on a CNC. Small parts are different. A soap dish, a threshold, a vessel-sink plinth, a lamp base, a set of cabinet knobs cut from offcuts, a mosaic medallion or a sample tile with a display hole are all too small to hold safely by hand and too easy to crack with a wandering bit. For that kind of work, a drill press fitted with the right diamond core bit, steady water and solid workholding produces cleaner, straighter and safer holes than any handheld tool in the shop.

This guide explains how to set up and run a drill press for small stone, tile and glass parts. It covers why diamond core bits behave differently from twist drills, how to get water to the cutting edge, how to choose speed using the bit manufacturer's published guidance, how to clamp small and irregular pieces, and how to prevent breakout on the back face. It also covers drill press safety rules that apply in any shop and the maintenance that keeps bits cutting. Where a specific number appears, it comes from a named manufacturer for its own product, and the instructions for the bit and machine you actually own always take priority.

Why a Drill Press Changes Small-Part Drilling

A diamond core bit does not cut like a twist drill. It is a thin-walled tube with diamonds bonded to its rim, either sintered into a metal matrix, vacuum brazed onto the surface or electroplated in a single layer. Instead of shearing chips, the diamonds grind a narrow ring through the material and leave a solid core inside the tube. The process depends on light, steady pressure and on water or coolant to carry away the slurry and keep the diamonds cool. When either is missing, the rim glazes, the bond overheats and the bit stops cutting long before its diamonds are worn out.

Handheld drilling makes those conditions hard to hold on a small part. The operator has to keep the bit square, control feed pressure, manage water and stop the piece from spinning all at once. Instructions from tool makers reflect that difficulty. MK Diamond, for example, tells users of its handheld wet tile core bit to start at about 45 degrees to stop the bit from skating, then raise it to horizontal once a groove has formed. On a drill press the column and quill hold the bit square and the table supports the part, so the bit starts where it is placed without walking.

Rio Grande, a jewelry supply company, makes the same point in its instructions for drilling glass and stone: a drill press helps prevent the bit from skipping or chattering against the surface at the start of the hole. Because the quill feed is controlled, pressure stays light and even, which matters for brittle materials such as polished marble, porcelain and glass. And because the part is clamped to the table, the drill press takes the operator's hands out of the path of a part that grabs and spins, which is the most common way small-part drilling injuries happen.

Precision is the other reason. A drill press lets you set a depth stop, repeat the same hole location across a batch of parts with a fence and stop block, and drill perpendicular holes for hardware that has to sit flush. For small decorative pieces, that consistency is the difference between a set of knobs that look professionally made and a set that look improvised. It also makes blind holes, such as anchor pockets in the back of a small panel, far easier to control.

Practical Guide: Bits, Water, Speed and Workholding

Choosing a bit for stone, tile and glass

Match the bit to the material and the machine. Sintered and brazed core bits for stone are built for granite, marble and engineered stone and usually expect a water feed. Bits sold for tile, porcelain and glass are often vacuum brazed or electroplated, with fine diamond and a thin wall that cuts with very little pressure. Some glass bits are designed for internal water cooling through the shank; Bohle states that its diamond hollow drills for glass require internal water cooling and that external cooling is not sufficient. Check the bit's packaging or the maker's data sheet for the materials it is rated for, the fitting it uses and the maximum speed.

Fittings matter on a drill press. Many stone core bits use a threaded fitting such as 5/8-11 or 1/2 gas, while tile and glass bits often have straight or hex shanks that fit a standard chuck. Use a proper adapter rather than gripping threads in a chuck, and confirm the bit runs true before it touches the work. A bit that wobbles in a drill press will chip the entry edge of a polished surface no matter how carefully the rest of the setup is done.

Getting water to the cutting edge

A standard drill press is not designed to carry water through its spindle, so stone shops use one of several approaches. For shallow holes in flat parts, a ring dam of plumber's putty or modeling clay around the hole site holds a small pool of water, and the bit cuts through it. MK Diamond describes the same idea for loose tile or horizontal surfaces: pool water over the drilling spot and drill through it. For bits with an internal water channel, a water swivel adaptor between the spindle and the bit delivers water through the bit to the rim, which is the method Bohle requires for its glass hollow drills.

Small parts can also be drilled in a shallow tray of water with the part supported on a rubber or wood block, the approach Eternal Tools recommends for its small electroplated core drills. Whatever method you choose, keep water and slurry away from the drill press motor and switch. Eternal Tools points out that using rotary tools near water is generally not endorsed by tool manufacturers, so check your drill press manual, plug the machine into a ground-fault protected outlet, keep cords off the wet table and wipe the column and table dry at the end of each session.

Setting speed from the manufacturer's chart

Diamond core bits have a speed window, and the right speed generally falls as diameter rises. Two manufacturers' published figures show the pattern clearly. Treat them as examples of how speed scales, not as numbers for your bit; your bit's own chart governs.

Bohle explains why the window matters. If the speed is too low, the diamond bond is not worn away fast enough, the bit dulls and has to be dressed on a sharpening stone. If the speed is too high, diamond grains can be torn out of the bond. MK Diamond also says to bring the drill to full power and the recommended speed before the bit touches the tile. On a belt-driven drill press, set the belt to the step nearest the bit maker's range and err toward the lower step for brittle or valuable parts.

Clamping small and irregular parts

Workholding is not optional. The University of Michigan's drill press safety guidance states that all stock must be secured with a vise or clamps before machining, and Purdue's wood research lab rules say work must be clamped or secured to the table by some means other than holding it. For small stone parts, a drill press vise with soft jaws or a wooden cradle protects polished faces. Irregular pieces can be held in a shop-made jig: a block of plywood with a pocket cut to the part's outline, clamped to the table, with a sacrificial board underneath to support the back face.

Advanced Tips for Clean Holes in Small Parts

Feed pressure is where most small-part holes are won or lost. Rio Grande advises light pressure and letting the bit do the work, warning that excessive pressure can crack fragile material and overheat the diamond surface. MK Diamond's instructions for its tile bit also call for low pressure. On a drill press, that means feeding the quill with a light, steady touch and listening to the cut. A bit that squeals or slows is being pushed too hard or running too dry; a bit that cuts quietly with a steady stream of slurry is working correctly.

Clear the slurry as you go. Bohle recommends lifting the drill at short intervals on deeper holes to flush the cut, and Eternal Tools describes pulsing the bit up and down to clear slurry when drilling small holes. On a drill press, a gentle peck cycle, lifting the bit a few millimeters every few seconds, lets fresh water into the kerf and prevents the core from packing inside the tube. Thicker parts such as stone knobs and plinths benefit the most, because slurry has further to travel out of the hole.

Breakout control matters on polished and glazed faces. A diamond bit that exits a hard, brittle material under pressure tends to spall a ring of chips around the hole on the back face. The cleanest approach is to drill most of the way from the show face, then turn the part over and finish from the back, as Rio Grande recommends. If flipping is not practical, back the part with a sacrificial piece of the same stone or a dense board clamped tight to the back face, and reduce feed pressure to almost nothing for the final millimeters.

Locate holes accurately on small parts by marking the center with a fine marker, then using the drill press's chuck and a center-finding pin or a pointed dowel to align the part before clamping. On polished stone, a strip of masking tape over the hole site makes marking easier and reduces the chance of the bit skating on the first touch. For holes near an edge, leave as much material between the hole and the edge as the design allows, because thin bridges of stone are where small parts usually crack.

Glass and porcelain deserve extra care. These materials are harder and more brittle than most natural stone, and they generate heat quickly. Use bits rated for them, keep the water flowing constantly, keep pressure very light and never let the bit run dry, even for a moment. Engineered quartz is a separate case: drill it only with diamond core bits rated for engineered stone, with water, and follow the surface manufacturer's fabrication guidelines, because engineered quartz is not a material that can be worked with conventional masonry bits.

Dust and slurry are a health issue as well as a cleanliness issue. For construction work, OSHA's Table 1 for respirable crystalline silica lists handheld and stand-mounted drills with a commercially available shroud or cowling and dust collection system, a HEPA-filtered vacuum for cleaning holes and operation according to the manufacturer's instructions. In the shop, wet drilling keeps dust down, but dried slurry on the table and floor can become airborne later. Clean slurry while it is wet, never dry sweep it and use a HEPA vacuum for any residue that has dried.

Maintenance and Long-Term Considerations

Drill press safety rules are simple and worth posting next to the machine. Purdue's lab rules require safety glasses and prohibit gloves and loose clothing, with long hair tied back. Both Purdue and the University of Michigan prohibit leaving the chuck key in the chuck, and Michigan specifies that the chuck key should only be inserted with the power off. Michigan also requires that guards be in place, that chips not be removed by hand and that the machine never be cleaned while running. If a part is seized by the bit and comes loose from the clamp, Purdue's instruction is direct: stop the press.

Bits last longer when they are treated as precision tools. After each session, rinse the bit to remove slurry from inside the tube and around the diamond rim, push out any stuck core with a wooden dowel rather than a screwdriver and let the bit dry before storage so threads and shanks do not corrode. If a bit stops cutting and looks polished on the rim, it has glazed; Bohle recommends dressing its glass drills on a sharpening stone, and for other bits, follow the maker's instructions for dressing the rim to re-expose diamonds.

Keep the drill press itself in good condition. Water and slurry are hard on a machine that was not built for wet work. Wipe the table, column and quill dry after use, apply a light protective coating to bare metal surfaces according to the manufacturer's recommendations and check that the quill moves smoothly without play. A quill with side play or a chuck that runs out of true makes clean holes impossible, regardless of the bit, so check runout periodically with a dial indicator if you have one.

Electrical safety deserves a periodic check too. Inspect the cord, plug and switch for damage, confirm that the ground-fault protection on the outlet trips when tested and keep the water source and catch tray positioned so that drips fall away from the motor. If your shop does enough small-part drilling to justify it, a dedicated wet core drilling stand or a drill rig designed for water feed is a sensible upgrade, because it is built from the start to handle the water that a standard drill press tolerates only with care.

Finally, keep records of what works. Note which bit, speed step, water method and jig produced the best results for each material, and keep a scrap of each stone you drill most often for test holes. Small-part work is often custom and low-volume, so the setup knowledge is easy to lose between jobs. A short log taped inside the cabinet next to the drill press saves trial and error the next time a customer asks for a set of stone knobs or a drilled sample board.

For bits and accessories, browse the core bits collection, including vacuum brazed options such as the APEXX brazed glass, marble and porcelain core bit with hex shank. For water feed on threaded bits, see the Aardwolf WSDA01 water swivel drill adaptor, and for anchor pockets, the blind hole bits collection.