A Multiple Drilling Machine is a stationary machine tool that drills two or more holes simultaneously through a single workpiece using a fixed array of parallel spindles driven from a common gear head or belt train. The gang head is the critical component — it carries the spindles in a precise pitch arrangement and synchronises their rotation and feed. Shops use it to eliminate the cycle time and positional error of single-spindle drilling on repeating hole patterns. A modern Peddinghaus beam drill can sink 9 holes through a W14 wide flange in under 30 seconds, replacing what used to take a layout man and a magnetic drill 15 minutes.
Multiple Drilling Machine Interactive Calculator
Vary the hole count and old-versus-gang cycle times to see throughput, speedup, and cycle-time saving for a fixed-pitch gang drilling head.
Equation Used
The calculator compares the total old single-spindle cycle time for a complete hole pattern against the one-stroke gang drilling cycle. Throughput is holes per hour, while time saved and speedup show the production advantage of drilling all holes simultaneously.
- Gang cycle time includes clamp, feed, drilling, retract, and unload for the full hole pattern.
- Single-spindle time is the total old process time for the same hole pattern.
- All gang spindles drill simultaneously in one feed stroke at fixed pitch.
How the Multiple Drilling Machine Actually Works
The machine takes one rotation source — typically a 5 to 75 kW motor — and splits it through a gang head full of meshed spur gears or timing belts so every spindle turns at the same RPM. The spindles sit on a fixed pitch (32 mm centre-to-centre on a furniture row-borer, or job-specific on a structural beam line), and the whole head feeds down together against a clamped workpiece. You load the part once, hit cycle, and every hole comes out in one stroke. That's the whole game — collapse N drilling cycles into 1.
Why build it this way instead of a CNC with a tool changer? Cost per hole. On a repeating pattern — a kitchen cabinet side panel with 22 shelf-pin holes, or a steel column splice with 48 bolt holes — a gang head finishes in one feed stroke while a single-spindle CNC indexes 22 or 48 times. The trade is flexibility: the spindle pitch is mechanically locked, so the machine only earns its keep on parts that match its hole pattern.
Tolerances matter more than people expect. On a 32mm system row-borer the spindle pitch must hold ±0.1 mm across the full bar, otherwise dowels won't seat when you mate two panels. If you notice holes drifting in pitch as the head warms up, the cause is almost always thermal growth in the gear case — a Biesse Techno or SCM Startech head with hot bearings can grow 0.05 mm over a 30-minute run. Common failure modes are spindle bearing wear (you'll hear it as a rising whine and see hole oversize), broken intermediate gears in the head when an operator force-feeds through a knot, and chuck runout above 0.05 mm TIR which shows up as triangulated holes in plywood.
Key Components
- Gang Head (Multi-Spindle Head): The cast iron housing that holds all spindles in fixed pitch and contains the gear or belt train that synchronises them. Pitch tolerance is typically ±0.05 to ±0.1 mm across the spindle row. On a Vitap Point K2 borer the head carries 21 vertical spindles on 32 mm centres.
- Spindles and Quick-Change Chucks: Each spindle runs in a pair of angular contact bearings rated for the drilling thrust load — usually 800 to 2,500 N per spindle in wood, 5,000 to 25,000 N per spindle in steel. Chucks must hold runout under 0.05 mm TIR or hole quality collapses.
- Drive Motor and Transmission: A single 5 to 75 kW three-phase motor drives the head through a belt or gear reducer, setting all spindle RPMs simultaneously. Wood machines run 2,800 to 4,500 RPM; structural steel beam lines run 200 to 800 RPM with through-spindle coolant.
- Feed System: Hydraulic, pneumatic, or servo feed pushes the entire gang head into the work. Feed rate must match the slowest spindle's chip load — overfeed and you snap the smallest drill first. Typical feed is 0.05 to 0.3 mm/rev in wood, 0.08 to 0.15 mm/rev in mild steel.
- Workpiece Clamping: Pneumatic top-pressure rollers or hydraulic clamps lock the part before the head descends. Clamping force must exceed total drilling thrust by 1.5× minimum, otherwise the part lifts and you get bell-mouthed entry holes.
- Depth Stop and Limit Switches: A mechanical hard stop or programmable servo limit sets the through-hole or blind-hole depth, repeatable to ±0.1 mm. On a Peddinghaus FDB beam drill line the depth feedback is closed-loop on a linear scale.
Industries That Rely on the Multiple Drilling Machine
You'll find Multiple Drilling Machines wherever a hole pattern repeats hundreds of times a day. The economics only work when the pattern is fixed or semi-fixed — that's why structural steel fabricators, furniture mills, PCB houses, and pallet plants own them, while a one-off jobbing shop sticks with a CNC mill or a magnetic drill. Below are real examples from working shops.
- Structural Steel Fabrication: Peddinghaus FDB-1500 beam drill line drilling W-section bolt patterns at a fabricator like Cives Steel for AISC-spec connections.
- Furniture Manufacturing: Vitap Point K2 21-spindle row-borer drilling 32mm system shelf-pin and dowel holes on melamine panels at IKEA component suppliers.
- Pallet and Crate Manufacturing: Storti or Corali multi-spindle pallet drilling head drilling deck-board nail-pilot holes at a CHEP pallet repair plant.
- PCB Manufacturing: Schmoll MX-6 six-spindle PCB drilling machine producing via and through-hole patterns at a board shop running 200,000 boards per month.
- Bridge and Tower Steel: Ficep Tipo B 1003 beam drill drilling splice plates for highway bridge girders on Skanska civil contracts.
- Truck Frame Manufacturing: Buffalo gang drill drilling cross-member bolt patterns on long-haul trailer chassis rails at a Wabash National plant.
- Door and Window Manufacturing: SCM Startech CN K2 boring machine drilling hinge-cup and lock-case patterns on solid wood entry doors at Andersen Windows.
The Formula Behind the Multiple Drilling Machine
The number that decides whether a Multiple Drilling Machine is worth buying is cycle-time saving per part. At the low end of the typical range — a 4-spindle gang head replacing a single-spindle drill on a 4-hole pattern — you save roughly 75% of cycle time but the capital cost is hard to justify under maybe 2,000 parts per year. At the nominal range — 12 to 24 spindles on a furniture row-borer — savings are 90%+ and the machine pays back in months. Push to the high end — a 60-spindle pallet head — and you're transmission-limited; the head gets so heavy that feed dynamics, not drilling, becomes the bottleneck. The formula below gives you cycle time per part so you can run the payback math.
Variables
| Symbol | Meaning | Unit (SI) | Unit (Imperial) |
|---|---|---|---|
| tcycle | Total cycle time per part, all holes drilled in one stroke | s | s |
| Dhole | Hole depth (drilling stroke through material) | mm | in |
| fr | Feed rate of the gang head (set to the slowest spindle's safe chip load) | mm/s | in/s |
| tapproach | Rapid approach time from home to material surface | s | s |
| tretract | Rapid retract time after through-hole | s | s |
| tload | Operator part load and clamp time | s | s |
Worked Example: Multiple Drilling Machine in a kitchen cabinet shop running a 21-spindle row-borer
A cabinet manufacturer in High Point North Carolina is running a Vitap Point K2 21-spindle row-borer drilling 5 mm shelf-pin holes 13 mm deep into 18 mm melamine-faced MDF side panels. The shop wants cycle time per panel to run a payback model against their existing single-spindle CNC router that takes 38 seconds per panel for the same 21-hole pattern.
Given
- Dhole = 13 mm
- fr (nominal) = 25 mm/s
- tapproach = 0.4 s
- tretract = 0.4 s
- tload = 2.5 s
- Number of spindles engaged = 21 —
Solution
Step 1 — at the nominal feed rate of 25 mm/s (typical for a 5 mm carbide brad-point in MDF at 4,500 RPM, ~0.33 mm/rev chip load), compute the drilling time for the full 13 mm depth:
Step 2 — add approach, retract, and load time to get nominal cycle time per panel. Note all 21 holes drill in this single stroke — that's the whole point of the gang head:
Step 3 — at the low end of the safe operating range, run feed at 15 mm/s (conservative for end-of-life drills or harder particle board substrates):
That's only 350 ms slower than nominal — the load time dominates, not the drilling. Step 4 — at the aggressive high end, push feed to 40 mm/s with fresh carbide drills and tight runout:
You only shave 200 ms by pushing feed harder, and you'll halve drill life doing it. The sweet spot is clearly the nominal 25 mm/s — that's where the Vitap factory recommendation lands and where Felder, SCM, and Biesse all set their default row-boring presets.
Result
Nominal cycle time is 3. 82 seconds per panel — call it 4 seconds with material handling slop. That feels almost instant on the shop floor; an operator loads the next panel before the head has fully retracted, so throughput is operator-limited not machine-limited. Across the 15 to 40 mm/s feed range, cycle time only swings from 4.17 s down to 3.62 s — a 14% window — because the tload term swamps the drilling time on this short-stroke pattern. Compared to the 38 s single-spindle CNC the shop runs today, that's a 10× throughput gain, which is why a $45k row-borer pays back in roughly 4 months at typical cabinet-shop volumes. If you measure cycle time at 5+ seconds instead of the predicted 3.82, look at clamp dwell first (cheap pneumatic clamps add 1+ s of settling), then check if the head is bottoming on a worn depth stop and rebounding, then verify the feed valve isn't bypassing — a sticky Festo flow-control on the hydraulic feed will silently halve your set rate without throwing a fault.
Multiple Drilling Machine vs Alternatives
A Multiple Drilling Machine is one of three honest answers to the repeating-hole-pattern problem. The other two are a single-spindle CNC drill or mill, and a magnetic-base portable drill. Pick wrong and you either overpay for flexibility you don't need or underpay and lose a shift to slow cycle times. Here's how they compare on the dimensions that actually drive the buy decision.
| Property | Multiple Drilling Machine | Single-Spindle CNC Drill | Magnetic Base Portable Drill |
|---|---|---|---|
| Holes per minute on a 21-hole pattern | ~315 holes/min (15 panels/min × 21) | ~33 holes/min | ~6 holes/min |
| Pattern flexibility | Locked to spindle pitch — pattern changes need head swap | Fully programmable, any pattern | Fully manual, any pattern with layout work |
| Hole pitch accuracy | ±0.05 to ±0.1 mm fixed-mechanical | ±0.02 to ±0.05 mm servo-positioned | ±0.5 to ±2 mm depending on layout |
| Capital cost (typical) | $25k–$250k | $40k–$400k | $1k–$5k |
| Best fit application | High-volume repeating patterns (cabinets, beams, pallets) | Mid-volume varied patterns, prototyping | Field work, one-off structural fit-up |
| Setup time per job change | 10–60 min (depth, fence, head swap) | 2–10 min (program load, tool offsets) | 30 s per hole (mark, position, clamp) |
| Spindle/drive complexity | High — gear train with 6 to 60 spindles | Low — single spindle, single servo axis | Very low — single motor, no gearing |
Frequently Asked Questions About Multiple Drilling Machine
On most production gang heads the pitch is fixed by the gear-mesh geometry inside the head casting — you cannot move spindles without re-machining the housing. What you can do on European row-borers like Vitap, Maggi, or Biesse is selectively engage spindles using individual pneumatic clutches, so a 21-spindle head set on 32 mm pitch can drill any subset of those positions. If your real production needs a different absolute pitch (say 25 mm shelf-pin spacing instead of 32 mm), you have to either buy a second head or move to a CNC drill.
Adjustable-pitch heads exist (Suhner Multi-spindle, Alzmetall) but they trade rigidity and accuracy for flexibility — pitch repeatability drops from ±0.05 mm to roughly ±0.2 mm, which fails the 32mm system tolerance for furniture dowels.
Because torque demand is additive at engagement. A 5 mm wood drill in MDF needs roughly 1.2 Nm at full chip load. Multiply by 21 spindles and you need 25 Nm at the gear-head output — plus a 1.5× to 2× peak factor on entry when the drill points are biting and the chip hasn't formed yet. Most undersized installs stall on the entry transient, not on steady-state drilling.
Fix it by either dropping feed rate for the first 2 mm of stroke (a 'soft start' on servo feed machines), staggering drill points (some heads ship with intentional 0.5 mm length variation across spindles so they don't all hit at once), or upsizing the motor. On a Vitap K2 the factory spec is 7.5 kW for the 21-spindle head — anything less and you'll see brownouts under load.
Buy the 24 if your patterns vary in position even slightly. With selective spindle engagement you can run any 16-hole subset of the 24 positions, but you cannot run a 16-hole pattern on a 12-spindle head without two passes — and a second pass kills your cycle-time advantage and adds a re-positioning error of ±0.2 mm minimum from the fence indexing.
Buy the 12 if your pattern is genuinely fixed at 12 holes or fewer. The 12-spindle head is lighter (better feed dynamics), cheaper (usually 40-50% less), and less power-hungry. The decision really comes down to product mix: if you make 3+ different parts on the same machine, the 24 earns its keep. One product, one pattern — go 12.
That's almost always thermal growth in the gear case, and the giveaway is that the error is progressive (linear across the row) rather than random. As the gang head warms up over a production shift, the cast iron housing expands roughly 11 µm per metre per °C. A 700 mm long head running 20°C above ambient grows about 0.15 mm end-to-end — enough to push your last spindle out of the 32mm system ±0.1 mm tolerance.
Diagnose it by measuring pitch on a cold first-shift panel versus a panel from 2 hours into the run. If the cold pitch is good and the warm pitch is bad, you have thermal growth. Fixes are gear-case forced-air cooling, lower-viscosity lubricant in the head (drops churning losses), or accepting a 30-minute warm-up and indexing the fence to the warmed pitch.
Either you're not using a backer/spoilboard, or the gang head feed is too aggressive at breakthrough. Wood drills — especially brad-point and lip-and-spur — tear fibre on exit because the unsupported chip lifts and splits the surface veneer instead of being sheared cleanly. The fix is a sacrificial spoilboard (5 mm MDF) clamped under the part, which provides the backing the drill needs to shear cleanly through the bottom face.
If you already have a spoilboard and still see tear-out, the spoilboard is probably worn through where the drills exit repeatedly — those entry pockets in the spoilboard stop providing backing. Replace the spoilboard or shift its position 5 mm. Final option: program a feed-rate decel for the last 2 mm of stroke, but most pneumatic-feed gang machines don't have that capability.
Production row-borers are nearly all perpendicular-only because the gang head is rigidly mounted to a vertical or horizontal feed slide. The exception is the dual-head construction-furniture machines (SCM Startech CN, Biesse Skipper) which have a separate horizontal head for edge boring at 90° to the vertical head — that gives you face holes and edge holes in one setup but not arbitrary angles.
For angled holes (like 5° hinge-mortise pilot holes on entry doors) you either tilt the workpiece on a wedge fixture or move to a CNC drill with a tilting spindle. Trying to retrofit angle capability onto a fixed gang head almost always fails because the gear-train geometry breaks when the spindle axes deviate from parallel.
References & Further Reading
- Wikipedia contributors. Drilling machine. Wikipedia
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