Automatic Stick-Placing Stackers
VPG Automatic Stick-Placing Stacker
Gillingham-Best's flagship stacker system — patented Variable Pan Geometry technology and Fastack frame design for maximum throughput, consistent stick placement accuracy, and a typical 25-year service life.
Typical System Life
Mill Installations
Of GBI's Business — Stackers
Patented Technology
Variable Pan Geometry — Why It Matters
Conventional lumber stackers run a fixed pan travel path every cycle — the full stroke executes whether the lumber needs it or not. The only way to increase throughput is to move the pans faster, which increases mechanical stress and accelerates wear.
Gillingham-Best's patented Variable Pan Geometry (VPG) system eliminates this constraint. By varying pan geometry dynamically through the stacking cycle, the VPG mechanism reduces the actual distance each pan travels per cycle — enabling higher boards-per-minute throughput without increasing stress on the drive system. Less mechanical work per board means longer service intervals, lower parts consumption, and higher uptime across the life of the machine.
See It In Motion
How the VPG Stacker Works
Six short mechanical animations isolate the core motions of the Variable Pan Geometry stacker. Start with the full side view, then drill into the specific mechanisms that make high-throughput stick placing possible.
Architecture
Built for the Mill Floor
GBI stackers are hydraulically driven — a deliberate design choice, not a legacy limitation. Hydraulic architecture absorbs the shock loads, temperature swings, vibration, and contamination that real mill environments deliver every shift. Where many automation architectures require tighter tolerances and cleaner operating conditions to maintain performance, GBI's hydraulic drive keeps working when conditions aren't ideal.
This architecture is field-proven across more than 100 installations and decades of continuous production use. It is why GBI systems routinely reach 25-year service lives without requiring annual service contracts or scheduled preventive maintenance programs.
Shock-Tolerant
Hydraulic architecture absorbs the impact loads inherent in stacking — without exposing servo drives or encoder feedback loops to mill-floor reality.
Cold-Weather Capable
Hydraulic systems tolerate the temperature extremes of northern and high-elevation mill sites where electric drive systems require additional conditioning.
Dirt & Vibration Tolerant
Designed to run in sawdust, bark, and water environments — no special housekeeping requirements or environmental controls needed to sustain performance.
In Operation
Auto Cycle at Pollard Lumber
The GBI VPG stacker at Pollard Lumber running in auto cycle — the machine advances through each course without operator input. The operator is present and monitoring, but the stacker is cycling itself. This is the single-operator production scenario GBI stackers are built for.
Key Features
Fastack Frame & VPG System
Variable Pan Geometry (Patented)
Pan geometry varies through the stacking cycle, reducing travel distance per board and enabling higher BPM at the same mechanical speed.
Fastack Frame
Minimized stacker motion reduces vibration and fatigue loading — lower wear cycles per board, extended service intervals, longer machine life.
Single-Man Operation
The VPG stacker runs at full production throughput with one operator — no secondary attendant required. High efficiency without added headcount.
Kiln Drying Integration
Precise sticker spacing produces uniform airflow through the lumber package — shorter kiln cycles, fewer drying defects, lower energy cost per MBF.
Bowed Board & Variable Stock Handling
Strong performance with bowed boards and challenging stock — GBI stackers don't require clean, straight stock to maintain throughput and accuracy.
No Scheduled PM Required
No annual service contract. No mandatory preventive maintenance program. Hydraulic architecture and Fastack frame design deliver uptime without a service dependency.
Maximized Stick Life
Your mill sets its own stick discard standards — the machine doesn't dictate them. Reduced consumable waste and lower sticker cost per MBF over the life of the system.
Third Generation Platform
Modern Controls, Sensing, and Operator Experience
The Third Generation Stacker is the current production version of the VPG Automatic Stick-Placing Stacker. The mechanical architecture is unchanged — VPG, Fastack frame, hydraulic drive. What is new is a modern controls, sensing, and HMI layer built around that proven machine. The result is a stacker that still runs when conditions aren't ideal, and now prevents the crashes that used to cause them.
Control System
- Rockwell Automation ControlLogix L8 processor with distributed I/O
- EtherNet/IP and IO-Link networking throughout
- Quick-disconnect field cabling for faster service
- Rockwell FactoryTalk Optix HMI with built-in web access to production reports
Sensing & Verification
- Allen-Bradley EtherNet/IP absolute encoders on carriage and distribution chain
- Keyence scanning curtain for pulled-back stick detection
- Keyence through-beam laser for overhead rake-off crash detection
- Pepper+Fuchs IO-Link laser at every stick position for stick-in-pan and lumber-length verification
The Third Generation Feature Set
High-Resolution Carriage Encoder
Absolute encoder on the carriage forks at 36,000-count resolution — up from 255 in earlier generations. Finer positioning, simpler re-homing.
High-Resolution Distribution Chain Encoder
Absolute encoder on the distribution chain eliminates tab-wheel adjustment. Re-time the chain by setting it to the timing marks and pressing Home.
Pneumatic Distribution Chain Tensioning
An air cylinder maintains chain tension under pressure-switch verification. If the chain skips a tooth, vent the cylinder, re-seat the chain, and re-apply air.
Automatic Front Stop Positioning
Enter course width on the HMI; the controller calculates the pinch point and positions the front lumber stops. Prevents boards from swinging out under the overhead rake-off.
Overhead Rake-Off Crash Detection
A laser scans the overhead rake-off as it descends. If any rake-off pad is not fully seated in its stick pan, the cycle halts immediately — preventing a major crash.
Pulled-Back Stick Scanner
A Keyence scanning curtain detects sticks that were not fully raked off the carriage forks. The stacker will not cycle until the condition is cleared.
Stacker Auto Cycle
Photoeye-driven auto-cycle runs the stacker when enough lumber is present to make a course. Requires the pulled-back stick and overhead rake-off safeties to be active.
Distribution Chain Light Bar
An indicator light at every stick position on the distribution chain shows the operator whether a stick should be present — direct, at-a-glance verification of chain sequencing.
Stick-in-Pan Detection & Lumber Length Verification
IO-Link lasers at every pan position confirm each stick is seated correctly, verify operator-entered lumber length against what the sensors see, and drive a console light bar. In auto-cycle, the stacker will not run if either check fails.
All Third Generation features are available as individual line items or as a bundled retrofit package for existing GBI stackers in the field. See the Controls, Sensors and Monitoring Upgrade →
Upstream Components
Stick Unscramblers
Sticks returning from a stick collection loop arrive at the stacker in bulk — unaligned, stacked, and sometimes nested. Before they can feed the distribution chain, they have to be singulated and oriented the same way every time. Gillingham-Best builds two unscrambler configurations sized to the throughput of the stacker they feed.
Double Stick Unscrambler
Two-wide unscrambling for mills running the VPG stacker at sustained high boards-per-minute rates. Handles the return flow from a full stick collection loop and keeps the distribution chain supplied without starving the stacker at peak cycle.
- Two parallel unscrambling lanes — higher sustained stick throughput
- Matched to sustained high-BPM stacker production
- Tolerant of the dimensional variation typical of used sticks returning from the kiln loop
- Rejects fractured, crooked, or short sticks before they reach the magazine
Single Stick Unscrambler
Single-lane unscrambling for mills where the stacker throughput does not require a two-wide return feed. Same mechanical reliability and the same sticker reject logic — scaled to the lower sustained feed rate.
- Single unscrambling lane — simpler mechanical envelope
- Lower capital cost where full double-lane capacity isn't needed
- Same reject logic for fractured or out-of-spec sticks
- Smaller footprint — easier retrofit into constrained stacker bays
Unscrambler selection is part of the stacker sizing conversation. Contact GBI to match the correct unscrambler variant to your target production rate and stick-return configuration.
Specifications
General Capability Reference
Specifications vary by mill configuration. Contact GBI for application-specific sizing.
| Parameter | Detail |
|---|---|
| Technology | Patented Variable Pan Geometry (VPG) |
| Frame Design | Fastack — minimized motion architecture |
| Stick Placing | Automated, magazine-fed, minimal operator intervention |
| Lumber Lengths | Typically 6 to 20 feet; longer on request |
| Package Widths | Typically up to 48 inches; wider on request |
| Handedness | Configured left- or right-hand to mill layout |
| Species | Hardwood and softwood; dimension lumber through timbers |
| Typical System Life | 25 years |
| Controls | Third Generation — Rockwell ControlLogix L8 + FactoryTalk Optix HMI |
Applications
Where Stick-Placing Stackers Fit
Automatic stick-placing stackers exist because green-end lumber has to be dried before it goes to the planer. Sticks between every course of rough, wet lumber let air flow uniformly through the package in the kiln. That's always a green-end (sawmill) job — by the time lumber reaches the planer mill, it's already been dried and surfaced, and it packages solid without sticks.
The one exception is the wood-products treating plant. There, sticks are placed between courses of dry lumber and between plywood sheets so pressure-treat chemical can reach every face of the product during the treating cycle. Same machine, same mechanism — just later in the value chain.
- Hardwood and softwood sawmill green ends — stacking kiln-ready packages downstream of the trimmer.
- Wood-products treating plants — sticking between dry lumber courses and between plywood sheets for uniform chemical exposure during pressure treatment.
- High-duty-cycle operations — mills requiring sustained single-operator throughput without daily preventive maintenance.
Planer mill dry-end packaging does not use sticks. For planer-mill and solid-package applications, see the Hardwood (Solid Pack) Lumber Stacker.
Ownership Advantage
What's Included — No Surprises
Startup & Training Included
Every GBI quote includes commissioning, startup, and operator training. There are no hidden end-of-job costs to negotiate after the purchase is made.
No Annual Service Contract
GBI does not require an ongoing service agreement to maintain warranty or support. You own the machine outright — without a recurring service dependency.
Specialist Focus
More than 90% of GBI's business is automatic stick-placing stackers. This is not a product line — it's the company's core expertise, built over decades of mill installations.
Configure Your Stacker
Tell GBI your throughput targets, lumber product mix, and mill layout. We'll engineer the right system for your operation.
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