Views: 0 Author: Nancy Liu Publish Time: 2026-07-06 Origin: Zhenghao Machinery
Table of Contents
Selecting a CNC precision vise sounds straightforward until you open a product catalogue and find twenty-two model variants across six jaw widths, each with multiple opening lengths, different clamping forces, and different overall footprints. The question — which one do I actually need? — is one of the most common technical enquiries the Zhenghao engineering team receives from new customers.
The answer is not a single number. It is the result of matching five variables — workpiece geometry, clamping force requirement, machine table envelope, 5-axis clearance budget, and production volume — against the vise specification. Get the match right, and the vise disappears into the process: parts come out accurate, cycle times are consistent, and the workholding never becomes the bottleneck. Get it wrong, and you are either over-clamping small parts with a vise that wastes table space, or under-supporting large parts with a vise that cannot hold them securely enough for aggressive cutting.
This guide walks through the complete GT Series jaw width selection process — from GT100 to GT300 — with real application examples, a full specification reference table, and decision logic you can apply directly to your own workpieces.
Before diving into selection logic, it helps to understand what the GT model designation actually describes.
A GT Series model number encodes two key dimensions:
The first number = jaw width in millimetres (the dimension parallel to the machine table, perpendicular to the clamping direction)
The second number = maximum jaw opening (Smax) in millimetres (the maximum distance between the fixed jaw face and the movable jaw face)
So GT150A means: 150 mm jaw width, 200 mm maximum opening. GT200C means: 200 mm jaw width, 400 mm maximum opening.
The jaw width is the primary selection variable. The opening length is selected after the jaw width is determined, based on the workpiece dimension in the clamping direction.
Model | Jaw Width (B) | Height (H) | Max Opening (Smax) | Overall Length (L) | Clamping Force |
GT100 | 100 mm | 30 mm | 100 mm | 270 mm | 3,000 N |
GT125 | 125 mm | 40 mm | 150 mm | 345 mm | 3,000 N |
GT150A | 150 mm | 50 mm | 200 mm | 420 mm | 5,000 N |
GT150B | 150 mm | 50 mm | 300 mm | 520 mm | 5,000 N |
GT150C | 150 mm | 50 mm | 400 mm | 620 mm | 5,000 N |
GT175A | 175 mm | 60 mm | 200 mm | 455 mm | 6,000 N |
GT175B | 175 mm | 60 mm | 300 mm | 555 mm | 6,000 N |
GT175C | 175 mm | 60 mm | 400 mm | 655 mm | 6,000 N |
GT175D | 175 mm | 60 mm | 500 mm | 755 mm | 6,000 N |
GT175E | 175 mm | 60 mm | 600 mm | 855 mm | 6,000 N |
GT200A | 200 mm | 65 mm | 200 mm | 495 mm | 10,000 N |
GT200B | 200 mm | 65 mm | 300 mm | 595 mm | 10,000 N |
GT200C | 200 mm | 65 mm | 400 mm | 695 mm | 10,000 N |
GT200D | 200 mm | 65 mm | 500 mm | 795 mm | 10,000 N |
GT200E | 200 mm | 65 mm | 600 mm | 895 mm | 10,000 N |
GT300A | 300 mm | 80 mm | 200 mm | 535 mm | 12,000 N |
GT300B | 300 mm | 80 mm | 300 mm | 635 mm | 12,000 N |
GT300C | 300 mm | 80 mm | 400 mm | 735 mm | 12,000 N |
GT300D | 300 mm | 80 mm | 500 mm | 835 mm | 12,000 N |
GT300E | 300 mm | 80 mm | 600 mm | 935 mm | 12,000 N |
GT300F | 300 mm | 80 mm | 700 mm | 1,035 mm | 12,000 N |
GT300G | 300 mm | 80 mm | 800 mm | 1,135 mm | 12,000 N |
All specifications: 20CrMnTi alloy steel · HRC 58–62 · Parallelism 0.005 mm/100 mm · Squareness 0.005 mm/100 mm · Repeatability 0.003–0.005 mm.
The most direct input to jaw width selection is the width of the workpiece in the direction parallel to the jaw faces — the dimension that determines how much of the jaw face is actually in contact with the part.
A widely applied workholding principle is that the jaw face should contact the workpiece across at least 60–80% of the jaw width. This ensures:
Clamping force is distributed across a sufficient contact area to prevent localised surface deformation
The workpiece cannot tilt or rotate within the jaw under cutting forces
The clamping moment is balanced — the workpiece is pulled evenly against the fixed jaw without a tendency to skew
Practical implication:
Workpiece width | Minimum jaw width (60% rule) | Recommended jaw width |
50–70 mm | 63–88 mm | GT100 (100 mm) |
70–90 mm | 88–113 mm | GT125 (125 mm) |
90–120 mm | 113–150 mm | GT150 (150 mm) |
120–145 mm | 150–181 mm | GT175 (175 mm) |
145–175 mm | 181–219 mm | GT200 (200 mm) |
200–280 mm | 250–350 mm | GT300 (300 mm) |
Note that this is a minimum recommendation. Selecting one size larger than the minimum is often correct when the workpiece material is soft (aluminium, brass), when the surface finish must be protected, or when the cutting forces are high.
A jaw that is significantly wider than the workpiece concentrates clamping force at the edges of the contact zone rather than distributing it evenly. On soft materials, this can cause edge deformation. On all materials, it creates a rocking moment that the vise's anti-lift mechanism must counteract. The workpiece is not as securely seated as it would be in a correctly sized jaw.
A jaw that is narrower than the workpiece contacts only the centre of the part. The workpiece overhangs the jaw on both sides, creating a cantilever condition. Under cutting forces — particularly in the Y-axis direction — the overhanging portion of the workpiece can deflect, introducing dimensional error into the machined features. For precision work, this is not acceptable.
Jaw width selection and clamping force are linked: larger jaw widths in the GT Series come with higher rated clamping forces. But the selection should be driven by the actual clamping force requirement of the application, not just by convention.
The clamping force required to hold a workpiece securely during machining is determined by the cutting forces generated by the operation. A simplified approach:
$$F_{clamp} \geq \frac{F_{cut} \times SF}{\mu}$$
Where:
$$F_{cut}$$ = maximum cutting force (N) — estimated from feed rate, depth of cut, and material
$$SF$$ = safety factor (typically 2.0–3.0 for production machining)
$$\mu$$ = coefficient of friction between jaw face and workpiece (typically 0.15–0.25 for smooth steel jaws on steel workpiece)
For most CNC milling applications on steel and aluminium workpieces up to 150 mm, the GT150's 5,000 N clamping force is sufficient. For heavy roughing operations, large cross-sections, or interrupted cuts on hard materials, the GT200 (10,000 N) or GT300 (12,000 N) provides the necessary clamping margin.
Application | Typical cutting forces | Recommended minimum clamping force | GT model |
Light finishing, aluminium | Low | 3,000 N | GT100 / GT125 |
General CNC milling, steel | Medium | 5,000 N | GT150 |
Heavy roughing, steel/cast iron | High | 6,000–10,000 N | GT175 / GT200 |
Large mould blocks, titanium | Very high | 10,000–12,000 N | GT200 / GT300 |
Dual-station high-volume production | Combined high | See ZQ83 spec |
The ZQ83 Double Action Dual-Station Vise is worth considering separately for high-volume applications: it clamps two workpieces simultaneously with a single lead screw operation, effectively doubling parts-per-cycle without requiring a larger machine table.
The vise must fit on the machine table. This sounds obvious, but it is frequently underestimated — particularly when multiple vises are to be mounted side by side, or when the vise is being specified for a machine with a limited table travel envelope.
1. Table width (Y-axis): The vise overall length (L in the specification table) runs in the Y-axis direction when the vise is mounted in the standard orientation (fixed jaw at the back, movable jaw toward the operator). The vise overall length must be less than the machine's Y-axis travel, with sufficient clearance for the spindle to reach all programmed features.
2. Table depth (X-axis): The jaw width (B) runs in the X-axis direction. For a single vise, this is rarely a constraint. For multiple vises mounted side by side, the combined jaw widths plus any inter-vise spacing must fit within the X-axis travel.
One of the defining features of the GT Series is its modular design — the vise body is precision-ground on all six faces to the same 0.005 mm standard, which means multiple GT Series vises can be mounted side by side on a machine table and will sit perfectly coplanar and co-height without shimming or individual qualification.
This is the basis of high-density multi-vise setups:
Two GT150A vises side by side on a 400 mm table: combined jaw width 300 mm, combined overall length 420 mm — fits a standard 400 × 500 mm VMC table
Three GT100 vises side by side on a 350 mm table: combined jaw width 300 mm, combined overall length 270 mm — maximises parts per cycle on a compact machine
Two GT200B vises side by side on a 500 mm table: combined jaw width 400 mm — suitable for large horizontal machining centre tombstone setups
The GT Quick-Change Jaw Vise is particularly effective in multi-vise configurations: when multiple vises are mounted side by side and jaw types need to be changed between jobs, the quick-change mechanism allows all jaws to be swapped across all vises in minutes rather than the half-hour or more required with conventional bolted jaws.
For 5-axis machining centres, jaw width selection has an additional constraint that does not apply to 3-axis work: spindle and head clearance.
On a 5-axis machine, the spindle tilts and rotates to approach the workpiece from multiple angles. The vise body, jaw faces, and any clamping hardware must not intersect the spindle's swept volume during any programmed approach angle. This means:
Vise height (H) must be minimised — the lower the vise sits, the more angular clearance the spindle has
Jaw width affects the lateral clearance available for tilted spindle approaches from the sides
Overall vise length affects the clearance for spindle approaches from the front and rear
Model | Height (H) | 5-axis suitability |
GT100 | 30 mm | ✓ Excellent — maximum angular clearance |
GT125 | 40 mm | ✓ Very good |
GT150 | 50 mm | ✓ Good — standard 5-axis choice |
GT175 | 60 mm | ◑ Moderate — check spindle clearance for steep approach angles |
GT200 | 65 mm | ◑ Moderate — suitable for most 5-axis work with standard workpiece heights |
GT300 | 80 mm | △ Lower clearance — best suited to 3-axis or 4-axis applications, or 5-axis with tall workpieces |
For 5-axis machining centres, the GT100 to GT175 range is the standard selection zone. The GT150 is the most widely used specification for 5-axis work because it provides sufficient jaw width for most precision components (automotive parts, mould inserts, aerospace brackets) while keeping the vise height at 50 mm — low enough for comfortable spindle clearance on most 5-axis heads.
The case study of the Canadian precision manufacturer who eliminated a 4% scrap rate using GT100 and GT150A vises on their 5-axis machining centres is a direct illustration of this selection logic: the GT100 handled smaller workpieces where maximum angular clearance was needed, and the GT150A handled the larger workpieces where jaw width was the primary constraint.
The fifth variable is less about the vise geometry and more about how the vise will be used over time.
If your shop runs many different part numbers with frequent changeovers — common in job shop environments, mould making, and prototype machining — the priority is setup speed and flexibility.
For these applications, the GT Series with Interchangeable Jaws provides the flexibility to adapt the same vise body to different workpiece geometries by swapping jaw types:
Flat jaws for prismatic parts with parallel faces
V-groove jaws for round bar stock and cylindrical workpieces
Step jaws to eliminate parallel blocks and increase workpiece exposure
Thread hole jaws for mounting custom soft jaws machined to specific part profiles
Elevation jaws to raise the workpiece above the vise body for full 5-axis access
The jaw type is selected based on the workpiece geometry; the jaw width (and therefore the GT model) is selected based on the workpiece size.
For the highest-mix environments where jaw type changes happen multiple times per shift, the GT Quick-Change Jaw Vise eliminates the time cost of jaw changeover entirely — jaws lock and unlock in seconds via a precision dovetail mechanism, with no bolts to remove.
If your shop runs the same part number in high volumes — common in automotive component production, medical device manufacturing, and consumer electronics — the priority is maximum parts per cycle and minimum operator intervention.
For these applications, two strategies apply:
Strategy 1 — Multiple vises side by side: Mount three to five GT100 or GT125 vises side by side on the machine table. Each vise holds one part. The machine runs a multi-part program that machines all parts in a single cycle. The operator loads and unloads all parts between cycles.
Strategy 2 — Dual-station vise: Use the ZQ83 Double Action Dual-Station Vise, which clamps two workpieces simultaneously with a single lead screw operation. This halves the number of clamping operations per cycle and maximises the use of the machine's work envelope without requiring additional vises or T-slot hardware.
Applying the five variables above to a specific workpiece, the selection process follows this sequence:
Step 1 — Measure the workpiece
Record the three critical dimensions: width (parallel to jaw faces), depth (in the clamping direction, determines required opening), and height (above the vise bed, affects spindle clearance).
Step 2 — Apply the 60–80% contact rule to determine jaw width
Jaw width = workpiece width ÷ 0.7 (using 70% as the midpoint). Round up to the next available GT jaw width.
Step 3 — Check clamping force
Estimate the required clamping force from the cutting parameters. Confirm the selected jaw width's rated clamping force is sufficient with a 2× safety margin.
Step 4 — Check machine table fit
Confirm the vise overall length (L) fits within the Y-axis travel. For multi-vise setups, confirm the combined jaw widths fit within the X-axis travel.
Step 5 — Check 5-axis clearance (if applicable)
Confirm the vise height (H) provides adequate spindle clearance for the programmed approach angles. If not, select a smaller jaw width with lower vise height.
Step 6 — Select opening length
Based on the workpiece depth in the clamping direction, select the Smax variant (A, B, C, etc.) that provides at least 20 mm more opening than the workpiece depth — to allow for jaw face thickness and clamping engagement.
Step 7 — Consider production volume
If high-mix: consider interchangeable jaw types or quick-change jaw system. If high-volume: consider multi-vise side-by-side or dual-station ZQ83.
Workpiece: steel bracket, 85 mm wide × 60 mm deep × 45 mm tall
Machine: 5-axis machining centre, 400 mm × 400 mm table
Cutting: medium roughing and finishing passes
Selection:
Step 2: 85 ÷ 0.7 = 121 mm → round up to GT125 (125 mm jaw width)
Step 3: medium cutting forces, 3,000 N clamping force sufficient ✓
Step 4: GT125 overall length 345 mm, fits 400 mm Y-travel ✓
Step 5: GT125 height 40 mm, excellent 5-axis clearance ✓
Step 6: 60 mm workpiece depth + 20 mm clearance = 80 mm minimum opening → GT125 (100 mm opening) ✓
Result: GT125 — single model, standard flat jaws.
Workpiece: P20 tool steel mould insert, 160 mm wide × 120 mm deep × 80 mm tall
Machine: 3-axis VMC, 600 mm × 400 mm table
Cutting: heavy roughing, high radial forces
Volume: 50 parts per week, same part number
Selection:
Step 2: 160 ÷ 0.7 = 229 mm → round up to GT300 (300 mm jaw width)
Step 3: heavy roughing on P20 steel, high cutting forces → 12,000 N clamping force required ✓
Step 4: GT300A overall length 535 mm, fits 600 mm Y-travel ✓
Step 5: 3-axis machine, height not a constraint ✓
Step 6: 120 mm workpiece depth + 20 mm = 140 mm minimum opening → GT300A (200 mm opening) ✓
Step 7: high-volume same part → standard flat jaws, no quick-change needed
Result: GT300A — maximum clamping force for heavy mould roughing.
Workpiece: aluminium 7075 bracket, 110 mm wide × 80 mm deep × 55 mm tall
Machine: 5-axis machining centre, 500 mm × 500 mm table
Cutting: light finishing, tight tolerances
Volume: 10–15 different part numbers per week, frequent changeovers
Selection:
Step 2: 110 ÷ 0.7 = 157 mm → round up to GT175 (175 mm jaw width)
Step 3: light finishing on aluminium, 6,000 N clamping force more than sufficient ✓
Step 4: GT175A overall length 455 mm, fits 500 mm Y-travel ✓
Step 5: GT175 height 60 mm — check spindle clearance for steep approach angles; acceptable for most 5-axis heads ✓
Step 6: 80 mm workpiece depth + 20 mm = 100 mm minimum → GT175A (200 mm opening) ✓
Step 7: high-mix, frequent changeovers → Quick-Change Jaw System recommended; thread hole jaws for soft jaw mounting on complex profiles
Result: GT175A with Quick-Change Jaw System — precision and flexibility for high-mix aerospace work.
Workpiece: stainless steel medical component, 40 mm wide × 35 mm deep × 25 mm tall
Machine: 5-axis machining centre, 350 mm × 350 mm table
Cutting: light finishing, very tight tolerances (±0.005 mm)
Volume: 200+ parts per day, same family of parts
Selection:
Step 2: 40 ÷ 0.7 = 57 mm → GT100 (100 mm jaw width) — workpiece is small, GT100 provides adequate contact
Step 3: light finishing, 3,000 N clamping force sufficient ✓
Step 4: GT100 overall length 270 mm — three GT100 vises side by side = 300 mm combined width, 270 mm length, fits 350 mm table ✓
Step 5: GT100 height 30 mm — maximum 5-axis clearance, ideal for complex approach angles ✓
Step 6: 35 mm workpiece depth + 20 mm = 55 mm minimum → GT100 (100 mm opening) ✓
Step 7: high-volume, three vises side by side → three parts per cycle, flat jaws
Result: GT100 × 3 side by side — maximum parts per cycle on compact 5-axis table, minimum vise height for full angular clearance.
Many shops default to a single jaw width for all applications because it is what they are familiar with. A GT200 on a machine that primarily runs 80 mm workpieces wastes table space, adds unnecessary vise height, and provides more clamping force than the application needs. The correct approach is to match the jaw width to the workpiece for each application.
Vise height is frequently overlooked in the selection process because it does not affect the clamping function. On a 3-axis machine, it does not matter. On a 5-axis machine, a vise that is 30 mm too tall can prevent the spindle from reaching a programmed approach angle, requiring a program rewrite or a workpiece repositioning. Check the vise height against the machine's head clearance specification before ordering.
The opening length (Smax) must accommodate the workpiece depth plus the jaw face engagement depth plus a small clearance margin. A workpiece that is 180 mm deep requires a minimum Smax of approximately 200–210 mm — not 180 mm. Select the next available Smax above the workpiece depth plus 20 mm minimum.
Interrupted cuts — where the tool alternately engages and disengages the workpiece — generate impact forces that are significantly higher than continuous cutting forces. For interrupted cut applications (slotting, face milling across a split workpiece, machining castings with irregular surfaces), apply a safety factor of 3.0 rather than 2.0 when calculating required clamping force. This often moves the selection up one jaw width.
A single GT300 vise holding one large workpiece per cycle may be the correct solution for some applications. But for many applications, two or three smaller GT vises holding multiple smaller workpieces per cycle will deliver higher throughput from the same machine. Always evaluate the multi-vise option before defaulting to the largest single vise that fits the workpiece.
Your primary requirement | Recommended GT model | Consider also |
Small parts, maximum 5-axis clearance | GT100 | Multi-vise side-by-side |
Small-medium parts, 5-axis, light cutting | GT125 | GT100 × 2 side-by-side |
Medium parts, 5-axis, general milling | GT150A/B | Quick-change jaw system |
Medium-large parts, 5-axis, high-mix | GT175A/B | Quick-change jaw system |
Large parts, 3-axis, heavy roughing | GT200 / GT300 | — |
High-volume, two parts per cycle | ZQ83 Double Action | — |
High-mix, frequent jaw changes | GT150–GT175 + Quick-Change | — |
Mould blocks, maximum clamping force | GT300 | — |
The complete GT Series — from GT100 to GT300, with standard interchangeable jaws, quick-change jaw systems, and the ZQ83 dual-station option — is available at www.pyzhjx.com/product-6-1.html
Contact the Zhenghao technical team with your workpiece dimensions and application details, and we will confirm the correct model selection before you order.
Email: zhjx@pyzhjx.com
Phone / WhatsApp: +86-18660185316
No. A 150 mm jaw clamping a 180 mm workpiece means the workpiece overhangs the jaw on both sides. This creates a cantilever condition that allows the overhanging portion to deflect under cutting forces, introducing dimensional error. For a 180 mm wide workpiece, select the GT200 (200 mm jaw width), which provides full jaw contact across the workpiece width.
Slightly larger is always preferable. A jaw that is 10–20% wider than the workpiece still provides good contact distribution and does not create the cantilever problem of an undersized jaw. A jaw that is significantly larger (more than 40% wider than the workpiece) begins to concentrate clamping force at the jaw edges, which can cause edge deformation on soft materials. The 60–80% contact rule provides the correct sizing range.
All three have the same 150 mm jaw width and 5,000 N clamping force. The difference is the maximum opening: GT150A = 200 mm, GT150B = 300 mm, GT150C = 400 mm. Select based on your workpiece depth in the clamping direction, plus 20 mm minimum clearance. If your workpiece is 160 mm deep, select GT150A (200 mm opening). If your workpiece is 260 mm deep, select GT150B (300 mm opening).
Yes. The GT Series vise body is precision-ground on all six faces to 0.005 mm squareness and parallelism. Multiple vises can be mounted side by side directly on the machine table T-slots and will sit perfectly coplanar and co-height without shimming or individual qualification. This is one of the key advantages of the modular design. See the full GT Series interchangeable jaw range for compatible jaw types across all jaw widths.
By the 60–80% contact rule, a 130 mm workpiece requires a minimum jaw width of 163–217 mm — which points to GT175 (175 mm) as the minimum correct selection. However, if 5-axis spindle clearance is tight, the GT175's 60 mm height versus the GT150's 50 mm height may be a concern. In this case, evaluate whether the workpiece can be held in a GT150 with step jaws or elevation jaws that raise the workpiece above the jaw body, providing more angular clearance for the spindle while maintaining adequate jaw contact on the workpiece. Contact our technical team to discuss the specific geometry.
