Universal Punch Concentricity Gaging System J Series · -20 Low Profile / Surface Plate / Comparator

J-20 Low Profile Concentricity Gage

Name: J-20 Low Profile Concentricity Gage
Brand: Universal Punch Corp.
SKU: J-20

Compact concentricity and runout inspection for 3/8–2 inch cylindrical components.

The Universal Punch J-20 is a compact Surface Plate or Comparator Concentricity Gage for parts from 3/8–2 in (10–50 mm) in diameter and up to 6 in (152 mm) long.

Its J-Series architecture provides a dedicated rotational support platform in a smaller fixture envelope for surface-plate, comparator and other precision inspection setups.

Request a J-20 Quote → Send Us Your Part Drawing

J-20 · Surface Plate / Comparator Gage. Compact -20 architecture for parts from 3/8–2 in in diameter and up to 6 in long.

3/8–2 in10–50 mm part diameter

Up to 6 in152 mm maximum part length

Low ProfileSurface Plate / Comparator architecture

4.4 lb2.0 kg published shipping weight

J-20 Definition

The medium-capacity low-profile gage in the J Series.

J Series identifies Universal Punch's low-profile surface-plate / comparator-oriented gaging architecture. -20 identifies the 3/8–2 in / 10–50 mm diameter class.

The J-20 is designed for applications where the part fits within a 6-inch inspection envelope and a compact rotational support fixture is preferable to a longer conventional bench-style gage.

The Universal Punch J-20 is a low-profile Surface Plate or Comparator Concentricity Gage for components from 3/8–2 in (10–50 mm) in diameter and up to 6 in (152 mm) long.

J-20 low-profile architecture. The compact fixture is designed around surface-plate and comparator-oriented inspection.

Low-Profile Inspection Architecture

Compact geometry can matter as much as capacity.

The J-20 provides dedicated rotational support for the -20 component class without requiring the longer footprint of shaft-gage platforms.

Low-profile J-20 base and support-block detail.

When the J-20 makes sense

Compact inspection envelopeUseful where bench or surface-plate space matters.

Comparator-oriented setupDesigned as part of the J-Series surface-plate / comparator family.

-20 component capacityFor cylindrical parts from 3/8–2 in / 10–50 mm diameter.

Up to 6 in longA dedicated rotational support fixture for compact components.

Selection principle: choose the J-20 when the part fits the -20 capacity class and a low-profile Surface Plate / Comparator architecture best matches the inspection environment.

Published J-20 General Data

A compact -20 platform with a six-inch part envelope.

Part Diameter3/8–2 in10–50 mm

Part LengthUp to 6 in152 mm

Gage TypeSurface Plateor Comparator Gage

Overall Length7 in178 mm

Width5 in127 mm

Shipping Weight4.4 lb2.0 kg

Specification	J-20 Published Data
Model	J-20
Gage Type	Surface Plate or Comparator Gage
Part Diameter	3/8–2 in / 10–50 mm
Maximum Part Length	6 in / 152 mm
Overall Gage Length	7 in / 178 mm
Gage Width	5 in / 127 mm
Approximate Height	5-1/2 in / 140 mm
Shipping Weight	4.4 lb / 2.0 kg

-20 Roller & Arm-Yoke System

Choose support geometry from the actual component.

Universal Punch publishes three principal main-roller styles for the -20 class:

120-20FP · Full PlainFull plain main roller set for -20 models.

120-20HP · Half PlainHalf plain geometry for applications requiring additional clearance.

120-20QP · Quarter PlainQuarter plain geometry for more constrained support-land applications.

Current parts documentation identifies 170-20, approximately 3/4 × 9/32 in (19 × 7 mm), as the standard -20 top roller.

Roller selection should be based on usable support surfaces, shoulders, grooves, threads, feature location and clearance—not simply overall part diameter.

Universal Punch J-20 main roller and adjustable arm yoke detail — J-20 roller and adjustable arm-yoke detail. Final support geometry should be selected from the actual component drawing.

J-20 profile and adjustment architecture for low-profile inspection setups.

Indicator & Comparator Configuration

Match the measurement system to the tolerance.

Universal Punch publishes multiple analog and digital test indicators, as well as indicator mounts, dovetail clamps, swivel supports, extension holders and fine-adjustment accessories.

Identify the measurement feature.Define the diameter, face, shoulder or rotational feature to be evaluated.

Identify the supporting surfaces.Select stable cylindrical lands for repeatable rotation.

Choose roller geometry.Match support width and clearance to the actual print.

Select the indicator.Choose resolution, range, stylus reach and contact direction from the inspection requirement.

Published Accuracy Classifications

The -20 model class can be specified for higher published accuracy.

Universal Punch publishes Standard Black and Precision Gold classifications and states that its Concentricity Gaging Systems are calibrated and directly traceable to N.I.S.T.

Standard BlackPublished performance better than or equal to 4 µm / 0.00016 in.

Precision GoldAvailable for -10 and -20 model classes; published performance better than or equal to 2 µm / 0.000079 in.

N.I.S.T. TraceabilityUniversal Punch documentation states its Concentricity Gaging Systems are calibrated and directly traceable to N.I.S.T.

Confirm the required accuracy class, indicator resolution and calibration documentation for the exact ordered J-20 configuration.

Manual & Motorized Rotation

Control part rotation around the inspection requirement.

Standard Architecture

Manual Drive

Universal Punch describes its standard Concentricity Gaging System as using a manual timing-belt pulley arrangement for smooth rotational inspection.

The support geometry, top contact, rotation and indicator contact together form the complete measurement setup.

Optional · Part No. 276-20

J-20 Variable Speed Motor Assembly

Published motorized configuration: 24 VDC · 0–10 rpm · variable speed · forward/reverse.

Universal Punch also publishes transformer and industrial foot-switch options for the motorized system.

Ask About Motorizing the J-20 →

J-20 Model Selection

Capacity matters. Architecture matters too.

J-20 vs. G2-20

J-20

Surface Plate / Comparator

3/8–2 in / 10–50 mm

Up to 6 in / 152 mm part length.

Choose when a compact low-profile surface-plate or comparator architecture matches the inspection setup.

G2-20

Side Checker · Vertical Carrier

3/8–2 in / 10–50 mm

Up to 6 in / 152 mm part length.

Choose when Side Checker architecture and Vertical Carrier access better match the measurement feature.

View G2-20 →

J-20 and G2-20 cover the same published diameter and length class, but use different architectures. Choose by measurement access and inspection environment—not capacity alone.

J-Series Capacity Comparison

Model	Part Diameter	Maximum Part Length	Published Shipping Weight
JSLP-10 / JLP-10 / J-10	1/8–1 in / 3–25 mm	4 in / 102 mm	3.5 lb / 1.6 kg
J-20	3/8–2 in / 10–50 mm	6 in / 152 mm	4.4 lb / 2.0 kg
J-40	3/4–4 in / 20–102 mm	8 in / 203 mm	9.2 lb / 4.2 kg

J-series logic: Universal Punch's J Series is the low-profile Surface Plate / Comparator family; -10, -20 and -40 progressively increase diameter and part-length capacity.

Universal Punch System Selection

Configure the J-20 in three engineering decisions.

Universal Punch describes its Concentricity Gaging System around three primary selections: the gage model, the main rollers, and the indicator/accessory configuration.

1 · Select J-20Use the low-profile -20 platform when the part and inspection environment fit the Surface Plate / Comparator architecture.

2 · Select support geometryChoose Full Plain, Half Plain, Quarter Plain or another suitable configuration from the actual component support surfaces.

3 · Select measurement hardwareChoose indicator resolution, range, stylus, accuracy class, mounts and optional motorized rotation from the inspection requirement.

J-20 Technical FAQ

Common questions about the J-20 concentricity gage.

What is the Universal Punch J-20?

The Universal Punch J-20 is a low-profile Surface Plate or Comparator Concentricity Gage for cylindrical parts from 3/8–2 in (10–50 mm) in diameter and up to 6 in (152 mm) long.

What diameter range can the J-20 inspect?

The published J-20 part-diameter range is 3/8–2 in (10–50 mm).

What is the maximum part length for the J-20?

The published maximum part length is 6 in (152 mm).

What is the J-20 designed for?

Universal Punch classifies the J-20 as a Surface Plate or Comparator Gage. Its compact J-Series architecture is intended for low-profile rotational inspection applications.

How much does the J-20 weigh?

The published shipping weight is 4.4 lb (2.0 kg).

What main roller styles are available for the J-20 size class?

Universal Punch publishes Full Plain, Half Plain and Quarter Plain main roller configurations for the -20 model class. Final roller selection should be based on the actual component support surfaces.

What is the standard -20 top roller?

Current Universal Punch parts documentation identifies the 170-20 top roller, 3/4 × 9/32 in (19 × 7 mm), as the standard -20 top roller.

Can the J-20 be specified with Precision Gold accuracy?

Universal Punch publishes Precision Gold for -10 and -20 model classes, with published performance better than or equal to 2 microns (0.000079 in). The exact ordered configuration should be confirmed when quoting.

Is the J-20 NIST traceable?

Universal Punch documentation states that its Concentricity Gaging Systems are calibrated and directly traceable to N.I.S.T.

Can the J-20 be motorized?

Yes. Universal Punch publishes Part No. 276-20 as the J-20 Variable Speed Motor Assembly.

What speed does the motorized J-20 operate at?

The published variable-speed drive system operates at 24 VDC and 0–10 rpm with forward and reverse control.

What is the difference between the J-20 and G2-20?

Both cover the 3/8–2 in diameter class and parts up to 6 in long, but the J-20 uses a low-profile Surface Plate / Comparator architecture while the G2-20 is a Side Checker Gage with a Vertical Carrier.

Configure the J-20 Around Your Part

Send the print. Let the inspection requirement define the setup.

Universal Punch can use the component geometry and measurement requirement to help determine the appropriate J-20 support rollers, top contact, indicator configuration, accuracy class and manual or motorized drive system.

part drawing or CAD print
part diameter
overall length
support journal dimensions
usable support widths
shoulders and flanges
threads and grooves
inspection feature
datum relationship
tolerance
required resolution
manual or motorized preference

Request a J-20 Quote → Explore Concentricity Gages

Compare the smaller J-10 family or larger J-40.

Precision Tooling, Gaging & Engineering