Small Diameter Gages

Small Diameter Internal Functional Size/Pitch Diameter Inspection – (⅝” (.625″) to 1½” (1.500″) Diameters)

Pitch diameter and functional size inspections are pivotal to nearly every threaded connection. This can be especially true in smaller diameters, but these smaller diameters require a unique gage design to perform the proper inspections.

The SPG-6000 line of thread inspection gages measures internal and external functional size and pitch diameter of thread diameters between .625″ and 1.500″. Mainly, these gages are used on ANSI and ISO standard straight thread forms. Primarily among these groups, the gages are used on the ACME, Stub Acme, Stub ACME Modified-1 & -2, Metric & MJ, and UN, UNJ, & UNR Series of threads. However, these gages are versatile in that they can be modified to inspect nearly any type of thread in our .625″ to 1.500″ size range. The SPG-6000 can be equipped with either thread rolls or contact points. Contact points are applied for pitch diameter measurement, while thread rolls inspect functional size.

Pitch diameter inspection requires the addition of contact point arms to hold the contact points. Contact point arms are sold in sets of two. Our standard contact point arms require straight shank contact points. Contact point arms designed for threaded shank contact points are available at additional cost.

For functional size inspection, thread rolls attach directly to the gage. Thread rolls for certain thread types may have a designated set for internal threads or external threads, while other thread types have one set of rolls for both internal and external.

The SPG-6000 can be set using our MIC TRAC™ gage setting systems, rod standards, calipers, gauge blocks, or micrometers. For best results, Gagemaker recommends our MIC TRAC™gage setting systems or rod standards. For gage setting dimensions regardless of setting method or selecting additional contact points, our helpful, easy-to-use TDWIN™ thread engineering software program may be required.

Contact points, contact point arm sets, thread roll sets, gage setting devices, and software are all sold separately. 

RangeIndicator TravelIndicator ResolutionDescriptionModel
⅝” – 1½”
(15.9 mm – 38.1 mm)
½”.0005”Small Diameter Internal Pitch Diameter/Functional Size Gage, 1” reachSPG-6000
⅝” – 1½”
(15.9 mm – 38.1 mm)
½”.0001”Small Diameter Internal Pitch Diameter/Functional Size Gage, 1” reach, with high resolution indicatorSPG-6000-1
⅝” – 1½”
(15.9 mm – 38.1 mm)
10 mm.01 mmSmall Diameter Internal Pitch Diameter/Functional Size Gage, 1” reach, with metric indicatorSPG-6000-M
Part TypeDescriptionModel
HandlesReplacement handles for SPG-6000 series, set of 2SPG-Handle
Screws and washersReplacement button head cap screws (#6-32 x ”)and washers (.300” x .150” x.025”) for contact point arms and thread rollslSPG-SCREWS
Gagemaker-SPG-6000-two-waysGagemaker-SPG-6000-on-part

Thread Rolls for Small Internal Diameter Functional Size Inspection

Gagemaker offers matched precision ground thread rolls for a variety of small diameter thread types. Thread rolls attach directly to the gage. If you do not find your pitch or thread type listed, additional thread rolls may be available. Please contact customer service for more.

Gagemaker offers matched precision ground thread rolls for small diameter ACME threads. If you do not find your pitch listed, thread rolls may be available. Please contact customer service for more.

PitchDescriptionModel
44 pitch ACME thread rolls (set of 2)SRA-4P
55 pitch ACME thread rolls (set of 2)SRA-5P
66 pitch ACME thread rolls (set of 2)SRA-6P
77 pitch ACME thread rolls (set of 2)SRA-7P
88 pitch ACME thread rolls (set of 2)SRA-8P
99 pitch ACME thread rolls (set of 2)SRA-9P
1010 pitch ACME thread rolls (set of 2)SRA-10P
1111 pitch ACME thread rolls (set of 2)SRA-11P
1212 pitch ACME thread rolls (set of 2)SRA-12P
1313 pitch ACME thread rolls (set of 2)SRA-13P
1414 pitch ACME thread rolls (set of 2)SRA-14P
1616 pitch ACME thread rolls (set of 2)SRA-16P
1818 pitch ACME thread rolls (set of 2)SRA-18P

Small diameter metric thread rolls are available as separate internal or external sets. SRMI thread rolls inspect the internal functional size of machine threaded parts with metric and MJ 60° “V” thread forms, while “TRME” rolls are used for externally threaded parts. Please ensure you select the corresponding internal or external application when ordering.

Rolls are sold in matched sets (2 rolls). Rolls sold separately from gages and software. Please specify the pitch of thread when ordering.  If you do not find your pitch listed, thread rolls may be still available. Please contact customer service for more.

PitchDescriptionExternal Thread Roll ModelInternal Thread Roll Model
1 mm1 pitch ISO Metric 60° “V” thread rolls (set of 2)TRME-1PSRMI-1P
1.5 mm1.5 pitch ISO Metric 60° “V” thread rolls (set of 2)TRME-15PSRMI-15P
1.75 mm1.75 pitch ISO Metric 60° “V” thread rolls (set of 2)TRME-175PSRMI-175P
2 mm2 pitch ISO Metric 60° “V” thread rolls (set of 2)TRME-2PSRMI-2P
2.5 mm2.5 pitch ISO Metric 60° “V” thread rolls (set of 2)TRME-25PSRMI-25P
3 mm3 pitch ISO Metric 60° “V” thread rolls (set of 2)TRME-3PSRMI-3P
3.5 mm3.5 pitch ISO Metric 60° “V” thread rolls (set of 2)TRME-3.5PSRMI-35P
4 mm4 pitch ISO Metric 60° “V” thread rolls (set of 2)TRME-4PSRMI-4P

Gagemaker offers matched precision ground thread rolls for small diameter Stub ACME threads.If you do not find your pitch listed, thread rolls may be available. Please contact customer service for more.

PitchDescriptionModel
44 pitch Stub ACME thread rolls (set of 2)SRSA-4P
66 pitch Stub ACME thread rolls (set of 2)SRSA-6P
77 pitch Stub ACME thread rolls (set of 2)SRSA-7P
88 pitch Stub ACME thread rolls (set of 2)SRSA-8P
99 pitch Stub ACME thread rolls (set of 2)SRSA-9P
1010 pitch Stub ACME thread rolls (set of 2)SRSA-10P
1111 pitch Stub ACME thread rolls (set of 2)SRSA-11P
1212 pitch Stub ACME thread rolls (set of 2)SRSA-12P
1313 pitch Stub ACME thread rolls (set of 2)SRSA-13P
1414 pitch Stub ACME thread rolls (set of 2)SRSA-14P
1616 pitch Stub ACME thread rolls (set of 2)SRSA-16P
1818 pitch Stub ACME thread rolls (set of 2)SRSA-18P

Small diameter UN, UNJ, & UNR series thread rolls are used to inspect the internal functional size of machine threaded parts with UN, UNJ, & UNR 60° “V” thread forms. Rolls are specifically designed for use on parts threaded externally (“SRVE”) or internally (“SRVI”). Please ensure you select the corresponding internal or external application when ordering.

Rolls are sold in matched sets (2 rolls). Rolls sold separately from gages and software. Please specify the pitch of thread when ordering. If you do not find your pitch listed, thread rolls may be available. Please contact customer service for more.

PitchDescriptionExternal Thread Roll ModelInternal Thread Roll Model
66 pitch 60° “V” thread rolls (set of 2)SRVE-6PSRVI-6P
77 pitch 60° “V” thread rolls (set of 2)SRVE-7PSRVI-7P
88 pitch 60° “V” thread rolls (set of 2)SRVE-8PSRVI-8P
99 pitch 60° “V” thread rolls (set of 2)SRVE-9PSRVI-9P
1010 pitch 60° “V” thread rolls (set of 2)SRVE-10PSRVI-10P
1111 pitch 60° “V” thread rolls (set of 2)SRVE-11PSRVI-11P
1212 pitch 60° “V” thread rolls (set of 2)SRVE-12PSRVI-12P
1313 pitch 60° “V” thread rolls (set of 2)SRVE-13PSRVI-13P
1616 pitch 60° “V” thread rolls (set of 2)SRVE-16PSRVI-16P
1818 pitch 60° “V” thread rolls (set of 2)SRVE-18PSRVI-18P
2020 pitch 60° “V” thread rolls (set of 2)SRVE-20PSRVI-20P
2424 pitch 60° “V” thread rolls (set of 2)SRVE-24PSRVI-24P
2828 pitch 60° “V” thread rolls (set of 2)SRVE-28PSRVI-28P
3232 pitch 60° “V” thread rolls (set of 2)SRVE-32PSRVI-32P

Contact Points & Accessories for Small Internal Diameter Pitch Diameter Inspection

To measure pitch diameter on small diameters with our SPG-6000 series of gages, contact points and contact point arms are required.

Gagemaker’s contact points are manufactured with carbide balls. Standard contact diameters are held to tolerances of ± .0002″. Contact point sizes are matched closely to thread inspection wire sizes. These contact point sizes are used in the TDWIN™ software program (sold separately). Contact points are sold individually and separately.

“SP” contact points only fit straight shank “SPA” contact point arms. Our “STPA” threaded shank contact point arms require threaded shank contact points, found here. Contact point arms are sold  separately as a set of two.

Below, we’ve provided  a list of our more popular straight shank contact points and contact point arms. However, if you do not find your pitch or thread type listed or need custom contact points, please contact customer service for more.

Our small diameter gage contact point arms hold “SP” straight shank contact points for pitch diameter measurement. These contact point arms are required for pitch diameter inspection. Threaded shank contact point arms are available and require threaded shank contact points for use.

Sold separately from gage as a set of 2. Specify straight or threaded shank contact point arms when ordering. Contact points are not included.

Custom arm sizes are available, contact customer service for more information.

Straight or Threaded Shank*Minimum BoreLengthArm DiameterDescriptionModel
Straight.700”1.00”.265”.265” diameter straight shank contact point arms (set of 2)SPA-265
Straight.950”1.25”.375”.375” diameter straight shank contact point arms (set of 2)SPA-375
Straight.950”2”.375”.375” diameter straight shank contact point arms, 2” reach (set of 2)SPA-375-200
Straight.950”3”.375”.375” diameter straight shank contact point arms, 3” reach (set of 2)SPA-375-300
Straight1.100”1.50”.473”.473” diameter straight shank contact point arms (set of 2)SPA-437
Threaded*1.032”1.25”.375”.375” diameter threaded shank contact point arms (set of 2). Requires threaded shank contact points.*STPA-375 *
Threaded*1.152”1.50”.473”.473” diameter threaded shank contact point arms (set of 2). Requires threaded shank contact points.*STPA-437*
*Threaded shank contact point arms require threaded shank contact points. Visit out contact points page to find your threaded shank contact points or contact customer services.

For inspecting ACME, Stub ACME, Stub ACME Modified-1, and Stub ACME Modified-2, our  straight shank truncated contact points are manufactured with carbide balls. Straight shank truncated contact points will only fit on our straight shank “SPA” contact point arms.

If you do not find your pitch listed, please contact customer service for more information.

PitchDescriptionModel
44 pitch straight shank truncated contact point SP-128T
55 pitch straight shank truncated contact point SP-105T
66 pitch straight shank truncated contact point SP-090T
77 pitch straight shank truncated contact point SP-090T
88 pitch straight shank truncated contact pointSP-062T
99 pitch straight shank truncated contact pointSP-062T
1010 pitch straight shank truncated contact pointSP-050T
1111 pitch straight shank truncated contact pointSP-050T
1212 pitch straight shank truncated contact pointSP-041T
1313 pitch straight shank truncated contact pointSP-041T
1414 pitch straight shank truncated contact pointSP-041T
1616 pitch straight shank truncated contact pointSP-032T
1818 pitch straight shank truncated contact pointSP-032T

Gagemaker’s “SP” straight shank contact points for Metric and MJ 60° “V” threads contact points are manufactured with carbide balls. “SP” contact points fit straight shank “SPA” contact point arms only.

If you do not find your pitch listed, please contact customer service for more information.

PitchDescriptionModel
1 mm1 mm pitch straight shank truncated contact point for Metric and MJ 60° “V” threadsSP-032
1.25 mm1.25 mm pitch straight shank truncated contact point for Metric and MJ 60° “V” threadsSP-032
1.5 mm1.5 mm pitch straight shank truncated contact point for Metric and MJ 60° “V” threadsSP-041
1.75 mm1.75 pitch straight shank truncated contact point for Metric and MJ 60° “V” threadsSP-041
2 mm2 mm pitch straight shank truncated contact point for Metric and MJ 60° “V” threadsSP-041
2.5 mm2.5 mm pitch straight shank truncated contact point for Metric and MJ 60° “V” threadsSP-057
3 mm3 mm pitch straight shank truncated contact point for Metric and MJ 60° “V” threadsSP-072
3.5 mm3.5 mm pitch straight shank truncated contact point for Metric and MJ 60° “V” threadsSP-072
4 mm4 mm pitch straight shank truncated contact point for Metric and MJ 60° “V” threadsSP-096
4.25 mm4.25 mm pitch straight shank truncated contact point for Metric and MJ 60° “V” threadsSP-096
4.5 mm4.5 mm pitch straight shank truncated contact point for Metric and MJ 60° “V” threadsSP-105
4.75 mm4.75 mm pitch straight shank truncated contact point for Metric and MJ 60° “V” threadsSP-105

For inspecting pitch diameter on small diameter UN, UNJ, & UNR threads, we offer straight shank contact points manufactured with carbide balls. Straight shank contact points will only fit on our straight shank “SPA” contact point arms.

If you do not find your pitch listed, please contact customer service for more information.

PitchDescriptionModel
55 pitch straight shank contact point SP-105
66 pitch straight shank contact point SP-096
77 pitch straight shank contact point SP-096
88 pitch straight shank contact point SP-072
99 pitch straight shank contact point SP-072
1010 pitch straight shank contact point SP-057
1111 pitch straight shank contact point SP-050
11.511.5 pitch straight shank contact point SP-050
1212 pitch straight shank contact point SP-050
1313 pitch straight shank contact point SP-041
1616 pitch straight shank contact point SP-041
1818 pitch straight shank contact point SP-032
2020 pitch straight shank contact point SP-032
2424 pitch straight shank contact point SP-032
2828 pitch straight shank contact point SP-021
3232 pitch straight shank contact point SP-021