{"product_id":"starrett-68131-inside-micrometer-0-375-0-500-inch-range","title":"Starrett 68131 Inside Micrometer 0.375-0.500 Inch Range","description":"\u003ch3\u003eProduct Description\u003c\/h3\u003e\u003cp\u003eThe STARRETT 68131 is a mechanical inside micrometer designed for precise internal bore and hole measurements in the 0.3750 to 0.5000 inch range. It uses three self-centering contact points with solid carbide measuring faces to deliver consistent, true readings without operator-induced alignment error. Graduation is 0.0003 inches with an accuracy of 0.000150 inches, making it suitable for close-tolerance work in machining, maintenance, and precision assembly. The ratchet stop thimble ensures repeatable measuring pressure, which is essential when working to tight tolerances on valve bores, cylinder sleeves, bearing housings, and similar applications.\u003c\/p\u003e\u003cp\u003eThis inside micrometer is used in machine shops, industrial maintenance, and precision trades where accurate internal measurement of small bores is required. The 0.3750 to 0.5000 inch range targets smaller-diameter bores common in hydraulic fittings, pump housings, and mechanical assemblies. A maximum extension rod length of 6.0000 inches and a gage depth of 2.25 inches allow measurement in moderately deep bores. The instrument ships complete with a case, contacts, setting ring, wrenches, and instructions, making it ready for immediate use on arrival.\u003c\/p\u003e\u003ch4\u003eKey Features\u003c\/h4\u003e\u003cul\u003e\n\u003cli\u003eThree self-centering contacts automatically align to the bore centerline for true, repeatable readings\u003c\/li\u003e\n\u003cli\u003eSolid carbide measuring faces resist wear on hardened or abrasive surfaces\u003c\/li\u003e\n\u003cli\u003eRatchet stop thimble maintains consistent measuring pressure to protect accuracy\u003c\/li\u003e\n\u003cli\u003eGraduation of 0.0003 inches and accuracy of 0.000150 inches for close-tolerance applications\u003c\/li\u003e\n\u003cli\u003eSetting ring included for field calibration verification without returning to a standards lab\u003c\/li\u003e\n\u003cli\u003eMaximum extension rod length of 6.0000 inches covers moderately deep bore access\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch4\u003eCompatibility\u003c\/h4\u003e\u003cp\u003eDesigned as an OEM-style precision measuring instrument for use across machining, industrial maintenance, and mechanical assembly applications requiring internal measurement of bores in the 0.3750 to 0.5000 inch range.\u003c\/p\u003e\u003ch4\u003eInstallation Notes\u003c\/h4\u003e\u003cp\u003eInside micrometers are precision instruments and should be handled by qualified machinists or technicians familiar with bore gauging procedures. Verify calibration against the included setting ring before use and after any impact or temperature change. Keep the instrument clean and lightly oiled per manufacturer instructions; store in the provided case when not in use. Do not force the thimble past its measurement range, as this can damage the spindle or contacts.\u003c\/p\u003e\u003ch4\u003eTechnical Specifications\u003c\/h4\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMicrometer Type\u003c\/strong\u003e: Inside\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMinimum Measurement\u003c\/strong\u003e: 0.3750 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaximum Measurement\u003c\/strong\u003e: 0.5000 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGraduation\u003c\/strong\u003e: 0.0003 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAccuracy\u003c\/strong\u003e: 0.000150 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eResolution\u003c\/strong\u003e: 0.000250 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eThimble Type\u003c\/strong\u003e: Ratchet Stop\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMeasuring Face Material\u003c\/strong\u003e: Solid Carbide\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNumber of Contact Points\u003c\/strong\u003e: 3\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eGage Depth\u003c\/strong\u003e: 2.25 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaximum Extension Rod Length\u003c\/strong\u003e: 6.0000 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSetting Ring Diameter\u003c\/strong\u003e: 0.5000 inches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNumber of Setting Rings Included\u003c\/strong\u003e: 1\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eIncludes\u003c\/strong\u003e: Case, Contacts, Instructions, Setting Ring, Wrenches\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWeight\u003c\/strong\u003e: 1.3 pounds\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch4\u003eStandard Information\u003c\/h4\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eBrand\u003c\/strong\u003e: STARRETT\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number\u003c\/strong\u003e: 68131\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"STARRETT","offers":[{"title":"Default Title","offer_id":51542970138930,"sku":"68131","price":1024.45,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0270\/4519\/9983\/files\/d1ed13cc81a4960f29f2c684dacc4a26.jpg?v=1785912646","url":"https:\/\/voomisupply.com\/products\/starrett-68131-inside-micrometer-0-375-0-500-inch-range","provider":"Voomi Supply","version":"1.0","type":"link"}