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The MI-500, MI-750, and MI-1000 mounts all feature large precision worm gear drives on both axes. Each fine pitch worm gear, made of either bronze or aluminum, is paired with a matching precision worm. The worm and stainless steel shaft are machined as a single unit to achieve accuracy of .0001 inches in residual run-out, thread lead errors, and concentricity.
Since the right ascension drive tracks continuously, there is generally more wear on this axis. As an option, we offer a bronze worm gear with a stainless steel worm for the RA axis. These materials are far superior to the more common aluminum worm gears one finds on nearly all other commercial mounts. The bronze-stainless steel gear option is also available for the declination axes. However, unless you have special requirements, we normally recommend using an aluminum worm gear with a bronze worm on the declination axis. With over 28 years of experience in manufacturing telescope gears, our drive systems provide high precision tracking and exceptional pointing accuracy. Prior to shipment, the tracking accuracy of each mount is measured. This report is provided to the customer to verify that the periodic error is no more than 5 arc seconds peek to peek. Each worm assembly is spring-loaded against the worm gear. The reduces backlash to near zero. When centering a star in the eyepiece, the telescope is responsive with very little delay when you change direction. |
Bronze worm gear with stainless steel worm
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Aluminum worm gear with bronze worm
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Hobbing gear teeth on a 15-inch bronze gear blank |
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Gears are machined on special equipment designed to cut an exact number of teeth on a machined gear blank of specific diameter. The teeth are cut as the gear blank rotates using special cutters called hobs. We use class A and AA hobs, which produce gears with very accurate tooth form and high dimensional tolerances.
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The MI-1000 mount features a 20-inch diameter, 640 tooth, bronze worm gear with stainless steel worm. The worm rotates in sealed class-7 ball bearings. A 12-inch diameter, black anodized, slip clutch supports the large worm gear.
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20-inch bronze worm gear with stainless steel worm
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