Measurement of shafts could be done for 2 reasons: • one to make sure that all the shafts either received or manufactured are similar, comparable to one another, • second, the most common, to make sure that the shaft is within manufacturing specs. While a direct reading can be done with calipers, a most precise method is by comparison. This implies the use of a comparative measurement instrument and a precise setting method and/or calibration method. Comparative measurement instruments are designed to read the delta between the part being measured against the master used to set the instrument. Therefore the precision of the reading directly depends on the setting/ calibration method and the instrument selected. The instrument will have to rest stable on the part so the technician’s impact is minimal. One of the best designs is a prism support so the gage rests self-centered on the diameter. Setting the inStrument: Various ways could be used to set the instrument: • Master part • Customized Masters • Horizontal setting bench • Assembly of gage blocks Prepare the instrument close to the final desired dimension so it doesn’t need much adjustment during the setting process. Make sure that the contact surfaces on the setting method are clean from any unwanted particles (dirt, oil...). Place the instrument onto the setting method. Zero the indicator or set it to the desired data. The setting time is about 5 to 10 minutes depending on the type of gages and their sizes. To this you have to add the necessary time to prepare the setting method. Be careful, this operation can vary from 2 minutes (Horizontal Setting Bench) to 15-20 minutes if using a gage block assembly. Note: Whichever manner is used to set it the instrument, bear in mind that to obtain the optimal results, your instrument should be set in the same position as it will be used to measure the part. In some cases, such as multi-diameter shafts, some additional kits would be needed to “duplicate” the different diameters by adjusting the height of the supports. Easy-METRIC Inc. PO Box 47710 Chicago, IL 60647 312.428.6619 Fax 312.854.2954 firstname.lastname@example.org www.easymetric.com
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