Modern Machine Shop

JAN 2017

Modern Machine Shop is focused on all aspects of metalworking technology - Providing the new product technologies; process solutions; supplier listings; business management; networking; and event information that companies need to be competitive.

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Page 66 of 148

64 MMS January 2017 QUALITY GAGING TIPS Columnist contact (the one pointing down). But suppose the operator turns the gage sideways (because that's what operators like to do). Now the weight of the gage is no longer suppor ted by the reference contact. The centralizer spring must not only support the weight of the gage head, but in cen- tralizer fashion, must basically pull the gaging head up against gravity into the center of the bore. For some gages, especially those set up for larger diameters, this can amount to a lot of weight and require some pretty hefty gaging force. The bad news/good news here is that while gage s get he avie r with incre ased bore size, chordal error gets smaller with increased bore size. So there is some balance. However, in the case of smaller bores—especially those smaller tha n a couple of inche s—bad c e ntraliz ation caused by improper gaging pressure can be a serious enemy to precision. Clearly, looseness and improper pressure are both enemies any championship-seeking team can do without. When troubleshooting a gage that isn't coming up with the right measurement, check that all the screws, nuts, bolts and connections are socked up tight. Post tight to base and square Back screws tight (indicator square to base) All screws on fine adjustment mechanism tight (fine adjustment screw locked) Arm locked to post Contact point light Platen secure

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