对点器对点器是在待钻目标点上放置一个有一定厚度的圆环,环的外围有固定手柄用来固定此仪器在目标工作点上,环内径可随钻头的大小改变.Pointaretobedrilledonthetargetpointisplacedaringofacertainthickness,theexternalringhasafixedhandleforfixingtheinstrumentatthetargetoperatingpoint,aninnerdiameteroftheringmayvarydependingonthesizeofthebitchanges.在电钻工作时把圆环对准工作点,通过固定手柄固定圆环,这样电钻在工作时再不会滑离目标点了.Whenworkingintheoperatingpointofthedrillisalignedtothering,theringisfixedbyfixingthehandle,sothedrillatworkandthennotslipawayfromthetargetpoint