Self Tapping Bolts,Self Tapping Screws For Metal,Self Drilling Metal Screws,Self Threading Bolts NINGBO YWC IMP. & EXP. CO.,LTD , https://www.nbywc-fastener.com Our workshop recently processed a batch of rubber stampers with a hole diameter of 40 to 70 mm and a hole depth of 400 to 500 mm. After machining on a lathe, the surface roughness of the aperture does not meet the requirements. Manual polishing on the lathe, first, the rotation speed can not be too high, because the length of the mold above 4/5 is suspended, and the second is the hand polishing rod for polishing, it is difficult to use the force for the hole of 400 ~ 500mm deep. . Later I