Related Products 8″ lap backing plate with one threaded adapter $140.00 excl GST Diamond lap disk 8” 360grit. PSA backing $50.00 excl GST Electroplated diamond core drill, 30mm dia. 10mm shank. $38.00 excl GST Quantity Add to cart Product added to wishlist. Add to WishlistProduct added! Browse WishlistThe product is already in the wishlist! Browse Wishlist Share Product code: 450030 Category: Core drills. Tags: core drills, Diamond drills, glass, glass work, lapidary.