Tool Steel EN31 Deep Hardened Ultra Precision 1-2-3 Blocks (23 Holes) (2 Pairs (4 Pc))

* EN31 grade of steel has a better proportion of carbon and chromium than mild steel and has a higher distortion control when hardened. Mild steel unlike EN31 can only be case hardened. Even the quenching happens in hot water in case of mild steel which is much cheaper than quenching the EN31 t in petroleum base oil for a much better hardening result for a longer life .The chemical composition of EN31 makes it double the cost of the Mild steel. * The drilling of 23 holes and tapping of the 5 drills (inclusive in count of 23) has been done on a computer control VMC machine with much better quality control and accuracy. Deep Hardened , Matched Pair, Precision Ground , Even Chamferring on all 6 sides. These matched pair can be bolted through any plain hole to the tapped hole to use as a Steps blocks, feelers, Jigs, Angle plate, orientation and setting up tool.

• Made of Quality Alloy Tool Steel Grade EN31 instead of Mild Steel. Read material characteristics of EN31 & its advantages over Mild Steel in description below.
• Size of the block is 1" x 2" x 3". Total 23 Through Holes being done in 1 operation (5 tapped drills 3/8" x 16 TPI & 18 plain drills) .Drilling & Tapping done on computer controlled Vertical milling center to avoid sloppiness & misalignment.
• The squareness and parallelism is controlled well within 2-3 microns.
• Deep Hardened , Matched Pair, Precision Ground , Even Chamferring on all 6 sides.
• These matched pair can be bolted through any plain hole to the tapped hole to use as a Steps blocks, feelers, Jigs, Angle plate, orientation and setting up tool.