eBay
4Pcs Woodworking Square Hole Drill Bits Wood Mortising Chisel Set Mortise Chish
This Mortising Chisel is great for drilling square holes in wood with a mortising machine or a mortising attachment.
Square hole drill can not be used on an electric drill, drill square holes need to fit a square hole drill drilling (mortise and tenon machine) to use.
Mortise and tenon square hole drilled by the terrible + outer sleeve in the middle of the combination.
Reduce labor intensity of construction workers, speed up the construction speed, reduce construction costs for construction, installation, renovation, decoration industries.
Size: 1/4 inch (6.35mm), 5/16 inch (7.94mm), 3/8 inch (9.5mm), 1/2 inch (12.7mm)

Material: high-speed steel
Hardness: HRC 48-50
Color: silver
Clamping diameter: 19mm (Round) Length: 210mm

Package Contents:
4 x Drill Bit

Only the above package content, other products are not included.
Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.