Precise Retention Knobs Style 1, BT-40 & BT-50

• BT-40 Heat treated alloy steel.
• BT-50 SNCM-21 alloy steel hardened to HRC 52-56
• All dimensions are in accordance to MAS specifications for BT holders.
• BT-40 thread is M16 X 2.0.
• BT-50 thread is M24 X 3.0

Item No. 3900-5392 3900-5393 3900-5503 3900-5504 Thru Coolant Yes Yes N/A N/A Angle A 45 60 45 60 Knob Dia. D1 0.591″/15mm 0.591″/15mm 0.591″/15mm 0.591″/15mm Neck Dia. D2 0.394″/10mm 0.394″/10mm 0.394″/10mm 0.394″/10mm Hole Dia. D3 0.150″/3.8mm 0.150″/3.8mm N/A N/A Pilot Dia. D4 0.669″/17mm 0.669″/17mm 0.669″/17mm 0.669″/17mm Diameter D 0.906″/23mm 0.906″/23mm 0.906″/23mm 0.906″/23mm OAL L 2.374″/60.3mm 2.374″/60.3mm 2.374″/60.3mm 2.374″/60.3mm Shoulder L1 1.102″/28mm 1.102″/28mm 1.102″/28mm 1.102″/28mm Shoulder L2 2.421″/61.5mm 2.421″/61.5mm 2.421″/61.5mm 2.421″/61.5mm Item No. 3900-5397 3900-5508 Thru Coolant Yes N/A Angle A 45 45 Knob Dia. D1 0.906″/23mm 0.906″/23mm Neck Dia. D2 0.669″/17mm 0.669″/17mm Hole Dia. D3 0.268″/6.8mm 0.268″/6.8mm Pilot Dia. D4 0.984″/25mm 0.984″/25mm Diameter D 1.496″/38mm 1.496″/38mm OAL L 3.346″/85mm 3.346″/85mm Shoulder L1 1.378″/35mm 1.378″/35mm Shoulder L2 3.937″/100mm 3.937″/100mm