This standard specifies the form and size of the spindle end and tool taper shank with a 3:20 taper connection. This standard applies to coordinate boring machines with a 3:20 conical connection at the end of the spindle.
JB/T 3753-1999 history
2014JB/T 2254.3-2014 Jig boring machines.Part 3: Dimension of main shaft end of 3:20 taper hole
1999JB/T 3753-1999 Jib boring machine Dimensions of main shaft end for 3:20 taper hole
JB/T 3753-1999 Jib boring machine Dimensions of main shaft end for 3:20 taper hole was changed to JB/T 2254.3-2014 Jig boring machines.Part 3: Dimension of main shaft end of 3:20 taper hole.