How to seat a motor shaft B taper connector correctly?

In summary, when assembling a tool using a B taper system, first apply a quick impulse by hand and check for slippage. If there is none, then start drilling. For larger drill bits, press the tool holder gently against the part or table before starting the drill.
  • #1
TL;DR Summary
How's actually to correctly seat most commonly B taper connector
Being so noob in taper connection, asking:
How do we correctly seat a motor shaft connector of B taper system, most commonly B12, B16, B18, into its chuck mate in such that if there's no bolt fastening axially in center it's still quite viable and reliable ?

it's just a press by a muscled hand, put weigh on top of connector after insertion, hit it gently or etc ?
Thanks much in advance
Last edited:
Engineering news on
  • #2
What's your application?

For applications that use axial compression, such as for drilling machines or lathes, the initial axial force for assembly is not too important as the more you press the tool against the part, the more torque you are able to naturally transmit. With those machines, I simply apply a quick impulse by hand:

and then I check whether I can turn the tool holder by hand or not, if I can't, then it's usually enough to start drilling without any slippages (if you can turn with your hand, then don't release the tool holder as it's going to fall out, just remove it and give it another impulse).

Also, when using larger drill bits (>12mm), with the machine off, I press the tool holder against the drilling table, jig or part, or the drilling tool itself against a high density rubber or wood block (also with the machine off), to give an extra compression just to be sure before I start drilling. Now with the machine on, I also bring the tool against the part very gently in the beginning to watch for any slippage and eccentricity, before putting more force or activating the automatic feed. This is done only for the first hole and every time the tool holder is replaced.

Example of using a tapping force (this is a bit painful, obviously it can only be used when there's no drill bit pre-assembled. Some operators use a wood stick or wood block instead of tapping with their own hand, and I used to operate much larger machinery so I didn't use this technique at all, but it covers your question as you mentioned it):

  • Informative
Likes abdulbadii

Suggested for: How to seat a motor shaft B taper connector correctly?