Well, I had purchased a brush from Whipped dog some years ago. A decent quality badger that I had set an extra few mm deep at the suggestion of Larry.
I never really like the brush as it didn't really splay well at all and just felt inadequate for me. I piffed the brush to my brother who was using a POS boar that looked like it had been dragged behind a truck. He was very happy with the upgrade the different brush brought.
Fast forward a few years till the other day he tells me "the knot fell out and how do I fix this"?
Bring it over.
Looking at the inside of the existing handle it looked stepped near the bottom. The top of the hole being a full inch in diameter the bottom much smaller. Well it turns out the step was entirely epoxy. The hole being almost 7/8 deep and a full inch wide.
I ask if he's attached to the handle or not. No was the reply.
Well I had a handle left over from another venture that I had already turned and would work perfectly. I just needed to drill it a little deeper to cover where epoxy had migrated to the hair as there was a ton of it.
The new hole by the way was a 7/8 NOT 1 inch!!

He's pretty happy with the new suit for his brush. Its an exotic from Australia much like Eucalyptus that has been stabilized.