The tooling is very clean, but its not a tight fit and the threads of the insert just fill with plastic
Response from Virtjoule | March 13, 2020
If you're getting that much plastic, it's likely you need to drill or design the hole to be deeper and or wider. The only time I've seen that much plastic come back up between the bit and the insert is if it's hitting the bottom and melted plastic has to go somewhere. So make sure the hole is deep enough and wide enough.