No assembly needed, and no worries about the tooth breaking easily. The tooth is printed together with the skull—yes, we are going to print the life-size skull with the tooth already in place!  Now supports A1 (one of the school teachers printed at home with A1), P1, and X1. And thanks for the feedbacks from @user_3226652973, I enhanced the print profile for A1 users.

Long story short—after visiting NHM, my son couldn’t stop asking for a life-size saber-toothed cat skull. So, I downloaded the 3D model, made necessary fixes, and printed it. Just like that, he became the superstar of his group again. Later, his teacher, eager to learn how I managed it, told me their school had tried multiple times to print the skull but failed due to the challenges of the long teeth.

I hope my share makes it easier for others—especially teachers—to successfully print the skull and share it with kids in the classroom. There is no assembly needed and also the tooth stays strong, because they are printed with the top skull.

If you are also interested in Mountain Lion (Cougar, Puma Concolor) Skull, you can find it here.

Important Preparation Tips Before Printing:
 

• It is big, really big, life-size big.
• It will take approximately 1 and half days to complete and will use about ¾ of a new filament roll.
• It is highly recommended to recalibrate your 3D printer before starting to ensure the best print quality.
• If you’re printing with PLA, I recommend keeping some UV-curing glue (like the J-B Weld UV adhesive) handy. In case a student accidentally breaks the model, this glue can easily fix it. That said, I’ve handed out about 10 prints, and so far none have broken!
• This model is too large for the A1 Mini.

If you are not going to play with the print profile settings, you can safely ignore instructions below. 

Otherwise, several things need to double check:
First, make sure you are using 0.16mm High Quality or 0.12mm High Quality process. Do not use fine, standard, draft or optimal process.
Then, very important for A1 users, go to Pinter Settings → Extruder → Z hop when retract, make sure the distance is 0.6mm (The default value is 0.4mm for a 0.4mm nozzle. We need to set it between 0.5mm to 1mm, 0.6mm is a good start). Otherwise, the nozzle will hit the tree support soon or later somehow. 

At last, go to Process → Support → Initial layer expansion, make sure it is at least 10mm (The default value is 2mm). This will create a massive combined brim for the tree support. 

Assembly & Installation

To fit the mandibular junction (jaw connection) to the skull, slowly heat the joint using a heat gun until it softens slightly for adjustment. However, note that there is no any way for the top skull to hold the jaw in place by itself, just use your hand as shown in the picture.

Credit:

The iconic skull of the Ice Age apex predator, Smilodon fatalis, was digitized from a cast specimen at the Natural History Museum of Los Angeles County. The original 3D model, “Sabertoothed Cat (Smilodon fatalis)” (https://skfb.ly/66JHn) by Idaho Virtualization Laboratory, is licensed under Creative Commons Attribution-ShareAlike.