Modelled threads can cause issues in 3D Printed parts as they have to be 3D modelled slightly differently to if you plan on machining a part.
For MJF we would not recommend modelling threads under M8 as they can be a little rough and not achieve full strength. If you need direct threads below this size model the tap hole at bottom limit with a lead in chamfer and use a text call out (not a thread call out) to specify the thread making as a post process. Alternatively using threaded inserts is a great way to achieve full strength, especially for threads that are expected to be used multiple times.
Here are three modelled examples: The Bad, the Ugly and the Good.
One the surface all look like working threads, however there are underlying issues that will spoil your print.
The BAD - Non-modelled Threads
This is not a fully modelled thread but a call out that will not print. Change your CAD setting to fully model the thread. For example in Fusion 360, tick the indicated box.
The UGLY - Incorrect chamfer
This is a common one that we have seen many times and normally catch before print.
The thread is fully modelled, so that is good. However, the lead in chamfer has been placed prior to adding the thread so if you look carefully the thread is unusable as it does not scroll out through the chamfer.
The GOOD: - Good to go!
The chamfer has been effectively cut into the thread so it is a fully modelled and working thread.
A simple tip: to achieve this in Fusion 360 apply the chamfer, to the hole top edge, then the thread to the body of the hole (ticking the modelled box). Once the thread is formed drag the thread on the timeline back to before the chamfer.
For more tips please return to our MJF Knowledge Page here.
If you already have your models in order and would like an Incremental-AM quick non-binding quote please go to our quotation page.