BELLMOUTH MACHINE OUTLET TO FIT 100MM (4") PVC

This is one of a series of dust collection ports and fittings  that can be found at this link:
DUST COLLECTION FITTINGS.

This bellmouth outlet is designed to be fitted into a 3mm material thickness and matches a 100mm (4") PVC fitting.
 

The standard machine fittings are sold as 4inch but rarely measure more than about 3.5 clear, so upgrading to a true 4" outlet makes a significant difference to air flow - the difference with the bellmouth is spectacular.

The comparison photos show the old and new outlets and the dust collected over one week of work in both cases.   The Bellmouth opening never has more than shown in the picture, the standard opening just fills up until  it sort of forms a natural funnel.

I have one of these fitted to my table saw, band saw and router table.

Print the bellmouth as shown in PLA,  with the small side down - no supports are necessary.   Holes are 3.3mm and run a tap through the part to suit M4 screws.