What size needle for 3D puff

I haven't heard of clients changing needles, ever. just the digitizing densities and method needs to change, not anything you do on the machine.

1) Are you sewing hats or flats?

2) Foam comes in various thicknesses and durometer values as well as how many layers are you going to sew through?

3) You might have to adjust the tension tighter depending upon the item being sewn and thickness of the foam.

My experience comes from mostly hats and some knit style flats. For hats I use the gros beckert gebedur titanium rg point in 80/12. If the foam is not cutting well I use the gros beckert standard 85/13 since they don't make the gebedur in that size. With the flats I use the 80/12 as above. Both needles are sharp point which cut through the foam and I've found that the gros beckert brand seems to do a better job making the cleanup much faster.

I mostly use 2,3, and 4mm foam from various sources sometime stacking them depending upon the application. What I have found is that soft foam (low durometer) doesn't cut well and stiff foam (high durometer) cuts like butter if made correctly. Craft foam is usually soft an doesn't cut well. I've also noticed that the 85/13 will cut through multiple layers better if stacking for a more pronounced effect. I never do multiple stacking of foam on flats so I can't speak to that.

In my previous business I had to re-adjust the timing of the walking feet on a JUKI 441 to sew through 1.25" inches of leather stacked in 8 layers. The feet on the machine were custom made and the tension on the top had to double to bring the lock at least though the 3rd layer. Embroidering foam has the same principle. I want the lock to be higher up in the foam so bird nesting doesn't occur so I raise the upper tension and sometimes adjust the take up spring tighter to account for the different thickness.