This is a replacement fan for the Ryobi P2108 18V leaf blower. They have changed the design in the newer model (P2180) to make removal easier, but in this original version you have to cut the fan blade to remove the original nut housing if you want to re-use it.
There are 4 files attached:
1 - Blower fan using the original nut
2 - Blower fan using M5 nuts (in case you can't get the original out)
3 - Blower fan using the original nut with an additional outer support ring (for PLA prints)
4 - Blower fan using M5 nuts with an additional outer support ring (for PLA prints)
I included several photos, including a photo of the original nut. If you have this part, you should be able to glue it into the appropriate fan model using epoxy (recommended over super glue.) I also included a photo of the original shattered fan blade -- it breaks very easily if something gets into the shroud -- showing the original nut in the original fan body.
The first picture is of the original-nut part, with a full conical end. The second picture shows the M5 nut version in which the conical end is truncated to allow for an additional nut to fit on the end of the drive shaft.
The M5 nut versions are less than ideal since the metal-to-metal contact surface is significantly smaller than with the original nut (~4mm versus the original ~28mm.) The M5 nut definitely works, but I cannot attest to the longevity of this as a permanent solution. You may be better suited getting a 15mm M5 female-female Coupling Nut and grinding the edges to match the original shape (for example: https://www.mcmaster.com/93355a320).
Make sure you don't lose the inner bushing that sits between the fan and the motor body. Without the bushing, the fan will spin itself onto the shaft too tightly and will cause the motor to bind.
Any ABS, Nylon, PLA (with outer ring)
You may want to use supports for the inner hole since it has a step at 29mm, but NO SUPPORTS are required for the fan blades.
If using the original nut, use epoxy if possible. I cannot attest to whether or not SuperGlue will be sufficient at the required RPMs.
Best if printed in ABS or Nylon, but PLA seems to work when printed with the outer ring to provide additional blade support. This reduces airflow a bit, but provides significant structural additional integrity with PLA. Try the no-ring version in PLA at your own risk (but please be sure the protective cover is on before you spin it up.)