Central Pneumatic (HF) brand tank drain valve knob

thingiverse

This is a replacement for the garbage, thin plastic piece that came on a Central Pneumatic air compressor. The original broke during unpackaging. This piece can be used stand-alone or, as I'm doing, a sacrificial arm can be added to allow the valve to be opened from the side of the tank without the need to reach underneath. The length and strength of the sacrificial arm would be up to the particular model of compressor you have. I call it a sacrificial arm because I have made this piece solid for strength. If the arm gets hit by a foot or something else and breaks (due to the leverage it would have), I want it to break somewhere away from this piece which is bolted to the brass valve on the tank. This piece was printed with PETG, a Prusa MK3S+, 4 shells (top, sides, bottom), first layer 0.15mm, other layers 0.1mm and 100% infill (rectilinear). I wanted to be able to mate a sacrificial arm to the flange with four M4 bolts and not crush the flange when tightening. The holes in the flange are for M4 bolts, and the back side holes are for M4 Nyloc nuts. You will need to use an M4 bolt to seat the nuts in the flange as the holes are very precise. The center hole is for an M3 bolt (12mm long). I used a longer one with my design for added strength at the attachment. I saved it in .scad and .step files to increase the ability to modify it to your compressor drain valve. Update: Just realized I haven't uploaded the FreeCAD files for those that use FreeCAD. I have now. I'm really too new at printing to recommend a filament brand, but of all the brands I've used (wasted?) making mistakes, SUNLU (not my link) has by far been the least stringy and least expensive, although I have had some breaks in the extruder at the gears with it when using retraction and high speed. Also when using the new "lightening" infill with retraction of any length or speed.