Rudimentary hydraulic directional control valve example, created for Hydraulic Training as an alternative to $1100 professional cutaway valves.

This model is a 3-position, 4-way, Closed-Center, Directional Control Valve, with spring return-to-center.

• At center, the P (Pump) port is closed. A & B (Work) ports are connected together.
• Right movement connects P to the A port. B port dumps to T (Tank)
• Left movement connects P to the B port. A port dumps to (T) (Tank)

Employs two small compression springs from Harbor Freight to center the spool.
Spool printed vertically, body printed flat. Approximately 10-hour print time with Cura 3.6 at .15mm Z resolution, 40mm/sec speed.
Usually you can rotate the spool in the body to find a loose fit that slides freely.
If not, the spool may need some light sanding after printing to slide freely.
Springs are ~7.5mm ID, and should fit over the 7mm end nubs to prevent them zinging-off.

I do not recommend painting the parts. It ruins the clearances and the parts don't slide easily. If you need different colors, print with colored filament.

Rev 1.1 (Added spring retaining nubs)
Disclaimer: I am a novice CAD designer using Blender.

Monoprice

Maker Select

Yes

Yes

.15

20%

I am a training instructor, not a CAD designer.
If you design any hydraulic valves or redesign this one, please let me know.

I watched this video on YouTube, then drew the model in Blender.
https://youtu.be/QaagWlHbxr0?t=1702