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, Open-Center, Directional Control Valve, with spring return-to-center.

• At center, the P (Pump) port connects to both the A & B (Work) ports.
• 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 paint for the parts. It ruins the clearances and the parts don't slide easily. If you need different colors, print in WHITE, then use colored sharpies to color-in the ways.

Open Center Directional Spool Valve Model Rev 1.0
Disclaimer: I am a novice CAD designer using Blender.

Monoprice

Maker Select Plus

Yes

Yes

.15

20%

This is the second valve cutaway I designed.
I looked at 2-D images online, and created a rudimentary 3D valve.

Disclaimer: I am a Technical Trainer, not a CAD designer.