It's cheaper for me to buy than scratchbuild... I live in a rather remote area with no access to materials, machines, custom cnc, ect. Everything would have to be mail order. I do enough fixing, head scratching, macguyvering on farm machinery nearly everyday that I prefer my hobby to be a ready made assembly that I can sit down and enjoy at the flip of a switch.
Per my JD850, it's 1.4m from pivot point to tip of bucket at its furtherest reach. Weighs about 39kg (86lbs). Hydraulic pressure set to 25bar with 20mm diameter cylinders.
The valves you show in the above photo are made by Leimbach for wedico, the same hydraulic system as my smaller Stahl constr equip.
http://www.leimbach-modellbau.de/start.html
What you have there now for valves is humungous, way more flow than what you need. It'll probably take 1/4 scale servos to operate them, the type of servos used in sail boats.
Anyways, on my way out the door right now, going on a short holiday for a week. Talk more later.