Peeling produce one piece at a time is tedious, and this build attacks it from a different angle: an experimental machine that strips skin from potatoes, fruit and a tomato using high-pressure steam and rapid depressurization, reviving the industrial flash steam peeling concept documented in a 1945 patent.
The construction is heavy-duty. The boiler is thick-walled stainless steel pipe stamped 'T40S-JP304/304L' with heavy end plates; the upper specimen chamber is stainless pipe and plate, TIG welded. Circular end caps were waterjet cut from plate stock, and flanges were cut with the 5-axis Pivot+ head. A custom three-arm brass and steel spider fixture was machined on a CNC mill and a manual lathe. The front hatch pairs a heavy stainless faceplate and aluminum ring with red silicone O-rings and a thick round glass viewport, sealed by gaskets hand-punched from high-temperature red silicone sheet.
The numbers are serious. Pressures run 10 to 20 times beyond a kitchen pressure cooker, the boiler is built to take roughly 10,000 pounds of force, and a 2 kW, 240 V immersion heater makes the steam. An air-operated piston valve vents the chamber from 150 psi to zero, a mechanical safety valve opens above 200 psi, and the boiler valve is worked remotely through an air cylinder linkage, which I think is a smart call.
One standout is how a design flaw was handled. Rigid tie rods were a problem because heating makes the stainless cylinder expand axially more than the rods. The answer was stacks of four Belleville conical spring washers beneath each tie-rod nut, tightened with a digital torque wrench to partially compress the springs. High-strength threaded rods hold the assembly in compression, and welding distortion was corrected with a boring head on a vertical milling machine.
On results, skin came off potatoes, apples and a tomato. One open question: whether the perforated brass muffler on the rapid-exhaust angle valve atop the chamber might be restricting the discharge and the peeling effect. That seems worth testing.
Project by Stuff Made Here. Watch it on their YouTube channel: