Cold Extrusion Domestic Squeezer: Slimak, Stainless Steel, Turner Tips, 250mm Length, 16-18mm Bolt

Question 1

What is the “ślimak” in a domestic oil squeezer?

Answer

It’s the helical screw that feeds and compresses seeds in the press barrel. In this thread, the ślimak was planned at ~30 mm diameter with a 16–18 mm core, sized to a ~30 mm inner pipe. It must fit closely to build pressure while allowing rotation under load. [Elektroda, Zenon407, post #16896095]

Question 2

What dimensions did DIY builders here target?

Answer

The builder targeted 250 mm overall length, 16–18 mm bolt (core) diameter, and ~30 mm screw outer diameter to match a 30 mm inner pipe. He proposed ~29.6–29.7 mm for a sliding fit inside a 30 mm ID stainless tube. [Elektroda, Zenon407, post #16896095]

Question 3

Can I use a standard welded stainless tube for the barrel?

Answer

Avoid it. A welded tube’s internal seam interferes with the screw and can cause binding or wear. Thin walls also limit threading options for end caps or nozzles. Use seamless or bore a solid tube for a smooth internal surface. [Elektroda, jalop, post #16896626]

Question 4

Which stainless steel grade was actually sourced?

Answer

The OP found high‑alloy chromium‑nickel steel 1.4307 (AISI 304L equivalent) as a 35 mm diameter, 260 mm long roller, weighing almost 2 kg. This provided adequate stock for machining the screw and shaft. [Elektroda, Zenon407, post #16898541]

Question 5

How hard is it to machine a stainless screw at home?

Answer

A turner noted it’s not conceptually hard but very time‑consuming due to many passes. Stainless work‑hardens and “rolls very badly,” demanding sharp tooling and controlled feeds. Budget time or hire a machinist experienced with austenitic grades. [Elektroda, jalop, post #16896626]

Question 6

What should I budget for a custom stainless screw (ślimak)?

Answer

Expect about PLN 200 as a minimum quote for material and machining. That figure reflected the turner’s baseline for this geometry and stainless complexity in the thread discussion. [Elektroda, jalop, post #16896626]

Question 7

Why did quotes vary from PLN 200 to PLN 250?

Answer

One turner priced the job at a minimum ≈PLN 200, while later stating he’d charge ≈PLN 250. Variations reflect time, tool wear, and stainless machinability. "I would take about PLN 250 for it." [Elektroda, jalop, post #17242703]

Question 8

Is threading a thin‑walled barrel a good idea?

Answer

No. The turner advised that with thin walls, threading is not an option, especially in seamed stainless tubing. Consider thicker seamless stock or external couplings to avoid stripping or distortion at pressure. [Elektroda, jalop, post #16896626]

Question 9

Is this truly cold pressing?

Answer

Participants clarified the setup behaves as hot pressing. Frictional heating in a compact screw/barrel raises temperature during operation. “It’s not cold, it’s hot.” Label your oil accordingly. [Elektroda, ^ToM^, post #16898354]

Question 10

Can I repurpose a meat grinder screw for oilseeds?

Answer

Yes, it was suggested to try a manual meat grinder screw. It may lack corrosion resistance if not stainless, and geometry may differ from dedicated oil presses. Fit and temperature performance will vary by model. [Elektroda, jalop, post #16897026]

Question 11

Any sources for ready‑made screws or presses?

Answer

Suggestions included searching for a “wolf shaft” and brands like Spomasz, plus vintage fruit press components with conical screws. Availability and sizes vary, so confirm dimensions before purchase. [Elektroda, jalop, post #16896626]

Question 12

What failure edge cases should I watch for?

Answer

A welded pipe’s internal seam can catch the screw, causing jamming or accelerated wear. Thin‑wall threads can strip under load. Choose seamless or bored stock and design joints that don’t rely on weak internal threads. [Elektroda, jalop, post #16896626]

Question 13

How do I machine a simple stainless screw at home?

Answer

Source solid stainless stock (e.g., 35×260 mm 1.4307) to exceed final dimensions.
Turn the core to 16–18 mm, then cut the helical flights to ~30 mm OD with multiple light passes.
Test the fit in a ~30 mm ID barrel; target ~0.3 mm clearance. “Stainless steel rolls very badly,” so use sharp tooling. [Elektroda, Zenon407, post #16898541]

Question 14

What if I must keep everything stainless?

Answer

That constraint was explicit in the thread. It rules out many repurposed carbon‑steel screws and some food‑safe plated options. Ensure all wetted parts, including screw, barrel, and tips, use stainless to avoid contamination. [Elektroda, Zenon407, post #16897091]

Question 15

Why did the OP abandon the machining route?

Answer

He concluded the turner wanted too much and gave up on the custom job. Later he noted similar parts around PLN 200 on Allegro, which undercut bespoke quotes. [Elektroda, Zenon407, post #17242697]

Question 16

Does upsizing the inlet help with rapeseed?

Answer

Yes. A very small inlet (~1.5 cm) was reported on a discarded screw press, likely meant for small oilseeds. For rapeseed throughput, the OP preferred a larger feed and tighter screw‑to‑barrel fit. [Elektroda, Tommy82, post #16898206]

Cold Extrusion Domestic Squeezer: Slimak, Stainless Steel, Turner Tips, 250mm Length, 16-18mm Bolt

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