Furnace V1 Waste-Oil Foundry Plans (Rev B)

No. Furnace V1 is a Rev B design package, not yet field-built. It was designed, calculated and drawn, then checked by two automated (AI-run) design reviews, one on the numbers and one on the drawings and guide (57 findings). Every ERROR-level finding was fixed on paper, and the fix register still lists 9 open risks that only a real build can close (see below). The first real build is next. Founder buyers get Rev C, which will include what that build teaches, free.

Only if you want a detailed, documented starting point and are comfortable building from an unproven design. Founder pricing (code FOUNDER25: 25% off Plans or Pro, first 25 orders) reflects the risk. If it is not what you expected, you get your money back within 14 days, no questions.

Nothing has been melted in it yet. It is designed for a 5 kg aluminium charge of recovered metal (about 6–6.5 kg of dry, crushed cans for a 5 kg ingot, added in small batches) or a 7 kg brass/bronze charge. Brass is marginal per the calcs: it needs high fire (38 kW) and good tuning, the lining and lid anchors run with no temperature margin, and lifting needs two people. Start with small charges. Cast iron and steel are out of scope.

The fix register lists 9: (1) a cad-cell flame sensor may read glowing refractory as flame and block hot restarts; (2) the cold-oil gravity feed has a thin pressure margin and must pass a flow test; (3) at brass duty the wall backup and lid anchors have no temperature margin; (4) the hand-built tongs and shank are rated only by a 25 kg proof test; (5) lid-lift clearances are checked on paper only; (6) the purchased castable's datasheet rating and dry-out schedule weren't verified and govern; (7) each aluminium charge addition needs a full shutdown and restart; (8) scavenged compressor/blower must pass measured tests, and all prices are unverified estimates; (9) stick-welding the thin 1.2–1.5 mm sheet is marginal, so practise on scrap or braze.

Model estimates: aluminium 5 kg about 62–96 minutes from cold and 20–34 minutes hot; brass 7 kg about 88 minutes from cold and about 30 minutes hot, both on high fire. These are first-order calculations (about ±30 %), not measurements.

The 72-line parts list estimates about $1,299 using salvage/scrap where sensible ($1,053 build + about $246 of PPE) or about $2,109 buying everything new. The scrap route still includes purchased parts: dense and insulating castable, ceramic blanket, an air compressor with receiver, the burner primary control, interlock switches and solenoid valve (controls alone about $170 scrap / $337 new), the crucible and PPE. Prices are estimates and were not quoted; the Pro spreadsheet lets you enter your local prices.

Comfortable cutting and welding mild steel, basic plumbing (oil and air fittings), basic 120 V wiring for the shutdown controls, mixing and casting refractory, and safe molten-metal practice. A purchased air compressor with a rated receiver (≥ 1 SCFM at 40 psi) is needed. If any of that is new to you, get an experienced person involved.

Filtered used engine oil from a known, traceable source (not "free oil" of unknown origin; the guide says to reject any oil you can't vouch for), atomized by a Babington burner. The guide covers oil quality, filtering, temperature limits and why contaminated oil is rejected. Burning used oil is regulated or banned in some places, so check your local rules first.

No furnace that burns oil and holds molten metal is "safe". The design includes a fuel-shutdown chain (air- and flame-proving interlocks, quick-close valve, lockout, no automatic relight), a spill pan, a dry-out schedule and a full safety section. It is not certified and not professional engineering advice, and you build and use it at your own risk. Outdoors only. Read the Safety Disclaimer before buying.

Pro adds the 18 DXF CAD files (cover/index + 17 drawings) and the parts spreadsheet (.xlsx/.csv). Take Pro if you use CAD, have parts cut by a shop, or want to price the build.

PDF (18 A3 sheets: cover/index + 17 drawings, plus the guide; prints fine at A3 or tabloid, readable on screen). Pro: DXF R2010 in mm, XLSX, CSV.

Millimetres, with inch equivalents for the main dimensions.

Yes. Castings and items you make with a furnace built from these plans are yours to sell. What you can't do is resell or share the plans or files, or sell furnaces built from them as a product without a commercial license.

No. The license is for one buyer. Your friend can buy their own copy, or get the free sample first.

The cover, the full contents, one complete drawing sheet (WOF-D01 general arrangement), a parts-list excerpt and the pre-run safety checklist.

14 days, no questions: email or reply to your receipt. Founder buyers can also get a refund if Rev C isn't out within 12 months.

After the first real build and commissioning. There's no fixed date, and progress will be posted in public.

Our merchant of record (Gumroad) processes payment, adds and remits sales tax/VAT where required, and delivers the files instantly by download link and email.

Please email support@scrapbuilt.com. Confirmed errors are fixed in free Rev B errata for every buyer.