Converting 2D Drawings and STEP into RTV Mold Geometry

If you are converting files into a custom RTV mold, a STEP file is a shape. It is not a pattern and it is not a resin production mother until someone decides parting, jacket / mother-mold support-shell offset, dump shrink, and what the 2D drawing still owns. Photos, sketch, or CAD. Free DFM. CAD revision about USD 50 when we still have to remodel. After CAD lock we typically 3D-print a pattern, often flip a temporary silicone tool, cast a resin production mother, then pour batch RTV. The mother is not the pattern.

Buyers send a STEP and a PDF that disagree, or a STEP with no PDF, or a 2D from 2011 and a "similar" model from a reseller. Shops then pour a cavity of the wrong authority. This is the intake order that turns mixed files into mold-ready geometry. It is not a click-path through a named CAM package, and it is not an LSR steel cavity file. Prototype usually 3-7 business days after CAD lock. Production MOQ 20 pieces per design. Bao'an since 2018. HTV/HCR compression mold tooling stays on RUUIPON. On this site the path is photos, sketch, or CAD, then a 3D-printed pattern, often a temporary silicone flip, a resin production mother, then batch RTV. The mother is not the pattern. Free DFM. HTV/HCR compression mold tooling is also quoted on RUUIPON.

Decide which file is the contract

Before you "clean up CAD," write the winner:

• 2D PDF/DWG owns: tolerances, hardness of the cavity, flash at the split, finish, notes, revision, ISO 3302-1 class if the article is rubber, inspection.
• STEP (or native) owns: faces, fillets that actually exist, positions, the 3D that will be offset for skin and split.
• If they disagree: stop. A 2D that says R2 and a STEP that is sharp is two parts. So is a STEP in mm and a 2D in inches with a converted-looking 25.4 error.

No STEP: the 2D is a remodeling job, not a conversion. Budget it. A pretty scan of a competitor tray is not a STEP. No 2D: the STEP has no class, no flash, no Shore. You can split a model. You cannot honestly pour a production mold. Native CAD plus STEP plus 2D is the adult package. STEP-only is a prototype conversation.

Common mix-up: offset the STEP 2% and split it

Shops that "just offset the STEP 2% and split it" on a platinum glove with a metal core will misplace the nest. Platinum RTV is about 0.1-0.3% after full cure; the dump's shrink is what you compensate. Metal cores stay at 1:1. Conversion includes not doing a uniform LSR scale. We will not quote a uniform 2% offset on a platinum mother.

ISO 3302-1 is a drawing class on the 2D, not a modeled second surface, and not another word for precision. If your email still says "master, box, keys, jacket" as the conversion deliverable, you are listing shop furniture. Name which body is the pattern, which body is the resin production mother, and which offset is the support shell.

What mold-ready means on the mother

The product model becomes a pourable chain only after these edits exist as explicit features or as a derived body, not as tribal memory:

1. Watertight, single body (or a defined multi-body: dump + core). Open surfaces and naked edges are a failed knit.
2. Cores at 1:1, dump as a separate body. Hollows are not one lump.
3. Pull direction as a named axis.
4. Parting surfaces that actually shut, including steps for a hidden split.
5. Draft on long walls so the dump and the skin release (about 1-3 degrees on walls that must still read).
6. Dump shrink on the pattern / mother only, from a named factor pending coupon. Never scale the 2D notes. Never paste LSR 2-3%.
7. Cores, plugs, loose pieces as separate bodies with extraction paths.
8. Pour and last-fill vents reserved - show faces marked untouchable.
9. Texture and logo as real depth or as a keep-out + plaque call, not a bitmap wrap.
10. Skin OD / jacket offset if a jacket / mother-mold support shell is planned. A product STEP is not a mother until you offset for skin thickness or accept brush variation.
11. Fillets the pattern can print or the mother can take, matching the 2D's radius notes.

If steps 4-7 are "we'll do it in CAM," you do not have mold-ready geometry. You have a product CAD in a CAM folder. Catalog copy that says CAD, then resin, then RTV - skipping the flip - treats the first hard copy as the production mother. We will not quote that shortened sentence. CNC of a pattern, or a named pour-on-print, stays valid DFM when we write it down.

2D drawings that still have to carry data STEP cannot

Importing a PDF into the model does not transfer: ISO 3302-1 M-class; measurement wait; flash remnant by zone; cavity Shore and platinum vs tin; dump compound and food-contact path (21 CFR 177.2600 and/or LFGB sections 30/31); which dimensions are critical; who archives the living mother; revision history. Those stay on the 2D and on the RFQ. Model nominal (plus dump shrink). Inspect to the 2D.

A 2D from a metal designer will often show ISO 2768, knife corners, and no draft. Translating that sheet into an RTV mold is redesign, not conversion.

Geometry that is usually not mold-ready even when the STEP is clean

• Zero-thickness sheets and surface leftovers
• Micro-faces from bad imports
• Logos as decals
• Threads copied from a bolt into a dump
• Internal voids with no core exit
• Assembly STEP of 40 components when you needed one pocket
• Fillets that are G0-sharp at the end of a blend
• A mirror body that is not actually symmetric, used as "2 cavities"

Typical shop values

Reference values only. Confirm material-specific limits against the supplier’s technical data and agree project acceptance criteria before production.

Worked example: 12-cavity bear, 2D vs STEP fight

A 12-cavity 18 mm bear, 4.0 g target, about 2,000 dumps a month. PDF said R1 at the chin; STEP was sharp. We stopped. After freeze: watertight derived body, open-back, jacket offset for a 10A-20A skin (mix 1:1, vacuum degas), dump shrink only, no LSR percent. Then pattern, often a flip, resin production mother, batch RTV. Recast priced. Living-mother custody named. A parallel steel cavity conversion is a different RFQ.

Stay on this page / skip this page

Stay when you have mixed 2D / STEP files and need mold-ready geometry before anyone prints a pattern.

Skip if you actually need LSR/HCR steel cavity geometry - shrink scale and gate faces belong on a parts pack (an HTV product or mold RFQ here, or ask us if you need a high-volume LSR cold-runner tool for the carton; RUUIPON if you are buying the compression tool). Skip if a physical sample is the authority - that is a copy path, not a STEP conversion. A one-off artisan tray from a sample can skip STEP.

We will not cut or print while the PDF and STEP disagree. We will not skip the jacket offset on a 10A-20A wet dump. We will not treat STEP-only as a production freeze. We will not convert this file into an LSR steel cavity "so we can scale later" while you still need a pour cavity.

Related: custom RTV molds, DFM checklist, RFQ seven details, contact.

What to send

Patch when: one open surface, a missing fillet that the 2D already shows, a tiny gap from export. Remodel when: the 2D is the only authority, the STEP is a scan, hollows have no separate bodies, or the "conversion" needs new draft/parting that would trash every face.

Send the package and the dump compound to [email protected] or contact. We will mark which body is the pattern, which is the resin production mother, and which factor is pending coupon.

FAQ

Is exporting AP214 the conversion? No. Conversion is derived bodies you can approve as a STEP before print or pour: pattern, cores at 1:1, support-shell offset, dump shrink tagged as pending coupon.

Can you offset everything 2% and split it? We will not quote that on a platinum mother. Platinum is about 0.1-0.3% after full cure. Cores stay 1:1.

What if I only have a 2D? That is a remodel, not a conversion. Free DFM. CAD revision about USD 50 when the scope is a simple 3D lock. Sculpture reconstruction is a separate quote.

Does mold-ready mean I bought the RTV tray? No. Mold-ready means the file can enter the pattern / flip / mother / batch path. Prototype usually 3-7 business days after CAD lock. MOQ 20 after approval.

Can the same STEP become an LSR steel cavity later? Not as a drop-in. Two shrink policies, two tools. Do not send the mold-tool RFQ as an HTV product RFQ here, or ask us for a high-volume LSR tool if you still need the compression tool on RUUIPON.