---
title: "Designing Internal Channels for Smoothing | AMT PostPro"
description: "Vapor smoothing seals internal channels as well as outer surfaces. A published example, and how to design channels you can clean out and check."
canonical: https://amtechnologies.com/community/guides/internal-channels/
updated: 2026-10-06
type: guide
---
Community guide Tips & tricks / Design for vapor smoothing

# Designing internal channels for vapor smoothing

Internal channels are one of the best reasons to vapor smooth. The process seals internal surfaces as well as external ones: the SF2X page says it “also seals internal cavities”. AMT’s systems run under vacuum, which lets the vapor travel into hard-to-reach areas of the part.

- By AMT Team
- Guide
- 1 min read
- Updated Oct 2026
- Sources[1,2]

## A published example

Norden replaced a multi-component, machined assembly with a single vapor smoothed part with internal vacuum channels, according to [AMT’s Norden case study](https://amtechnologies.com/resources/case-studies/vapor-smoothing-for-production-machinery/) (Nov 2025). The case study describes the result as a sealed, uniform surface.

## Design so the channel can be cleaned first

A channel smooths well when it is clean, so design it so the loose powder can come out first:

- **Give every channel an exit.** Dead ends trap powder.
- **Avoid sharp internal corners** where powder packs in, where your design allows.
- **Plan cleaning access.** Can you blow air through it, or pass a brush or a wire?
- **Check before you load.** Shine a light through the channel, or flow air and check it comes out clear.

## Test it

Channel diameter, length and shape all play a part, and AMT does not publish a single minimum channel size for every material. The fastest answer for your design is a test part: [send it for a benchmark](https://benchmarking.amtechnologies.com/submit?utm_source=amtechnologies.com&utm_medium=community-page&utm_campaign=site-2026&utm_content=internal-channels-guide).

Forum · Over to you

What channels have you smoothed? Share the material, a rough size and how you cleaned them, or post a cut-open part in [Show your parts (opens the community forum in a new tab)](https://amtpostpro.discourse.group/c/show-your-parts).

[Answer in the forum thread (opens the community forum in a new tab)](https://amtpostpro.discourse.group/t/designing-internal-channels-for-vapor-smoothing/44)

Next step

## See the price. Run the numbers. Hold the part.

List prices are public and the cost-per-part math is yours to check, with no email needed for either. The free benchmark puts your own parts, vapor smoothed, in your hands.

1. 01 Quote

   ### Build your quote

   Pick a system and its options and get an itemized total on screen, from AMT’s published list prices.

   [Build your quote](https://amtechnologies.com/quote/)
2. 02 ROI

   ### Calculate your ROI

   Compare your cost per part with manual finishing, using your own labor rate and volumes. Every assumption is editable.

   [Calculate ROI](https://amtechnologies.com/roi/)
3. 03 Benchmark

   ### Test your parts, free

   Ship us your parts with a prepaid label. We vapor smooth them and send them back with before-and-after photos and a benchmark report.

   [Test your parts, free](https://benchmarking.amtechnologies.com/submit?utm_source=amtechnologies.com&utm_medium=community-page&utm_campaign=site-2026&utm_content=internal-channels-decision)

   No cost to evaluate · Parts returned · Typical turnaround 2–3 weeks[3]

Prices: AMT list prices, excluding tax and shipping; confirmed in your formal quote.

[Not sure which system? Help me choose](https://amtechnologies.com/configurator/)

## Sources

1. [Vapor smoothing: SF and X-series family page and SFX, SF2X, SF50, SF100 product pages](https://amtechnologies.com/products/vapor-smoothing/) · AMT · read Oct 6, 2026 · also [AMT](https://amtechnologies.com/products/vapor-smoothing/postpro-sfx-desktop-vapor-smoothing-system/) · also [AMT](https://amtechnologies.com/products/vapor-smoothing/postpro-sf2x/) · also [AMT](https://amtechnologies.com/products/vapor-smoothing/postpro-sf50/) · also [AMT](https://amtechnologies.com/products/vapor-smoothing/postpro-sf100/)
2. [How Norden improved efficiency with vapor smoothing for production machinery (case study)](https://amtechnologies.com/resources/case-studies/vapor-smoothing-for-production-machinery/) · AMT · Nov 27, 2025
3. [PostPro benchmarking: send us your 3D printed parts](https://benchmarking.amtechnologies.com/) · AMT · read Oct 6, 2026