Avalon A15 Vertical Dual 120 mm to 200 mm Metric Duct Shroud

Description

Overview

This is the Avalon shroud for Avalon ducting: 200 mm metric duct is the size the Avalon kit’s own ducting uses, so if you are extending or replacing that run, this collar speaks its language — an inch collar does not, because inch fittings do not fit metric duct.

The fan side carries the dedicated Avalon geometry: two vertically stacked 120 mm fans on a 122.0 mm pitch, which is 1.0 mm per side away from the Antminer-style 120.0 mm pattern — more than mounting-slot slack can absorb. Single-piece PETG, flex-over collar: the duct slips over and clamps on the 198.0 mm sealing land under the 200.0 mm crest.

What it fits

Canaan Avalon A13xx, A14xx and 15XP miners with two vertically stacked 120 mm exhaust fans on a 122.0 mm pitch, exhausting into 200 mm metric duct — including the ducting supplied with the Avalon kit. One honest note on that number: the 122.0 mm pitch and 105.0 mm screw square come from a single community CAD lineage — the designer’s intent, not a caliper-verified measurement on a production Avalon.

Measure before you order. Fit dimensions in this line are derived from published fan and chassis geometry and are not yet validated against measured production hardware. Check your flange size and clearances against the footprint below. If something does not fit, tell us — that is how the next revision gets better.

One more honest number: the collar’s sealing land sits at duct nominal minus 2.0 mm, while measured male metric hardware runs nominal minus 1 to minus 2 mm. Our land sits at or under that hardware and never over — which is a retention argument, not an exact-match claim. The metric ring coupon measurement that would settle it is still open.

At 200 mm the published male-interface evidence genuinely splits — 198.0 mm in one lineage, 199.0 mm in another — and we deliberately did not average it. Our 198.0 mm land sits at the bottom of that bracket.

How it is used

Mount the shroud over the two stacked exhaust fans using the fan screw pattern. The flange holes are 5.0 mm (with 5.424 mm slots); put a 9 mm or larger flat washer under each screw head, or reuse the miner’s own large-head fan screws. Then slip 200 mm metric flex duct over the collar, clamp it on the sealing land behind the crest, and route the duct to a window port, a plenum, or the space you want to heat.

Why it helps

• Matches the Avalon kit’s own 200 mm ducting size — no inch-to-metric bodging.
• Dedicated Avalon geometry: 122.0 mm stacked-fan pitch, not the generic 120.0 mm pattern.
• Flex-over collar cut for metric duct: crest at duct nominal, sealing land 2.0 mm under it, so the duct slips over and a clamp lands on the land — no tape, no forced inch fit.
• Every fan screw stays reachable: minimum measured tool radius 8.6 mm on this part, against a project target of 8.0 mm — all screws rate GOOD.

Specifications

Open source

This design is open source under CC BY-SA 4.0. The files are free at /3d-models/, and anyone may print, modify or sell them. Buying the finished part supports the work that produces these designs — you can also support it directly via the fund.

Works with

• Avalon A15 dual 120 mm to 6-inch duct shroud
• Avalon A15 dual 120 mm to 8-inch duct shroud

See the full D-Central shroud and ducting system.

Frequently asked questions