Antminer S19 / S21 Dual 120 mm to 6-Inch Clamp-Groove Shroud — Wide Base

Description

Clamp-groove duct shroud: a seat that will not let the band walk

A clamp-groove duct shroud exists because a worm-drive band on a smooth collar is held by friction alone, and a running miner spends every hour of its life vibrating. Given enough hours the band creeps toward the open end and one morning the duct is on the floor. This shroud hoods both 120 mm exhaust fans of an Antminer S19 or standard S21 into one 6-inch duct, and cuts a recessed seat into the collar between two raised shoulders so the clamp is held by geometry, not by grip.

The seat takes a 12.7 mm stainless worm-drive band — the common half-inch hardware-store size — nipped up hand-tight with a small nut driver. Not a power driver, not a T-bolt, not a constant-tension clamp: the groove is proportioned for a hand-tight band, and the shoulders hoop-reinforce the collar so the load lands on the duct, not a thin wall.

What it fits

• Antminer S19, S19j Pro, S19 Pro, S19 XP — dual 120 mm exhaust panel
• Antminer S21 and T21 standard chassis — dual 120 mm exhaust panel
• Any dual 120 mm exhaust face on a 120.0 mm pitch and 105 mm screw square
• 6-inch flexible duct secured with a 12.7 mm stainless worm-drive band, hand-tight

The same captive seat on a narrower flange is the standard-base clamp-groove shroud. If you are happy to push duct on and leave it, the plain plain wide-base 6-inch shroud has a retention bead and no groove. And if the duct comes off weekly rather than yearly, skip the band entirely and take the wide-base bayonet shroud.

How it goes on

1. Mount the shroud over both fans with M4 screws through the eight flange slots, using a 9 mm or larger flat washer under each head, or the miner’s own large-head fan screws.
2. Push 6-inch flex duct over the collar until it covers the groove and the shoulder beyond it.
3. Drop a 12.7 mm stainless band over the duct, line it up with the recess, and nip it hand-tight.
4. Check it once after the first day of running, then leave it alone.

Why a groove beats a bead

A retention bead stops a duct sliding off in one direction. A recessed seat between two shoulders stops the clamp itself moving in either — and the clamp is the part actually holding the joint. The shoulders do a second job: a printed collar under band tension is a thin hoop in compression, and hoops fail by going out of round. Thicker walls either side keep the ring circular, so the band squeezes duct into the recess instead of dishing the collar.

• Captures the band between two shoulders so vibration cannot walk it toward the open end.
• Reinforces the collar either side of the groove so it stays round under clamp load.
• Pulls flex duct down into the recess, giving the joint a mechanical lock rather than a friction grip.
• Takes ordinary 12.7 mm stainless bands from any hardware shelf, with no special clamp to source.
• Rides on the 260 mm plate so the assembly loads the exhaust face, not four screw slots.

Specifications

Open source — groove profile included

The band seat, the shoulder thicknesses and the plenum behind them were drawn in-house by D-Central Technologies, and the file goes out free under CC BY-SA 4.0 through the 3D models download center with the rest of the line. Print it, change the groove, sell what you make — the licence says yes. This model’s card links the ZIP, which carries the STL, the licence and the installation and safety guide.

This page sells the finished part, made to order in black or orange PETG in Montreal, Quebec. The D-Central fund page is there if the free files have been useful.

Works with

• Antminer S19 / S21 Clamp-Groove Shroud — Dual 120 mm to 6″
• Antminer S19 / S21 Dual 120 mm to 6-Inch Shroud — Wide Base
• 6-Inch Flex Duct Adapter — Rigid Socket to Flex Collar
• 6″ Duct Coupler
• 6″ 90° Duct Elbow (Compact)

The flex adapter carries the same band logic further down the run. See the whole D-Central shroud and ducting system.

Frequently asked questions