Connect a Stationary machine 4 in dust port to a 2-1/2 in shop-vac hose
How to join a Stationary machine 4 in dust port to a 2-1/2 in shop-vac hose, and what stops it leaking dust.
Not compatible without stepping down. A 2-1/2 in shop-vac hose is far larger than the Stationary machine 4 in dust port, so it needs a 4 in to 2-1/2 in step reducer.
Rings drawn to scale from the measured diameters in the table below.
The two ends
| End A | Stationary machine 4 in dust port (3-15/16 in OD, 99 mm OD, 91 mm ID) |
|---|---|
| End B | 2-1/2 in shop-vac hose (2-1/4 in OD, 2-1/4 in ID) |
| Fit type | male port into hose cuff |
| Reducer needed | 4 in to 2-1/2 in step reducer |
Shop notes
The hose is about 57 mm and the port about 99 mm, a gap of 42 mm, so the port simply swallows the hose with no contact. A 4 in to 2-1/2 in step reducer is needed, and even reduced the airflow is mismatched between the Stationary machine 4 in dust port and the 2-1/2 in shop-vac hose.
Wrapping tape to close a 42 mm gap never seals cleanly and chokes the airflow further. Step the sizes properly, or pair each end with a fitting closer to its own size.
The reducer to buy
Search Amazon for 4 in to 2-1/2 in step reduceraffiliate searchRelated connections
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