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Connect a Bosch 35 mm tool port to a 1-1/4 in shop-vac hose

How to join a Bosch 35 mm tool port to a 1-1/4 in shop-vac hose, and what stops it leaking dust.

Reducer required

Not a direct fit. Joining the Bosch 35 mm tool port to a 1-1/4 in shop-vac hose needs a 35 mm to 1-1/4 in step reducer.

END A35 mmBosch 35 mm tool port (1-3/8 in OD, 35 mm OD)
END B31.8 mm1-1/4 in shop-vac hose (approx 1-1/2 cuff in OD, 1-1/4 in ID)

Rings drawn to scale from the measured diameters in the table below.

The two ends

End ABosch 35 mm tool port (1-3/8 in OD, 35 mm OD)
End B1-1/4 in shop-vac hose (approx 1-1/2 cuff in OD, 1-1/4 in ID)
Fit typemale port into hose cuff
Reducer needed35 mm to 1-1/4 in step reducer

Shop notes

Measured across the joint between the Bosch 35 mm tool port and the 1-1/4 in shop-vac hose, the port (35 mm) is 3 mm larger than the hose (32 mm), so it will not seat. A 35 mm to 1-1/4 in step reducer closes that 3 mm step so the two hold together instead of leaking at the gap.

A 3 mm mismatch feels close enough to force, and it will hold for a minute before it works loose under airflow. Fit the step ring rather than trusting friction on a gap this size.