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Connect a Bosch GCM12SD miter saw port to a Festool D27 antistatic hose

How to join a Bosch GCM12SD miter saw port to a Festool D27 antistatic hose, and what stops it leaking dust.

Reducer required

Not a direct fit. Joining the Bosch GCM12SD miter saw port to a Festool D27 antistatic hose needs a 1-1/4 in to 27 mm step reducer.

END B35 mmFestool D27 antistatic hose (35 mm tip in OD, 7/8 in ID)
END A31.8 mmBosch GCM12SD miter saw port (1-1/4 in ID)

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

The two ends

End ABosch GCM12SD miter saw port (1-1/4 in ID)
End BFestool D27 antistatic hose (35 mm tip in OD, 7/8 in ID)
Fit typehose cuff into female socket
Reducer needed1-1/4 in to 27 mm step reducer

Shop notes

Measured across the joint between the Bosch GCM12SD miter saw port and the Festool D27 antistatic hose, the hose tip (35 mm) is 3 mm larger than the port socket (32 mm), so it will not seat. A 1-1/4 in to 27 mm 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.