The HL 850 planer is a great tool, but I immediately discovered that it's the only Festool not designed for use with the 27 mm hose. The hose does fit, but not as well as the 36 mm. While it's held securely in the suction adapter, it doesn't create a tight seal. Unfortunately, most dealers make no mention of this incompatibility. In fact, many offer a combo package including the planer, dust extractor, and 27 mm hose. There's no question that the 36 mm hose is superior, but a minor modification yields more than adequate performance with the 27 mm hose. The 36 mm hose may be necessary for trimming doors, but I've found that the 27 mm hose works fine for most tasks.
The fundamental flaw is the large gap between the hose and the suction adapter. The forceful exhaust blows smaller bits of dust through this gap and larger chips become lodged only to fall on the floor when the hose is removed. Sealing this gap should fix the issue.
I machined an aluminum sleeve to create an air-tight seal between the hose and suction adapter.
The sleeve's o-ring creates a semi-permanent seal with the suction adapter, and its internal retention ring secures the hose.
The final assembly facilitates maximum airflow and efficient chip extraction. I have not seen a speck of wood since installing this sleeve.
It's a great looking looking mod in my opinion. [big grin]

The fundamental flaw is the large gap between the hose and the suction adapter. The forceful exhaust blows smaller bits of dust through this gap and larger chips become lodged only to fall on the floor when the hose is removed. Sealing this gap should fix the issue.

I machined an aluminum sleeve to create an air-tight seal between the hose and suction adapter.


The sleeve's o-ring creates a semi-permanent seal with the suction adapter, and its internal retention ring secures the hose.

The final assembly facilitates maximum airflow and efficient chip extraction. I have not seen a speck of wood since installing this sleeve.

It's a great looking looking mod in my opinion. [big grin]