Specsheet
Dust stub sizing makes sure your extractor or filter connects properly to your machine, avoiding leaks and poor suction. Getting it wrong creates wasted time and dust hazards.
By Ms Nomsa Khumalo, MD, Dust
When fitting dust extraction to CNC routers, saws, or engravers, the size and position of the dust outlet, or 'stub', is too often guessed or assumed. This causes mismatched hoses, loose clamps, or even worse, a poor seal that lets fine dust escape. In fabrication and joinery, this is more than a mess, it is a health hazard and a direct violation of the occupational regulations on dust exposure.
Many machines are imported with metric or imperial stubs. The wrong fit wastes time and money, especially if you are adapting from one brand to another or working with local ducting suppliers. If you rely on shared extractors between several bays, a mismatch on one machine can break the airflow for the whole system. Proper sizing is about getting an airtight connection the first time, so the extraction works as designed and you avoid extra spares and patches.
A quick measuring tape is not enough. Here is what I recommend in every new install or retrofit. Always document the result and label the stub at the machine, don't trust memory or a drawing from years ago.
Do not skip any step, as a small error can cost hours in rework or even a failed safety audit.
If you are unsure about your equipment’s stub sizing, send us a message through our contact form. We can verify the standard sizes on Feature Equipment machines, and advise on the best way to connect to your existing dust extraction system.
Ask your installer if the stubs are compatible with locally available hose or duct, what adaptors might be needed, and whether the extraction airflow will be affected by any reducers or elbows. You should also confirm that all connections are airtight and that the system is easy to maintain for filter changes or cleaning.
One typical error is assuming a stub is 100 mm because it looks like it, but in reality, it measures 98 mm or 102 mm, which means standard hose or boots will not seal properly. Another is fitting a flex hose too tight or too loose, both cause leaks and lower suction.
We often find stubs with no label or record, so when a new extractor or boot is needed, it becomes a guessing game. Fitting reducers at the last minute to 'make it work' is another mistake: these create airflow restrictions and extra dust build-up. Always measure, document, and check before buying any parts.
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