Guides
Part of How workshop ventilation works, from planning to finished
A weekend plan for fixing your shop ventilation
Two days on shop ventilation: inventory what you actually breathe, find the leaks, improve capture at one machine, and test it before you call it done.
What to take away
- Start with an inventory of what you actually generate: which dusts, which vapors, from which operations.
- Fix one machine properly rather than improving four badly. Capture is a per-machine problem.
- Leaks and bad connections cost more airflow than most people believe. Sealing is the cheapest upgrade there is.
- Test at the end. A system nobody has tested is a system nobody knows the state of.
Two days is enough to move a shop from no capture to genuine capture at the machine you use most. It is not enough to design a whole-shop system, and pretending otherwise is how bad ducting gets installed and then lived with for years. Treat this weekend as one machine solved properly, plus a written list of everything still outstanding.
Saturday morning: inventory what you breathe
Walk the shop and write down every operation that puts something into the air, with the material next to it. Sanding hardwood, cutting sheet goods, grinding steel, spraying finish, mixing epoxy, soldering. Note which are frequent and which are occasional.
Then look up what the frequent ones actually involve. OSHA's occupational chemical database collects exposure information, sampling methods and physical data for a large number of substances, which is a better starting point than a product marketing page for anything you use often.
Do not try to convert this into a personal exposure figure. You have no sampling data, and neither do we. Use it to rank what deserves attention first.
Saturday afternoon: find the leaks
Run the collector and work along the system with your hand and your ears:
- Every joint, looking for air moving where it should not.
- Every flexible hose, which leaks at the cuff more than along its length.
- Every blast gate, which leaks when open elsewhere and when closed here.
- The filter and its seal, which is where a surprising amount escapes.
- The machine port itself, which is often the worst connection of all.
Seal with proper clamps and tape rated for the job. Replace any hose that has been repaired more than once.
Sunday morning: improve capture at one machine
Pick the machine you use most and improve the hood. Close the gap, add a shroud, extend the port toward the cutter, or box in the area where material leaves. The published requirements for exhaust systems in construction operations show the shape of what a real hood does: enclose the operation as far as practicable and draw the contaminated air away from the operator's breathing zone.
Those obligations belong to employers, not to you at home. The design principle stands: the enclosure and its position do most of the work, and the machine on the end of the hose does less than people assume.
Sunday afternoon: test and record
Run the machine and look for what escapes. Use a tell-tale ribbon at the port, watch where dust settles, and check whether anything reaches your face. Photograph the result. Write down what you changed and what is still not working.
End with a written list of the operations still uncontrolled. That list is what you wear a respirator for until it shrinks.
Our ventilation overview covers the whole system, and our garage weekend plan covers the wider shop audit this fits into.
Common questions
Should I buy more machine or fix the hood? Fix the hood. Capture geometry usually limits the system before the motor does.
Is flexible hose acceptable? In short runs, yes. It costs far more airflow per foot than smooth duct, so keep it short.
How do I know if it worked? Less settled dust across the room, and less on your clothes at the end of a session.
What if I cannot capture at a machine at all? Work outdoors where the weather allows, wear a fitted respirator when you cannot, and put that machine at the top of next month's list rather than accepting it permanently.
