Is Machining Printed Circuit Board (PCB) Material (e.g. FR4, Garolite) Dangerous?

Are FR4 PCB’s really that dangerous to mill on the nomad (because of the glass fibre)?


Any time you machine glass–filled plastic you need to contain the swarf. Tiny broken glass fibers are not good to breathe, but are also very abrasive to sliding and ball bearings. When machining PCB’s I stand by with a fine tip on the shopvac and vacuum the swarf as it comes off. I don’t have a Nomad, but have done that on my Sherline and Tormach mills. Just my experience.


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Thank you for your response!


Vacuuming while milling is good… but it can be more dangerous than not if the vacuum doesn’t have a filter that blocks the particles. For CNC work a HEPA filter rated at 0.3 micron is necessary to meet the highest level of safety.

The 5 micron filters that are common are essentially useless in preventing the particles that are most dangerous to your lungs/health.

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Good point @mbellon, I didn’t know the standard HEPA wasn’t up to the task, but it does at least help the bearings out regardless :wink:

Do you have any recommended things you use?

HEPA filters come in several grades. Those rated for 0.3 micron are the ones that meet or exceed the requirements for air safety in Europe and the US.

Machining metals and plastics there is no real need to vacuum (unless one machines to make the materials burn!). Wood and friable (easily flaked materials like FR4, fiberglass and Renshape) materials generate some nasty particles when CNCed. Some exotic hardwoods - tropicals and such - release some real nasty compounds and even viruses when machined.

Ideally, it’s important to maintain a negative pressure inside the enclosure (lower pressure inside than outside) to ensure that things stay where they should. Sucking air out of an enclosure requires an equal amount of air to enter into it so the particles are taken out. When a job completes, let the vacuum run for a few minutes to ensure the air is cleared. Turn off the vacuum, open the enclosure, turn on the vacuum and immediately vacuum the inside of enclosure.

Don’t want to add a fitting to have negative pressure? That’s “ok” but still wait a few minutes for things to settle.

HEPA filters, at least the good/safe ones, are not cheap. One always tries to avoid unnecessary costs. Some HEPA filters are cleanable, at least for a few cycles.

In shops that generate a lot of dust (e.g. wood shops), one uses a dust collector with a cyclone dust separator ahead of it. The cyclone removes 99+% of the particles before the dust collector. The dust collector either dumps the air outside or through a filter. If the filter is in the room with workers, a 0.3 micron HEPA filter is called for.

ALWAYS, ALWAYS dump the collected particles outside. Ideally wearing a filter mask. Upwind works if you can pull it off.

For something as small as the Nomad, a high end dust collector and dust separator are overkill. There are a couple of approaches that one can pursue:

A) Festool makes top rated small dust collectors with HEPA filters. Fein is an alternative.

A good deal better than a shop vac… with a price to match.

B) A shop vac with a HEPA filter rated at 0.3 micron.

There are so many of these they are very easy to find. The HEPA filter rating is key.

For the safest air quality and the lowest HEPA filter replacement cost one can add a small cyclone dust separator. They can be added ahead of a shop vac or a Festool/Fein. There is even one for Festool that stacks on top of one, minimizing space.

Oneida and ClearVue sell dust separators that are priced fairly and their low end, small, plastic ones are inexpensive.

Budget tradeoffs with safety should err on the side of safety. The small particles are more dangerous than Asbestos and are significantly more damaging to children than adults.

Don’t do wood or friable materials (metals and plastics only)? You’re all set.

Tight budget? Shop vac with a 0.3 micron HEPA filter.

Generate a lot of dust or want really safe air quality? Add a cyclone (dramatically reduces your HEPA filter costs).

Very serious about air quality? Get a Festool with the special cyclone made for it.


For everyones information, I have many decades of machining experience (hand milling, 3, 4, and 5 axis CNC machining) and have taught students and helped people learn machining and CNC.

I also help with the design of CNC machine enclosures, dust handling, noise handling, and air quality issues.

I’ve seen too many people with damaged lungs (due to the small particles) and ears generated by todays equipment… That’s why I warn people and help them find solutions within their budgets that provide the most protection.

I have a Nomad on order. It’s cute! A small mini-mill inside the house will serve me well. Mine will have the HDPE sides. I will modify it to have a vacuum outlet and any necessary inlets. The vacuum outlet will use the same fitting as I have on the enclosure I designed for my mini 5 axis CNC mill.

These mini-mills are not large and do not need top end fittings and equipment. Plastic fittings, low cost anti-static hoses, plastic cyclone dust separators, HEPA filters and a good vac allow for good, inexpensive and safe solutions. Be safe!

@mbellon Could you post about your dust collection setup once you’ve received your Nomad??! :slight_smile:

Health, dust head, and enclosure discussions have come up more than once. Currently, we’re discussing related things in a few places.

Please see:


Thanks @mbellon I thought I had read all the posts re. dust/particle safety but had skipped the last two you posted above. The Dust Head Prototype looks really good! The custom enclosures are really great too but a bit beyond me at this point in time I think, especially with no workshop and few tools to speak of. I will watch the threads unfold with interest…