Thread: Pre-emptive dust/sound control for a CNC router.

I have a large DIY CNC, but no enclosure just good dust extraction, so your machine would need quite a large enclosure to give yourself some working space around it and then there's the acoustic part, which really needs a stud wall with sound insulation, so maybe build a room within a room.

Enclosure is impractical for a full sheet CNC. You have to get a sheet on and off. Would have to be a full separate room.

For dust control, you need to remove enough air at the tool to get rid of the dust.

An enclosure contains the dust but does not help in removing it. You then have an enclosure full of air containing fine dust that you get exposed to when the enclosure is opened.

Part of the reason people build enclosures for small CNC machines is that it's very hard to put decent dust collection on them. If you have a trim router spindle on a dinky lightweight machine, it's unlikely you will be able to mount a 6inch dust collection hose to near the tool.

Remember also that for extraction to work, your enclosure needs to admit air at the rate that the extractor is pulling it out. The exception would be to make the enclosure large enough to accommodate the machine and the extractor so that air is sucked up and carries the dust with it, gets filtered to eliminate as much dust as possible, passes through the extraction unit, and is released back into the enclosure to recirculate. Issues with this approach are;

1. there will be a lot of fines accumulating in the enclosure even after a short run, and any motion like opening or closing the access doors will create air currents that cause these fines to escape beyond the enclosure.

2. The extraction system will be denied access to cooling air and would overheat eventually, as would any an air cooled spindle and the stepper/servo motors providing the carriage movement.

I have experience operating commercial full sheet units with a 10KW extractor and 100mm extractor plumbing and a large (44 gal) dust receiver and filter unit. It was very effective at collecting the chips and larger dust particles, much less so the smaller and fine particles.

I'm not sure what you would do with a vertical full sheet unit, full sheet suggests that you would like the machine to be used for nesting or similar but how ever you clamp the sheet, anything that you cut to point of release is ultimately going to move during the remainder of the cut and would get damaged or damage whatever it bumps into. I suspect that it would be harder to load and clear than a horizontal unit.

Just my thoughts.

Originally Posted by malb

Remember also that for extraction to work, your enclosure needs to admit air at the rate that the extractor is pulling it out. The exception would be to make the enclosure large enough to accommodate the machine and the extractor so that air is sucked up and carries the dust with it, gets filtered to eliminate as much dust as possible, passes through the extraction unit, and is released back into the enclosure to recirculate. Issues with this approach are;

1. there will be a lot of fines accumulating in the enclosure even after a short run, and any motion like opening or closing the access doors will create air currents that cause these fines to escape beyond the enclosure.

2. The extraction system will be denied access to cooling air and would overheat eventually, as would any an air cooled spindle and the stepper/servo motors providing the carriage movement.

I have experience operating commercial full sheet units with a 10KW extractor and 100mm extractor plumbing and a large (44 gal) dust receiver and filter unit. It was very effective at collecting the chips and larger dust particles, much less so the smaller and fine particles.

I'm not sure what you would do with a vertical full sheet unit, full sheet suggests that you would like the machine to be used for nesting or similar but how ever you clamp the sheet, anything that you cut to point of release is ultimately going to move during the remainder of the cut and would get damaged or damage whatever it bumps into. I suspect that it would be harder to load and clear than a horizontal unit.

Just my thoughts.

You would have to use tabs rather than cut all the way through to stop things moving around

Originally Posted by Camelot

You would have to use tabs rather than cut all the way through to stop things moving around

Tabs are fine on a horizontal table with vacuum hold down, not sure how the would fare for larger panels in a vertical orientation unless there were a lot more of them, or they were thicker than what we used to use. We would run around 6 to a part and they were left at basically the melamine thickness so we could touch them with a knife to release parts and two strokes with a file on each would remove all trace of them from parts.

Hi All,

Thanks for the responses. I'll definitely consider those suggestions.

Initial thoughts inspired by your responses...

1. Thinking outside the box: The "room inside a room" is an intriguing one. However, any space saving advantage in "going vertical" would be lost. However, insulated multi-paneled/insulated construction is one design I was considering. The other one I was considering was a large, double shelled box lined with sound absorbing materials. Much like my "sound damping box" for my previous shop vac. The link (and design images) can be found here:

misadventure-in-sound-damping-enclosures-for-loud-workshop-machinery

2. Dust: The idea about the fine dust being a problem is indeed one I need to consider seriously. I had some vague plans to have a secondary vacuum hose/dust collection "gutter" for "mopping up" since a vertical machine would likely gather the dust at the lower edge of the bed. I acknowledge the inflow has to match/exceed airflow of the air being drawn from the enclosure, but I had two thoughts about that....

• Thought A: Enclose the entire dust extraction system within the enclosure with the CNC, eliminating the negative/positive air pressure entirely, and allows cyclical (repeated) opportunities for refiltration. However, as previous responses has pointed out, there's the problem of heat build up with such a setup. To that... perhaps a secondary (filtered) fan could vent hot air with better (finer filtration) could help with that...
• Thought B: Have the dust system outside the box (less heat buildup) and still face all that noise... and use an indirect ventilation system, lined with sound absorbing materials to keep the noise in.

3. Access issues: I agree that being able to insert/remove whole sheets is a major consideration and if I don't get it right, it'll be an ongoing frustration. I was actually thinking about having side-on access for loading sheets, with front on access for work holding and general trouble shooting. Details still in the formulation stage.

4. Work holding: As I've said, I haven't built the machine yet. Tabs, whether vertical or horizontal shouldn't bea problem if I have them either numerous or thick enough. I don't need ultimate thin-ness in the tabs.. but it'll be an interesting consideration. I presume most CAM software can adjust tab dimensions/number, but if not, can anyone please tell me which CAM package you use so I find an alternative )

Clearly, I've got a lot to think about, and I really appreciate your help. I'll keep you posted. Kinda have renovations going on, so please forgive me if I'm slow to respond.

Take care out there!
Hamish.