Thread: Collecting and extractinng surfboard foam dust

I had a customer who had a similar problem when mass producing chairs and he built a small sanding room that was designed too isolate the rest of the workshop from the finishing/sanding area. He had air inlets matched to the extracted air capacity of the dust extractor and the room was big enough for a person to work inside it with several chairs at a time. You will need a very capable dust extractor with at least a 17" impeller and it will be very noisy when working and I think without personal experience that a force fed respirator would be a must have also. A grid floor could be used for the uncollected stuff to fall through and this would mean that piles of material would not be disturbed and dust created when working in the area. If it was me and your current situation the floor would be swept every day to prevent airborne dust being created by walking around.

Thank you, Chris. All great suggestions. Let's see if I can convince the boss!

claim OH&S issue

Years ago my friend in QLD set up what was essentially a large spray booth with two 10 Hp extractor fans, into a skip, she still had a small amount of dust but nothing a quick sweep at the end the day could not handle.

I shaped a dozen or so boards when I was young with little care about the mess, so I remember this dust. I googled "dust extraction for surfboard shapers" and saw what people were doing, but nothing poped as a modern, well conceived solution.


You probably noticed there are a couple of engineers on this site that can be really generous with their ideas. If you need a small formal consult try Bobt...but he's on the W coast.

Nowadays, even if you are located rural, you can't just exit the shaping bay with fans and dump into a skip with clouds of fine dust freely escaping. You need to collect the chips/granules and filter the fine dust as the air exits your DE system.

So maybe some version of a WW dust collector will work. But the foam is a lot lighter than wood, the density is less than 8% that of pine. So the dust may behave differently. And one may need to make some assumptions about what the composition of the dust is, chips, granules and fine particles that may be too small to see. The health risks at various particle sizes may be similar to wood, but I would read up on that. With wood, the fine, invisible particles are bad, and harder to remove and contain with common DE systems.

One useful thing you could do right away is get a cheap particle counter which will measure the tiny invisible particles. PM1 is 1 micron and less. It would be interesting to see how quickly/slowly the smaller particles fall out of suspension.
EDIT: see More fun with Bell Mouths on page 2 post #27 there's a link to the particle counter on Banggood, and interesting ideas on that issue begin.

If you want to get the dust into garbage bags, I'm guessing because it suits your disposal method, it might work if you used the bags as liners. Some have even done that in a cyclone collection bin, using an internal cage to stop the vac imploding the bag.
If the fan is pumping dirty air into a small WW style DC unit then the garbage bag liner is pressurised.

Even double bag WW style DC units might not have the air flow you need. And they would probably need expensive pleated filters. Maybe 1 micron bag filters are possible and not too expensive. And maybe they will work with foam dust.

Guessing on where good solutions ly...my instincts went straight to a small bag house, fed with dirty air from the fan, maybe with a cyclonic function at the bottom....for example

bag-house-dust-collectors-500x500.png
That wasn't the right picture to suggest a cyclone function in the lower part...try this one..of course I could be wrong and they are just using the cone shape for collection.
Baghouse-Dust-Disposal-Types.jpg

You could build this yourself. I think the filter socks are sold on the net, or if you can find the material, make your own. A small baghouse floats by cheap here on Trademe every few months, mabe over there also.

Aside from the DC ideas above, you need some good ideas on how the dust is sucked up in the first instance. Through the floor was mentioned. If so you feet need to feel good on that surface. Lots of additional ideas are possible, and you might use a few at once...a perimeter intake at the edge of the floor, a large overhead bell mouth hood over the blank, intake hoods under the blank....

Cheers,
Gregg.

Originally Posted by GreggMacPherson

One useful thing you could do right away is get a cheap particle counter which will measure the tiny invisible particles. PM1 is 1 micron and less. It would be interesting to see how quickly/slowly the smaller particles fall out of suspension.

PM2.5 is the one to look at. and at this size as wood dust particles fall out of suspension from still air at the rate of about 50% every 20 minutes.

The rate depends on things like the density of the particles and the amount of turbulent air movement so different woods will sty in the air more or less accordingly. If the foam is 8% of the density of wood dust it will stay in the air about 12.5x longer so half life in suspension should be about 250 minutes. This is most undesirable so they real do need to be collected or vented.

Below 2.5 micron weird stuff happens as the dust (especially the light foam) will act more and more like air so most of what you breath in also comes out. This is counterbalance by the fact that there are heap more tiny particles that PM2.5.

That dust collector that you've pictured couldn't suck the skin off a rice pudding. For hand sanding could you use one of the sanding pads that take mesh sanding media with a vac attached? I assume you're using a high spec. self cleaning vac or a small cyclone to reduce the need for constant filter cleaning. As others have indicated solutions are possible if you're prepared to invest the necessary dollars.

Bob,
The one commonly called the PM2.5 is the one I was thinking of. Lots of folks bought one, including me, and I'm guessing you. I added an edit with a link to the forum page with info on that.

Maybe Johknee will send you his Learjet and you can go take a look.

- - - Updated - - -

I think the best thing to do here is let the OP find a way forward with his boss, simple stuff such as using a broom every day is a good start but even that can be resisted by someone who does not think good house keeping is important.

Back to the foam density. I look into it a bit further and see it's a form of expanded polystyrene? So its chains of styrene, which according to Wikipedia (C8H8)n an actually has a density of about 1 g/cc so there's a chance that the PM2.5 dust will be as dense or even denser than dry wood. This means it should not hang around as long. Sounds like a some measurements are needed )

and FWIW I'm was not an engineer but a Physicist, and have been studying dust in various forms since 1978 - Yeah I know it sounds like an AA affirmation. I agree with Chris - let the OP work with his boss in the first instance - he may well give the OP a mask and tell him to get on with it

Originally Posted by BobL

Back to the foam density. I look into it a bit further and see it's a form of expanded polystyrene? So its chains of styrene, which according to Wikipedia (C8H8)n an actually has a density of about 1 g/cc so there's a chance that the PM2.5 dust will be as dense or even denser than dry wood. This means it should not hang around as long. Sounds like a some measurements are needed )

and FWIW I'm was not an engineer but a Physicist, and have been studying dust in various forms since 1978 - Yeah I know it sounds like an AA affirmation. I agree with Chris - let the OP work with his boss in the first instance - he may well give the OP a mask and tell him to get on with it

I think that Wiki is refering to the density of unexpanded polystyrene beads. That totally flumoxed me and that was the only explanation I could think of. I dimly remember the explanation of how the beads are expanded..steam?

Nowadays there are supposedly 4 different core materials for boards. The material and the tools used affect the form of the "dust".

Polyurethane foam (PU) density about 32kg/m^3
For decades, 99% of boards used a polyurethane (PU) foam. You mix two parts and, in the blank factory, quickly put it in a pressure mold. In the early days the mold sometimes was rumoured to explode. It's still supposed to be the dominant material. It shapes, sands beautifully.

Polystyrene foam(PU) density..guessing 30-50kg/m^3
Polystyrene beads that are expanded into a big bun then sliced up with a hot wire.
The hot wire I assume is used to cut the rocker so there may be less dust.
Not as nice to shape as PU, but still OK.

Expanded Polystyrene (EPS)....density..guessing 30-50kg/m^3
I don't know why this has a special name, it just looks like poly that's been expanded in a mold, maybe not for shaping....?

Extruded Polystyrene (XPS) estimate 30kg/m^3...?
You've seen it as Green Styrodur or blue Styrofoam, the whole block is one unitary thing, not cells. I've used 30kg/m^3 for pattern making in composites.
Shapes and sands quite well, but not as well as PU.


Bob, your not an engineer? Had me fooled. It was an honorific.

I didn't realise that Johknee was not the boss. Back in the day, shapers were heroic artisans, normally contractors for hire per board.

Gregg.

The absolute first issue in a project such as this is getting all the vested parties to agree that the problems exist and that action is needed to address it and the next problem is getting everyone to agree what that action is and how much it costs. I have been involved in a few of these style of projects and invariably it is a long and difficult road to reach a point where everyone agrees and it is only after all that the technical aspects can be addressed. I am advising on a problem installation at the moment with all the above problems all because of a badly designed system by professional engineers that simply does not work. The issue is that they have spent thousands on the system and it will take a lot of talking to get any sort of agreement to rip some of it out because the basics are simply wrong. I know of another system designed by professional engineers which has not yet been installed that will be a disaster and they too have spent some serious big dollars on consultation and design. Let the OP see if the will is there to look at the problem and then we can move on from there. BTW I am unaware of any engineers here of any type.

Originally Posted by GreggMacPherson

Polyurethane foam (PU) density about 32kg/m^3
For decades, 99% of boards used a polyurethane (PU) foam. You mix two parts and, in the blank factory, quickly put it in a pressure mold. In the early days the mold sometimes was rumoured to explode. It's still supposed to be the dominant material. It shapes, sands beautifully.

Polystyrene foam(PU) density..guessing 30-50kg/m^3
Polystyrene beads that are expanded into a big bun then sliced up with a hot wire.
The hot wire I assume is used to cut the rocker so there may be less dust.
Not as nice to shape as PU, but still OK.

Expanded Polystyrene (EPS)....density..guessing 30-50kg/m^3
I don't know why this has a special name, it just looks like poly that's been expanded in a mold, maybe not for shaping....?

Extruded Polystyrene (XPS) estimate 30kg/m^3...?
You've seen it as Green Styrodur or blue Styrofoam, the whole block is one unitary thing, not cells. I've used 30kg/m^3 for pattern making in composites.
Shapes and sands quite well, but not as well as PU.
.

Sure BUT these are all bulk densities and I wasn't referring to the visible stuff on the floor I'm talking about low micron size particles floating in the air which could have most of all of the air smashed/squished out of them? A guide might be how big are the bubbles in the expanded foam. If then are bigger than 2.5µ then the 2.5µ dust will be solid PS.

Thank you to those who have contributed ideas so far. I appreciate it!

I'll try and address some of the questions from above.

This is a one-man operation, so time and money are limited. I'm motivated to find a solution purely because I'm convinced, thanks to this very forum, the dust collection and extraction could be improved. Well, something has to be better than nothing! Also, he's a mate, so I'd like to help make his work easier/safer/healthier.

Most boards are PU and they are cut on a CNC machine in a sealed room. The room does not have dust extraction/ventilation and the machine does not have a dust collector. In fact, the CNC machine operates as a 'snow thrower', spreading dust throughout the room, onto walls and the ceiling. So, all dust from the machine builds up in the room and is swept, bagged and disposed of off-site. As I mentioned in the original post, I am inclined to use a dust collector with bags to collect the majority of the dust. Of course, coveralls, safety glasses and a respirator will be required too.
I cannot think of another solution that would be cost effective and make clean-up of the CNC room easier/faster, and that is why I asked for some advice. I understand there are other solutions that would require remodelling and significant expense. I'm not sure the shaping bay can be improved without some significant remodelling too. Perhaps the only solution is, as mentioned above, vacuuming/cleaning regularly and wearing a respirator?

Anyway, thanks again!