Controlling Dust At The Lathe - Collector ***AND*** Fan ???

[Glen Blanchard]

I have seen many suggestions to have a fan blowing across the lathe (in an attempt to move the dust away from the work area) in concert with using a dust collection system, but this has always made me wonder. It seems counterintuitive to me. I have a 3HP cyclone dust collector with a 'big gulp' at the lathe, which seems to do a very nice job of collecting the dust created when sanding. Yes, I know it is the dust that you CAN'T see that is harmful, and thus I have no way of really knowing if THAT dust is being collected. However, I figure if the big gulp is sucking up the dust I CAN see, that it is probably collecting the smaller stuff as well. But anyway......does it make sense to also have a fan blowing the dust away from the lathe before the DC has a chance to grab it? Wouldn't that just create a great deal of airborne dust? I mean, it would make sense if one has no DC - just get the dust away from the lathe. I get that. But if one has a (seemingly) effective DC?

Jim Burr, what say you?

[Michael Stafford]

I have a cheap dust collector and I know it collects a lot of dust however when I clean and dust my shop the very next day after using my lathe invariably there will be a fine layer of sanding dust on every horizontal surface.

My shop is not heated so I do not turn much in cold weather but whenever I am sanding I place a high velocity fan in the window behind my lathe exhausting out. This seems to remove more of the sanding fines than my dust collector. When it is hot I place another high velocity fan in the second window behind my lathe exhausting out and a third on the floor in front of my shop door blowing toward me providing the ultimate in flow through ventilation.

It seems to work better than dust collection alone. I do not have one of the ceiling mounted dust collectors which might pull the fines that my cheapo collector misses. But in my case I like the efficiency of the fans at removing dust and cooling Big Mike.

By the way when I clean the shop I sweep and vacuum all of the material I can get up and then I turn on all three fans to high with them exhausting out. Then I take the electric leaf blower and blow every surface in the shop until they sparkle. By the way it is a good idea to put away your sanding discs if you use this option as they tend to end up all over the shop and in the back yard. DAMHIKT! The fans clear the air for me and I have a clean shop for a few days. Beats mopping and since I can't get the wife to do it for me it is the best available option I have.

Airborne dust is more than an eyesore. It is a hazard to your lungs so remove it at the source if you can. Learning to use your tools so that cleanly cut surfaces are present and less sanding is needed is one good reason for becoming proficient in tool sharpening and use. I also sand lots of my turnings with wax which controls a lot of the dust. I have also seen some professional turners who were irritated by sanding dust sand with water. Just do something to control the dust to reduce shop cleaning time and to protect your lungs.

[Fred Belknap]

258306Glen I guess there isn't any great answers. I am particularly sensitive to dust, having worked in dusty conditions most of my life and old age, so if I want to continue woodturning I needed some protection. I put a exhaust fan blowing out at the end of my lathe, I also have a 6" pickup to a DC that travels with the headstock and exhausts outside to a collector with no filter. I found that in sanding and dry dusty wood I still need to use a Trend Pro face shield. It works for me. I tried the big gulp but got frustrated with having to move it each time I moved the headstock. I also tried the fan blowing toward me with filters on the intake side. It seemed to just spread the dust around. Even in the winter I open a window about 2" across from the lathe to let in fresh air, I can handle the cold better than the dust.

[Bernie Weishapl]

I also have problems with dust and bronchtis. I use a air cleaner that hangs from the ceiling above my lathe, along with the DC with two hoses on either side of the lathe bed and a Air Stream 400. It has cut down on the dust accumalating in my shop by at least 80%. Now I just have to get off my duff and get something done about controlling the chips from going everywhere.:D I had but don't use the big gulp because like Fred it seemed like it was in the way all the time. So I just have the hoses positioned at the lathe bed and it seems to work as well.

[David C. Roseman]

Glen, great question. Interesting to see how other turners approach this. A recent SMC thread in the Workshops section touches on this; you may already have seen it:
http://www.sawmillcreek.org/showthread.php?200853-Dust-suspends-how-long!

I think a large fan blowing air indiscriminately across the lathe would probably just scatter the finer dust unnecessarily, and could even disturb the cone of vacuum into the Big Gulp that the DC sets up. But a more focused stream of air blowing from behind the operator toward the Big Gulp could enhance its effectiveness.

My DC is a 3 hp four-bagger that sets up quite a vortex through the Big Gulps behind the lathes. It even pulls in some of the largest chips. But I'm intrigued by the idea of trying to create positive-pressure air flow, as distinguished from vacuum, to direct clean air past my face. Turners tend to stand in one place for longer periods of time, so it seems feasible to come up with a way to have a gentle, positive flow of cleaner air directed over our shoulders toward the direction of the vacuum intake. My JDS ambient air filter is above and behind the operator, but it has a very diffuse exhaust that isn't easily directed.

One idea I’m toying with is to locate a small air-supplying turbine at one end of the shop (or in another room), plumb the clean air along the ceiling to above each lathe using 1” cpvc sch. 40, then do short ceiling drops to put the output behind and above the operator’s head, directed toward the Big Gulp intakes. Turbine Products makes one that should work for that for about $250. http://www.turbineproducts.com/servlet/Detail?no=3

An easier, cheaper way would be to just hang a couple of six-inch fans on brackets from the ceiling, blowing over the head or across the shoulder toward the intakes.

We can always wear a dust mask or respirator under our face shield, or a dedicated supplied-air face shield or bump-cap with shield. But there are some disadvantages there, too.

David

[Roger Chandler]

My dust collection process has three steps:

1 - dust collector with big gulp hood behind the lathe. It collects most sanding dust

2 - An overhead air cleaner......just above the lathe and behind me a little when I stand there........hopefully it gets down to 1 micron or less particles floating in the air.

3 - A Trend Airshield Pro helment.........worn when sanding especially.......sometimes as well when the wood being turned is dusty and dry. In my current shop configuration.......I don't know if I can get it any better than that........however, if I had room for it, I would also have a fan blowing the dust away from myself and outside whenever I could, but my space is very limited.......

[Reed Gray]

Maybe it is time to post this clip again. The fans work better if they are blowing the dust away, rather than sucking it away. Mostly the 'plume' expands as it goes away from the fan, so it covers a larger area. This method can be very effective if your shop has 2 doors, and preferably garage car doors so it all blows away. The idea with my sanding hood is that the piece I am sanding is entirely inside the hood. This means the sand dust plume is also entirely inside the hood, so none of it escapes. I do get some on my hands, and some on the front of my smock, but nothing on the glasses or in my nose. A hose close to the turning can get a bit of the plume, and a big gulp cup type can get more of the plume, but not all of it. The only down side to mine is that I can't leave it on for turning. My next version will involve getting some sheet stock of the plastic (available in 4 X 8 sheets), and having a frame made that stays on the lathe, and I will be able to put baffles in it to section it off for turning and sanding bowls or long spindles.

http://www.youtube.com/watch?v=AZsVc7qVx7A

robo hippy

[Michael Stafford]

Trust me Reed, the high velocity fans I am using pulls the dust right out the window. When the sunlight streams in you can see the dust plume leaving the room. You need to get a stronger fan out there. ;) :D

[Jim Burr]

I have kind of a funny set-up Glen. My shop is 8x22'ish.There is a Jet AFS 1000 (http://www.amazon.com/708620B-AFS-1000B-Filtration-Electrostatic-Pre-Filter/dp/B00004R9LO/ref=sr_1_fkmr1_1?s=hi&ie=UTF8&qid=1364430221&sr=1-1-fkmr1&keywords=jet+AFS+1200) scrubber on the ceiling that is an amazing work horse and reasonably priced I might add. The window, a 3o5o is usually open and I have abox fan blowing out the window. There is also a big scoop on the back of the lathe run by the 5hp shopvac. Once a week I open door, turn everything on and blow everything out, takes 10 minutes and gets the dust out from under the cabinets...there is very little! I set it up so the tools can do the work. The only time I use a fan pointed at the work is when using CA. If I even think of walking out the door w/o my Trend, my wife gets involved...she likes me around and can be very convincing! It works really well and I haven't had to adjust anything yet.

[robert baccus]

Thought I was going to die of respitory? problems my first year of turning. Year 2 I bought a 20" general and put it on a back wall. A few minutes with a chainsaw and I mounted a 32" exhaust fan just behind the lathe. Added some baffles to concentrate the suction and a foot on/off switch--useful in cold weather. I do grab a light mask on really dangerous woods. In hot weather I add a 36" rolling fan to the opposite side of the shop for cooling and added dust and spray removal. Both of these are an explosion hazard as well as lung problems.

[Ron Rutter]

David. The 1" pipe would give you a concentrated air flow when what you need is lazy flow that will cover a larger area. The same principal applies on a pick-up. A large pick-up doesn't tunnel. The volume is the same but the lower velocity is better at picking up fines. Ron.

[David C. Roseman]

David. The 1" pipe would give you a concentrated air flow when what you need is lazy flow that will cover a larger area. The same principal applies on a pick-up. A large pick-up doesn't tunnel. The volume is the same but the lower velocity is better at picking up fines. Ron.

Thanks, Ron. Agree with you that a lazy flow around the face would be best for the positive-air pressure approach. The 1” cpvc sch. 40 would be to bring the clean air from the remotely-located turbine to the ceiling above the work stations. I’d then transition to a fitting (maybe a DIY manifold) to fan it out around the shoulders. I’d then also have the option of dropping a 3/4” flex hose to a supplied-air bump-cap face shield for very dusty projects, or toxic finishing.

I’m no engineer, but I do think there may be a difference in cfm fall-off as between a plume of blown air and a cone of vacuum-induced flow. Another turner, Larry Kunkler, makes this point in the SMC thread I linked to above. If I’m understanding it correctly, the concept is that the fall-off in the volume of blown air varies as the square of the linear distance to the target, while vacuumed air falls off as the cube of the distance. So, in terms of moving fines suspended in air away from a specific place (our face/work station), positive pressure is more effective than negative pressure (vacuum). Does that sound right? Maybe Larry or some others can jump in with how we know this is so, assuming it is. One thing that occurs to me is that what we really care about is the effective pressure acting on the dust, rather than cfm of air moved in a given area.

David

[Reed Gray]

Again, for me, the more enclosed the piece you are sanding is, the higher percentage of dust goes into the dust collector. Even if you use a box fan, make a big vent to enclose the work, and you will get all of the dust, not most of it.

robo hippy

[Jim Burr]

WORKPLACE MONITORING AND MEASUREMENT

Determination of a worker's exposure to airborne wood dust is made using a tared low ash polyvinyl chloride filter (5 microns) preceded for respirable fraction sampling by a 10 mm nylon cyclone. Samples are collected at a maximum flow rate of 1.7 liters/minute (respirable fraction) or 2.0 liters/minute (total dust) until a maximum collection volume of 816 liters (respirable fraction) or 960 liters (total dust) is reached. Analysis is conducted by gravimetric methods. This method (for nuisance dusts) is described in the OSHA Computerized Information System [OSHA 1994] and is fully validated. NIOSH has published a similar methods (Method No. 0500 and 0600) for the sampling and analysis of nuisance dusts [NIOSH 1994b].

All this assumes there is laminar (perfectly smooth) intake and flow patterns to your collection device. Keep in mind that if you meet/exceed the flow requirement, this should work for all but the smallest particles, but they just bounce off stuff anyway. Reducing the area/volume of the affected area should result in better particle removal. Keep in mind though, any distrupion in suction flow or a positive charge on a surface will allow particles to deposit where they darn well please.

[Josh Bowman]

I have modified mine since this picture, but the concept is still the same. I just aim it close while I sand or turn dusty woods. It works great. I also discharge my DC outside into a trailer. If the DC catches it, I get 100% dust removal.

[Glen Blanchard]

Josh - That looks like a Pelton and Crane light. Very cool!

[Ron Rutter]

Thanks, Ron. Agree with you that a lazy flow around the face would be best for the positive-air pressure approach. The 1” cpvc sch. 40 would be to bring the clean air from the remotely-located turbine to the ceiling above the work stations. I’d then transition to a fitting (maybe a DIY manifold) to fan it out around the shoulders. I’d then also have the option of dropping a 3/4” flex hose to a supplied-air bump-cap face shield for very dusty projects, or toxic finishing.

I’m no engineer, but I do think there may be a difference in cfm fall-off as between a plume of blown air and a cone of vacuum-induced flow. Another turner, Larry Kunkler, makes this point in the SMC thread I linked to above. If I’m understanding it correctly, the concept is that the fall-off in the volume of blown air varies as the square of the linear distance to the target, while vacuumed air falls off as the cube of the distance. So, in terms of moving fines suspended in air away from a specific place (our face/work station), positive pressure is more effective than negative pressure (vacuum). Does that sound right? Maybe Larry or some others can jump in with how we know this is so, assuming it is. One thing that occurs to me is that what we really care about is the effective pressure acting on the dust, rather than cfm of air moved in a given area.

David
David. The problem I see with blowing is you are spreading the dust far & wide & not capturing it. Reed's approach is best & can be applied to the turning as well. The only problem there is that the shavings can plug up any screen you may have over the inlet. To me the best overall solution would be a fairly high volume fan pulling the (low velocity) air through a cyclone with a drop box. This keeps the chips out of the fan & ideally you could filter that heated air & return it to the shop!! I built two cyclone/ drop box set-ups for our seniors WW shop 4 years ago & if the drop boxes are checked properly the bags never accumulate dust or shavings. Check the Bill Pentz website for the cyclones. Ron.

[Rick Markham]

Glen, I'm in the process of building a version of Reed Gray's sanding shroud. The shop is nearing completion and I will take some pics as soon as I have it completed, mine is going to be piped via a 6" connection in a straight 8' run to the 5HP Clear Vue :cool:. My guess is little will escape it's grasp (like the vortex.) But I will still be wearing my 3M Adflo, the simple fact is sanding on the lathe is essentially flinging the dust particles in all directions. There really isn't a perfect mousetrap (hence the PAPR, best money I ever spent, next to the clearvue.) Personally the idea of using a fan to create more turbulence in the surrounding air just spreads the fine particulates and causes them to remain airborne longer. Realistically, there isn't an operation, no matter how good or powerful your dust collection is, that you shouldn't be wearing breathing protection. The way I look at it, the PAPR system is for my health, the Clear-vue cyclone is for my families health, and makes it easier to clean LOL.

I always wore my faceshield, but until I integrated the breathing protection, I didn't always use that. Now it is incredibly uncomfortable not to wear it, and you never have wood boogers again :eek:

[Glen Blanchard]

Well I have never had wood boogers, so I would imagine that's a good sign. I wear a faceshield and a 3M N100 respirator anytime I am at the lathe. My 3HP Oneida cyclone is turned on and I have an air scrubber directly above the lathe. It appears that the big gulp is catching it all, but then again it's the stuff we can't see that is of concern. I hope the measures I employ are sufficient as I have heard of turners who acquired emphysema later in life supposedly as a result of refusing to wear any kind of lung protection.

It appears that I am doing a pretty good job of acquiring the fines at the source, and that a fan would be counterproductive. The reason I started this thread is to see if I am missing something when it comes to using a fan along with a DC system.

[Rick Markham]

Sounds like you are doing a very respectable job of getting the dust, the breathing protection is really the most important thing. Not having wood boogers is always a good thing

[Jim Burr]

Well I have never had wood boogers, so I would imagine that's a good sign. I wear a faceshield and a 3M N100 respirator anytime I am at the lathe. My 3HP Oneida cyclone is turned on and I have an air scrubber directly above the lathe. It appears that the big gulp is catching it all, but then again it's the stuff we can't see that is of concern. I hope the measures I employ are sufficient as I have heard of turners who acquired emphysema later in life supposedly as a result of refusing to wear any kind of lung protection.

Either emphysema or worse...Fibrotic lung disease. I can treat emphysema and stabilize it. Fibrosis can be cured with a lung transplant.

[Chris Parks]

Lathes are an issue that take a bit of thinking about and a lot of serious work on the dust capture side. I would build an overhead hood and put as many exhaust fans in it as possible, run them into a plenum and exhaust that directly to atmosphere through a big duct. The duct would be built from timber/MDF/plywood as it is unlikely a round one could be bought that would carry enough volume from the fans. It could be quite shallow but wide to limit intrusion of head height. You want to feel a strong draught passing your body into the hood, if you can't you are not moving enough air. You could run the plenum into a good DC instead of a dedicated duct but the DC might struggle to remove the quantity of air that multiple large exhaust fans move.

[Rick Markham]

Volume of air movement in as efficient a manner as possible is the name of the game. If you can't vent outside or provide adequate make up air for venting outside then serious consideration must be made to how you are processing the return air for ultra small particulates. If your system isn't efficient at processing the air you are moving then essentially you are creating a giant mechanism that is going to keep the small particulates in a "liquified" state in your environment. It's all a delicate balance, and it's important we discuss these issues. :)

Bottom line the only sure way to make sure you aren't breathing the crap is to wear an excellent respirator and take care of it.

[Chris Parks]

This man knows ^. There is a large body of WW's who refuse to acknowledge that fine dust is the enemy let alone agree on methods needed to control it. They accuse anyone who advocates this approach of being fanatics and there was a case of this recently within these forums.