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dust control via sanding booth

Joined
Aug 19, 2021
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Location
Mt. Vernon, IA
I have been using a box fan with a furnace filter hanging behind my lathe for a while now, and for the most part, it seems to work well. I've been thinking of upgrading to the typical dust cyclone/fan system. However, given the challenges of trying to collect dust using a suction system and the fact it's the invisible stuff that kills you, I am starting to ponder the idea of designing a sanding/spray booth like they use in industry. Any turners have their lathe in a cross-draft booth for dust control? Anyone have a sense regarding the feasiblilty of designing one using common MERV13 furnace filters and still catch the invisible stuff (PM2.5)?
 
Joined
Nov 15, 2020
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Huntington, VT
Robo Hippy has documented his "sanding in a barrel" setup here sanding hood

A sanding booth is a good idea but you will need to plan for sufficient airflow and effective filtration (or exhaust to the outdoors). Spray booths typically are designed for 50-100 linear ft./min. If the booth opening is 8' x8' (64 sq.ft.) that would call for a blower moving 3200-6400 cfm while accounting for any loss due to filters. That's a lot of air- if it's going outside you may need a heated makeup system. If it's being recirculated you still need a big blower. It's more efficient to restrict the catch area with good hood design. You might think about designing a "booth" with wall and ceiling panels enclosing the lathe closely to keep the airflow requirements down.


Filters are another big subject. MERV 13 furnace filters are not going to capture the smallest particles. Some people insist on HEPA level filtration which is supposed to snag most particles down to .3 micron. A common rule of thumb in dust collection systems is to have a minimum1 sq.ft. of filter area for 10 cfm of airflow. That gets expensive fast. That ratio might not be applicable to a low velocity "booth" though. You also need to consider cleaning the filters- a single stage system will blind the filters with fine dust relatively fast and anyone who has had to clean out a cartridge filter after accidentally clogging it knows what a pain it can be.



I assume most turners (and woodworkers) in general) struggle with this. I have a 6" drop from a 3hp cyclone system to a rudimentary hood on a pivoting arm behind my lathe, and I run a 2,000cfm ceiling mounted ambient air filter, plus I wear a papr when sanding.
 
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Joined
Aug 14, 2007
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Eugene, OR
Thanks for posting that link Brian. I do plan to upgrade my sanding hood. Mostly I want one that can stay in place for turning, rather than my design that only goes on when sanding. I did try a more open booth, but you need huge air flow to make that work, like maybe 10 times what any average shop dust collection system could put out. You can buy that white plastic like my barrel is made out of in sheet stock, up to 5 by 10 sheets. I found out that 1/4 inch thick stuff is pretty difficult to bend to the shape you want, but with lots of ropes, you can get it to bend. I am thinking that 1/8 inch stock would be perfect. The black hole/slurpy type hoods do about half the job, maybe fine for spindles, but not as good for bowls. It would be fairly simple to add wings to the sides, and/or an under and over part that you could add on or take off, depending on what you are sanding. Been on my mind for a number of years not. I do like the idea of having a hood on rails behind the lathe so you can slide it around to properly position it.

Still trying to come up with a better model of my articulated arm for bowl sanding. Can't sand without it. I want a flex shaft that mounts on a vs mini lathe and/or motor, and a mandrill that goes on the arm, and can handle a 5 or 6 inch disc.... Always some thing else to invent....

robo hippy
 
Joined
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Bozeman, MT
Brian, I'm not as expert as the posters above, but I will offer one observation. I used to use the box fan/furnace filter set up and it certainly collects dust. About 1.5 years ago, I installed an actual air cleaner, and it's 2 orders of magnitude better at getting fine stuff out of the air. Now if somebody would only make the odd filter size for these units and provide some competition for the manufacturers...
 
Joined
Feb 26, 2019
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Lebanon, Missouri
It’s certainly feasible to create a x- draft booth for dust control. It would be similar to a paint booth. Research is required to determine the velocity in the open end to carry the dust to the collection point. Take into account the negative velocity (dust traveling against the air flow) particularly if power sanding. The blower size will get big, and the sq ft of filter area to maintain flow will get big, but it’s doable. You will have to filter/recirculate unless you turn at outside ambient temp. Look up Bill Pentz dust collection. How much $ you got budgeted?

I looked at dust collection several years ago, more flat work oriented vs turning, but all the concepts apply. To get the airflow and filtration necessary to actually meet OSHA type stds became prohibitive in my view, and I chose a cheaper route, a papr system (Versaflow).
 
Joined
Aug 19, 2021
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Mt. Vernon, IA
At this point I'm just trying to wrap my head around the feasibility of a wind tunnel, as Mark puts it, and there is always the cost/benefit angle to consider. The PAPR route is certainly less $ than a cyclone-type but doesn't keep dust from infiltrating every square inch of the shop. The cyclones have to be big enough to capture the small stuff in the air stream and there is the filtration issue at the other end you have to contend with--otherwise you are just pumping the small stuff into the shop. Seasonal temperatures here also make replacement air a real thing to contend with. I am quickly understanding why there are engineers...
I'll tinker around with specs and see if I can come up with a design we can poke at to see if it makes sense.
 
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Feb 26, 2019
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Along with a papr I do use a small 1-1/2 hp DC with large pleated paper filter to catch dust, it just isn’t 100% effective. I have a 1000 cfm filtered blower for spraying I use as a “shop filter” though it doesnt have as fine of filter as the dc. There are the fine filtered shop filters available also. These help with capturing a lot of the dust that settles around the shop, but do not prevent inhaling the dust as you are sanding. You might figure some of these ideas into your “ dusting program”.
 
Joined
Jun 6, 2018
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La Grange, IL
Is anybody here using the PM 1250?


I have been wondering about positioning one so that filtered air is blown at my face? I wear a PAPR and run DC and a room air filter, but I'm wondering if this offers any alternatives/benefits? Particularly if the price would come down by a factor of 2 or 3 :) .
 
Joined
Aug 14, 2007
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Eugene, OR
The box fans do move a fairly small amount of air. The dust sources in the shop are many. Just about any hood will get most of the dust, but not all of it. Just getting dust on your shirt or smock and walking through the shop stirs up dust. Picking up shavings creates a lot of dust. Best bet is to try to get it before it escapes, so at the source. The air scrubbers are a nice addition.

As for a wind tunnel, that would cover it. On my bucket list is to get into one of the vertical wind tunnels. It won't be as much fun as my days of being a hang glider pilot, but it would get me off the ground again....

robo hippy
 
Joined
Jun 6, 2018
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Wait! You're on to something. A lathe in one of those skydiver wind tunnels. Plenty of filtered air, no cleanup and no sore feet or tired back from standing at the lathe all day. A real boon for seated turners and just think of the body motion that's possible. :Do_O:eek:
 
Joined
Jan 22, 2009
Messages
238
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225
Location
TN
Robo Hippy has documented his "sanding in a barrel" setup here sanding hood

A sanding booth is a good idea but you will need to plan for sufficient airflow and effective filtration (or exhaust to the outdoors). Spray booths typically are designed for 50-100 linear ft./min. If the booth opening is 8' x8' (64 sq.ft.) that would call for a blower moving 3200-6400 cfm while accounting for any loss due to filters. That's a lot of air- if it's going outside you may need a heated makeup system. If it's being recirculated you still need a big blower. It's more efficient to restrict the catch area with good hood design. You might think about designing a "booth" with wall and ceiling panels enclosing the lathe closely to keep the airflow requirements down.


Filters are another big subject. MERV 13 furnace filters are not going to capture the smallest particles. Some people insist on HEPA level filtration which is supposed to snag most particles down to .3 micron. A common rule of thumb in dust collection systems is to have a minimum1 sq.ft. of filter area for 10 cfm of airflow. That gets expensive fast. That ratio might not be applicable to a low velocity "booth" though. You also need to consider cleaning the filters- a single stage system will blind the filters with fine dust relatively fast and anyone who has had to clean out a cartridge filter after accidentally clogging it knows what a pain it can be.



I assume most turners (and woodworkers) in general) struggle with this. I have a 6" drop from a 3hp cyclone system to a rudimentary hood on a pivoting arm behind my lathe, and I run a 2,000cfm ceiling mounted ambient air filter, plus I wear a papr when sanding.
For what it's worth, I've evolved to essentially the same system as Kevin. 6" drop coming from 3hp cyclone attached to rig on PM3520 headstock so it's always right behind where I sand; a whole-shop air filtration box on the ceiling over the lathe; and I wear a PAPR. I purchased the CleanAir PAPR 1.5yrs ago and have gotten in the habit of always wearing it when I turn which has the added benefit of being that I have a face shield on (which I didn't use very often before). Habits are a nice thing: first thing into the shop I put on my smock, then wireless noise canceling earbuds tuned to my favorite radio station, then my CleanAir; cyclone is always switched on before I sand.
 
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