Wood Shop Dust Collection

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Matt Triano (Officially)

History

  • 2014-05-22 - Discussion open on member list
  • 2014-05-27 - Announced
  • 2014-06-02 - Vote

Background

The proposal is to buy a cyclone style wood dust collection system that can bring the dust down to a safe level. The current system (Jet collector on the table saw, shop vacuums on the small machines) catches only the large particles and distribute the smallest, most dangerous, particles through the shop. Some of the woodworking tools, e.g. drill press & bandsaw, have no provisions for dust collection.

Health Hazards of Wood Dust

Exposure to wood dust has long been associated with a variety of adverse health effects, including dermatitis, allergic respiratory effects, mucosal and nonallergic respiratory effects, and cancer. Contact with the irritant compounds in wood sap can cause dermatitis and other allergic reactions. The respiratory effects of wood dust exposure include asthma, hypersensitivity pneumonitis, and chronic bronchitis.

Do we produce enough dust for it to be a problem?

A single ripping cut with a thin kerf blade of 5/4 oak plank 8' long will create 10 grams of <15 micron dust. If distributed evenly throughout the shop, this would create a dust concentration of 9.1 mg/m**3, much greater than the ACGIH hardwood limit of 1.0 mg/m**3. In addition, fine dust is difficult to remove. When it finally settles, sweeping causes much of the dust to again become airborne. Vacuuming is only effective when using a fine filter. So the fine dust tends to accumulate, bringing the airborne dust levels higher and higher.

Calculation: https://docs.google.com/spreadsheets/d/18togRk2AZD1RfjSE-m5PjONLy_UOMeJCfzvsSp8gQTg/edit?usp=sharing

10% of dust (by volume) generated by sawing oak consists of particles smaller than 15.1 microns. http://annhyg.oxfordjournals.org/content/44/6/455.full.pdf Approximately 1/3 of this is < 10 micron.

This is an interesting graph showing the distribution of particle sizes created by various woodworking operations. http://en.wikipedia.org/wiki/File:Particle_size_distribution_of_hardwood_dust.jpg

Particle Monitoring

The most hazardous dust particles are too small to be seen (<10 microns). To determine the effectiveness of the collection system, we will use a relatively inexpensive laser particle counter, such as: http://www.dylosproducts.com/dcproairqumo.html This will help us fine tune the collection system and tell us when there is insufficient flow due to duct blockage, excessive open gates, or dirty filters.

Goals

  • Achieve better air quality inside the shop than outside.
  • 4000 FPM air flow in ducting.
  • Meet American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) of 1 mg/m**3 Time Weighted Average (TWA).

Dust Collector

http://www.clearvuecyclones.com/cv-max/13-cv-max-three-phase-with-filters.html

Collector dimensions are approximately 24" x 52" x 96" tall.

5 HP motor (Leeson 132242.00, frame 184TC, 86.5% efficiency, 12 f.l. amps, 230v. 3 phase)

This dust collector will have sufficient flow with two open gates. Occasional use with three gates open is acceptable. The 'nano' filter option ($100) is recommended (Efficiency: 99.999% at .5 micron) Collector cost with nano filter is $2070.

Clearvue technical support does not recommend mixing wood and metal dust in the same collection system.

Ducting

6" PVC solid core sewer & drain pipe for drops

8" PVC solid core sewer & drain pipe for main lines

Down Drops

Each large machine or cluster of small machines will require a down drop from the main duct to the machine port or manifold. The drop will require:

  • 8x8x6 DWV PVC Wye fitting (the last drop on the main could use a 8"45 & 8" to 6" reducer instead of a wye. this would probably be cheaper the wye plus a cap.)
  • 6" 45 elbow
  • approximately 5' of 6" PVC pipe
  • 6" blast gate
  • short length of 6" flexible hose (length dependent on machine).
  • switch (wireless or wired) to control the collector motor near the blast gate.

down drops:

Automating this stuff

Initially, the dust collector will be turned on and off manually and the blast gates will be opened manually. After all the wood working machines are connected to the dust collector, we will work to automate the gates and collector motor - turning on a tool will activate the collector. https://wiki.pumpingstationone.org/File:Blast_gate_back.svg https://wiki.pumpingstationone.org/File:Blast_gate_front.svg

Wood Working Machine Collection Strategies

  • ShopBot Router - A dust skirt with port is included with the machine. We will need to provide a flexible hose and support. Probably a transition from 6" down to the skirt port. Size of the port is unknown at this point.
  • SawStop Table saw = Initially use 6" drop to a 6" to 4" tapered transition connected directly to the stock cabinet port. 3" duct to the blade guard. Consider this blade guard: http://www.thesharkguard.com/ Monitor result and increase the cabinet port size to 6" if required. Useful discussion on dust collection for the sawstop: http://lumberjocks.com/topics/33892
  • Jointer = currently has a port approximately 4" in diameter. It appears that we an install a 6" port without difficulty and with no permanent changes to the jointer.
  • Mitre saw = this tool throws a lot of dust at high speed and is one of the more difficult tools to collect dust effectively. Definitely needs a shroud.
  • Delta 14" Bandsaw = Add a 4" port to a new lower wheel cover (make out of wood?) This is Ed's saw and we don't want to permanently modify the existing cover). http://www.highlandwoodworking.com/bandsaw-dust-control-that-works-2.aspx
  • Belt/disk sander (probably needs a shroud for the belt, or just a better sander)
  • Planer (could probably use side shrouds)
  • Drill press

Collector Location

The dust collector will be either centrally located in the wood working area ( to minimize duct lengths) or at the back of the shop to keep it out of the way and minimize the effects of the noise. The main duct will be run overhead, most likely lying on the bottom member of the ceiling trusses.

Bill of Materials & Budget

See spreadsheet for cost details: https://docs.google.com/spreadsheets/d/1DEpszf0J_o_FLTqVH8XopYjlOpG-GloZYVA1FlCf_E8/edit?usp=sharing

Clearvue CVMAX 3 phase with nano filters

Filter clean out box

round fiber drum (at the base of the cyclone. stores chips & coarse dust)

Dylos DC1100-PRO-PC air quality monitor

For each down drop (5 total):

  • 6" blast gate
  • 3' 6" flexible tubing.

Shark Guard blade guard for SawStop

7 pieces of 8"x10' DWV PVC solid core pipe

6" flexible PVC hose 25' $92 http://wynnenv.com/products-page/woodworking_hose/pvc-hose/

miscellaneous mounting hardware (all thread rod, beam clamps, hose clamps)

Caulk (for PVC pipe)

electrical (wire, conduit, circuit breaker, switches, relay)

Operating cost estimate:

3.24kw X .12$/kwh = $.39/hour

(filters last indefinitely with regular maintenance)

Installation

The installation of the dust collection system will be done by PS1 volunteers. We will target the machines that produce the most dust first (likely the CNC router and table saw). Many of our woodworking machines have inadequate provisions for dust collection and will require custom shrouds and some tinkering to make them effective. This work may take longer than 90 days to complete for all the machines. Because of this, the spending authorization for the ducting and accessories will be extended.

The PVC joints will be sealed with silicone caulk rather than glued, to allow for reuse of the pipe and fittings if we have a layout change.

For planning purposes: the current woodshop is approximately 34' x 21'. Ceiling is 14'.

Electrical Requirements

3 phase 230v, 12 amps. The collector motor will be switched through a relay controlled by a low voltage switches near each blast gate.

Dust Collection Links

http://billpentz.com/woodworking/Cyclone/index.cfm

http://sandwichtechskis.com/ski-builders-shop.htm

Overview of wood dust and collection:

http://www.fwwa.org.au/Art005_WoodDust_c1.pdf

Language

Authorize the board to spend up to $4854 on a dust collection system. Authorization for the dust collector expires in 90 days. Authorization for the related equipment (ducting, hardware, ports, etc) expires in 180 days.

Receipts

[1]

[2]

[3]