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Delta 50-767 Dust Collector Performance

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Blog entry by deejay34 posted 01-07-2017 10:36 PM 1129 reads 1 time favorited 3 comments Add to Favorites Watch

Still being relatively new to woodworking, it didn’t take me long to figure out that my shop vac just wouldn’t cut it when it comes to dust collection. So, I did what I always do and spent way too much time looking at different makes/models/types of dust collectors, trying to figure out what might fit the bill. Several months back, Home Depot was running a special on the Delta 50-767 unit for $400 (regularly $499). Since I had $350 in Lowe’s gift cards, I went to the store, asked them to price match (which they did), and they even deducted an additional 10% (total purchase price with tax was $395). In my past experience dealing with Lowe’s and price matching, it was always my understanding that they would only deduct the additional 10% if the item was available in-store (which the dust collector was not). I certainly wasn’t going to argue. Bottom line, the customer service that I received was very helpful and professional. Below are some quick specs. on the unit:

• 1-1/2 hp max.
• Electrical capability for 120V (12-Amps) or 240V (6-Amps) (factory pre-wired at 120V)
• 11-1/2 in. diameter impeller
• 6-in. inlet (comes with adapter to convert to two 4-in. inlets)
• 1-micron filter bag (a quick note on this below)
• Max. performance of 1500 CFM

Regarding the filter bag, the manual specifies “1-micron”, while the Delta website specifies “2-micron”. For what it’s worth, both Home Depot and Lowe’s both state “1-micron”. I’ve inquired with Delta customer service on two separate occasions to try and resolve this discrepancy to no avail. Both inquiries were submitted via Delta’s online support; maybe I should give them a call? In any case, I’ll likely upgrade to a canister filter in the future, at which time this will be a moot point…but I’d still like to know what’s what.

Fast forward another 2-weeks and the dust collector arrived…on its own pallet, removed from the truck with lift-gate service, and wheeled right into my garage…at no additional charge. I have to admit, before I even plugged the unit in I was very satisfied with the process thus far. The unit was well-packaged, no missing/damaged parts, and all the nuts/bolts/odds-and-ends were there. Assembly was straight-forward, and I had everything together in about an hour. Lifting the motor assembly was the most difficult part given the weight/bulk, but I managed on my own without issue. I plugged the unit in, it fired right up, and sucked the wind right out of the garage.

I’ve had this collector for several months now, and I’ve put a little bit of time/use into it already. Not extensive use by any means, but enough to know that I’m satisfied with the purchase of my first dust collector. I should also mention that I have no intent of asking this dust collector to serve as a central unit for all of my tools. Given that I operate out of a two-car garage (in which my wife and I both park our cars), all of my tools are mobile. When working, I simply move my car out of the garage, roll the necessary tools away from the perimeter and into working space, and roll the dust collector around to connect to whatever tool is in use at the time. Not ideal by any stretch, but it works for me. The main downside that I’ve noticed thus far is the assembled height of the unit…a whopping 92-inches. The rear part of my garage has a lower height ceiling than the front part due to some plumbing runs, but it’s not that big of a deal. Should I choose to set-up shop inside the house in the future, I think it will barely fit beneath the floor joists in the basement…but that’s another problem for a later time.

Now on to the main point of this post. Before I get started, I have to thank Redoak49 for his blog post on performance testing of his Oneida Dust Gorilla for giving me the motivation to pursue a replicate experiment on my own dust collector. Having put a little bit of time on my new dust collector and been mostly satisfied with its performance (it sucks good and picks up most of the dust), I was curious about putting some hard data to that performance. The ultimate goal of this experiment was to develop a fan curve specific to my machine. So, I perused Ebay for some equipment to get me started. I settled on a Dwyer 167-6 pitot tube, a Dwyer 2002 Magnehelic pressure gauge, and a Dwyer A-302 static pressure tip. I connected the pitot tube to the magnehelic using clear vinyl tubing in order to measure velocity pressure and secured them in place using synthetic wine bottle corks (the rubber kind), which provided a fairly rigid connection between the instrumentation and the duct. Total Ebay investment was about $55.

I also made a homemade manometer to measure static pressure, per the Stumpy Nubs tutorial. The left side of the tubing was connected to the static pressure tip attached to the duct and located in front of the pitot tube, while the right side of the tubing was left open to the atmosphere. I did not have any food coloring or dye at the time, so the water-line is a bit difficult to see in the picture, but was clearly visible in-person for recording measurements. For reference, the water-line on each side of the manometer is at +1-inch in the picture below.

While I typically use a 10-foot stretch of 4-inch diameter flex-tube for my standard dust collector connection, I decided to go with a 6-foot section of 26-gauge HVAC ducting for this experiment in an effort to minimize frictional losses associated with the rough inner surface of the flex-tube. Yes, I realized at the time that I would not be measuring performance as it pertains to my specific set-up (i.e. with flex-tube), but I wanted to try and minimize any artifacts that might distort the measurements as they would typically be measured in a real laboratory set-up. Now, the unfortunate part of the Delta 50-767 inlet port is that it is oriented vertically, not horizontally like a lot of dust collectors I’ve seen.

Accordingly, when set-up in the standard (i.e. out of the box) configuration, one needs to incorporate an elbow directly off of the intake port in order to permit a horizontal run of ducting. This in itself induces frictional loss right from the start; but, that’s exactly what I did by using a 4-inch HVAC 45-degree elbow.

In order to restrict air-flow for varying the static pressure loss, I mounted a cone-shaped oil funnel to a piece of dowel, which was supported by a roller stand. Inching this assembly closer into the end of the duct run allowed me to restrict airflow for characterizing flow as a function of static pressure.

Overall, it was a rather crude set-up, complete with a foam cooler and shop-rag box base and a Home Depot bucket support, but overall the test set-up worked rather well.

Below is a quick summary of the measurements. The static pressure measurements correspond to the readings on the left side of the manometer (connected to the static pressure tip), the readings on the right side of the manometer (open to the atmosphere), and the calculated delta, or difference, between the two (static pressure). The velocity pressure was measured directly from the magnehelic pressure gauge, then converted to air velocity and flow (CFM) using the information provided on the Dwyer website. I should point out that this experiment was conducted several months ago (I’m only now just getting around to posting), and the air temperature at the time was around 70-degrees, so I have not implemented any corrections for air temperature, as the calculations assume 70-degree ambient temperature.

Cross-referencing test data for the older Delta 50-850 as published by Wood Magazine (March 2008, pp. 66-71), I created a plot of the resulting measurements for comparison purposes. Overall, pretty comparable between the two.

This was in no way intended to be an exhaustive experiment, as it is admittedly incomplete. I underestimated the amount of velocity pressure that would be measured using the 4-inch duct, so I was unable to get higher up the CFM scale (maxed out just shy of 500 CFM). With a little more foresight, I would have purchased a higher capacity pressure gauge such as the Dwyer 2010, which measures up to 10-inches of water instead of 2-inches of water, in order to develop a more complete fan curve…which I still may do. Additionally, I would probably use PVC pipe instead of the HVAC duct, for no other reason than I could get a longer continuous run (10-ft. instead of 6-ft.) without a seam down the middle, which may or may not have influenced the results. If I were to repeat the tests, I would also install more permanent pressure taps in lieu of the synthetic wine bottle corks, as they may have protruded too far into the duct resulting in localized flow turbulence, thus potentially skewing the results. Finally, I’d measure current draw using a clamp-on ammeter (both at initial start-up and at constant impeller velocity) in order to characterize amps as a function of static pressure loss and/or flow. In theory, characterizing that relationship would allow me to better understand performance using current draw readings, which is a much simpler way for monitoring flow during dust collector use.

Overall, there are a few things I’d do differently if I were to do it again, but I’m happy with the results, and more importantly, I had fun learning some new things. Hopefully this may help others in the future!



3 comments so far

View Rick_M's profile

Rick_M

10451 posts in 2190 days


#1 posted 01-08-2017 05:57 AM

Good write up. I have no idea if the bag is 1 or 2 micron. I have an older Delta DC and it came with a 5 micron which I upgraded to a Delta 1 micron. I can’t tell a difference other than the new bag is made of different material and passes more air.

-- http://thewoodknack.blogspot.com/

View Redoak49's profile

Redoak49

2848 posts in 1798 days


#2 posted 01-08-2017 12:14 PM

You did an excellent job and got good info. Based on similar dust collectors and testing in Wood Magazine, I think that the max flow is probably around 700 cfm.

This is good info for others looking at dust collectors.

View pintodeluxe's profile

pintodeluxe

5421 posts in 2623 days


#3 posted 01-10-2017 02:46 AM

I used a similar Jet unit for years. The problem I had was the bag filter would clog with fine dust, with no easy way to clean it. When the filter clogged, the flow would drop to about 200 cfm, which isn’t enough to clear the pipes of chips. I switched to a cyclone because of these problems. Maybe you can add a separator of some kind to make it a two stage collector.

One HP collectors don’t do well with a separator added, but most 1-1/2 HP units will support a separator.

Good luck with it.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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