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Jet Proshop II dust collection or lack there of!

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Forum topic by NJWoodCrafts posted 10-26-2021 04:41 PM 405 views 0 times favorited 4 replies Add to Favorites Watch
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NJWoodCrafts

4 posts in 259 days


10-26-2021 04:41 PM

Topic tags/keywords: dust dust collection proshop

I took delivery of a new Jet Proshop II table saw a few weeks ago. As others have previously mentioned the dust collection needs some work. I made some changes to help with this yet they only helped slightly. I thought I would share what I did and accept any feedback as well as help anyone else struggling with this. The stock blade was replaced with a Freud full kerf combination blade. My dust collector is a Harbor Freight 2hp unit with a 10ft 4 inch flexible hose to the saw.

For those not familiar with this saw the dust collection is via a 2.5 inch hose connected to the saw blade dust chute down to the bottom panel. A 4 inch connection mates up to the 2.5 hose and a smaller opening is provided to pick up any dust that happens to fall into the cabinet.

The first change I made was to add 2 pieces of plexiglass in the cabinet that slope down toward the small opening provided from the 4 inch dust port in an effort to direct the dust closer to the port.

The second change I made was to try and block the open space surrounding the dust chute thereby allowing the dust collector a better chance of collecting the dust. From the photo you can see 2 magnets were used to secure the fixture to the cast iron table.

The last photo shows the saw dust that made it into the cabinet after ripping approximately 4 feet of a 2×4 and 2 feet of 1 inch poplar.


4 replies so far

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WilsonLR

40 posts in 49 days


#1 posted 10-26-2021 11:15 PM

Stepping back a moment … all saw dust is created by the blade contacting wood. The majority then follows the blade until centrifugal forces expel it. The more dust collected at the source, the better.

Unfortunately the Jet dust shroud on the blade is badly designed as are many. Most leave an opening opposite the arbor (so that the blade can tilt). That gap is the problem. Dust that flies past the suction of the collector and bounces off the insert can end up leaving the shroud. That gap is what allows dust to transition to the bottom chamber where you are putting energy. Saw dust is heavy enough to settle and stick like snow. You need a very steep angle to make an avalanche of dust close enough for your collector to overcome. It’s fundamentally a poor design and in terms of percentage effect, rather inefficient.

The 2.5” hose in the middle of the 4” port is getting 4.9 square inches out of the total 12.5 square inches of a 4” port. However, being in the middle, it’s getting the strongest part of the airflow so what’s left to evacuate dust from the cabinet is weak. This makes attempts to collect dust from the cabinet using the Jet design difficult. What some folks do is the put a Y in the dust collection and have one collect from the shroud and the other from the cabinet. With 2HP collection, I’d think you have lots CFM to spare. But you gotta get it before it rests on a surface.

I think the biggest gain will come by focussing on collecting as much of the dust as possible before it leaves the shroud. My Skilsaw Worm Drive compact jobsite saw has a shroud that does an extremely good job. There is very little dust on the floor. I believe it accomplishes this by fully enclosing the blade. Skilsaw did this by engineering a fixed piece of the shroud (aka it does not tilt with the blade but overlaps it as it moves. This piece closes gap opposite the arbor. I think that’s what you are trying to do with the wooden part but I can’t quite tell. A zero clearance insert will also help keep dust off the table

The good news is that the Jet cabinet at least captures the dust and keeps it from going all over the floor like the open body Delta 36-725 and Fusion F1 do. Think of it as a dust collector staging area where you come in and vacuum it out once a month.

I almost got a Jet but went for the Grizzly instead for it’s landing zone. I don’t expect it to have the Skilsaw design. I did notice the second generation Delta T2 models added a piece of fabric to close the gap and collapse like bellows during a tilt. Perhaps Skil holds a patent on its design. Dunno. But that doesn’t prevent us from DIY’ing one. YMMV

-- Les

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NJWoodCrafts

4 posts in 259 days


#2 posted 10-31-2021 06:16 PM

Les, thanks so much for your reply. I believe you are right on the money regarding where the collection needs to occur. I looked at the Delta 725 T2 and was impressed with the fabric they used to surround the blade. Alas like you said I will be periodically vacuuming out the cabinet!

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Wood_Scraps

203 posts in 311 days


#3 posted 11-02-2021 07:09 AM



Les, thanks so much for your reply. I believe you are right on the money regarding where the collection needs to occur. I looked at the Delta 725 T2 and was impressed with the fabric they used to surround the blade. Alas like you said I will be periodically vacuuming out the cabinet!

- NJWoodCrafts

I have the T2. Out of the box, it’s mediocre at dust collection. Collection to the rear port is pretty good. All the dust that gets tossed on top of the table is a different story. But, it doesn’t take much to make it significantly better. I designed and 3d printed two main components. One that sits under the throat plate that helps to deflect dust down towards the rear chute. The other is a chute that sits on the blade guard. Which can attach to either a 2.5” DC hose or a standard shop vac.

Between the two components, they make a massive difference. To the point where I barely get any dust on the table, even when ripping the edge off a sheet of MDF. And there’s frankly next to nothing that ends up on the floor.

Point is, don’t give up. Improving dust collection isn’t necessarily a tall order. Just takes some ingenuity, experimentation, and maybe a bit of luck.

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WilsonLR

40 posts in 49 days


#4 posted 11-04-2021 11:01 AM

I have a Grizzly G0899 arriving and am going to try and beef up its collection with my own extra DC capacity. To prove to myself I have it, I purchased a Dwyer Magnehelic gauge and a Dwyer pitot tube as per Bill Pentz recommendations. Then I ran a test at the intake of my collector. I have 4” ducting all around and only two 4” blast gates. The gauge reported more inches of water with two gates open versus one. I could be wrong but I’m interpreting that as proving I have excess capacity when only one port is in use.

Another note of interest is this paragraph from Bill Pentz where he recounts a time when he tested the air quality in his friend’s brand new shop who had designed and built the DC using Bill’s website. It failed due to the poor design of the table saw over arm guard dust hood. He explained why:

”The only way to capture the fine dust as it is made is to start with hoods that block the fast moving air streams. His dust problem was simple. His big new over arm blade guard was wide open in front so launched the dust off the tip of the saw blade right out under his guard. A 3450 RPM blade speed with a 10” diameter blade creates a 102 miles an hour air stream. His saw pulleys increase the blade speed closer to 4000 RPM so the blade tips launched the dust even faster. A typical dust collector or cyclone only moves air at about 40 miles an hour. With the hot rod oversized impeller on his cyclone, he was got 60 mile per hour air speed which had zero chance of capturing the well over 100 mile an hour dust stream. To effectively control the fine dust as it is made we must have hoods that mechanically block all the fast moving air streams or there is zero chance of effectively capturing the fine dust before it escapes collection. ”

EDIT:
He goes on to say how the Shark Guard solved that problem as well as some other interesting things such as collecting dust at the source etc. Here’s a link to that section: http://www.billpentz.com/woodworking/cyclone/ducting.php#dust_hoods

-- Les

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