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Okay revisiting my dust collection again (can't leave well enough alone?)

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Forum topic by WorksInTheory posted 03-04-2019 03:55 AM 1331 views 0 times favorited 29 replies Add to Favorites Watch
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WorksInTheory

177 posts in 2113 days


03-04-2019 03:55 AM

Topic tags/keywords: dust collection harbor freight 6 duct 4 duct split impeller

This is my current set up. I reconfigured the Harbor Freight special ala April Wilkerson and early Jay Bates. I also changed the impeller to the Rikon 12”. I kept the run pretty short and tried to keep it big and straight as long as I could. The total run is about 10 ft distance. I feel though I think somewhere I messed something up that is sucking the performance out of it, pun intended.

Everything works okay, better than nothing but could be better. The big issue that doesn’t seem to be working is question #3.

I have 3 questions (marked by the blue circles for reference):

1) Does piping outside vs putting on a filter bag (I do reduce the mouth of the bag to fit the 5” diameter outlet but left the rest of the bag that came with HF as is.) affect the performance. Theory is that piping outside will be better than using the bag.

2)Is running 6” (yes it’s increased from 5” just because it was easier to get 6” HVAC ducting) at the beginning helpful or should I run 4” for the whole run for more velocity?

3)Finally, this is the real issue that lead to this post, I hacked a SawStop TCG Dust Shroud Blade Guard to fit my table saw. So now I need to split the dust collection to 4” to the bottom and then 2.5” to what I believe is 1.5” port of the SawStop dust shroud.

3a) One way I can do this is just use the 2.5” hose I have going to the router table fence. That’s a split then that happens way back

3b) The other is to split the current 4” Table Saw to a 4” and 2.5” and make the split closer to the point of the table saw.

Not sure which is better though either way seems to not have much suction coming off the dust shroud.

I guess I could connect a shop vac instead to that but I have poor electricity in the garage and running the DC, the shop vac and the table saw… I feel I will just trip a breaker and also that’s a lot of noise at the same time.

Looking for thoughts and also anything else I am not thinking off. I will also try to seal off more stuff sources of leaks (got some of that xtreme tape).


29 replies so far

View ibewjon's profile

ibewjon

999 posts in 3303 days


#1 posted 03-05-2019 01:50 PM

Motor size? Why the impeller change? It was designed with the original impeller, that might hurt performance. Also, 6” duct may be too big for the unit. I have a 2 HP north state DC converted to use a jet pleated filter. I also used 5” heavy guage steel duct because that is the size of the machine.4” drops with y fittings. Do you have y or T heating fittings? I don’t know why any company makes t dust collection fittings. There are no t intersections on the interstates, just y exits and entrances. I also use long radius DC pipe fittings, heating 90’s slow the flow. I have over 40 feet of duct with 4 90’s to my 8” jointer, and it works great.

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Lazyman

3976 posts in 1898 days


#2 posted 03-05-2019 02:19 PM

While using 6” should offer less resistance, I wonder what effect the lower velocity has on the actual effectiveness? Also, how air tight is your shop? If you are venting outside, you need a way for the same amount air to get back in so, if it is really airtight, you could actually have a net reduction if airflow compared to a filter. Try cracking a window or door open and see if it makes any difference. I don’t have a DC but on a shop vac at least, you can sort of tell the difference by the pitch of the motor changing when you reduce the resistance. I saw a youtuber using a phone or tablet app a while back to measure the actual change in pitch of a motor to estimate the RPMs with the changes in load.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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Robert

3537 posts in 1991 days


#3 posted 03-05-2019 03:22 PM

Venting outside will improve performance, but as Nathan said, you will have to take into account the heat loss issue.

Assuming this is a 2HP blower. I think 6” is a good choice. I would run the 6” as far as you can rather than reducing.

DC ducting does not follow the same principles as HVAC. I would focus on maintaining CFM’s and let air velocity take care of itself. You do this by keeping the ducts as large are you an as close to the machine as you can.

-- Everything is a prototype thats why its one of a kind!!

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ibewjon

999 posts in 3303 days


#4 posted 03-05-2019 03:34 PM

How big is the motor? Can you post a picture of the DC?

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WorksInTheory

177 posts in 2113 days


#5 posted 03-06-2019 02:39 AM

Good news bad news – not insulated freezing cold garage with lots of air holes (like my garage door is not straight along the bottom and left and right corners you can see light. No waters or furnaces in the garage either.


Venting outside will improve performance, but as Nathan said, you will have to take into account the heat loss issue.

Assuming this is a 2HP blower. I think 6” is a good choice. I would run the 6” as far as you can rather than reducing.

DC ducting does not follow the same principles as HVAC. I would focus on maintaining CFM s and let air velocity take care of itself. You do this by keeping the ducts as large are you an as close to the machine as you can.

- rwe2156


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WorksInTheory

177 posts in 2113 days


#6 posted 03-06-2019 02:50 AM

It looks pretty much like this – from Jay Bates. https://www.youtube.com/watch?v=BCXAHFXpkws

Or April Wilkerson: except mines more like Jay’s where the motor part goes right into the thien vs having a hose connection.

The reason I didn’t do a lot of pics is I have a lot of stuff leaning up against stuff right now but here’s an attempt to see part of it:

The impeller change is a well known change. Apparently the impeller is really small for a DC this size/spec.

View WoodenDreams's profile

WoodenDreams

742 posts in 421 days


#7 posted 03-06-2019 03:28 AM

I have the HF #31810 dust collector. 660 CFM with 4” inlet/outlet, I don’t have any issues with it. I don’t think the CFM it produces can handle the 6” tubes. I’d stay with the original inlet size. If you have the HF #97869 dust collector, 1550 CFM with 4” inlet. this should handle the 4” or 5” with minimal air flow lose. I’d be hesitant to use 6” tubes. Also the quality of the Blast Gates can vary in the seals.

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ibewjon

999 posts in 3303 days


#8 posted 03-06-2019 04:51 AM

I still think the 6” duct is too big for the unit. By the time it sucks the air out of the pipe, there is nothing left to move the chips.

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Rayne

1228 posts in 2050 days


#9 posted 03-06-2019 05:00 AM

I agree the 6” is probably killing a portion of your performance. I would look into local HVAC dealers for 5” snaplock duct. It’s most likely cheaper than what you bought (I know mine was by a long shot). That might resolve any issues you have; just make sure there are no air leaks anywhere.

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ibewjon

999 posts in 3303 days


#10 posted 03-06-2019 12:42 PM

Remember to tape all the joints with aluminum tape. Buy some air duct sealer and paint it down the length of the snap lok joint, and also paint the joints in 90’s and y’s. If you have T fittings, replace with Y ’s.

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WorksInTheory

177 posts in 2113 days


#11 posted 03-06-2019 05:57 PM

I received a ton of 6” and 4” HVAC pipes left over from a friend’s DC project. So was saving money.
Would changing it to 4” be better?


I agree the 6” is probably killing a portion of your performance. I would look into local HVAC dealers for 5” snaplock duct. It s most likely cheaper than what you bought (I know mine was by a long shot). That might resolve any issues you have; just make sure there are no air leaks anywhere.

- Rayne


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WorksInTheory

177 posts in 2113 days


#12 posted 03-06-2019 05:57 PM

Thanks – yes I do tape everything – actually love taping, weird addiction.


Remember to tape all the joints with aluminum tape. Buy some air duct sealer and paint it down the length of the snap lok joint, and also paint the joints in 90 s and y s. If you have T fittings, replace with Y s.

- ibewjon


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WorksInTheory

177 posts in 2113 days


#13 posted 03-06-2019 06:00 PM

Thanks for all the tips so far – anyone comment on the table saw dust shroud part?


3)Finally, this is the real issue that lead to this post, I hacked a SawStop TCG Dust Shroud Blade Guard to fit my table saw. So now I need to split the dust collection to 4” to the bottom and then 2.5” to what I believe is 1.5” port of the SawStop dust shroud.

3a) One way I can do this is just use the 2.5” hose I have going to the router table fence. That s a split then that happens way back

3b) The other is to split the current 4” Table Saw to a 4” and 2.5” and make the split closer to the point of the table saw.

Not sure which is better though either way seems to not have much suction coming off the dust shroud.

I guess I could connect a shop vac instead to that but I have poor electricity in the garage and running the DC, the shop vac and the table saw… I feel I will just trip a breaker and also that s a lot of noise at the same time.


View ibewjon's profile

ibewjon

999 posts in 3303 days


#14 posted 03-06-2019 06:21 PM

If you have the 4”, it is no cost to try it. Once the pipe size is correct, the saw should be an easy fix.

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WorksInTheory

177 posts in 2113 days


#15 posted 03-06-2019 10:24 PM

True but it is a pain in the ass to undo all the 6”, esp since it’s all taped up and then do the 4” (they are in sheets you have to roll up, cut, etc) and I do have to buy the joints (45’s, Y’s) – so before I do all that would want to see someone can validate that will definitely improve it.


If you have the 4”, it is no cost to try it. Once the pipe size is correct, the saw should be an easy fix.

- ibewjon


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