HF DC and 4in ducting

[Bill in Buena Park]

I am considering an upgrade in CFM by moving from my current DC (Delta, 650cfm) to the HF 2hp DC (1500cfm). I have a separator piped into the front end of my ducting with 4in fittings on my Thien baffle.

My question is: is there any benefit to up-sizing the fittings to 6in to match the impeller intake and then reducing to 4in to tie in to the ducting. .. or should I just leave the y-splitter on the impeller and just tie one 4 in leg into the existing separator fittings?

Thanks for any thoughts on this.

[jdon]

First, the specs for the HF dust collector are "optimistic" (inflated). AFAIK, dust collectors with authentic 2 hp or more power require 240V; HF's can run on 120V. So, your planned upgrade might not be as great as you anticipate. That being said, most blogs consider the HF collector the best value, for what it actually is.

From my read (as a non-professional), widening ducting diameter (cross sectional area) as a rule will improve performance, by reducing resistance, even if the diameter has to be reduced at the end. The analogy in my mind's eye is like having less power loss with a beefy extension cord, even though the wire gauge of the tool at the end of the cord is smaller, compared with an extension cord with small gauge.

This is assuming the 6" and 4" runs are comparable. Longer runs obviously reduce performance, and sharps bends in the ducting particularly degrade performance. The longer the run, the greater the improvement with wider ductwork. I'd recommend moving up to 6".

[LCHIEN]

first of all the reports from testing articles show that the HF CFMs are over-rated as we all suspected from the power requirements. Probably more in the range of 1200-1300 CFM, abd that's with no ducting at all. Once you start to add ducting the Pressure drop increases and the CFMS fall.

CFMs are the means by which you carry away big chips and suck in the fines. Lower CFMs mean you will let a lot of fine particles in the air and you will breathe them and they will settle everywhere in the shop. The CFMs also suspend bigger chips in the air stream. Too little and they can settle in the hoses or pipes nd eventually clog (mostly when using jointers and planers).

TO keep your CFMs up you must minimize air restriction losses. Here's the list of air restrictions (off the top of my head):
1. Length of piping and hose
2. smoothness of pipe and hose, flex hose is worse than smooth pipe
3. Diameter of the pipes and hose. Twice the cross section area will have about half the loss due to velocity drag from the side walls (larger dia= lower velocity; it possible to go too large and lose velocity where the chips won't carry).
4. Number and severity of turns, elbows etc. larger radius elbows and 45s instead of 90s help.
5. changing diameter, do it infrequently and for as short a distance as possible.
6. Adequate power wiring - DCs always run near maximum current, unlike table saws which only draw current when loaded, i..e. cutting) if you have extension cords you may have voltage drop that reduces voltage and hence power to the motor causing loss of CFMs. Use 12 Ga. extension cords if needed and keep them short (10 ft, not 50 ft!)

Interestingly, your DC's current draw is maximum when running with no piping, i.e. sucking on open inlets. Add hoses and/or partially block the inlet and the current will go down even though theres a lot more noise. Its because the work is moving air, at maximum air flow, it pulls maximum current.

Specifically, you should use 6 inch hose and piping when possible, mostly its very hard to get. 5" theoretically will work well, but its virtually non-existent. I use two 4" hoses in parallel for most of my run. two 4" hoses is almost as good as 6" hose in terms of restriction.

The pressure drop (and hit on CFM ) is additive. So your best bet would be 6" hose to the Seperator, 4" inlet on the seperator, and a short 4" hose to the tool. Better would be a 6" outlet on the sepereator. It would be OK to have two 4-inch hoses to the seperator and add a second 4" outlet if possible.
I think Changing the DC inlet to 6" and going straight to a 4" to 6" adapter would pretty much be a wash over just using one leg of the Y that comes with it.

[dbhost]

This is just from MY experience. YMMV...

I go from the 5" port on the DC, to a 5" stove pipe on the separator, then out of the 5" stove pipe side exit on the separator to the stock HF 5x4x4 wye, I then take a branch of 4" to the ceiling, and one to the floor. I utilize upper, and lower pickups on the table saw, and band saw. The lower on the table saw is split to a belly pan, and the blade shroud. Honestly as long as the belly pan keeps the junk IN I couldn't care less how it is working. The Shark Guard and blade shroud are what I worry about...

Dust collection on the machines I have had hooked up is best defined as fantastic. My runs are short, my bends are few and gentle (long radius 90s, or a 45, a short run of straight, and another 45), and I keep the flex hose to a minimum.

Simply put, I would keep the dust collector 5x4x4 and use it. Don't bother with 6" as the HF DC isn't really rated for it, and 5" when you can find it is super expensive...

I think if my shop was bigger / had longer runs, I would position my DC such that no run exceeds 20'.

[JR]

I don't have a Thien baffle, but FWIW I'd think setting up the connection between it and the DC with wider pipe would be a good idea

My HF DC is set up with a pleated filter and I can highly recommend this mod. Part of getting max flow in the system is getting out the other side. Pleated filters offer much more area for exhaust, improving overall flow. You're also likely to get better filtration of the fines vs the OEM bag.

[Bill in Buena Park]

Thanks for the thoughts guys. Picked up the HF DC today and hope to find some time to assemble in the coming week.

The picture in Ruben's response to Dave's DC thread - the 6in intake on the impeller, piped straight to the exhaust on the Thien baffle - is the setup I was thinking about.

I dont understand exactly why you want to get rid of the separator? if it's just floor space, there is a lot of designs for HF dust colector adding the separator and keeping the same footprint like this one. (picture from lumberjocks)
PS: after reading your first post again, now i understand what you mean.
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I'll try to set mine up like that, and report on how it works.

[Ruben]

i think that's the best way to set up the separator with no elbows to maximize the flow.

[Bill in Buena Park]

Finally got my HF DC set up like this one, and I'm very pleased with the increase in airflow overall throughout my ducting. I haven't added the Wynn filter yet and will continue to use my old Thien baffle arrangement (which I had upgraded to 4in fittings), but otherwise I made the same framework with the same impeller positioning, etc., I'll post some pictures of the setup shortly. If anyone is interested in the dimensions of my setup, let me know and I'll post.

[Bill in Buena Park]

Promised pictures, attached. Although the dust collection bag is a heavy thickness, I decided to "pad" the base of the stand with a piece of foam mat. Interestingly, I believe this setup is quieter than my Delta 1HP DC.

[JR]

Nice setup!

FWIW - I use a cloth bag installed over the plastic bag for protection.