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Thread: Thein baffle vs Dust Deputy
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19th February 2020, 03:09 PM #31Intermediate Member
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Hi jack620,
The 4" one. If I go for the 5" one it's a couple of hundred dollars dearer and the reticulation will be proportionately dearer. I don't NEED a system that big, none of my machines are heavy chip/shaving/dust producers as they are all handyman scale, but I do want a system that will get me as close to a dust free environment as possible.
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19th February 2020 03:09 PM # ADSGoogle Adsense Advertisement
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19th February 2020, 03:21 PM #32GOLD MEMBER
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Jon,
you mentioned in a previous post you were going to buy the Sherwood FM-400. That’s a 3HP 2900CFM machine. The 4” DD is WAY too small for that DE. It will choke that DE to death. I reckon even the 5” SDD would be too small for the FM-400. If your budget won’t allow a 5” or 6” SDD, I reckon you should make a big Thein baffle.
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19th February 2020, 03:37 PM #33GOLD MEMBER
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The air flow capacity of a 5" SDD will be at least 150% of the 4" version. If you're only going for the 4" one I'd suggest you buy a 2HP DE, the 3HP machine will be a waste of money for a 4" system.
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19th February 2020, 04:32 PM #34.
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Something that few folks (they are all over UT) who use third party separators on vanilla DCs appreciate, is that to obtains optimised flow and particle separation from any DC/Separator combo requires some serious computer modelling. It's most definitely not like lego, whereby any DC and separator/cyclone can be paired. The DC and separator have to be designed in combination.
At a minimum the flow rate of the DC has to match the separator requirements for flow rate otherwise one will over restrict the other, and the particle separation will be compromised. Of course some, even a surprising amount, of particle separation may be achieved, but effective separation should retain all the visible dust and only let through the invisible dust preferably <5 micron. This simply that cannot be checked by sight and is also very difficult to check with particle detectors because testing the input dust distributions is a sure fire way to destroy most conventional particle counters. I could go into detail about this but I am probably well past the "nerd point" by now.
Now back to the OP
A DC2 with 90 mm ducting and clean filters is going to have a flow rate of about 250 CFM.
Adding any sort of separator will further drop the flow rate (in this case not much because the flow rate is already so low) but let's say its 225CFM. Thus the separator needs 90 mm inlets and outlets and to be designed for a nominal 225 CFM.
As Aldav says using a 5" separator is not going to as efficient as a 4" because the flow rate difference between 4 and 5" ducting at the same static pressure is about 180%.
Because 90mm ducting is in use even the 4" will not be that effective at separation but if you are not worried too much about particle separation efficiency then maybe even a chip catcher will be all that you need. At such low flow rates this combo won't lose too much flow but that still ignores the elephant in the corner - these flow rates are just too low and none of these combos will capture anywhere near enough dust in the first place.
It's a bit like a boat with 100L/min leak and trying to pump out said leak with a fancy looking 20L/min pump, and then adding some bling that reduces the pump flow even further.
I fully understand why an occasional WW might not want to shell out for a larger DC so maybe it's time to look outside the square?
So what about leaving the pump alone to catch the chips and using some buckets (eg bathroom exhaust fans) that remove the 80L/min ?
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19th February 2020, 05:24 PM #35GOLD MEMBER
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Bob, there's no point talking about the DC-2 or the 90mm duct as the OP has, thankfully, committed to upgrade both. Like you I don't see the point of going to the cost of buying a DC-7 (Sherwood FM400 - $549) only to hang 100mm duct off it, better to buy a DC-3 and put the price difference into 6" duct.
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19th February 2020, 05:59 PM #36GOLD MEMBER
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Bob,
you must have made that comment, or some variation of it, about 20 times in the last few weeks I've been active on this forum. And for the life of me I don't know what point you are trying to make. To optimise anything you either need to computer model it, or design-build-test-refine it. But that doesn't mean you can't get very good results by combining a separator (Thein or cyclone) with a dust extractor, provided the DE has sufficient airflow and static pressure. Most of us are happy with an improvement- we aren't chasing optimisation.
The appropriate size Dust Deputy does a fantastic job of removing most of the dust (they claim 99%). It costs you a bit of your airflow, but it prevents your filter prematurely clogging. Very important if you have expensive pleated filters.
And don't forget, many people add a separator for no other reason than to rid their DE of those horrible plastic dust bags.
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19th February 2020, 06:12 PM #37Woodworking mechanic
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Exactly!!
No computer science went into mine.
i built my system by trial and error. Admittedly, towards the end, I bought an anemometer to “fine tune” the system.
Check airflow, make a mod, check it again, etc etc.
My large Thein works well and I can tell that by measuring flow before and after installation, checking what’s in the drum and collecting samples from the outlet.
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19th February 2020, 10:22 PM #38Intermediate Member
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Hi jack620,
I selected the FM-400 because it's at the top of the range I would buy. According to the spec I just looked at, the FM-400 is good for 1900CFM at 14" WGP, The one you quote as the FM-400 is actually the DC-2900, which DOES pull 2900 CFM, at 22.5 " WGP. That's from the 2018 cattledog.
If the FM-400 too big, the next step down would be the FM-300, 1200CFM at 8" WGP
The specs for the 4" SDD say it's suitable for blowers to 3HP, minimum flow 350 CFM. Those are the figures quoted by Timbecon. They also say the inlet and outlet ports are 4" OD, 3.75" ID.
Do you, or any other readers, have any modelling to determine what the maximum effective air flow is? My rheology theory is too sketchy and too long ago, (like 32 years!) to be any use to me.
Empirically, the FM-300 might be a better match for the 4" SDD. Any thoughts on that?
Cheers,
Jon
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19th February 2020, 10:37 PM #39Intermediate Member
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Hi aldav,
I just straightened out jack620, the figures he quoted for the FM-400 are actually those for the DC-2900 at 22.5"WGP, also 3 HP but with higher efficiency rotor. FM-400 1900 CFM at 14" WGP
I think I agree with you there, going on inlet /outlet diameters and rule of thumb, the FM-300 might be the way to go. 1200CFM at 8" WGP, with 1 X 5" or 2 X 4" inlets. This is a 2 HP machine.
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20th February 2020, 07:36 AM #40GOLD MEMBER
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My mistake Jon. I Googled Sherwood FM-400 and for some reason it took me to the Timbecon page for the DC-2900.
Also quoted on the Oneida website. However, my experience with my 2HP DE and the 5" SDD tells me the 4" DD would be too restrictive.
I reckon so. BUT, if you are buying a new DE I would go for the 3HP model and build a Thein. I reckon (no evidence sorry) a 3HP DE with a Thein would be a better option than a 2HP DE and 4" DD.
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20th February 2020, 11:53 AM #41Intermediate Member
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Hi jack620,
Easy mistake to make, the DC-2900 is on one page, the FM-400 is on the next page, in the same position. BIG difference in the $$$ though! AND 1,000 extra CFM!
OK, I can understand the 3HP plus a Thein, are we looking at 4" or 6" piping here? Reason for asking is that the dust ports on the Triton gear are 30 mm, The bandsaw is 4" and the thicknesser is 4". 6" down to 30mm is a huge stepdown!
Being curious here ..... you say your experience tells you a 5"SDD with a 2HP blower is OK(??) but a 4"" would offer too much restriction. The restriction being in the SDD or the associated pipework? I would have thought that 4" pipe on the 4" SDD would make for an easier transition because the ID's are pretty much identical, OR are we looking at the friction losses in the smaller pipework? If you are using larger pipework I can see the stepdown being a problem.
Incidentally, I wholeheartedly agree with your comment to BobL about people using a separator is to get shot of those bloody awful plastic bags. Actually it's not the bags per se, it's the hassle of getting them back onto the machine. I wound up using tags of gaffer tape to hold the thing in place while I got the metal band on. If you're putting pine through the thicknesser it means stopping every couple of minutes to clear the intake screen and clearing the bag every half hour or so.
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20th February 2020, 12:06 PM #42.
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Replacing DC plastic bags back on is dead easy using 3 - 4 REE magnets. Mine were even more awkward when inside an enclosure with no visual access behind the bag but magnets made it quick and easy. My current DC does not use any clamps but uses a snap in HD plastic ring. The bag top folds over the ring which is then linked so it fits inside the bag housing and the ring is let got and pushed open for a tight fit to the inside of the bag housing.
A better reason for not using a plastic bag is they will eventually leak especially if the DC is towed around inside a shed but also because the swirling sawdust inside the bag can puncture or abrade tiny holes. However this does not matter if the DC is located, or enclosed in an airtight enclosure and vented, outside..
Also a reminder to ignore manufacturers claims on DC flow rates. Besides the conventional Aussie DC limit for 150 mm pipe on most DCS is ~1250 cfm, for 100mm duct it’s ~425 cfm. Using a 3 phase motor and VFD I’ve managed to run up to 490 cfm through a 100 mm pipe and it starts to sound like a jet engine. At 60Hz on an open 150 mm duct I find I have to wear ear muffs. This is ok for machines like thicknesses and table saw but it’s a right royal PITA when turning or sanding
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20th February 2020, 02:52 PM #43GOLD MEMBER
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6" for a 3HP DE. I think you have two options with the Triton. Either open up the dust ports to something larger if possible, or use a dedicated Shop Vac type vacuum cleaner for the Triton. For my router table I use a Festool dust extractor with a 50mm dust deputy and 50mm hose.
My blower power measurements indicate that the SDD is nearly twice as restrictive as 4m of 5" flexi duct. I guess all that swirling air generates a lot of drag.
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20th February 2020, 08:31 PM #44Senior Member
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20th February 2020, 09:32 PM #45Intermediate Member
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