I have the Delta 50-850 1.5hp “1200 cfm” dust collector. So far I’ve used it with the 4″ hoses connected to the two ports supplied (with blast gates for all tools). It works as well as I could expect, but I’m in the process of reconfiguring the shop (just added 48 sq ft – what a difference!!) and was thinking about improving performance.
The first step is to minimize the amount of flexi-hose (that’s all I use now). Then I got to thinking… The two-headed 4″ hose port thingie slips over a 6″ O.D. flange on the side of the blower. Anyone have any ideas about using a 6″ PVC main-line off the blower, with 6″ to 4″ wye’s to conncet to the tools? Will this non-standard use of the DC cause any problems? Will I get much benefit, vs. staying with 4″ pipe?
Thanks, Wayne.
Replies
Your plans are great, for a 1200 cfm machine that 6" main will make a BIG difference.
I am not sure what a 6" main line gets you since you have a 4" line at each end of the 6" line. I use a 4" PVC in several places and it works fine.
6" piping is less restrictive than 4". The more you can replace 4" with 6" solid piping the less your ducting resistance since your ducting resistance is cummulative from DC to tool. This will also allow you to (perhaps at a later time) to modify your 4" hoods to further increase your performance.
Sounds like you are on the right track.
--Rob
I don't have any 6"; it's all 4" to the DC. That's why I thought this might help.
Do some searchs here and in Tool Talk. There has been some posts over the past few weeks on dust collectors. Forestgirl has been doing some research for the system she is setting up and has posted comments about the 4" vs. 6" mains.. there are a number of liks that others have posted in regards to DC design and performance issues
The down-side of going too big with trunk lines, is that too little velocity will allow larger chips to drop out of the stream and drift. The area of a 4" circle is 12.5" and is 28.27" at 6"so it goes up faster than you may think.
I did try some searches before posting but it was kinda late and I wasn't thinking particularly clearly about different search options. I'll check out FG's posts and also spend some more time reviewing Bill Penz's info. Thanks!
I can't get anwhere near technical enough to explain the advantage of having some 6" ducting off your DC. Pentz's site should help. Also, if you read through the 2 main threads I'm thinking of, you'll see some explanations of how the physics works. I'll go find those threads, come back and post the links.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
Here's one thread:http://forums.taunton.com/tp-knots/messages?msg=23553.1
Note the reference in AlanS's post (#17) to Woodnet and a guy named Bob Dodge. I missed it earlier, have to check him out.
Here's the other one:http://forums.taunton.com/tp-knots/messages?msg=23105.1forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
make sure you run a grounding wire on the inside of the PVC pipe to kill that static electricity buildup.
This has been totally bebunked as urban myth. Sparks from metal objects hitting a metallic impeller are of more concern than any static charge in a home shop DC system.
Edited 5/24/2005 2:44 pm ET by Doug
I didn't say that it will start a fire or short anything out. I only meant to kill the static buildup as it is an annoyance. when I'm vacuuming chips and dust, I'm always getting those wee little shocks that are big enough to make you notice. And my hair stands on end.
Also, understand that my backround is Air Force munitions, and we are sorta kinda concerned about static buildup. I'm not suggesting that you should be concerned about storing munitions in your workshop or anything, because if you're doing that, I think you have other problems then keeping your work area dust and chip free
/wry humor.
I have the same machine, and did exactly what you describe. the discovery I made is this: a 4" drop to the tool still only allows as much air into the system as a 4" pipe all the way to the collector. So, what ended up happening was, when the dust entered the 6" main from the 4" branch, the airspeed dropped by more than half, allowing larger chips to settle along the floor of the main trunk. I then went 6" all the way to to the "big" tools, planer. table saw etc. that helped, but then the dust bag itself (i have the 0.5micron dutch felt bags) wasn't allowing enough air OUT of the system to let the 6" pipes work to their full potential. Long story short, I now am going to try a 6"main trunk with 5" branches. This should offer improved performance over 4", allow sufficient airflow in the main, and not over-pressure the filter bags.
One other neat trick: If you need to use a 4" or smaller hose, you can keep airflow in the 6" trunk up by opening another gate in the system "upstream" from the tool you are using.
Tony
The large main/smaller branch design is good for factories and big shops where more than one person will be using the DC at the same time. For the individual personal shop, going the same size all the way gets you the same airspeed all the way.
You want to make the duct as big as possible for minimum resistance, but not so big that airspeed falls below 4000 fpm, and chips start to fall out of the airstream.
-- J.S.
I was just at my local plumbing supply house looking at the big pipe, and I can't figure out how to make the connections or smooth transitions in pipe size. The 6" flange on the blower housing is very close to 6" O.D. The 6" plastic pipe is all 5-7/8" or less I.D., and the connectors are all 6-3/8" I.D. or more. How did you connect the pipe to your DC? At the end of the main run (which is only 7' or so) I want to reduce down to 4" for a floor sweep and couldn't find anything that would do that.
Ditto for the 4", at least to connect to my existing blast gates (4" O.D.). Looks like I'll need to build my own - this project is growing quickly!
Quoting Mum, "One thing always leads to another."
Quoting Phil, "Q=SXP" (throughput = speed x pressure)
Yep, that would be accurate. In this case the pressure to get the shop back to some form of workable so that I can complete the kitchen cabinet cases before they need to get installed makes this particular upgrade a "defer" project, so that I can fully appreciate the journey of the dust collector upgrade at another time - LOL!
Woodhoarder:I hadn't noticed your earlier post. You observations with 4", mixed sizes, and 6" duct make sense, but I don't quite understand the problem when you used all 6" duct on this DC. You say the dust bag is limiting the flow. Is it low enough to cause dust to drop out in the 6" duct? If not, what's the problem? If so, why should 5" drops help?If the bags limit the flow, you could improve the airflow by either using larger or more permeable bags, or by adding an extra bag to increase the filter surface. If you do make your DC draw much more air than it was designed for, it will draw more current as well, and may need attention to prevent burning out the motor. This is not a worry if you only change the duct leading to the DC. But adding extra filter capacity, or removing flow restrictions at the blower inlet or outlet, could increase flow beyond that of the bare DC.
I am with those who suggest that 6" duct will not be of much help.
I have 3" PVC pipe in my shop with 4" flex tubing on the ends. It picks up what is necessary. (My hand plane chip pile is larger than my bandsaw ship pile.)
Check the Bill Pentz web site. You may be collecting most of the visible dust, but it's the tiny stuff, 30 microns to sub-micron sizes, that can do permanent lung damage. According to Pentz, a 3" or 4" system won't protect you from that stuff.
-- J.S.
Bill Pentz is not a source I would rely on.From a very reliable source (who I have quoted in the past and cannot remember):Dust collectors pick up chips not dust. To get rid of dust under 5 micros you exhaust the inside air filled with dust to the outside, and replace the exhausted air with clean air from the outside.30-1 micron dust does less damamge than the 1-0 micron dust that dust collectors recirculate.
George R:
Bill Pentz seems pretty reliable to me. You may disagree with his opinions, but his facts are supported and he gives reasons for his opinions. It can be a challenge to read his site, but if you do, you might be interested to discover that his opinion of DC's that don't filter below 5 microns may not be very different from yours. Venting outside is not always practical, but he does mention its advantages, and the bulk of his site deals with arguing for getting rid of those smaller particles, and describing how. wrudiger:
Getting back to the thread topic, 6" duct will have the largest effect if it's used for the entire run. With a 4" takeup at the end of a 6" duct, the air will slow down in the 6" part and likely drop some dust, eventally clogging. That's not likely very much better than 4" duct for the whole run, unless you have a trashcan separator at the 6/4 junction to collect most of the crud. If you split the 6" to two 4" ducts, both open and preferably at the same machine, it will get the 6" advantage and draw very well. If all you are trying to do is get rid of the chips you can see, there might not be much advantage of 6" duct over 4" duct. The importance of larger duct is that it allows you to move a lot more air, making possible capture of most of the very small particles. These are apparently the ones that can cause the most health problems, but as you can't tell how well they are collected without very sophisticated measurement, this is not equipment where you can simply ask how someone likes their system to see how well it works. This has led to lot of discussion and controversy because making sure you have collected the small stuff is complicated, and not everyone is even trying to do that.
Edited 5/26/2005 5:36 pm ET by AlanS
"the air will slow down in the 6" part and likely drop some dust, eventually clogging."
The dust will keep moving, the heavier particles such as chips will eventually clog, but in a 6" line, this will only occur at below 3000 ft/m, or around 590 cfm. If he can only pull around 600 cfm, he should not consider a 6" line anywhere in the system.
"That's not likely very much better than 4" duct for the whole run, unless you have a trashcan separator at the 6/4 junction to collect most of the crud."
If he cannot pull enough cfm, to keep a 6" pipe clean, a trash can collector will kill his system without any doubt.
"If you split the 6" to two 4" ducts, both open and preferably at the same machine, it will get the 6" advantage and draw very well."
Two 4" lines running next to each other, gives almost the same cross sectional area, as a 6" line, but with the disadvantage that he has to run more pipes. Area = pi x d x d /4
2 x 4" line = 2 x 3.142 x 4 x 4 / 4 = 25.1 square inches
6" line = 3.142 x 6 x 6 / 4 = 28.3 square inches
The problem is that pressure loss (suction loss) is proportional to the velocity squared and the inverse of pipe diameter, so even although you get close to the same cross sectional area, the pressure losses are still substantially more in the two 4" lines, compared to a 6".
Sheesh..... If anyone needs help with design and it's not too much work, email me, I use to do this for a living a long time ago and will charge nothing for a bit of fellow woodworker help.
There is no way to explain everything one says in detail. I don't think I meant to say anything very different from what you did, except in one case: the trashcan separator. He asked about running 6" duct from the DC, and using 4" drops to the machines. My assumption was that the 4" drops would restrict the flow to the point that sufficient flow in the 6" line was unlikely, and I think that's reasonable for a DC that's nominally 1200 CFM, under operating conditions with dirty bags, some length of 6" duct, and 4" flex drops to who knows what sort of hood. It could be that it's not a problem, but the main idea was supposed to be that the 4" drops are a bad idea.I had started by saying that 6" all the way was better, and the point about two, rather than one 4" line was to say that using two drops from the 6" duct would get the flow back up to where you want it. This might be practical, for instance, with one line drawing from just below a bandsaw table, and the other from the bottom of the lower wheel. I certainly had not meant to suggest two 4" lines all the way. Even though two 4" ducts would cost half as much as one 6" duct around here, it would have more flow resistance and be a pain to set up. For the short drop, I didn't think the difference was a big deal.What I meant by the trashcan separator comment was that if collection through the 4" duct were sufficient, and crud dropped out in the larger duct, you could take some advantage of the smaller flow resistance of the 6" duct by using a separator after a short run of 4" duct, since there should not be much left to settle out in the 6" duct. Yes, all 6" is better for collection, but most trashcan separators will be swept clean with the larger flow. This is not the only solution to the problem, or even the best one, but it is one situation where 6" duct is significantly better than 4" duct, even though the line has been choked off by using a 4" drop at the end. It would only be relevant to something like a planer, that produces huge quantities of chips that can settle out, but not much in the way of small particles.I guess this shows some of the difficulties of the topic. If I could not make myself clear to you, who already understood the fine points at least as well as I do, it must be really tough as you are learning. This sort of forum is very good with focussed questions, but designing a DC setup is something that requires a fair amount of conversation to get to a good solution.
Edited 5/26/2005 9:57 pm ET by AlanS
Thanks to all for your very helpful comments. I am in the process of doing a slight rebuild of the shop. Once I cleared out the old TS outfeed table (actually my workbench, which now gets to stand alone in the new shop extension - yea!) I got to thinking about improving the efficiency of the DC. I was hoping - silly me! - that I could do that fairly easily and quickly. I can't afford to upgrade to cyclone at this point so I need to get the most possible out of my 1-1/2 HP "1200 cfm" machine.
The shop remodel is tied to a much larger house remodel. The GC is making great progress, and expects me to have the cabinet cases ready to install in a couple of months, so I need to stay focused on getting the shop back to production-capable ASAP. The DC upgrade will just have to wait until I can do it right, including 6" to all the machines. Thanks again for all the great advice - I will definately put it to use when I restart this project.
It could be a good idea to put it off, but it might be worth doing something. For instance, if you were to change only part of your setup from 4" to 6" duct, the way to do that would be to change over the whole link from DC to one of your machines (likely the tablesaw) to 6", leaving the rest of the system not too much different from the way it is in effectiveness. If you find dust building up in the 6" run when you use the 4" part, you might be able to flush it out now and then by opening the tablesaw gate. That would not be fun long term, but could be something one could live with until the rest could be converted. Or if you were to take jellyrug's generous offer of help, he might come up with something better, given more details of your situation.
somtimes the bigger the pipe creates dead spaces where chip s will lay in the bottem of the pipe eventully clogging also where pipes connect the longer the pipe run the more problems occure good luck
This may be a dumb question, but if there was concern about chips "laying in the bottom of pipes," couldn't one periodically close all the blast gates and turn the DC on for just a few second to get everything cleared out? It works with vacuum cleaners, but maybe not with a DC?? Leave one blast gate open half-way? Or forget about it? :-0
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
Edited 5/29/2005 11:00 am ET by forestgirl
I've seen a good technical discussion about piping sizes, and I think it might have been on the Oneida or Penn State websites (dust collection vendors). The argument I recall was that the optimal size pipe for shop systems was 5". They explained -- and other posters have said -- at some point the pipe is large enough so that air speed drops and the larger stuff doesn't clear the pipe. 5" is, they say, big enough to allow sufficient throughput to prevent clogs.
The issue of filtering at the business end is a whole other question. Pentz's site is replete with admonitions about filtering the fine dust. Serious stuff.
Onieda designed my DC duct work for a 2hp system and and 60% of the 45' of horizontal run is 5" and I have modified most of the machines for 5" ports. You want to cluster the large chip producing machines close to the intake and use the largest diameter for these and 5" is sufficient to handle the small dust from things like the RAS, TS and band saw. I have my drum/thickness sander, planer and planer/jointer on the 6" line and everything else is on 5". I am planning on moving the the 15" planer to the 7" main line for better chip extraction.
What size is the inlet pipe on your DC, Doug?forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the "I Rocked With ToolDoc Club" .... :>)
Jamie,
The inlet is 7". The system starts at 7", transitions to 6", which is the main line from which the 5" ducts branch.
Doug
The cynical side of me says that 5" is optimal because you can't get that in PVC :-)
I will check out the sites you mention - thanks!
I certainly never neglect my cynical side; but there did seem to be some thinking (and $$) behind it...
You can buy thin-wall PVC in up to 12" in diameter with a variety of fittings necessary for DC's from irrigation supply companies. A company just down the road from me uses it to house insulated copper pipes for refrigeration systems.
This forum post is now archived. Commenting has been disabled