Help with DC Questions
I’m hoping the collective genius (or just plain, good old experience) of the forum can help me out.
I’m “almost” ready to take the plunge and get a real DC. My shop vac with the hepa filter is doing ok, but I realize I need a better solution.
The first question I have is kind of strange given all the other questions out there, but a lot of my questions have already been answered by searching the forums.
1) How many folk use their DC to drive a floor sweep to pick up the shavings and what-not from your shop floor?
2-A) If you do, how effective is it and what sort of DC do you have? I’m trying to get an idea of how CFM / static pressure are going to affect this. My point of comparison is my shop vac, btw…
2-B) if you don’t use the DC that way, why not?
The responses I get will help direct what type of DC I get. I’m looking at either a cyclone (Penn, Oneida, or Clearvue) or a 2HP single with after-market filter (Wynn Env.) and a separator bin. What I’d really like to do is get a cyclone and use that as a whole house vac. I don’t have any carpets in my house – it’s all hard surfaces. I can’t see that picking up dog fur and dirt is any different than sweeping up the shop. Obviously the duct runs will be longer for that portion.
So much for round one, on to my second set of questions:
3) Due to financial constraints, I won’t be able to install ductwork at the same time I get the DC. How well / How poorly will my DC likely operate with with a 4″ x 15′ hose as the hookup?
4) How effective is your DC when hooked up to an insanely small port, such as on a ROS? Or is a better idea to put a large mouthed port near the sanding? Bust out the shop vac?
I got the 2HP Gorilla and am very satisfied. Oneida offers a starter kit of hose and a few ft of ductwork. I used that and later added the ductwork using 26 ga pipe. Use a downdraft table for sanding. Didn't use a floor sweep. Hose connections are slip fit and I vacuum the floor around the tool w/ that and sweep the rest up. A DC is not designed for whole house vacuuming, they deal w/ volume air to carry the dust not suction as in a vacuum. I heard it this way: If a vacuum picks up a bowling ball, that's good. If a DC does.... that's bad!
"What I'd really like to do is get a cyclone and use that as a whole house vac." Dust collectors move air, vacuums create suction. There's a difference between the two goals, so you may not have the best luck trying to get one to do the other.
"How poorly will my DC likely operate with with a 4" x 15' hose as the hookup?" Depends on how big your DC is, and what the CFM requirement of any given machine is. The table saw usually needs the most CFM, the planer less, the jointer far less (in my experience, 6" jointer).
How effective is your DC when hooked up to an insanely small port, such as on a ROS? Much less hassle to just hook the ROS up to a vacuum. I use a small shop vac for mine, works great, and the electric draw is low enough I can hook them both up to a router-table switch and turn 'em on and off simultaneously.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
I don't use a floor sweep now, because they reduce the overall effectiveness of the DC system on the major tools due to leaks. For the same reason, I don't use a cyclone anymore. I had one those cheap ones that sit on a garbage can, and the leaks were a problem. (in spite of my best efforts) I have had a 1.5 hp single tower unit, a 2 hp twin tower unit, and now am using a Jet single tower, 1.5 hp unit with the pleated filter in a cannister. I am reasonably happy with this unit after learning to use and maintain it properly. I suspect the higher quality cyclones work much better than the cheapo that I tried. A well designed system with minimal restrictions to air flow, a matched cyclone and filter system, and enough power to get the required air flow when the filter is dirty is the best bet for table saws, joiners, and planars. Adding other requirements will probably require more power in order to maintain performance.
I don't think a system designed for DC will work well as a house vacuum. House vacuums usually use smaller ducts and require a blower with much higher static pressure. The air flow in your house vac will be too low to work properly.
I haven't experimented with using my DC system with the RO sander. I bought a switch at Sears that allows me to turn on my shop vac when the RO sander is turned on. I adapted a hose to connect them and that system works very well. But, it is noisey and you will have to clean your shop vac filter more often.
I hope these comments are helpful.
Good luck, Tom.
Hi TrimJim, ForestGirl, & Tom,Thanks for the replies! I appreciate your insights.I got news today that I'll be receiving a larger bonus than what I had thought I would. So of course I'm starting to eye the cyclones a little bit more. =) I'm leaning towards a 2HP model as that should help overcome inefficiencies in the design. (Yes, I've been doing some reading on Bill Pentz's site). If nothing else, I like the idea of having the bulk separated out of the stream and cleaning the filters less often.And it sounds like I should be okay with lugging a hose around until I can afford (time AND $$) to put in ductwork. I'm not sure yet how I'll address (cheaply) pulling air from below the TS and above. I should tune the TS table some more to cut down on "spray" coming from the top, but I just haven't motivated myself yet.Tom -- it sounds like you have had quite a few models over the years. Am I correct to infer that all of yours have been single stage units and you've tried converting (at least one) to a double stage by using a trash can cyclone? It didn't sound like you were terribly happy with that setup due to leakage.I currently have a TC cyclone with my shop vac right now, but I think the fundamental problem is simply not enough flow. I will say it's done a good job at separating out the big stuff and cutting down on how often I have to empty the shop vac.The whole house vac thing seems kind of negative too. I'm afraid I'm going to have to break down and do the actual calculations for what I think the system and lengths of ducting will look like. If the DC can be used effectively with a floor sweep, then it becomes a question of resistance and airflow in the pipes. I'm glad this house doesn't have carpets!And of course this really just means I'm too d*mn stubborn to give up on the idea until I prove the idea right or wrong with calculations. In my particular case, the runs are relatively short and wouldn't be beyond what you'd see in a larger shop. Or so I keep telling myself. Please don't take my stubborness the wrong way. Once I get the calcs done, I'll post them to the forum and let you know you can tell me "I told you so...."All I can say in my defense is to mention the politics of a tool purchase. :-)For those picking up on this thread, I would be curious to know your results using a floor sweep with your DC.Glen
A DC floor sweep is basically a large open ended duct w/ a large pipe or hose connection to the DC, in a fixed position. It's not a floor vac attachment like you use on a vac.trimjim
So then all I have to do is acquire floor sweeps that won't scrape up my hardwood floors.
Hopelessly rolls eyes at own self.
Seriously though, thank you for the additional piece of information. I will shamefully admit I haven't held an actual floor sweep in my hand so I haven't been able to examine them. And the catalog photos are really only so good...
Treating it like a rectangular duct makes sense for doing the calculations. Ignoring the whole house vac thing, I want to make sure that my (eventual) lines will be able to pull enough air to clean up the shop floor.
"I'm not sure yet how I'll address (cheaply) pulling air from below the TS and above." There are plans out there for DIY overhead blade guards. Here's the one by Gordon Sampson from Badger Pond. Maybe that'll help. If you Google, you might sind some others, I only bookmarked this one. Seem to recall at least one guy who simply added overhead collection to his stock blade guard. Not sure how hard that is to do.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Hi forestgirl,Thanks for that link! Gordon's design looks really good, and I already pulled down a copy of the pdf. If I can't modify my existing blade guard, then I'll build his.Clearly I'm not thinking straight today as I hadn't thought about googling the overhead blade guard. I'll claim I'm focused on just getting the DC in the first place.... :-)On hacking up existing blade guards, I think the nature of the guard will determine how easy it would be to modify. In my case, I have a fairly tall blade guard , so I would attack it from the side and throw in a 90 to redirect the flow. I could then run the flex hose up towards the ceiling and over to the DC.Glen
I used the Gordon Sampson design, but used it with the replacement blade guard from Penn State and it works great for safety and dust collection. I have it mounted on the ceiling so it can easily swing out of the way when I need the space over the blade (cutting tenons, etc.)
Good idea, just ordering the guard from them (Penn State). I have their overhead guard/collector, mounted from the floor. One of these days, want to mount it to the ceiling so it's not quite as much trouble to get it out of the way when needed. When doing something like finger-joints, I take the hood assembly off the boom.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
You are right, single stage units only. One did have two towers, each with its own filter bag. The cyclone on trash can was nice for easy disposal of big chips. I miss that. But the overall air flow in the system was lower and, as a consequence, the TS and jointer weren't kept clean enough. I could have overpowered the problem by just getting a bigger blower, but at the time the easiest solution was to just bypass the cyclone.
best regards, Tom.
Hi Tom,Thanks for confirming I read your note right. One of my goals is to make sure I get the right equipment so I don't have to purchase another DC for quite some time. Your comments helped remind me just how much I dislike blowing out filters and that I like the cyclone's separation capabilities.Glen
I have a 2HP Penn State unit, but no floor sweep. I typically use a Shop-Vac to cleanup the floor at the end of each workshop session. (The Fein mini-turbo works so nice and quiet, we now use it as our primary house vacuum upstairs).
A few observations:
The ductwork system has a 6" primary "trunk" and works well.
Each stationary point (Unisaw, DJ-20, Benchdog router table, 13" Delta "lunchbox" planer) has a dedicated manual blast gate - works OK for a hobbyiest (sp?)
I have two 4" ports for a long (3M) Bosch hose. I plan to add two more.
The value ductwork line from Penn State - works good.
Hi Dave,Thanks for the input. I'm leaning towards either PSI or ClearVue now, so I'm glad to hear your like your PSI model. As an aside, I felt that I had done enough research to where I could ask direct and not otherwise answered questions. So I finally broke down, wrote Bill Pentz, and asked him for his input. I had resisted doing so because I respect his time and contributions and didn't want to waste his time.For those who haven't chatted with Bill, he's a great guy and I was very surprised at how quickly and thoroughly he answered my questions. I know that some don't agree with his opinions, but I found that he's very easy to chat with and carefully thinks through his responses. He's really put a lot of thought into dust collection.Bill helped me wrap my head around the two sides of the same coin -- ie, CFM and FPM. The reality holding those two together relates to what the equipment can do and the ductwork on the system. That proved the key to understanding how to tweak the system. For anyone reading the thread and still struggling with sizing a DC, spend some time focusing on how CFM and FPM work together.Regarding floor sweeps, Bill uses (or used) one in his shop off of his cyclone and didn't have any problems with it. So long as you can get 4000 FPM to the end nozzle of the sweep, it'll work. Obviously, the nozzle size can't be so small as to kill off all that flow you're trying to get. But if you can get the dirt / chips / junk moving, it'll work.Continuing that, you *can* use a DC as a whole house DC. Please note that I didn't say vacuum. The limitations though are 1) you're going to run some really fat pipe all over your house in order to keep the flow up. 2) the tools are going to be different than what you would expect for that sort of thing. 3) if you have carpets, just forget about it (which was never _my_ case... :-) ) 4) the DC you use is going to need to be on the professional grade / level in order to handle the static pressure you're going to see in the pipes. Hobbyist grade doesn't do well enough on the performance curve for the really long runs. (No new news there)For the example I pondered, I used the numbers of 350 CFM @ 4000 FPM, which correlates to 4" pipe. There are some cyclones out there that can support the amount of static pressure I expected and still pull the 350 CFM. PSI's Tempest 1425S looked like it was close to pulling it off. But again, that's for my house and where I could place things. In any case, my better half vetoed the idea due to the dearth of cleaning tools we would have available. But it is technically possible. ;-)So I'd like to thank everyone who contributed to this thread. The replies were most helpful and I was happy to hear about the various configurations that folk have out there.Glen
I have been using a $150 delta 650 CFM for 2 years and dragging a hose around the shop. Worked perfectly fine on TS, BS, jointer and planner. Bought a rectangular metal “port” for $5 bucks at Lowes for sanding. Use a floor sweep as well. All worked great.
One day I stepped sideways on the DC hose and busted my a$$ in the shop. Was lucky not to bust my head open on cast iron. SO I mounted a 4” PVC system overhead. I have access to some measuring equipment so measured the CFM/ velocity of the before and after system and calculated the Static Pressure loss. The CFM and air velocity were decreased by ~ 60% the end of the longest run (using gates, only 1 run at a time). Here is what I found in my travels:
So, dragging a $25 hose around is perfectly fine with a 650 CFM machine @ 4500 ft/ sec velocity (like my $150 Delta). Busting your #### on a dust collector hose - could happen to anyone- no foul. Bust it twice, shame on you. New Jet 1.5hp 1100CFM, 11” SP with an overhead system- priceless. Pick it up Saturday.
Its really pretty easy to calculate the SP using the worksheets. Before you decide to put in a “system” do a google on calculating DC requirements. Take 5 minutes and sketch out your system, 5 more minutes to add up the SP loss. Then you will be better able to size your dust collector.
As for the shop vac- HD/ Lowes sell vacuum bags for the shop vac. A box of 3 bags was $7. Now my filter stays clean and the air is cleaner as well because it is double filtered. Combine that with a $5 metal floor vent with a 4” inlet, connected to a DC with 15" drag hose, and you're good to go.
Edited 2/28/2007 1:36 am ET by Keef
Hi Keef,Thanks for the reply and thanks for the word of caution with hauling a hose around! That's a concern in the back of my mind, and I definitely want to put in ducting. Paying for the ducting and finding time to get it done are two other completely different stories. :-) This is one of the joys of rehabbing my house. Knowing me though, it'll probably take two close calls before I move it up on the priority list. :-(I hadn't thought about putting a pre-filter on the shop vac, but that makes sense now that you mention it. If nothing else, it keeps the HEPA filter from having to work as hard. That gives me an excuse to head to HD and check out the pre-filter bags.It's good to know that you are happy using your floor sweep. Once I have everything (DC, ducts, etc..) in place, I think it would kill me to have to break out the shop vac to do a final cleanup after a dust making session. I know it shouldn't, but there's something about dropping that amount of money and then not being able to handle a basic task. ;-)Glen
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