Wanting a dust collector for as long as I can remember, and for some strange reason I am finally going to purchase one, I am just now getting my mind adjusted to modding it as I discovered this thru DC reviews.
With that said, I am green at this concept, but intrigued enough, and read enough to know I`ll want to do this when I get my DC later this week. So, not seeing any newbie sections of this forum, I just want to get a few questions out of the way.
- I see there are two basic ways of creating a baffle. One that sits inside the collection container, and a completely manufactured baffle system that sits on top of the container (Top Hat?). In both of these designs, seems more people are leaning to creating the inlet on the side, as opposed to dropping it down from the top. Is this proven better, and does the 'material drop section' of the baffle need to be enlarged/lessened or modded differently because of the side inlet?
- Also, in Phil`s design, both the inlet and outlet are angled in from the top. Are the top side builders getting better results with this?
- I also noticed there is no real set best design for doing any of this? I`m guessing the size and strength of the suction requires all the experimentation with different designs? Thinking out loud, be nice to have different threads started for different machines? This would put readers on a similar track to there needs and thoughts.
With all the different designs, dimesions and materials, there is no best way?
Okay, WoodCzar, since nobody else has replied yet, I'll jump in. I'm a newbie myself, and had some of the same questions myself, before getting a handle on things. Hopefully, someone with more expertise will add later, but in the meantime, here goes....
First, there is no real "best" design- the design depends on multiple factors- capability (size) of your DC- shop vac or multi-HP; cost (scrap bin inventory); time/ease of construction; available tools; shop space; degree of attention to detail/fussiness/compulsion; etc.
That being said, here are some general "rules" I have gleaned from the collected wisdom:
Overall, top hat designs offer better performance, but are a bit more complicated to build, in particular the separator wall, and the side inlet junction. Making airtight seals between the lid, wall, baffle, support ring and waste container is vital. With "drop-ins" (for lack of a better word), the inlet is through the lid, and the walls of your waste container are the separator walls; you only need a good seal between the lid and container lip.
Separation is best with straight (non-turbulent) air flow, so a side inlet, coming in tangent to the separator wall, is better than from the top, with a right angle bend under the lid. Also, a rectangular inlet, instead of round, reduces turbulence as the incoming flow hits the separator wall. Side inlets are easier to incorporate into a top hat design. If you're going to go to the effort of making a top hat, definitely incorporate a side inlet.
Also, a straight air flow exit port is better for DC performance, esp. if the DC impeller is near the exit port, such as when the impeller is located just above the separator, usually with top hat designs. Check out retired2's postings about air straighteners.
Generally, the larger the separator, the better the separation, esp. with fine dust (the hardest to separate). Unless you want to go with an elaborate funnel shape below the baffle, the maximum diameter of your separator is determined by the diameter of your waste container.
A tall separator (increased height between the lid and baffle) allows more time for air to circulate, and better separation. The inlet is best just located just beneath the lid.
One complicating factor is that a larger separators need more powerful collectors for good airflow, so generally shop vac couple separators are coupled with smaller separators. I don't know of any specific guidelines, though.
A narrow slot width (7/8", of even 3/4") offers better separation of fine particles, but clogs more easily with large chips (planer or jointer, e.g.). The 1-1/8" slot width seems to be the best compromise. Note that slot width doesn't scale in relation to separator size: the slot for a 24" wide chamber is NOT twice as wide as one for a 12" wide one.
Bottom line: As long as you follow Phil's general design, you should get very good separation. Top hats with side, rectangular inlet offer best performance, but are more involved to build. Phil's original design is cheap, fast, and easy to build. Like a lot of things, performance improves with complexity and expense, but with diminishing returns; where on that performance/price curve you sit depends on personal preference.
Just my .02 :)
Thanks jDon for the much needed explainations. The rectangular inlet sounds good. All mentally noted.
This might be a dumb question, but I have to ask. Has anyone tried putting the inlet just below the baffle? Why would`nt the seperation by the baffle be helpfull? Letting the 1" slot in the baffle transfer the suction to the outlet?
WoodCzar/jdon I've attached my near finished build and open for any questions you have. I used Plexiglas for my wall and it is about 6" high and I have a 4" input. Originally I was going to use a 6" input but then decided I wanted my unit to be portable. Today I'd go with a stationary unit and run duct pipes (I still may run the duct pipes). Currently I have a 20 gal can under the TopHat but I suggest a 32 gal, the 20 gal fills up much too fast. I plan to modify my unit and use a 32 gal but this is a LOT of work, I'm almost rebuilding the unit.
I place the impeller above the tophat because I did not want to draw dust and other junk through the impeller. Before arriving at this decision I did draw a rather large piece of wood that managed to get past the web before the impeller and boy did that make some noise. The web before the impeller was consonantly getting blocked when I was doing some serious work on the planer. After the 5th time I decided the impeller unit had to go after the tophat.
If you go with a design as such be mindful that you have to empty the can, either you need something that can lift the motor, mine is about 70 lbs and is stationary or have a way to drop the can (this is what I will do) or have a flex hose between the tophat and the impeller so you can lift it enough to remove the can. I highly suggest you have either something that will lift the tophat or something that will lift the can. I will be installing a lazy-Susan on a threaded rod to lift my can.
Some guys have gone with 50 gal containers but IMHO this is MUCH too big.
The can under the Tophat must be rigid, e.g. it cannot be just a plastic bag (I tried this).
There are several drawings for Tophat plan, somewhere I have a SketchUp drawing that I found on the web. I would suggest that you build a Tophat, I'm super pleased with my unit.
jgt1942 - not to hi-jack this thread, but can you elaborate a little bit on your lazy susan "waste can raiser"?... I'm particularly interested in a description of the threaded rod mechanism. I'm picturing a relatively small diameter threaded rod like a 1/2" all thread rod... but knowing optimally the concept would be best with a much wider heavy flange/pipe of 4-6" width for stability. I've guessing you used your threaded rod in conjunction with a plywood platform or two sandwiching the lazy susan ball-bearing plate.
The Lazy Susan raiser is over the top. You guys come up with some of the coolest stuff.
i just used an old scissors jack.
http://www.jpthien.com/smf/index.php?topic=1017.msg5431#msg5431
Bullseye - I'm considering that, but past experience with a variety of jacks has them "drooping" after a short time and since my dc is in a seperate closet... I didn't want to risk running the dc for a period before I noticed the dust bomb I caused. Maybe l've just only used cheap leaky jacks before, or I'd need to check the dc closet frequently, right now I'm just happy if I remember to turn the dc on! Right now I'm using a large ratchet strap to pull the can up to the fixed top hat, and while it "works", it's kind of a pain.
Do you find your scissor jack holds it position well over time?
never had an issue of it coming loose
Quote from: JeffQ on March 25, 2014, 08:56:51 AM
jgt1942 - not to hi-jack this thread, but can you elaborate a little bit on your lazy susan "waste can raiser"?... I'm particularly interested in a description of the threaded rod mechanism. I'm picturing a relatively small diameter threaded rod like a 1/2" all thread rod... but knowing optimally the concept would be best with a much wider heavy flange/pipe of 4-6" width for stability. I've guessing you used your threaded rod in conjunction with a plywood platform or two sandwiching the lazy susan ball-bearing plate.
I'll try. I picked up a weight lifting barbell at a local salvage yard for $3, the bar came with two threaded nuts (I call them nuts) to hold the weights on. All I wanted was the threaded end section of the barbell and the two nuts. Now let's reference the pic I've included.
- My threaded rod is almost 1" dia with 4 threads per inch. I wanted it to go up/down quickly
- The nut is a large, about 2 1/2" dia
- The bottom nut will be welded to a 8" sq plate 1/4" thick (see #1 & 2)
- The bottom plate (#2) will be either welded or bolted to the red frame (#3). This will force the rod to move up/down
- The top nut (#4 will be welded to another 8" sq plate, see #5)
- Not shown is a wooden circle 1 to 2" thick, dia is about 1 to 2" larger than the bottom of the can. The top sq metal plate will be attached to the wooden circle. The edge of the wooden circle will be routed out on the edge of the circle thus making it appear as if I have two circles glued together where the smaller circle (formed by the router) will be about 1" smaller. This will allow me to grasp and turn the circle. I could just cut two circles of wood and glue them together.
- The Lazy-Susan, #6, will be attached to the top of the wood circle.
- Another circle of wood, dia to match the dia of the can will be attached to the top side of the Lazy-Susan
At least this is the current plan. Another forum member made a lift that you might like, see http://www.jpthien.com/smf/index.php?topic=1091.msg5925#msg5925