My DC Experience
Introduction
Well I have begun some DC Testing, nothing too scientific. If exact science is what you are looking for go, may I suggest taking a look at Bill Pentz's Cyclone Page. Bill's site is the most comprehensive information I have reviewed. I have also recently read Woodshop Dust Control By Sandor Nagyszalancy. Although Sandor doesn't get anywhere near as detailed as Bill does, he does put DC systems in retrospect. I would say Bill's information was very scientifically investigated, but in order to achieve the requirements Bill talks about you will have to spend a small fortune, which I think is not practical for most weekend woodworkers. Which brings me back to Sandor's work, his is less scientific, but squewed for a much larger audience and is more practical. If you are a total Newbie to DC systems then I suggest dipping into these articles first before you hit Bill Pentz's site. These articles are provided by Woodcraft. Woodcraft Dust Collection Articles. This page will NOT cover my opinion on what I think is the best way to collect dust. It will however cover what I think is the best way to collect dust for me and what I have discovered along the way. Please take it with a grain of salt.
Let me first say if you have 10' ceilings and deep pockets, quit reading the basics and get into the Cyclones! This is by far the best way to go. If you have not spent any money on your DC system yet and are beginning your shopping; I would say do it right, do a Cyclone, don't waste time and money upgrading your way to the cyclone. If you spend enough time in your shop and do a little research you can easily get wrapped up in DC requirements and realize you want more. A better DC promotes better Health which I know doesn't sink in for all of us, but how about less cleanup and minimal dust lurking about! If neither of those interest you, then you don't need worry about DC.
Of coarse a lot of us are working in the basement with low ceilings or garages with shared space and so a cyclone is commonly not an answer for us. I know that when I move to the next place I would really like to do go cyclone, but at this point the 8' ceilings have limited me in the shop that have now. I have read of 8' Cyclones, but according to what I have learned, it is the ratio of the cone (1:64) that becomes most important and I guess an 8' Cyclone doesn't get it done for the dollars. I have seen many manufacturer's now making 8' Cyclones to widen the sales, but I have not seen first hand how well they work so I can't say they are all wrong. If you're a reader with an 8' Cyclone I would love to hear the results please EMAIL ME.
Experiment
I don't know if you can call what I have done an "Experiment" as I have not taken the time to be fully exact with all the variables and of coarse the more I play the more I learn...
Original System:
When I first got into DC a few years back I bought what I could afford without knowing a thing. All I knew is that having a DC system is better than nothing. I originally purchased a JET DC-1100C and let me tell you it was great for me. I bought a few blast gates and 50' of 4" Flex hose. I had two main branches, one for the Jointer and one for the TS. I also shared the Jointer branch with my surface planer. When planing lumber I would just disconnect the jointer and tie in the planer.
Within about two projects I learned about the significance of 2 stage separation as well as dust particle sizes. It was also at this time I bought a house and was moving so the baby system that had put together served it's purpose and had to be disassembled. So when I started setting up shop in the new place I decided to incorporate a Cyclone Lid from Veritas on top a 55 gallon drum and new 1 micron filter bags. I would recommend a cyclone to anyone using a similar single stage collector. I know that manufactured 2 stage systems already do this same operation, but generally the 2 stage systems have a lower CFM output of that of a single stage.
SIDE NOTE You will loose some CFM performance by adding a Cyclone Lid into a single stage system due to adding a higher static pressure to the overall system. However, I feel it all balances out because of how the air is exhausted in a bag system. As the lower bag fills with chips the volume for the air to be exhausted decreases thus pushing more dust through the bags, pumping that harmful dust back into your shop as well as creating more force on your motor due to added pressure. By adding the cyclone lid, my 55 gallon drum collected just about everything. The only thing that made it into the lower bag was the "flour." Leaving the bags mostly empty to allow for the air to be properly exhausted over its full surface area the DC requires to filter effectively. Also by adding the Cyclone Lid, the chips no longer pass through the Impeller of the DC, lower the risk of sparks and jams in the impeller housing.
I have since gotten rid of my JET DC-1100C to upgrade to what I thought was going to be a cyclone system. For those of you who are new around here, I recently lost space in my basement to the Wife's laundry rm. So I got the crazy idea of moving my DC out of the shop to gain back some space, which would require much longer runs of duct work, which meant upgrade the DC to the cyclone system. Well I sold the JET DC-1100C in a hasty decision and then realized their will be no real effective way of getting good DC due to all the bends and turns the ducting would have had to go through. I then thought of moving my DC into the laundry rm, but knew right away that would be counter-productive on the clean laundry, not to mention there was no way I was going to get approval from the lady. Now I have no DC and have gained nothing!
Current System:
Well I looked into the products I could buy, including a new Single Stage or new 2 stage system. I did manage to keep the Veritas Cyclone Lid when I sold the JET DC-1100C, thinking I would attach a single DC-650 and Cyclone to the surface planer due to all the chips it produced. Also the location of my surface planer in relation to my shop made it hard to install any overhead ducting to it, this the DC-650 would have been a good idea. I had been fooling around with the idea of finally installing duct work in my shop (I waited a while to make sure the current shop layout would be the final before installing duct work) and decided yet AGAIN to move the shop layout to satisfy work flow and ductwork!
Moved the shop layout around and everything looks better yet again (minus some minor electrical work I will have to complete). I decided to purchase the JET DC-1200CRC, which is the Canister Model with the Remote Control. I assembled the unit and tried it out with the existing 4" flex that I had. Bad news, the new 1200 was much stronger than the 1100 and was pulling all dust and chips right through the 55 gallon Cyclone separator! I guess it was nice to know the 1200 had some more power, but now I was defeating the purpose of the separator. After asking some questions at the forum Sonny Edmonds told me build a taller Cyclone and so I did. I managed to find a plastic 55 gallon drum this past week and gave it a try. I cut the bottom and top off the plastic model and fitted atop the current metal 55 gallon drum. Tested out the system and I was back in business!
I started looking into ducting next. Metal or PVC? 4" or 6" or both? Well they all server their purpose. Naturally the 6" is better, but after using Bill Pentz's Static Calculator with my duct runs and machine requirements most runs came out to be 5". If I would have used the 6" the ducting would have allowed for too much drop off in the air velocity. Being 5" this required me to use Metal as I have never seen 5" PVC 2729 (Sewer and Drain). Well I had some 4" runs as well, thus I decided to sacrifice a bit (as I know I will never achieve the 800 CFM Bill Pentz suggests for fine dust pick up).
I ran out and bought a 4 pcs of 4" x 10' PVC2729 and all the appropriate fittings , of coarse a roll of duct tape too (Under $75!). Turned out my longest run was about 30 ft from start to finish (including the vertical runs as well as the horizontal), which was to my band saw luckily as it has the lowest requirement for CFM.
I was able to break the system down into two major branches. One branch dedicated solely to the band saw as it is in an area all by itself. The other branch had a series of Wyes with blast gates on to branch off to the TS, Planer and Jointer. All lines were fitted and duct taped accordingly. Next step, actual testing
Well the results are in and let me say Bill Pentz couldn't be more correct! I used a digital manometer to do some testing on my DC system to find out what my actual Velocity, CFM and Static Pressures are. To do this I used a 4" x 60" tube with a hole drilled 30" downstream of the open end to locate the pitot tube. The results were:
Base Unit (no ducting)= 6580 fpm, 2.7" WC, 574 CFM.
Band Saw Branch (~30' 4" Pipe, ~8' Flex Tube, 2 90 Degree Elbows, 1 Wye, Cyclone Lid) = 2550 fpm, .39" WC, 223 CFM
TS, Planer, Jointer Branch (~15' Pipe, ~8' Flex Tube, 1 90 Degree Elbow, 2 Wye, 2 45 Degree Elbows, Cyclone Lid) = 2300 fpm, .35" WC, 201 CFM
Sad Sad results! With minimal ducting only 223 CFM on my best run (also my longest run, but their are less bends in it than the TS, Planer, Jointer branch though)! Tell me about a waste of time and money. Once I give this system a good working in the shop I will evaluate if this 4" ducting is getting the job done. I did manage to do some sawing on the band saw and it was sufficient even though it was about 150 CFMs lower than the required amount. If things don't work out I may try installing either 5" or 6" duct work. The problem is I installed my ductwork in between my rafters in the basement; I barely was able to slide the 4" pipe in, I don't know if 5" or 6" will fit?
For now all testing is at a halt. I will actually run the system and see how it all goes for now. If the results are too poor I will have to figure out a way to install larger ducting, no matter the cost.
Update - May 25th, 2005
After such sad results with the 4" Duct work I quickly became curious of what 6" ducting performance may yeild. Granted I have not ripped out my 4" system I did construct a 6" test tube (using the same ratio to measure the location for the pitot tube, 45" downstream of a 6" x 120") to see what base CFMs of the JET DC-1200CRC would yeild.
Base Unit (no ducting) = 4105 fpm, 1.1" WC, 806 CFM
Between 4" @ 574 CFM and 6" @ 806 CFM you come across a 232 CFM increase from 4" to 6" a 43% difference!
Gaining 232 CFMs just by increasing 2" in duct work! Although the 4" system is contructed from PVC 2729 and the testing tube was constructed using snap-lock HVAC duct work, which obviously has a different coefficent of friction. I try and test some 5" duct work some time soon if possible.
Update - June 3rd, 2005
DC Layout
I made a mock up of my current duct collection system using 6" and 5" rather than 4". This system was constructed using the ducting provided by JET, and let me tell you spend the money! This is premium 20-gauge baby's ass smooth "Snap Clamp" ductwork. Here is why it is worth it for me, the "Snap Clamp," let me tell you it makes installation and maintenance SO EASY, not to mention you don't have to worry about grounding and leaks in this system. What took me hours to measure, cut and fit all the fittings and pipe lengths together on the 4" PVC 2729 (Sewer and Drain), took me literally no more than 25 minutes to assemble using the "Snap Clamp" system! The fittings are pretty much standard sizes from 4" - 6", so snapping in and out different fittings sizes and styles is just a snap of two clamps. After working with this product I can not stress how Easy and how great it is to work with this product. After installing a PVC system and working with JET's premium ductwork, I'll never go back to wasting time on playing around cutting fitting for hours when I can do a decent size installation in a hour. I will admit this product costs more than going economy with PVC, but my time in the shop is minimal, so the last thing I want to be doing is working ON the shop rahter than IN the shop.
I tested this system by using a 4" x 60" Testing tube. The pitot tube was inserted 30" (7.5 x duct diameter) downstream of the last transition and another 30" of ductwork after the pitot tube. I used 4" because just about every stationary machine I have run into these days has a 4" DC connector.
The results of this system are as follows:
Bandsaw Branch = 6375 fpm, 2.5" WC, 556 CFM. That is an increase of 333 CFM, 40% increase
TS, Planer, Jointer Branch = 5250 fpm, 1.75" WC, 458 CFM. This is an increase of 257 CFM, 43% increase
I did NOT test each individual blast gate of the 5" Branch, I just measured the TS, which was the longest distance with the most amount of transitions to go through. I figured if I was happy with the TS results then I would surely be satisfied with the Jointer and Planer as they are closer to the DC unit.
I am considering putting in a floor drop rather than just a cleanout at the end of the BS branch due to the high amount of CFM available at the end of that branch. I would say this concludes my Dust Collection Experiment for now, I am most satisfied knowing the difference between the 4" system and 6"/5" system. This article should incourage all to upgrade to 5" or 6" ductwork. I know Bill Pentz stressed the importance of this point, but after actually running tests on my system I have now seen the light.