I have been lurking and researching for awhile, so first ... Thanks to everyone for all the information available on this forum!
I have a samll enclosed basement shop, very limited space, and a family with many allergies. I have done the majority of my dust producing woodworking outside in the past, but living in Minnesota makes this very limiting. Therefore I have decided to add some real dust collection to my shop and give things a go indoors.
I recently purchased a Delta 50-850. It is a standard original Type 1 unit with dual 30 micron bags. Clearly not going to cut it from both a collection and footprint perspective. So planning to condense the unit using the Thien baffle inside the DC ring and at least start by venting outside with maybe a future addition of a WynEnv filter. I realize there is somewhat of a debate on "push through" versus "suck through" topic, but I currently plan to go "suck through" primarily because of the condensed footprint. I attached a photo of my proposed design and I would like some feedback prior to construction. And please dont worry I have very thick skin and would just appreciate some input from those that have been through this process.
Thanks in advance, Greg
I forgot to mention that I would also like to keep the DC components used in the unit as unmodified as possible. The attachment above shows the original DC components being used in green lines to indicate that they are unmodified components from the DC.
I have no experience with the internal baffle but it sure looks like it will work well.
You must have thick skin to woodwork outside in Minnesota ;) , ouch!
A few of my more specifc concerns of this design are ...
- Diameter of the DC canister - The DC canister is only about 19" in diameter. With 6" intake and exhaust there will be lots of air flow and a rather minimal distance between the exhaust pipe and canister wall. I would think that this will result in lots of particle discharge through the exhaust. This isn't really a big deal when venting outside, but if I switch to a filter it become problematic.
- Mounting of the Thien baffle - It may not be apparent from the diagram, but I was hoping to not use the traditional three supports between the top of the tophat and the Thien baffle. Has anyone done this? The baffle would only be supported by sealant around the exterior of the DC canister and of course the 120 degree solid section of the baffle along the exterior.
Quote from: galerdude on January 12, 2012, 05:51:37 PM
You must have thick skin to woodwork outside in Minnesota ;) , ouch!
Thick skin comes with the territory :) ... just happy to have all my fingers as they can get numb in the process.
If you search around you will find others that have used the ring of their DC as the top-hat portion of the separator. It works well.
Thanks Phil. I have searched, found, and read many posts here and elsewhere on using your baffle inside a DC canister. All that I have read have reported good results, but many have also reported a fair amount of fine dust getting to their filters (at least more so then custom made tophats). I guess I am trying to decide if using the DC canister if worthwhile or if I should build a larger diameter tophat with some of the other "bells and whistles" people have used to improve seperation.
I haven't been able to find any specific recommendations on tophat diameter based upon CFM or pipe size, so any pointers there would be much appreciated.
I went through some of the some thought processes when I built mine. I think you might consider my setup. The only thing I used from the HF dust collector was the blower. I get nearly no dust in my filter.
One concern I'm sure you though of: exhausting to the outside in the winter will make your house very cold.
(https://lh6.googleusercontent.com/-O18rMYbHxqo/S3rg-SdWuiI/AAAAAAAAABo/J7LTiNbsH2Y/s640/IMG_0172.JPG)
Quote from: GMan on January 12, 2012, 07:21:06 PM
I haven't been able to find any specific recommendations on tophat diameter based upon CFM or pipe size, so any pointers there would be much appreciated.
As D increases, fine separation performance improves. The problem you run into with too small a D is that the air mass doesn't slow enough by the time it makes a full revolution. When it comes around and hits the incoming air, the super-fines can be pushed towards the center, where they exit the outlet pipe.
If you're worried about fines getting into a filter, then a larger D will help. If you're exhausting outside, it is moot. Either the 19.5" ring of your DC, or a larger shop-made unit, will exhaust minimal fines (they won't accumulate, you won't see any evidence of dust outside).
I have little doubt that I will eventually convert to using a filter, and thus my desire to build a design that would work for both external venting and filtered venting. With the unit running it wouldn't take long to exhaust the entire air volume of my house ... and heat/AC is expensive :)
Interesting point Phil. Does most of the separation occur on the first pass around the ring?
Has anyone experimented some type of internal veritcal baffles (either between top and baffle or connected to internal exhaust pipe and baffle) to redirect airflow towards the exterior wall ... especially near the intake? I have seen examples of round to rectangle intake conversion to direct the incoming air flow down and to the exterior wall. However if I use the DC canister with round intake this would be difficult.
Quote from: phil (admin) on January 13, 2012, 07:13:41 AM
Quote from: GMan on January 12, 2012, 07:21:06 PM
I haven't been able to find any specific recommendations on tophat diameter based upon CFM or pipe size, so any pointers there would be much appreciated.
As D increases, fine separation performance improves. The problem you run into with too small a D is that the air mass doesn't slow enough by the time it makes a full revolution. When it comes around and hits the incoming air, the super-fines can be pushed towards the center, where they exit the outlet pipe.
If you're worried about fines getting into a filter, then a larger D will help. If you're exhausting outside, it is moot. Either the 19.5" ring of your DC, or a larger shop-made unit, will exhaust minimal fines (they won't accumulate, you won't see any evidence of dust outside).
By "D" are you meaning the diameter of the vessel or the distance from baffle to actual lid. I'm using a five inch distance with a 19.5 inch diameter and four inch ports. Still get alot more fines than I'd really like in my filter bag( 1 micron)
Quote from: BT3100 on January 13, 2012, 11:21:07 PM
By "D" are you meaning the diameter of the vessel or the distance from baffle to actual lid. I'm using a five inch distance with a 19.5 inch diameter and four inch ports. Still get alot more fines than I'd really like in my filter bag( 1 micron)
D=diameter.
The greater the diameter, the greater the velocity drop, and the greater the fines separation.
However, increasing the distance between the baffle and the top will also increase the velocity drop and improve fines separation.
If you increase the height enough, you can extend the outlet tube below the bottom of the inlet tube, and eliminate a great deal of bypass, as well.
I have been looking at various posts on this site and have been very impressed with the design ingenuity of many of you folks. I have a Delta 50-850 that I have used as a portable, but I would like to upgrade my shop to a central system and a better pre-separator. Presently I have a plastic trash can lid-type of pre-separator on a 30 gal. trash can, which helps with the big stuff, but it still lets a lot of dust get through to the bag. I'm anxious to give the Thien system a try!
I'm new to this forum, so forgive me if this subject has come up before. Here are my questions:
1. I will be connecting to the 50-850 with a 6" duct. On the inside of the 6" inlet flange is spot-welded a piece of metal with a 4" hole in it that would seem to direct the air to the center of the fan. Does anyone know if this metal reducer is necessary when connecting to 6" ducting? It would seem that removing this would reduce the static pressure at the inlet, which would be good. Of course, that would also reduce the air speed hitting the fan, which might be a problem. Any thoughts on that?
2. I would like to eliminate much of the flex hose by mounting the blower horizontally, with the end of the motor pointing upward. I read on one blog that orienting the motor in that way might put excessive stress on the motor bearings. Anyone have anything to share about that question?
Thanks again for giving me inspiration to upgrade my system.
Well not sure I can be much help as I have yet to complete my baffle (other priorities at the moment).
My 50-850 did not have the internal baffle you describe, but while researching I found that other newer models did have this and people have removed them with no bad side effects. The concensus seemed to be that it was there to prevent large chunks of scrap from getting sucked into the fan blades. My inlet is about 6.5" in diameter and all open to the fan blades. I need to use a HVAC 7"-6" reducer to connect 6" hose to the inlet.
It is possible vertical motor mounting could cause wear, but unless you use the motor very frequently I personally would not be too concerned ... but I am FAR from an expert in this area. In my research I saw many mounting as you described and I have no recollection of any related problems. Many of the new DC's orient their motors in this fashion, but of course they could be using different motors to compensate.
Good Luck!
Greg
Thanks, Greg. It sounds like they changed the model I have, because the outside diameter of the inlet is 6", not 6.5" like yours. I think removing the inner baffle would be possible, although there are about 8 spot welds on mine that I would have to grind or break loose. I an always put it back together again if it causes problems. I know what you mean about having other priorities. I've got a bunch of unfinished projects I should be doing, but this looks more interesting!
Thanks again!
So, did you ever build it? how does it work for you?