Delta 50-760 baffle conversion to single stage DC

[Biowood]

I am in the process of designing a Phil Thien baffle for the Delta 50-760 DC. The DC "ring" where the lower baffle would be installed is circular enough to install without any major issues. However, when I look at the circular area where the impeller air is dumped, the area has what I would describe as a corner. Basically a pocket that collect large amounts of dust and chips therefore creating turbulence in the ring. Should I create a sheet metal cover to eliminate the corner? Also, would there be any value in creating a short extension to the ring inlet port? This would probably act as a neutral vane.

I am planning on adding a Wynn filter so am also wondering if I should build a doughnut with an ~8" hole and if there would be any value in extending the hole with a pipe or sheet metal into the ring area. This delta DC does not have any inverted doughnut designed into it.

Looking forward to all of you expert opinions on this as I have not found these issues specifically addressed in other forums.

Biowood

[JTJ]

Biowood, I built my 50-760 with a pre-separator sitting under the inlet, but just for you  ;D, I pulled my bag to see the inside.  Not a pretty picture from the standpoint of trying to put the baffe into the 760.  For one, the bottom ring is indented about an inch from the sides, so it would seem to me that a lot would still be in suspension trying to find it's way to the 240* drop zone.  Two, Delta did not make the filter area circular as it butts against the circular ring of the input area, so the turbulence in the side opposite the blowing action would be considerable and I found some shavings and dust in that area, so it will definitely build up there, and yes I believe you would have to put a vane there, and for that matter I believe that you might have to vane the entire section out to the bag ring to get a "wall" for the dust and shaving to slow down against and drop into the bag.  So, you still have to make two baffle sections, the bottom one with the 240* drop zone, and the top to restrict the airflow into the filter.  The top one would have the inlet to the filter, and I believe that the circular inlet would have to extend a couple of inches down.  Now, since I don't do this, nor did I want to do it, I would rely on others that have made this type of mod to their systems and try to find information from them to understand the airflow needed for a baffle in the filter / bag area. 

You can find my setup in the topic http://www.jpthien.com/smf/index.php?topic=277.0, "YA Delta 50-760 Baffle Implementation".  When I pulled the bag from mine today, there was some shavings and dust in the area that you are getting buildup, but not a huge collection, so as a pre-separator, I'm very happy with my implementation.  The biggest mistake I made was in having the bottom of the baffle butted up against the inlet elbow.  I will correct that one of these days by dropping the bottom another 1 1/2", so that shavings don't hang up on the elbow, since I pulled out all my hand planes and did a major rework and sharpening, they now have a tendency to create nice long shavings, that hang on just about anything they can wrap themselves around.

  It was far simplier for me to cut off the brace to center a garbage can under the DC inlet, and build it into the can. I also reversed the stand, so that the platform is under the garbage can, rather than under the bag.  If the bag ever needs supports (Perhaps in a couple of years, given the amount of material that collects there), I'll just put a wooden shelf there. Very little was lost by doing that, and if I every feel like I need the support, I'll just make a wooden brace for that area curved to allow the can to sit under the inlet.  I also didn't want "stuff" getting into the impeller.  I believe that I still have all the benefits, don't have to pull the collection bag from the  DC, same mobile foot print, as Im currently a dragger of the DC from place to place, and have the convenience of not having to deal with popping the annoying bag holder, even though it really isn't that hard.

At any rate, best of luck with your build.  Sorry that I couldn't really be of  more assistance!

[Biowood]

JTJ, Thanks for your input! I am choosing to use 5" sheet metal vent pipe for the main duct in my single car garage and 5" flex tube for the drops to the machines as I don't really have the ability to drag the DC around. Because of that choice and based on the reading I have done on this and other web sites, I want to get the maximum cfm and minimum SP losses for my system. I will create the most aerodynamic DC ring I can to start with and also use the extension I have added to the ring input and hope for the best.

I am trying to find a no cost way to measure the suction power I end up with so I will be able to gauge any changes I make to the system...still thinking about that but I didn't make any measurements before I started so I lost that chance.

[jfin]

Biowood - and Others - I am brand new to posting to this forum. I read your question re: measuring actual DC flow before and after ducting, mods, etc. I would be installing/building my system right now, but we engineers like to engineer 1st, then build. But, with a new HF 2HP unit, I don't have (and can't get) any baseline data anyway. So, whatever I do, I'm just "shooting blind". I have posted similar to this post  on other forums, but there does not seem to be a lot of interest in "hard data". Maybe, since all you folks are into building, modding, etc., this may be the best forum for this post.

I believe I can get the instrument setup to do this for about $100.00. I'm an Aero Engr, so I can do the "number crunching", set up instructions, conversion charts, etc. I'm STRONGLY considering doing this for myself, so I would have to do the tech work anyway, but then I would only have one data set. That would be great for me, but why not "share the opportunity". The instrument is small & easy to mail.

Folks - does anyone else have any interest in this idea? Please post, if only a "yea" or "nay" -

Jim Finnegan

PS. One question I really want an answer to is, given two identical built-in DC systems, one with expensive welded ductwork and one with the common ducting you can get at Home Depot, Loews, etc., how much more does the "cheap" ducting cost me in static pressure loss, if any?