Question on Oneida SSD and HF Mods.

[Steve Eure]

For those here who have modified their HF DC with the Oneida Super Dust Deputy; Is it more efficient to mount the moter and fan of the dc on top of the SDD or just connect a hose between the two? I've seen it done both ways, and outside of the several feet of hose between the two, I can't figure if there would be an advantage to mounting it on top other than to save space.
Does anyone have any figures or actual experience on this matter?

[Victor Levey]

Steve,

I set mine up with the motor on top of the SDD. You can see build pictures here: https://www.lumberjocks.com/projects/408781

I love the way I have mine set up.

Best,

Victor

[David L Morse]

I looked at that question a while back when contemplating my own mods. I ran some numbers and, surprisingly, was able to find the spreadsheet again.

What I did was use this online calculator (http://www.freecalc.com/ductloss.htm) to estimate the added pressure loss of various types of ducting compared to a straight connection with the fan above the SDD. I assumed a length of duct, I think 10', and three 90 degree turns. Now the relative effect of the added duct varies a lot with flow, I used 500CFM for the straight through flow and then calculated the reduction in that number due to the effect of adding duct.

410814

This assumes no modification to the fan and the use of a 6 to 5 reducer, either at the SDD for 5" duct or at the fan for 6" duct.

5" hose is of course the worst of the choices, but 16% flow loss is certainly not devastating. 6" hose or 5" snaplock cut that loss in half and 6" snaplock or PVC would make it nearly unmeasurable.

The biggest disadvantage for me of the long duct approach is the bigger footprint; it would be nice to get the fan up and out of the way.

[Steve Eure]

Thanks David. That's exactly the type of info I was searching for. I was thinking of adding the SDD to replace my Thein system to get better results out of my setup. If I leave it as is and swap the Thein with the SDD, I would still have a short (approx. 4') hose attached between them. I realize I would lose some CFM's, but how much was my question.
I think for all practical purposes, I may try the fan/motor assembly on top to eliminate any problems.
Thanks again.

P.S. If anyone still has more info, I would really appreciate all comments.