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Discussion Starter #1
How would using the DD, which has 6'' connections, work with a Harbor Freight DC with 4''? Would the 2'' reduction make it not such a wise choice?
It would be used one machine @ a time, e.g., TS, planer, 8'' jointer
and a miter saw.
 

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How would using the DD, which has 6'' connections, work with a Harbor Freight DC with 4''? Would the 2'' reduction make it not such a wise choice?
It would be used one machine @ a time, e.g., TS, planer, 8'' jointer
and a miter saw.
If I am not mistaken, the top connection, to that DC is 6 but the machine connection is 5.

Here is an exerpt from Bill Pentz's website


  1. Ducting Resistance Ducting resistance is known as static pressure. Even a short run of duct that is too small for a blower will cut the airflow down to the highest speed that pipe can sustain. The impact on most hobbyist blowers is terrible. A 3/4 HP blower with a maximum airflow of about 600 CFM will rarely provide more than about 300 CFM real air flow when connected to a 4" pipe. On that same 4" ducting a 1 HP unit that gives 650 CFM maximum rarely will maintain 350 CFM. A 1.5 HP rated at 1100 CFM barely gives 350 CFM. And a 2 HP capable of 1200 CFM is lucky to provide 450 CFM. Bumping up to 5" pipe adds about 100 CFM to each of these configurations. Bumping up to 6" pipe causes problems for the under 1.5 HP units because the air speed (FPM) can fall too far and make dust block the pipes, but with this bigger pipe, the bigger units end up going to 800 and 900 CFM. As a result, you need to use at least 5" duct for any hobbyist blower rated up to 1100 CFM and 6" or larger duct for blowers rated 1100 CFM to 1800 CFM.
  2. Ducting Reductions Unlike big industrial sites, most hobbyists should run the same sized ducting, fittings and hose right up to their machines. Don't do like many and run a 6" or 8" main trunk line then come off with smaller duct or flex hose. The smaller pipe will kill the airflow needed to keep the air in the mains moving fast enough to avoid plugging and building up dust piles. You have to keep three 3" ports open at once or two 4" ports to avoid the plugging a 6" main and even more open for larger mains. Having so much open often kills the airflow needed to collect the fine dust. If you use standard hoods you should still convert over to 6" ports. Even reducing ducting size right at the machine for the shortest possible distance to a small 4" port will still kill system performance. The smaller ducting, flex hose, and small ports limit the maximum airflow just like we proved in that little air test sucking experiment! If you do change size ducting, use a big enough blower to support opening multiple blast gates and appropriate connections for enlarging and reducing:
  3. My friend Sugi found a better way to do ducting reduction and expansion. His mixed combination of Imperial and Metric sized ports on his tools required lots of different reducers and expanders to work with his 6" mains. He found a very elegant solution that gives far better airflow than we get with even the nice tapered reducers shown above. Kanaflex makes a polypropylene rigid duct hose they call Kanaduct with interlock construction which allows the inside diameter to be changed by twisting the hose. This duct starts off as a flat strip rolled into a spiral. On one side of the strip is a male rib and on the other a female socket very similar to zip-lock bags. Depending upon direction of twist this duct either expands or contracts in diameter up to about 50%. This results in very smooth clean transitions without all the nonsense of expensive transitions. The retail price per meter is about $24 which is cheaper than having to buy metal reducers and flexible hose. We can easily make long transitions that very effectively reduce pressure loss.
hope this makes sense,


Paul
 

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Discussion Starter #3 (Edited)
The info on the HF website says the inlet/outlet diameter is 4''. So I would have to make a 4'' to 6'' transition @ the cyclone. Most of the information I read make little sense to me. I may well call the company and see what they say. I basically need a yes or no answer. Reading directions or long explanations do not work well for me.
Thank you for you'r time and effort.
 
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