Understanding suction

[DynaGlide]

I've been avoiding using my Dewalt DWS782 SCMS in my new basement shop out of fear of the dust cloud until I realized my 27mm vac end fits inside the dust port perfectly and does an admirable job of catching most of the dust. Wanting to make it better I bought an old style ribbed Festool 36mm 3.5m hose for half off. Now my question: if the 36mm hose doesn't fit over the dust port of the saw and I end up using a 36mm to 27mm adapter, do I negate the benefit of the larger hose? Not sure how to think about this one. Thanks.

 

[nvalinski]

You won't entirely negate it, but you will end up with some reduction due to the increased friction through the fitting. You will gain having less friction on the remainder of the length though, which should be a significant gain over the 27 mm hose.

 

[Svar]

You won't entirely negate it, but you will end up with some reduction due to the increased friction through the fitting. You will gain having less friction on the remainder of the length though, which should be a significant gain over the 27 mm hose.

Agreed. Friction losses are to some extent additive.

 

[cpw]

I have an old ribbed 36mm hose, which fits perfectly over the port on my Dewalt SCMS (780).

 

[DynaGlide]

I have an old ribbed 36mm hose, which fits perfectly over the port on my Dewalt SCMS (780).

Well there I have it then. It's like they designed the port for the Festool vac.

 

[Steve1]

Its like when you are routing your dryer exhaust, and instructions say a 90 degree elbow is equivalent to 15 feet of ducting.  Adding the adapter increases the resistance to airflow.    But I would not worry about it.