Replies

1. 
   Beasley7 | May 29, 2020 09:14pm | #1

   I think the best answer is "it depends". Your dust collector is going to try and suck the same cubic feet of air all of the time. So using a smaller pipe forces the air to move faster. That's not always a good thing. Dust collectors are designed to move a high volume of air at a fairly low pressure. Shop vacs are designed to be higher pressure lower volume. The larger ducts moving a high volume of air will allow larger chips to pass without clogging your system. So, if the tool is a spindle sander (no chips, just dust) you can probably pipe down at the Y. If the tool generates chips like a planer or table saw, pipe down as late as possible. If you are really looking for a one answer for everything, pipe down as close to the tool as possible.

2. 
   stantheman | May 29, 2020 09:37pm | #2

   if you have the adaptor at the tool, you can always leave it attached to the tool while moving the hose to other places.

3. 
   bashinsk | May 30, 2020 10:36am | #3

   Thanx for the replies and suggestions. I have a 3hp "dust sucker" and just wasn't sure about the best place to make the "transition" from 4" to 2.5". Sounds to me like the place to put the adapter is at the tool and use the 4" pipe across the system. Thanx again!

4. 
   geedubbee | May 30, 2020 06:22pm | #4

   Rule of thumb is to keep the diameter large up to as close to the tool as you can. I see this mostly when moving from a 6" or 5" duct to a 4" whip that connects to the tool. I often use a blast gate to manage this transition from duct to hose. That being said, reducing a 4" DC to 2-1/2" is moderately successful; smaller than that and you want to switch to your shop vac.

5. 
   rob_ss | May 31, 2020 07:23am | #5

   If you can, try to use a conical section adaptor such as are usually sold!
   My system uses an MDF plug turned to jam into the 4 inch pipe and a suitable hole for second-hand vacuum cleaner hoses.
   It works well enough and collects all the dust from my drop saw and some of the dust from the router.
   I do find there tends to be a collection of dust around the plugs, and though this does not prevent the system from working, it does tend to choke up the cheap plastic blast gates I use.
   Still, I have three of the small ports on my system and they work well enough that I have not spent the money on anything better. I tend to leave the drop saw blast gate open all the time as it does not stop my small sucker from working effectively on the larger machines.