Extraction pipe size advice

[Jamied]

Evening everyone,
I am installing a ducted extraction system in the Workshop.
The fan has a 125mm inlet on the extractor and I have installed my ductwork the same size going as near to my machine's as I can, blast gates, straight Run's, gradual bends, short 100mm flexi to each machine.
All good until I got to my sedgewick table saw.
It has a 125mm outlet at the rear and a 40mm from the riving knife blade guard.
Should I branch of to the top of the machine and continue to the rear in 125mm pipe , or reduce to the rear in 100mm to compensate for the overhead branch.
The main duct so far to the saw from the fan is about 3 metres , needing to go another 2 meters to the back of saw.
Your help would be appreciated.
Jamie

 

[Noel]

Evening everyone,
I am installing a ducted extraction system in the Workshop.
The fan has a 125mm inlet on the extractor and I have installed my ductwork the same size going as near to my machine's as I can, blast gates, straight Run's, gradual bends, short 100mm flexi to each machine.
All good until I got to my sedgewick table saw.
It has a 125mm outlet at the rear and a 40mm from the riving knife blade guard.
Should I branch of to the top of the machine and continue to the rear in 125mm pipe , or reduce to the rear in 100mm to compensate for the overhead branch.
The main duct so far to the saw from the fan is about 3 metres , needing to go another 2 meters to the back of saw.
Your help would be appreciated.
Jamie

Hi Jamie. I've a ducted system, maybe in total around 15m or so in total. It's all 100mm and the TS is is at the end of one line, say around 8/9m from the extractor. There's a 100mm duct into the back and a 60mm (I think) line for the overhead guard and all works well
I'd suggest keeping to 125mm for the main TS port and inserting a Y connector for the 40mm line to the riving knife guard (assuming a 125/40 Y is available or using a 125 Y with a reducer).
Having said that if you have everything to hand you could try both but I'm not sure you'll see much difference.

 

[Jamied]

Thanks Noel, that's a big help, thanks

 

[deema]

Keep it at 125 to the saw, a saddle connector will suffice for the 40mm connection and is significantly cheaper than a Y connector. I silicone or gap fill glue the saddle into the pipes as well as self tap screw it.

 

[chris-a]

I realise this is a few days old but my solution for my Felder which as yours has, a 125mm port and then a 50mm fitting at the riving knife was to get a cheap Titan hoover from Screwfix and have a 50mm hose connected directly to that leading up to the guard port.
Good for a few reasons, doesn't stifle suction power from the main hose to the saw, excellent suction in its own right, and convenient in that I have it hooked up to a remote switch I keep on my fence so when i'm doing a couple of small cuts that I don't need the full extraction going I can just turn the guard extraction on just to keep things neat. I realise you've then got the expense of a vacuum and some hose but its worth it to me for the amount it manages to suck up