Thread: 150mm quick clamp things

Originally Posted by DeeSki

Hi Bob - yes exactly, the port for the Hammer units is 120mm. Might need to get creative.

I'd be trying to turn the 120 into a 150 mm port.

Otherwise, does it need to be moved around? I would avoid flex altogether and I look at running the 150 mm PVC right up to the a tapered junction direct to the 120mm port

Originally Posted by DeeSki

Hi Bob - yes exactly, the port for the Hammer units is 120mm. Might need to get creative.

What machine is this on? The tablesaws have a worse issue, they step down through the duct to something like 90mm.

A N4400 and A3 31.

Have a look at these.

https://www.ebay.com.au/itm/Quick-Re...frcectupt=true

If you don't want to upgrade to 6" then head to bunnings and buy a 6"x 5" adapter for exhaust ducting. Something like this.
Duct_reducer.jpg

Originally Posted by Tonto

If I had 2 or 3 different machines that needed shifting around to be used and all had 150 outlets, if there anything that would allow me to quickly clip flexi hose from one to the other, without pulling off one pushing onto next then tightening with screw clamp etc.

I cut up a large stepped reducer and used it to attach to the end of a 6 inch flex hose. One like this https://www.carbatec.com.au/dust-con...versal-yw-1039

I would include photo's but manage attachments does not work at all for me. Seems to be an error in vbullentin_attachment.js script. AJAX_Compatibility is not defined.

Originally Posted by MrSlow

I cut up a large stepped reducer and used it to attach to the end of a 6 inch flex hose. One like this https://www.carbatec.com.au/dust-con...versal-yw-1039.

Those stepped reducers will generate considerable restriction, the tapered galv reduced shown by Flindersia would be better. Better still, if you have room, is to make one that has a longer taper. Best of all is of course to re-jig things to suit the full 150 mm ducting.

Originally Posted by BobL

Those stepped reducers will generate considerable restriction, the tapered galv reduced shown by Flindersia would be better. Better still, if you have room, is to make one that has a longer taper. Best of all is of course to re-jig things to suit the full 150 mm ducting.

There is no reduction in the reducer as it steps up from 120 to 150. Flex hose is on the outside. Reduction is on the machine outlet itself. Sorry its not that clear without a picture or two.

They are internally stepped like the outside. These steps cause turbulence and restrict the airflow as BobL stated.

E4AA7C66-DF8D-4E88-AADD-FE702ED2E3D7.jpg

As Lappa says they still cause turbulence.

Just because the air moves from a smaller to larger diameter makes little difference.
It turns out the air flow can be run either way for almost the same result.

The diagram below is a rough representation of what goes on.

If the air runs from left to right (larger to smaller diameter) there is a back up in flow due to the constriction.

When the air runs from right to left, the step area experiences a rapid pressure drop which causes some of the air to dive rapidly sideways and bounce of the reducer wall and causes turbulence.
Unfortunately the turbulence is not just limited to the immediate area of the step but propagates well outside that area and affects much more of the flow causing a air flow bottle neck.

Screen Shot 2019-04-06 at 1.44.23 pm.png
The other issue is the port/ducting/flex goes over the reducer which means the ID of the reducer is even smaller than the ducting.
This applies to most of those black plastic dust fittings from CT and TC.
Where possible fittings should go over the flex/duct/port.

Interesting. Guess I will look for conical fittings then.

Originally Posted by MrSlow

Interesting. Guess I will look for conical fittings then.

You can get a significant improvement by filling the step space with some material to form a sort of ramp.
The longer the ramp the better.
Reducer.jpg

It won't solve the problem of the reducer fitting inside the ducting/flex etc,