Thread: Ducting - transitioning from big pipe to smaller pipe at cyclone inlet

I got a very nice 8" DC inlet to 6" PVC ducting transition from a gardening store (plastic plant pots )
I also added a PC viewport which allows me to look down into the impeller - and also reach in there to clear anything out - haven't had to do it in 3 years - of course if I hadn't done that I would have had to do this

Bob,

that definitely has potential and is certainly a lot simpler than my turning idea. I'll check out the local nursery

thanks

Mick

If the flower pot solution doesn't work then another option is a truncated cone rolled up from sheet metal, easy thing to do for a good sheety to do, just need the diameters at each end, the length and if it's on center or offset.
Whatever you do remember to avoid blunt edges or shoulders that impede flow, if there has to be a shoulder the better option is to have the air flow over the shoulder rather than into it, for e.g. have the large pipe fit inside the large cone end and then the small cone end fit inside the inlet to the cyclone.


Pete

Hi Mick

I had a similar problem (but not quite so severe) in joining the 160mm OD of my PVC pipe to the inlet transition of my CV1800. The inlet transition was too small to let the PVC pipe slide inside which is ideal but was also at the wrong angle. The inlet transition is about 10deg above horizontal and that does not match any PVC bends that I could buy to get the pipe either horizontal or vertical (mine had to be vertical).

The saving grace for me was that the CV1800 and the inlet transition is made out of Thermo Plastic which softens very easily with a Heat Gun. Applying mild heat to soften the inlet I had no difficulty in both expanding the inlet and angling the inlet up a further 5 deg to accommodate the angle and larger size of my PVC pipe.
Might be worth a try particularly if you can modify the transition before installation. Unfortunately I am not sure how much you can practically stretch the transition. My transition was made with the taper to the opening size that was very steep to the end, so stretching the end was very easy.
Cheers
Ron

Pete and Ron,

thanks for the suggestions. I also checked out a plastic bucket at home and this looks like it can be made into a good fit. I think a plastic bucket / pot plant will be my first attempt although I am still tempted to turn an attachment - mostly just to see if I can do it!

cheers

Mick

Originally Posted by mick59wests

Pete and Ron,

thanks for the suggestions. I also checked out a plastic bucket at home and this looks like it can be made into a good fit. I think a plastic bucket / pot plant will be my first attempt although I am still tempted to turn an attachment - mostly just to see if I can do it!

Up to a point the longer the transition, the less flow will be lost, the length of the transition of around 5 average ducting diameters is considered about right e.g. transiting from 6 to 4" the average is 5" so the transition should be 25" long. In most case this is not possible but if you can turn this up the that will be great.

Originally Posted by BobL

Up to a point the longer the transition, the less flow will be lost, the length of the transition of around 5 average ducting diameters is considered about right e.g. transiting from 6 to 4" the average is 5" so the transition should be 25" long. In most case this is not possible but if you can turn this up the that will be great.

Bob,
I did expect that the longer the transition the better. For my turning I was thinking of closer to 25mm than 25" !!!

I have cut up a bucket which is a pretty decent fit - I will silicon it in. I ran the bottom of the bucket inside my cyclone shute as I thought this was better in regards to build up of dust, even though it fractionally cuts down the size of the 'pipe'. However, I am concerned with the strength of the bucket. Even though it should not be under any real pressure, it is pretty soft/flimsy compared to PVC. Can I strengthen the bucket? My thoughts are:
- duct tape
- silicon the whole bucket

I'd be glad for some further thoughts......

cheers

Mick

Mick - it depends in the bucket. If it lis one of those 72c plastic one from Bunnings then you may have a problem. Our puppy shreds these in about 10 minutes.
OTOH that plastic pot I used it thin polypropylene and its' very strong especially under compression.

it is definitely a cheapie. So, can I make it stronger or should I look for something a bit more sturdy?

cheers

Mick

Originally Posted by mick59wests

it is definitely a cheapie. So, can I make it stronger or should I look for something a bit more sturdy?

It will probably be OK - the situation where failure is likely is if it was to get a knock and shatter while it was running - but it would just break up and fall into the cyclone so no biggie really.