A sucking problem

[JamieNE]

Hello all,

I’ve spent the weekend “upgrading” my dust collection system from a standard 500w dust collector with the bag, to include a new cyclone and steel drum.

Here’s a bit of background.
I have one of those small Chinese cyclones that is attached to a 50l blue plastic drum. The suction is through my old house vacuum that I broke the main attachment for, rendering it useless for the house.
This system is used for my thicknesser, belt/disc sander and my bobbin sander and works wonderfully.

So then I decided to do a similar thing for my table saw and router table and bought a bigger cyclone with a 75mm input and output. I only spent £32 on the cyclone as I couldn’t spend over £300 on the 100mm dust deputy one.

The cyclone arrived last week and I’ve put it all together. It sucks really well and the cyclone is almost exactly the same as my smaller system.

Here is the problem.
I was only expecting a tiny amount of very fine dust to get through the cyclone, through the vac and into the other bag. This is not the case. I’m getting quite a significant amount of dust in the bag.
Does anyone know why this might be?

Don’t get me wrong, a lot is dropping through to the steel drum, but too much is getting through.
How can this be?

Any help will be much appreciated.
Thanks!

 

[sunnybob]

Assuming you are using the same vacuum cleaner?

Dust will go through the cyclone if the speed air isnt very high.
The principle of the cyclone is that the centrifugal force pins the dust to the outside as it slowly descends into the lower canister. With a 75 mm cyclone and only a 32 mm suction, youre not swirling the dust fast enough so it just hangs inside the cyclone and then goes out the exhaust pipe.

Just a thought, you have connected it the right way round? machine to the side inlet, cleaner to the top outlet?
If so, then you need a bigger vacuum.

 

[JamieNE]

Hi!

Thanks for your reply.
Also, apologies for not explaining properly. The vac I’m using for the bigger cyclone is a 500w dust collector with 100mm input and output. It’s one of those standard ones with a filter bag at the top and the dust bag at the bottom. (I’ve taken the filter bag off though and attached an actual 1micron filter.)

I wonder if that is, in fact, the problem? Maybe I need to get a more powerful machine? Maybe a 750w or even 1500w?

Any thoughts?

 

[LancsRick]

I suspect airflow is your issue as 500w isn't very powerful for a dust extractor and going from 100mm to 75mm is going to further exaggerate the problem.

 

[sunnybob]

In that case... its not so cut and dried.
The basic principle of the cyclone is as I described. 100 mm suction on a 75 mm system might be just a bit too strong, stopping some of the dust from sliding down to the bottom and just sucking it through the outlet.
If its a big problem to you, try fitting a 100 mm blast gate in the line from extractor to cyclone, and closing it by increments untill you get the desired effect. But that should not be closed more than 50% or you will overload the extraction motor.
But I suspect the cyclone bucket will fill up before the main bag, so just empty both at the same time.

 

[JamieNE]

This sounds like a great idea!
Thank you!

I’ll give that a go tomorrow and report back.
I just happen to have a spare blast gate I can use.

Thanks again
Jamie