Dust Extractor noise

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Jensmith

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I had a thread a while ago about the noise my dust extractor creates when both motors are switched on.

There were a few posibilities suggested such as an air leak and Camvac themselves also suggested this.

Link to original post:
dust-extractor-odd-noises-t52703.html?hilit=%20bandsaw

It's a kind of wailing noise that increases when I'm using the machine and dies away when I switch off a motor.

I think I've worked out what it is but I'm not sure how to resolve it.

Essentially I think I'm producing too good a seal and essentially there's not enough air flow into the pipes. It's kind of what would happen if you put the dust pipe against a flat surface and left it sucking.

The other problem is I have a 4" Camvac unit but all my machines are small so I've had to use a length of 2.5" pipe to connect to the machines and my bandsaw and to keep weight down the 2.5" pipe is about 2m long so I'm already reducing airflow.

I have the bandsaw extraction directly under the table as per Olly's design so the connector is right under the table and the blade runs through the drainpipe elbow so the seal is pretty good. Excellent for extraction but not so good for the airflow it seems.

Post on the extraction with photos:
bandsaw-dust-extraction-my-solution-t52252.html?hilit=%20bandsaw

I have holes in the plate in my bandsaw but the original was damaged and I had to make a new one so the holes arn't the best. They didn't frill very cleanly.

It's worse though when material passes over the plate.

I can stop the wailing by leaving a gap where the pipe connects to the bandsaw but then I don't get very efficient extraction and when I'm cutting plastic this gets pretty messy.

I'm thinking I could maybe make a couple of holes in the drainpipe elbow to let air in but I don't want to compromise my design before getting some opinions.

Any thoughts?

Thanks,

Jennifer,
 
My Record DX5000 has a couple of overlapping holes in the pipework that you can adjust to control the pressure.

Rod
 
Ah. With the Camvac and 2 motors it really does produce a lot of suck!

Is there a way I could incorporate that into my system without messing things up?
 
I notice it most with the bandsaw as I use that the most. Also happens with my little proxxon table saw but with that there us a tiny extraction port and the suction will threaten to pull it off the bench if I don't clamp it down. The extraction on that is poor tbh. Doesn't move much material out if the housing and it's an enclosed box. Just the blade providing the throughput of air.

Hope that makes sense.

My router table seems to be ok most of the time.

Sometimes the noise starts immediately, sometimes after a while, and simetimes not at all but it does happen mist consistently with the bandsaw.
 
The inlet pipe connected to the main body and the connecting flexible pipe both have matching holes. The suction is controlled by opening and closing the hole by rotating the flexible pipe which fits over the inlet pipe.

Rod
 
Thanks Rod. Mine doesn't have quite the same connectors - the flexible pipe screws into the connector and it pushes onto the dust extractor but I might be able to do something with the flexible pipes themselves.
 
It sounds like you're starving the system of air. Holes in the throat plate will often be covered by the workpiece - I wouldn't worry too much about them. Underneath the table shouldn't be sealed completely,a gap or holes in the duct behind the blade will allow air to be drawn into the system.
A really well designed hood will capture dust purely by using Tooling-Induced-Airflow. A bad hood design will conflict with this and have poor efficiency needing a huge airflow, 6" ducting, massive filter area etc.
Matt
 
Shrubby":3tuetcbu said:
It sounds like you're starving the system of air. Holes in the throat plate will often be covered by the workpiece - I wouldn't worry too much about them. Underneath the table shouldn't be sealed completely,a gap or holes in the duct behind the blade will allow air to be drawn into the system.
A really well designed hood will capture dust purely by using Tooling-Induced-Airflow. A bad hood design will conflict with this and have poor efficiency needing a huge airflow, 6" ducting, massive filter area etc.
Matt

Yes, that's what I thought - it was just how best to introduce the air that I wanted advice on.

The thing is, perfect hoods are great, but I had to adapt a design to work with my bandsaw and I went through several designs before I got one that fitted under the table and also worked to extract the dust.

It's always about compromise. Every design for a bandsaw will be different. I just need a way of improving the airflow. If holes in the connector are the answer then that's what I'll try.
 

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