Monitoring Sawdust Level in Dust Collector Drum

[Izzy Charo]

Hello,
I have the Oneida 35G drum and the sensor/flashing light to alert you when it's near full,,,but it doesn't seem to be reliable. Not sure why, but I've had it flash red when the drum was was only 1/2 full, and fail to flash red when it was over the top full,,,, I'll keep trying to adjust the sensor, but I was wondering if anyone has found a 35G drum that you can see through (? heavy plastic) or found a way to modify a steel drum so you can see how full it is-- low tech!
Thanks!

[Dwayne Watt]

Sounds like a sensor problem to me. I have a ~35 gallon fibre container that is very consistent. I have the sensor set for roughly 4 inches below full. The sensor is set about 4 inches from the container edge. Sawdust does build up a bit higher at the edge of the barrel than the middle. I doubt you will see through a window or plastic drum after the first fill up due to dust contamination. If this is not new enough to be under warranty, you can buy the exact same sensor on the famous auction site or other for less than $15.

[Bob Hinden]

Maybe check that the sensor is not blocked, has saw dust on it. If you can remove the sensor, easy to test it with your hand to see what distance it trips.

If this doesn't work, suggest contacting Oneida.

[Andrew More]

I've got the DIY sensor from the pinned thread at the top of the forum. I occasionally get "false" positives, which I believe are likely caused by the sawdust not sitting correctly at the bottom of the bin, or perhaps the plastic bag tripping the sensor. I have yet to have an issue with it NOT tripping when it's supposed to do so.

As for "see through" drums I'd suggest modifying your existing drum. You can cut out a "viewport" with an angle grinder, and fill that port with some very heavy plexiglass. Fair warning, I attempted to design a see through drum, and ran into issues with the pressure collapsing the drum. In my case the plexiglass was not thick enough, and it covered a 4'x4' area. I did not realize that the collector was also under pressure, don't make my mistake.

[Prashun Patel]

I thought about modifying the drum but then decided a leaf liner bag inside the drum was more important than a level sensor to me. My level sensor is the drop flex-hose between the cyclone and the drum. It's clear enough for me.

[Darrell Bade]

I built my own sensor system and have posts in the pinned thread. I put a timer on mine, sensor must show full for 15 seconds before it alarms full. Never had a false full alarm, don't know if that is why or not. Also never had it overfill.

[Frank Pratt]

The Oneida sensor is entirely unreliable. I'm tossing mine and putting in a vibrating rod sensor. It has a rod that protrudes into the drum and vibrates ever so slightly. When spoil comes in contact with it, the vibrations are altered, which sets off the alarm.

[Thomas Wilson]

Level detection might be difficult for the rod too. At least on mine when collector is running, the air rotation is pretty high in the drum and and there is a lot of suspended dust in the air so that the level is not so distinct. Do they say how they process the vibration signal to detect level?

[Chris Parks]

For those that have replied to this thread or reading this thread I would like to ask if you could tell us if it was used with a cyclone and if so did it work reliably. TIA.

[Darrell Bade]

For those that have replied to this thread or reading this thread I would like to ask if you could tell us if it was used with a cyclone and if so did it work reliably. TIA.

Mine is on an Oneida Cyclone. It has been reliable and shut off every time it was full for 4 years. I have never gotten a false alarm but like I said, I built my own circuit and put a timer in it where the sensor must show full for 15 seconds before it shuts off to eliminate any false full readings.

[Dwayne Watt]

Mine is also beneath a Oneida cyclone. It works well thus far (2 years and counting). As I mentioned earlier, you may have bad sensor giving erratic results. Also, the sensor may be mounted too close to the outer edge of the container. Debris tends to accumulate higher there than the center of the pile. I have mine adjusted to close the circuit when the debris level is roughly 4" below the sensor.

[Malcolm McLeod]

Level detection might be difficult for the rod too. At least on mine when collector is running, the air rotation is pretty high in the drum and and there is a lot of suspended dust in the air so that the level is not so distinct. Do they say how they process the vibration signal to detect level?

We use a LOT of vibrating level switches/detectors - as many as 4-5 on any given vessel. They were equally common in my previous lives. Most of ours use a 'tuning fork' design for the sensing element (making them more compact than a 'rod'), but operating principals are the same.

Without getting too far into the weeds, there is a circuit that induces a vibration in the sensing element (...like a Sonicare toothbrush, but so subtle you would probably never notice any motion). Another circuit measures this vibration and compares it to a (typically) adjustable setpoint. When the product to be sensed covers the element, it dampens the vibration and triggers a switch (typically just dry contacts). You can use the contacts to drop out your DC blower, flash a warning strobe, sound an alarm, or shock the dog. Your choice.

They work very well with liquids. I have never seen any issues with their use in the turbulence typical of industrial baghouses, so long as very abrasive dust does not erode the element. Not likely in the case of wood dust. However, they do have a Achilles' heel:

1. They will have a manufacturer's specification for the minimum density product that they will detect; pay close attention to this. Most will sense the compacted dust that I generally see in my DC barrel, but might struggle with large fluffy shavings off a J/P on softwood. I've never tried to use them like this and not sure about the density of these larger shavings. They might not detect them?
2. Maybe TMI, but they also struggle with sticky or electrostatic powders. With wet or 'static-y' powders (all that dry moving air creates static), the dust may stick to the element and give false positives. I don't think wood dust will suffer from this unless you are processing VERY green wood.

Most will be 24VDC powered, so you need a power supply for them, but a 3-5A 'wall-wart' should easily suffice for 1 sensor. Pay attention to the power requirements of the sensor and the alert device, and use the same power source for both..?? Or, skip the alarm and use the dry contact to stop the DC? Or, find one with DPDT contacts and use one for an immediate alarm and the other to drive a timing relay (after 40-60sec, the relay drops the DC - - just in case you are working in your sleep?).

Options abound.

Rotating paddle switches are IMO the reference standard for dust, but $$.

[Clifford McGuire]

Has anyone contacted Onieda and asked them to comment? Do they deny it's a problem?

[Chris Parks]

Just to clarify my previous post, I am not using an Oneida level sensor.

[Maurice Mcmurry]

Mine is a 2 hp Grizzly barrel top blower sitting on top of a homemade cyclone. The top barrel is steel, the collection drum with the window is plastic. When there are planer shavings swirling around they clean the window. If I saw a lot of MDF the window will dust over. Tapping on the window usually causes enough dust to fall to see in.