Want to measure how full a saw dust collection container is. Have a working code using ultrasonic HC-SR04 sensor with LED stick indicating the level. Works on the bench and while holding it over saw dust. When placed in an closed container it goes crazy, lighting all the LEDs and some flashing.
I'm thinking, when enclosed inside the container the ultrasonic is echoing or bouncing around causing this?
Any way I can correct this or should I be looking at an IR sensor? From what I read, IR is better for rough surface. 10 to 80cm would be enough range.
Weigh it....
Could You make a drawing showing the dimensions of the saw dust container and the sensor mounting?
That's a idea. This is a 30 gal container and since all wood is not created equal in weight and moisture content, the weight might not equal volume.
Thanks for the reply
It is just a 30 gal plastic barrel. The sensor is mounted under the top lid and points straight down. If you need more I can work on a drawing or picture.
Maybe ...
A rod is fixed to the top of the container, on the inside of the container. The rod projects down into the container.
A pressure sensor pad (or microswitch) is located on the end of the rod.
When the bag fills up, it pushes against the sensor to indicate a full condition.
If the extraction motor is pulling air out of the container, and hence is pulling the bag upwards. then the reading has to be taken with the vacuum off.
Sawdust is terrible at sonic reflection. Weigh the bag and dump when weight exceeded.
PS I have a dust collector in my wood shop. A scale is easier to read and not sensitive to "fluffing".
That's true.
How is the dust delivered into the container?
Make a simple drawing or post some pictures.
What is the action when the container is full? Changing to a new empty container or emptying this container?
Good suggestion. I was wanting to see the level as it progressed. knowing this, I could decide if I wanted to empty it now (before I started a project) or have to stop in the middle of a wood working project to empty it.
Thank for your input
The black things on top are cyclonic separators. Vacuum is applied to the top and the dust enters in the lower elbows. The dust spins around inside the black portion and falls out the bottom into the barrel.
Pic 2 is the bottom of the upper part that locks on the barrel. The sensor is seen mounted there. The 2 openings are where the dust drops out.
When full I normally empty it but could put a new container on. Either way it gets emptied at some point.
Thanks for Your time and work.
Using weight sensors looks not so easy. The tubes leading to the cyclonic separators will affect the reading.
I'm thinking of an optical sensor, looking through the barrel near the top, measuring the level. Mount the sensor and the receiver outside the barrel, having holes to "see each other".
Possible? Worth trying?
What do You think?
Dust blocks optics. Cyclone weight is static. Weigh full barrel, empty it and note spread. Sawdust tends to be more uniform as the particle size is all in the same size range.
The whirling dust will clog the ultrasonic unless you saran wrap it (thin enough to let the sound thru with minimal loss.
But I gots to tell you those sensors are noisy in a whirlwind and you're going to get lots of false trips whilst the DC is on.
True but using a sender emitting light at high intensity there could be a chance of looking through the cloud until the obstacle gets more solid.
Of course, getting the receiver clogged... Preventable? Possible to calibrate the sensing?
It's a tough environment.
Im a member over on lumberjocks.com and this issue comes up regularly and optics don't work reliably. My old dust collector bag had a clear panel, but you could just look at the bag to know it was time.
Post your code.
I have a suggestion, an idea, it is also based on optics, but it might be more successful, I don't know.
Attach an addressable led strip vertically inside the container. At regular intervals, light each led in turn, from bottom to top or top to bottom. An LDR mounted at the top of the container measures the light level as each led lights. Calibrate the light level received, from each led, when the container is empty. When the container begins to fill, the sawdust at the bottom will block the light from the lowest LEDs. Sawdust in the air will block some but not all of the light from the upper LEDs. By calculating a threshold for each led, compared to its calibrated level, it might be possible to decide which LEDs are covered by sawdust, and from that, calculate how full the container is.
(I also woodwork, and understand the problem you face) The contents are likely not predictable, sawdust one day, planer shavings the next, variable moisture content and wood density, la la la; this probably defeats most surface sensing techniques. I might try a string of optical sensors down one side of the inside of the barrel(perhaps, embedded in a clear plastic tube for protection), with a high-intensity IR source at the top of the barrel, but I wouldn't be confident of repeatability; would need a lot of fiddling to determine best sensing. Certainly, you'd need to wipe the sensor string every time you empty the barrel, as the finer dust will cling to just about anything. And, beware of static buildup in a plastic container; sooner or later your electronics will suffer.
I too am a member of Lumberjocks but haven't posted anything in there recently. I don't have a clear bag and basically using a home made system.
Some have concerns about dust interfering when running. I would only take measurement while not operating.
You probably only need to 'sense' the upper half of the container, unless you're (for example) planing a truckload at a time; however, that's your call. Do you want to be able, at a glance, to say "well, I've got room for at least 5 minutes planing", or is it more a "more than half full, don't care how much it's time to empty it"? The answer defines the extent of your measurement needs. But then, drilling a 2" hole in the barrel and gluing in a piece of clear plastic would suffice for a half-way sensor. YMMV.
I think you'd do better with an optical sensor than ultrasonic, but I'm not sure what the reflective characteristics of a pile of sawdust would be! You might look at reflective sensors like the VL53L0X--there are lots of references around if you just do a search on it.