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  1. #31
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    Good idea on use of an US sensor but pity the DC has to stop to take an accurate reading.

    However, a highly accurate (+/- 1mm) reading is not needed as the bin should be emptied well before it is full so +/-5 cm would be good enough if you target an empty point of say 10 cm from the top.

    I reckon it would be worth looking at averaging the fluctuating output while its running. ie over say 30 seconds worth of data.
    Then perform a calibration run, ie make dust and perform and record the averaging and then stop and measure the actual depth.
    From these readings set up a calibration curve so that the real depth can be determined from the dynamic depth measured while it's running.

    In the actual implementation you could use an output from the DC to let the RP know whether the DC is running so it uses the dynamically calibrated depth while running, but not when the DC is stopped.

    I'd offer to do it but my rate of sawdust generation is very low these days and it would take me months to do it.

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  3. #32
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    That's a good call Bob. Will do some data logging over the next couple of weeks and see what I come up with.

  4. #33
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    Quote Originally Posted by maxxsinner View Post
    That's a good call Bob. Will do some data logging over the next couple of weeks and see what I come up with.
    I just contacted my son and asked him if if I could borrow a spare US sensor that he uses for his autonomously controlled vehicles. One problem with those is they have a mesh front where sawdust might get lodged.

    How much are the garage US units?

  5. #34
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    The one I used in the garage was from Ocean Controls for ~ $36 - Distance Sensors :: Prototyping :: Welcome to Ocean Controls

  6. #35
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    Default Don't call it a come back :)

    Over 6 months since my last update. Nothing like life, family and work to get in the way of doing what you want.
    Finally got some time off for good behavior so decided to take a new look at my workshop DC system and machine layout, armed with the information of all that I have been reading. Decided it was time for an improved layout.

    I installed cable trunking around the perimeter of the workshop and cable basket for data/low voltage cable.



    Should make any future changes a lot quicker.

    Next was some serious ventilation. I put the mistress of finance into bloodhound mode on Gumtree and she eventually came across a duct mounted fan with an attenuator for a good price.



    Going to install a return air 'egg crate' type finger stopper over the fan when I come across one.
    Variable speed built in, so goes from 0 to ludicrous speed. Think I will end up incorporating my dust sensors to readings to automatically ramp speed as needed.



    The attenuator (section with all the pop rivets) has the side walls with perforated mesh and sound absorption material. Apologies for the crappy photo. Getting cramped in my little DC enclosure.

    While my shrine to consumerism was on the hunt, she scored me another attenuator for my Clearvue.



    Similar to the duct mount unit, this one has perforated mesh all round with sound absorption material.
    Making the transition section from the Clearvue to the attenuator was a bit of mucking around - ended up using MDF and a couple of scraps of aluminium composite panel held together with prayers, silicone and a few lengths of all thread.

    Redoing almost all electrical and air line, now that I know where things belong and where I need air.
    Should have it completed just in time to have to turn my back on it all and return to servitude.. I mean work.

  7. #36
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    One of my hobbies besides woodwork is home automation / smart home type stuff and I stumbled across a bit of software - ESPHome. It works with cheap circuit boards that have wifi capabilities (ESP8266) that can connect to all kinds of sensors, including a few different flavors of particle sensors.

    So I decided on the Sensiron SPS30 and built a few boards -

    Dust_sensors (2).jpg

    Installed one over the Tablesaw, Workbench, Bandsaw and the Lathe on the ceiling so it's not in the direct line of fire. The last two units will be installed in the brides sewing room to keep an eye on how much of the nasties are making their way in there.

    Home assistant does all the heavy lifting along with a database built with InfluxDB.

    Dust_sensor_graph.jpg

    Next step will be automating the exhaust fan to ramp up when sensors detect a high particle count.

  8. #37
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    I found Its just easier to turn the fans on before making any dust.

  9. #38
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    I normally have the fan running at low speed Bob, as the incessant noise drives me to drink and the last thing I need is more encouragement.
    But I finding that I am not turning it up faster when the dust making starts due to human nature - focused on the how and where to cut and not the resulting cloud.

    Also as we discussed previously, I am going to run the control of the fan with these sensors in parallel with a differential pressor sensor between my workshop and wifey's cotton welding studio, to make sure my area is negative pressured and hopefully reduce dust finding its way in there too.

  10. #39
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    It will be interesting to see if the dust in her room goes up when you are not in your shop. I suspect there can be a fair amount of dust becoming airborne as she is cutting and sewing away. She might need her own ventilation.

    Pete

  11. #40
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    Quote Originally Posted by QC Inspector View Post
    I suspect there can be a fair amount of dust becoming airborne as she is cutting and sewing away. She might need her own ventilation. Pete
    Looking forward to seeing some data on this one cause I think you are on the money Pete. The rooms are pretty well sealed from each other than the door to my workshop, which is self closing.

    Of course ANY dust in her area must have originated in mine.... Couldn't be the fabric, concrete footpath leading to the studio or dust from outside

  12. #41
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    Quote Originally Posted by pintek View Post
    I normally have the fan running at low speed Bob, as the incessant noise drives me to drink and the last thing I need is more encouragement.
    But I finding that I am not turning it up faster when the dust making starts due to human nature - focused on the how and where to cut and not the resulting cloud.
    The most effective thing I found for this was a $3 pressure/Vacuum switch attached between the BG and the machine.
    This prevents some machines from starting unless I have the blast gates open and the DC running at least at 50Hz.
    Making sure your DC is on

    Depending on how it's made, dust production can highly variable and directional which means setting meaningful thresholds is difficult.

    What also happens is the fine dust does not remain local but moves around so you night make a cut or 2, or 3, - then have a break and make a few more cuts during which time this dust will diffuse into the shed without triggering the threshold set for a fan, especially if the sensor is located above the machine. By the time the threshold is reached at the sensor the lower parts of the shed may be contaminated with fine dust at a much higher level. I've experimented with sensor location and found that placing sensors above machines is not really indicative of what operators experience. I did some testing with a TS and found that fine dust levels were much higher at the front of the saw where the operator stands compared to above the saw. The most meaningful location is near an operators mouth which is why I made a wearable sensor but even then I wouldn't use it to control a fan.

    I too dislike noise but dislike dust more so I reckon its better to use max or near max flow when machines are making dust and then quieter general ventilation fans at other times or for something like hand tool use.

  13. #42
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    I think you're right Bob. We have had strong winds over the last couple of days and the sensors are picking up external dust pollution.
    Would be running my fan for no reason if I have the sensors controlling it.


    DustSensors2.JPG

    Most of my machines have automatic control of the dusty and blast gates and the ones that don't, have manual control or control via my control panel.

    ControlPanel.jpg

    I think I will look at configuring the ones with manual control to automatically run the fan at full speed for 2 minutes if the current sensors are activated.

  14. #43
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    USA, Indiana, West Lafayette
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    Your "Dust Measurements" chart labels the Y axis as "μm". What exactly are you displaying there? It seems like that should be "μg/m".

    Nice switch labels!
    Dave

  15. #44
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    Quote Originally Posted by dmorse View Post
    Your "Dust Measurements" chart labels the Y axis as "μm". What exactly are you displaying there? It seems like that should be "μg/m".
    InfluxDB displays the data from Home Assistant with the default suffix but I am betting that the software can't parse the forward slash making the m drop off -
    Dust measurements.PNG

    Quote Originally Posted by dmorse View Post
    Nice switch labels!
    Need to have some shenanigans in the workshop to remind me to not take life too seriously.

    Coat rack - 3rd generation Carbohydrate Foam Wrecker
    P_20210410_072535.jpg
    Router control panel - The Digit Destroyer
    P_20210410_072610.jpg

    And even the first aid kit is not safe from a dose of silly
    P_20210410_072502.jpgP_20210410_072516.jpg

  16. #45
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    Haven't been happy with my ultrasonic sensor that is keeping an eye on my dust extractor drum level as I am finding that temperature affects the reading too much and the sensor is not accurate over the short detection range, so went down a rabbit hole on electronic distance sensors and found some cheap 'time of flight' sensors. Adafruit VL53L0X Time of Flight Distance Sensor - ~30 to 1000mm : ID 3317 : $14.95 : Adafruit Industries, Unique & fun DIY electronics and kits

    They are reasonably priced and seem to be more accurate than the ultrasonic sensor in the under 2M range, so will give one a go and report back.

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