Drum level sensor


dwacker

Recommended Posts

I’ve used two: One is an IR sensor that attaches to the bin’s lid and fires a strobe when the dust level gets within about 3” of the top. The other is a more professional affair – it’s a mechanical paddle-wheel design with a relay. You mount the sensor high on the bin and when the paddle-wheel is interrupted by dust, the relay is thrown. The relay is wired-into the mag switch: bin almost full = cyclone shut-down. I then modified this design to allow an override so if I’m at the end of the day with just a stick or two remaining, I can override the interrupter… This is my preferred setup…

 

The hobby-shop approach is the IR sensor. They’re about $150 for the kit and just about everyone sells them… They work (mostly)… I’ve always been suspicious of IR sensors, but I’ve been told they are very reliable. http://www.oneida-air.com/inventory.asp?CatId={4CA9A078-61CB-463F-B843-8C681E38534F}.  I used one as a 'backup' when I left the override on for too long and overflowed the bin -- too smart for my own good... Note: There have been times when this sensor failed to detect a full bin... Not often, but it's happened...

 

The paddle-wheels are around $250, require quite a bit more knowledge to install (given only a schematic diagram, you’ve got to wire them into the mag switch), but have the advantage of robust commercial-level construction… I got mine from Air Handling Systems (where I get my ductwork) or McMaster-Carr – someone like that… If you go that route, you need some 6 (or maybe 8) wire sensor cable (fairly cheap) to wire-in the relay… There are no instructions provided – the assumption is if you can’t read a wring diagram, you should hire a pro… http://www.apgsensors.com/level-switches/PWS, http://www.binmaster.com/products/info/54-rotary. The rotery sensors have never failed...

 

The actual way I monitor bin level -- close all blast gates, if the bin fails to lift off the ground, then it's near full...

 

<edit>

One other note: If you use an internal collection bag in your dust bin (which I do), you've got to be more particular if you get a paddle-wheen design... The paddle wheels are offered in wheel, auger and/or tilt-rod. You need the auger design and mount from the lid down into the bin -- this won't interfear with the bag hold-down setup...

Link to comment
Share on other sites

I've just spent a few minutes looking at McRabbet’s sensor... I’d be interested in your experiences...

 

I find it hard to believe that optical sensing through the flex-connect is a robust approach. On the up-side, it overcomes the issue with IR sensors becoming dirty and false-firing (or not firing at all)… But McRabbit’s optical approach suffers from a similar issue: over time, the bin’s flex connect evolves from transparent to translucent to nearly opaque… I suspect that at some point in the process, the sensor will begin to false-fire… I prefer McRabbit’s tendency to false-fire over the IR’s weakness of not sensing a full bin…

 

I also noted several users on the CV forum reported false firings when planning long/wide boards… If you’ve got a big jointer, planer, etc the dust column can easily exceed the 10s-12s trigger-point. I was surfacing some 14” stock last night and the dust column would have exceeded 12s on every pass… McRabbit handles this with a bypass, which is good… But I built a bypass into my setup and one day I forgot that it was set – not so good… After spending several hours cleaning my filter, I added an IR setup as a backup…

 

One further limitation to the optical-approach, if I've only got only one or two blast gates open (unless my bin is nearly full), the cyclone lifts the bin clear of the floor and compresses the flex connect so that it becomes completely opaque -- I strongly suspect that McRabbet's approach would fire every time I turn the system on until I got about 30+g of dust in the bin... I suppose I could overcome this limitation by placing something heavy on the bin, but I use the bin’s lifting as a surrogate for dust-level…

Link to comment
Share on other sites

==>my barrel gets some moisture being outside

Yea, I'd go with a paddle wheel design. If you google them, you'll find hundreds... For exterior use, maybe look at the versions used in the agro field...

 

This is the one I use:http://www.apgsensors.com/level-switches/PWS, but have no idea if its weather proof...

 

Been revisiting McRabbet's approach... I don't like the optical-based detector, but I do like the control box (depending on how he's done it)... It might be a bit much for folks to wire-in a control relay to the mag switch and provide an override... McRabbet seems to have done that for you... Someone may want to look at his control box with a paddle-wheel sensor...

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.