Controlling the Hidden Beast

[McRabbet]

Originally Posted by fernhollowman

Go here: http://www.ralphpill.com/calculators.shtml

Scroll down midway and find a table based on NEMA std. 10-MG which allow calculation of the MAX starts/hour for larger motors. Both NEMA and the individual motor mfrs. provide a MAX starts per hour. The 5HP Leeson in the CV system is rated at 6 starts per hour. As installed, the only motor I cannot access and remove singlehandedly is the DC motor. Why tempt fate?

I agree, Jim -- In my case, I'd rather not go outside my shop on the east side of my house, traverse the full length of the back of my house through my natural (i.e., thorn-infested) area to the crawl space door and then come back 60 feet to climb up a ladder to press the thermal overload button -- it will be enough trouble making this trek to empty the bin when it fills! That is why I'm also trying to design a pre-separator that will handle the chip outputs of my planer and jointer to reduce the CV to true dust collection. I plan to avoid multiple on/off motor cycling.

[McRabbet]

Originally Posted by PurpleThumb

Good Luck on the Pyrenees necessitated surgery if I don't talk to you before. I'm through the "pain" to the "sore "part of mine.
Thanks for the diagram and the sharing of info by you, Alan, and so many others. This truly is a GREAT site.

Jerry,

I've been meaning to call you, but I've been busy with our WNCWA meeting this past Saturday, tinkering on DC stuff and getting ready for the rotator cuff surgery I'm having -- I'm glad you are through the hardest part following the knee replacement and will be diligent with your PT so you can get back to full throttle soon. My shoulder procedure is much less invasive, but I'll have similar phases -- mine is outpatient because it is arthroscopic (LOML wondered when they'll install a "drive up" window at the hospital!!) and they send me home the same day.

I uploaded the pictures I took of your ClearVue installation to my Dust Collection Album and will post a few pics later for everyone's benefit.

Glad you're feeling better!

[McRabbet]

Originally Posted by bladeburner

I trust that when you guys get this design finalized that you'll put in into a download area. When I finally get around to setting a DC up, I'll probably not be able to find this thread.
Good work & thx,
Joe

Count on it!

[Alan in Little Washington]

I finally got around to drawing up my DC control circuit. Here is my CAD (crayon alternative drawing) :




My circuit is similar to Rob's but uses multiple pushbutton control stations vs a remote- a personal choice. Here are the differences and features-

• A 3 pole contactor with 24V coil. Extra set of contacts is used for a "latching circuit."
• Full "START" and "STOP" using any of an unlimited set of spring loaded, momentary contact, pushbuttons located throughout the shop. This function allows starting the DC from any station and stopping it from that or any other location, and visa versa.
• This schematic shows only one set of "START"/"STOP" pushbuttons, however any number can be added and wired the same as the set shown.
• No remote- It could be added (with some difficulty, however)
• The "additional START" represents a normally open (N.O.) micro-switch or magnetic reed switch mounted on a blast gate. Having a blast gate start the DC is desired, but I do not want a blast gate to turn it off due to motor cycling issues. I could incorporate a "delay on off" relay but that would make the circuit more complex especially since I want the buttons and high dust circuit to cause immediate shut down.
• The SPST relay depicted as part of the high dust circuit can be any 110V relay (e.g. DPDT) with at least one set of normally closed (N.C.) contacts.
• A high dust condition breaks the "latching circuit" and turns off the blower. The blower will not restart without pushing a start button (or opening a blast gate if I equip the gates with start switches)

Operational description:

(The schematic illustrates an "OFF" circuit state.)

• To start - momentarily press any START pushbutton.
• This action completes a 24V circuit which temporarily energizes the main contactor coil.
• The contactor contacts close and provide 220V to the DC motor through the top two sets of contacts.
• The bottom set of contacts provides 24V to the contactor coil (via the latching circuit) and keep it self-energized. (this function is identical to the magnetic starters on most WW machines)
• Momentarily pressing any STOP pushbutton, breaks the latching circuit, which de-energizes the main contactor, cutting power to the DC motor.
• When a high dust condition breaks the light beam to the sensor, the sensor provides 110V, via the "RED" lead, to the coil of the relay. A set of N.C.contacts in the relay open and break the "latching circuit" so the DC turns off. (Even if the high dust condition is resolved while dumping the bin, the DC will not automatically restart; a start button must be pushed.

Many different circuits can be used to control a DC and the choice depends on your needs and how much you want to spend. One alternative START/STOP circuit uses only two wires and a single button at each control station to provide full START/STOP control from each of any number of locations, using a "Pulse Sequencing" relay. It is easy to wire. I won't even get into using a PLC (programmable logic controller) base system similar to what is used by the EcoGate and similar systems.

Since there has been so much interest lately in DC matters, maybe Steve could add a "Dust Control" forum to North Carolina Woodworker.

[McRabbet]

Well, I hope this is the last revision I need to make to my bin sensor circuit. One of the concerns that I had is premature restarts to the dust collector during servicing of a filled bin. Since my design uses a remote transmitter to control the 30 Amp DC Contactor, if it is not shut off, then the unit could restart easily. Alan Schaffter suggested a latching circuit modification, but I have been concerned about burning out the photoeye with his design (conjecture on my part because I didn't test it -- but I think this new plan is just as good). Here is the revised circuit:

The wiring next to the Photoeye has been altered with the addition of a Single Pole, Double Throw (SPDT) switch with a center "Off" position. In the position shown here, the sensor is in normal operating position; when the bin fills, light is blocked from the photoeye and the relay shutting down the DC is tripped along the Red wires and the Shop Indicator Light is turned on. When servicing the full bin, the switch is moved to the Down position, feeding 110V from the hot side of the circuit to the same relay, keeping the DC off and the photoeye is disconnected. In the middle position, the bin sensor is deactivated all together and only the remote control operates the DC. Obviously, you don't want to leave it in this position or continued dust collection could lead to clogging filters.

Jim, now you know what I planned with that "Monster" switch! For the rest of the readers, the SPDT switch is a very petite toggle switch measuring .34" x .25" x .32" and with a .4" long toggle!

[Alan in Little Washington]

Rob, that should work just fine! The DC might momentarily try to start when you flip the SPDT switch (unless you are really quick ), but that shouldn't be a problem.

[ptt49er]

What is the sensitivity of the photocell? I've acquired 10 bright LED's and a convertor with a 5v DC output. I've done a little research and talked with the guys up in the EE dept. at school. All I need now is a resistor and the gumption to try to wire it up.
If I can get something worked out, would you guys be interested in buying the parts and I'll wire'em up?

[McRabbet]

Originally Posted by Alan in Little Washington

Rob, that should work just fine! The DC might momentarily try to start when you flip the SPDT switch (unless you are really quick ), but that shouldn't be a problem.

Alan, I realize that for the short time it takes to move the toggle from the On position (through the center Off) to the Service position that the power to the control relay drops and the DC contactor will start to close. It should just be momentary and I don't think it will cause any real problem -- on the plus side, this sequence does break the Red wire from the photoeye before making connection to the hot side, thus eliminating any possible harm to the photoeye circuitry. And it insures that the bin can be serviced under lighted conditions. Once complete, the switch goes back to the On position and the DC can start.

Okay -- now it's your turn to design a simple flasher circuit for the bin full indicator light in the shop! I read somewhere that Jim's strobe/siren puts out 110 decibels when activated -- my poor dog would go nuts and so would LOML!

[McRabbet]

Sounds like an interesting option to the 7 watt candelabra bulb (which puts out a low level of light similar to a candle flame). They cost about $0.20 each. The photoeye didn't come with any sensitivity specifications, but I have tested my mockup of the circuit with a 6" clear plastic jar across the beam and I dumped saw dust into it -- it tripped the circuit only after there was a pile of sawduct blocking the beam (the dust in a stream did not trip it).

How expensive would an LED array be?

[Alan in Little Washington]

I just ordered a strobe/siren similar to the one Jim did. There are a bunch on Ebay from many sellers. I just looked for the best price/shipping and came out at about $18 total. I plan to put foam, tape, silicone sealer, or whatever it takes, in the siren hole to dampen the noise!

FYI, I'm gonna post some pics of the portable high dust alarm shortly.

[Alan in Little Washington]

Originally Posted by McRabbet

Sounds like an interesting option to the 7 watt candelabra bulb (which puts out a low level of light similar to a candle flame). They cost about $0.20 each. The photoeye didn't come with any sensitivity specifications, but I have tested my mockup of the circuit with a 6" clear plastic jar across the beam and I dumped saw dust into it -- it tripped the circuit only after there was a pile of sawduct blocking the beam (the dust in a stream did not trip it).

How expensive would an LED array be?

I had some problem with tranmissivity through the 9" flex on the Oneida I used for my testing. I had to increase the wattage of the illuminator from a 7 watt bulb to a 15 watt bulb. Even with that, I got a few false alarms when we were really hogging off wood with a 15" planer. The alarms cleared almost immediately- part of the problem may have been insufficient flow/air supply that work to dilute the chip concentration. My home unit has never had a false alarm.

Achieving adequate intensity isn't a problem, but the 15 watt bulb does put out a bit of heat, but I wouldn't want to replace it with something expensive. I am trying to keep the costs down.

[ptt49er]

Looks like a led array is going to be pretty cheap...I'll let you know more after I can get back into the lab at school and get this wired up. The LED's are highly directional so hopefully you won't need as much light as w/ an incandescent.

[ptt49er]

What is the size of the pocket the LED cluster needs to fit in?

Early indications are showing that 100 LEDs can be had for under $20 and resistors are even cheaper. So if a ac to dc converter is available (think cell phone charger) wiring a LED cluster up doesn't look too expensive. It probably won't be a pretty as a commercial unit, but it won't cost $50 a piece either.

[McRabbet]

Phillip,

Here's a few pictures of some of the key components. First is Alan in Little Washington's 7W light source shining through a ~3/4" hole behind a sealed plastic window in the metal connector tube at the base of his cyclone:


and then the photoelectric sensor that is mounted opposite (threaded section with sensor is ~5/8" diameter)


Next is the reflector equipped bulb that Fernhollowman (Jim Murphy) used on his Clearvue. He used a candelabra bulb too, but rigged it in a flashlight reflector to provide a stronger beam that had to pass through his "clear" flexible duct above the bin.


In his most recent implementation, Alan used a 15W bulb because his prototype had to shine through the "clear" wall of flexible duct and the sensor was 9-10" away.



So here is your challenge -- light source that is reasonably collimated (parallel beam) that will shine through a 3/4" diameter hole. In lieu of a "wall wart" transformer AC-> DC power supply, is it cheaper/easier to make a small power supply integrated with the LED electronics? Alan's latest unit fits in a standard waterproof PVC LL or LR conduit elbow with a single wall plug for power (Photoelectric unit needs 110V power).

[ptt49er]

Originally Posted by McRabbet

So here is your challenge -- light source that is reasonably collimated (parallel beam) that will shine through a 3/4" diameter hole. In lieu of a "wall wart" transformer AC-> DC power supply, is it cheaper/easier to make a small power supply integrated with the LED electronics? Alan's latest unit fits in a standard waterproof PVC LL or LR conduit elbow with a single wall plug for power (Photoelectric unit needs 110V power).

Getting the collimated beam isn't not a problem as the LED's are extremely directional. The 3/4" hole shouldn't be a problem as there are some rather bright LED's out. I will look into the AC-DC conversion. The main reason I was looking into using the "wall art" transformers is because almost all of us have an old cell phone charger kicking around that could be sacrificed. The LED's only need a few volts and a scant 20 milliamps per light to burn.