Need help determining what I need

Hey guys,

First time PLC user here. I've been wanting to play with them for a while and an opportunity has just presented itself.

I will be installing a new dust collector in my woodshop and I was thinking of using a PLC to automatically turn it on and off when my tools turn on.

Here's the idea:

Each machine has a current sensor installed in it. When machine X is turned on the PLC signals the dust collector to turn on (if it's not already running). Once the machine is turned off the dust collector is shutoff (unless it was on beforehand, in which case it would be left on.)

At the same time I would also like to use the PLC to create a bin full sensor by using 2 garage door type sensors to shutdown the unit when the bag is full (sawdust breaks beam and signals unit to shutoff).

The dust collector is controlled by a motor relay, so hooking in to it to control the unit shouldn't be hard (http://www.clearvuecyclones.com/supporting-products/36-heavy-duty-motor-relay.html).

I would also have a seperate wireless switch to turn the unit on manually.

I am hoping someone can point me in the right direction as to what sort of unit I should be using. This is a small home shop so I am looking to go with the cheapest/simplest units available.

Thanks in advance!

Well sounds like a good project. I have some experience with dust collectors in my wood shop but i haven't got around to automating yet. First off let me tell you that there are already such controls on the market. I dint think I have seen the bin full option however.
I'm not sure if the sensors you are talking about will work for the dust bin think about dust passing in front of the sensor?.Most people i know simply gut a slot in the bin and install a Plexiglas viewing window to tell when the bin is full. however you may want to look at a DP sensor or switch to let you know the dust bag is clogged.as far as the plc if you plan on using one look at a micro plc I like the click for this type of project. Plan all your inputs like are you using analog or digital or both before selecting a plc. most all should have plenty of outputs. The click would allow you to add I/O latter if you find other needs for controls in your shop. It is low cost and the software is Free!One thing I do in my shop is use a pre-collector chip/shavings drum to keep large wood chips out of the collector. Its a simple trash can with a store bought top that the duct runs in and out of before it enters the collector.also have you looked at auto slide gates for each machine to increase the efficiency of the system?
Good luck ,Steve

I have a question for you. What brand of PLC do you have and do you have the programming software to program it?

If you haven't picked out the PLC, then you may want to use Smart Relay (Micro PLC) like Allen Brandy Pico

What you are trying to do is easy and can be done with relay logic. This is a great way too learn PLC's by doing what you want to do.

At the same time I would also like to use the PLC to create a bin full sensor by using 2 garage door type sensors to shutdown the unit when the bag is full (sawdust breaks beam and signals unit to shutoff).

Click to expand...

In order to use photoeye to detect if the bin is full, you will need be able to see across of the top of the bag and you will need to have a timer to give time for the dust to settle.

Smart Relay (Micro PLC) like Allen Brandy Pico

Click to expand...

Very limited for expansion!

Thanks for your quick replies guys!

bce123: what sort of item like this is already on the market? do you have any product links?

I have not heard of autoslide gates, do you have a link? I was planning to use manual blast gates that would be opened/closed before turning on each machine.

The cyclone itself has a pre-collection bin that collects most of the woodshavings. I was planning to use the garage door sensors as it has been used by many people on the dust extractor forum with good results. The cyclone drains into a steel drum through a short length of clear hose, I was planning to put the detector at this clear piece of hose to shutoff the system when the hose starts to fill.

I'll look into the Clik PLC's, they sound like what I want.

Also, am I right in thinking that a current transducer is the cheapest and easiest way to sense when a machine has been turned on?

I am trying to keep costs down as much as possible.

Also, am I right in thinking that a current transducer is the cheapest and easiest way to sense when a machine has been turned on?

Click to expand...

No, not necessarily. Often a simple SPST relay is cheaper than a current transducer. A relay can be wired to some part that is energized when the machine is running. Then use the relay to signal that the machine is running.

For other machines it is safer to check and see the live action (like your garage door example) rather than ASSUME that it is stopped when it might not be. I think for some woodworking equipment, you might want photoelectric sensors to prevent starts when your hands are on the cutting blades.

Try this link it would be a good place to start:
http://www.woodmagazine.com/woodworking-tools/reviews/dust-collection/
I will try and find more info when I have time. There are lots of brands out there.
Best regards, Steve

invictive said:

Hey guys,

First time PLC user here. I've been wanting to play with them for a while and an opportunity has just presented itself.

I will be installing a new dust collector in my woodshop and I was thinking of using a PLC to automatically turn it on and off when my tools turn on.

Here's the idea:

Each machine has a current sensor installed in it. When machine X is turned on the PLC signals the dust collector to turn on (if it's not already running). Once the machine is turned off the dust collector is shutoff (unless it was on beforehand, in which case it would be left on.)

At the same time I would also like to use the PLC to create a bin full sensor by using 2 garage door type sensors to shutdown the unit when the bag is full (sawdust breaks beam and signals unit to shutoff).

The dust collector is controlled by a motor relay, so hooking in to it to control the unit shouldn't be hard (http://www.clearvuecyclones.com/supporting-products/36-heavy-duty-motor-relay.html).

I would also have a seperate wireless switch to turn the unit on manually.

I am hoping someone can point me in the right direction as to what sort of unit I should be using. This is a small home shop so I am looking to go with the cheapest/simplest units available.

Thanks in advance!

Click to expand...

I have a GEIP Series 90 PLC for this. A couple of points.
** You may want an off delay timer to keep the Vac on for about 1 second after the tool goes off.
** A paddle switch works nice for bin shut-off.
** I have the amp switches at the breakers, this way I don't need switches on all the tools and it kept wiring down as the PLC is near there too. Although a couple do have their own breaker.
Nearly any brand PLC will work, you just need the right price-point for the I/O and software. I use GE because I can readily get them.
I suggest the GE Micro 20point or Nano depending on the I/O count. Either of these you can get as a "kit" (see the catalog for details) that includes software & cables for around $200+/- US.
Or Eaton would be high on my list to look at.

Thanks everyone

Lancie1: Could you provide me with a link or model # for a relay? This system is only to control the dust collector, not the machines, so a photoelectric sensor to make sure your hands are out of the way is not necessary (although a great idea for a future project).

bce123: I had a look at your link, looks interesting, however I would love to do this with a PLC for the learning experience, and once I add up the cost of a gate system and bin full sensor it is almost as much as a PLC setup.

RussB: Yes, I will definately want a delay timer, probably about 5 seconds to make sure the ductwork is clear, I assumed that this could be done with the PLC, am I wrong? Do I require something additional? I definately want to install some sort of paddle switch by the unit as a "Master" switch to shut it off when cleaning and to turn it on manually for floor vacuuming. I am looking at the Click series of PLC as they will likely be the easiest for me to get.

Also, am I right in thinking that a current transducer is the cheapest and easiest way to sense when a machine has been turned on?

Lancie1: Could you provide me with a link or model # for a relay? This system is only to control the dust collector, not the machines,

Click to expand...

Sure, but nearly any old control relay will work, if it has the correct coil voltage. I ASSUME you need 120 volts, but that depends on the details of your installation. If it is 120 volts, here is one I used for another project. This relay has 3 DPDT (Double Pole Double Throw) contacts, but 1 SPST may be all you need, so that will be a cheaper relay.

If you want to know if a machine is running, you can connect a relay to starter coil and use the contacts of that relay as your input to the PLC. Or, you can use current switch made by Hawkeye, which senses when current of the motor is running. These are used in the building automation to know when the air handler or a pump is running.