240 volt relays?

Hi, I'm working on the spec of my second Arduino project. Which is pretty simple in context, I want to use a Nano to make a controller for the dust extraction and spindle coolant for my micro CNC mill. At the mo I turn the coolant pump and dust extraction on by hand, hit cycle start on the CNC and walk away.

What I want to do is...

1) Turn on coolant and dust extraction (both 240 volt) by pressing a button on the Nano control. 2) Have the Nano time and then stop the extraction for 20 seconds or so and run some small vibration motors to clear the filter, then restart extraction.

What I'm not sure on is the 240 volt side of things and the ratings of small vibration motors, I'm open to and inviting your thoughts on that. I've got a bunch of old broken PS2 controllers and I think the vibration motors will do just fine?

I would also like to put in a simple temperature sensor on the spindle, which needs to read between cold (room temp) and up to bath water hot.

I'll put an OLED on for displaying spindle temp and a few buttons to allow setting changes in terms of vibration times. And a small speaker so I've got an alarm if spindle temp goes above normal.

I'm running a licensed Mach3 CNC emulator, which will connect to all sorts of things, encoders and the like. So in the long run when this is sorted I intend/want to use the Nano as a M code so that it performs just like any other M code with logic ladder. So I can call and turn it on and off at the start and end off program.

Many thanks for any input, Phil.

All of the big component suppliers will stock a range of relays that can switch 240v power - you need to know how many amps at 240v you need to switch. IMHO get a relay that can manage 2 or 3 times what you think you need. Also, if necessary, make sure that the relay is suitable for switching an inductive load.

Be aware that an Arduino I/O pin cannot provide enough current for the coil in an electro-mechanical relay and for that you would need to use the Arduino to control a transistor that controls the current for the relay coil. You can probably get solid state relays that can be controlled directly from an Arduino.

I’m not sure what question you are asking in relation to vibration motors.

…R

I use two 240 V 30 A relays (Seeed Grove SPTD 30 A relay module) and the UNO has no problem to hold the coils with current from pins. Or one of the relays and stable PWM.

Juraj: I use two 240 V 30 A relays (Seeed Grove SPTD 30 A relay module) and the UNO has no problem to hold the coils with current from pins. Or one of the relays and stable PWM.

Are you using these relays?

If so, that web page says they need 185mA and the absolute max for an Arduino I/O pin is 40 mA - expect smoke from your Arduino.

...R

Robin2: All of the big component suppliers will stock a range of relays that can switch 240v power - you need to know how many amps at 240v you need to switch. IMHO get a relay that can manage 2 or 3 times what you think you need. Also, if necessary, make sure that the relay is suitable for switching an inductive load.

Be aware that an Arduino I/O pin cannot provide enough current for the coil in an electro-mechanical relay and for that you would need to use the Arduino to control a transistor that controls the current for the relay coil. You can probably get solid state relays that can be controlled directly from an Arduino.

I'm not sure what question you are asking in relation to vibration motors.

...R

Thanks Robin, it's a Hetty Hoover that google says is rated at a 5amp fuse. the coolant pump is Jap and unmarked and was unfused until I put a UK plug on, but it's a toy pond pump with not a very high flow rate. Which is part of the reason I want a temp sensor on the spindle in case the pump lets go.

I'll look into solid state relays for the Arduino.

Many thanks :) , Phil.

You can also get "relay boards" or "relay modules" that have the relay and a driver circuit.

Or for a little more money, there are industrial solid state relays similar to [u]this[/u] that can be directly driven by 5V at low current, and they are super-easy to wire-up since they just have 4 screw-terminals.

...and run some small vibration motors to clear the filter, then restart extraction.

I think there's something wrong if you have to shake/vibrate the filters that frequently. I assume most debris-collection systems are made like a shop-vac, where the debris fall into a container and there is only a filter at the exhaust. And of course, a filter with a large surface area is less prone to clogging.

I would also like to put in a simple temperature sensor on the spindle, which needs to read between cold (room temp) and up to bath water hot.

Measuring the temperature of a rotating spindle sounds tricky... Maybe an IR thermometer module?

Your spindle will heat slowly, unless it has sleeve bearings. So, you can make a heat pipe out of copper or even aluminum, clamped firmly to the spindle housing and ending at your temperature sensor.

Paul

Robin2: Are you using these relays?

If so, that web page says they need 185mA and the absolute max for an Arduino I/O pin is 40 mA - expect smoke from your Arduino.

...R

sorry, my error. the module doesn't use power from the pin. is powered from Uno 5V pin thru the Grove shield and connector. Power source is 12 V adapter.