Spra-Kool midget intermittant spray mod

[pdxalz]

I've been using the Spra-Kool midget mist coolant system on my Taig with pretty good success. My only complaint was I felt I was getting things a lot wetter than I needed to, even with the spray and air pressure as low as I could get it.

So I tried an idea I saw on cartertools.com and made it spray intermittently. For my implementation I used Pneutronics 12v. solenoid valve I got off of ebay, a LM555 timer chip and a 12v. power supply.

It's working better than I had expected. I've got it set for 1/2 second on and about 1 1/2 seconds off. My air supply is set to around 25 psi. I'm getting a nice blast of air and coolant instead of a constant light flow.

The trickiest part was getting Spra-Kool air supply line to fit the connections on the valve. One problem it has is that if the coolant supply is much lower than the nozzle it has trouble sucking the coolant when it starts, so I either raise the coolant supply until it starts or turn it on always. The valve also seems to have a limit of about 30 psi. If the pressure is too high, the valve stays open (on).

Al Z.

[SpeedsCustom]

How easy was it wiring the timer chip with the solenoid, and whats your power supply? Any pics?

-Jason

[pdxalz]

The circuit is pretty simple:
LM555
50K and 100K resistor
8uf capacitor
2 .1uf caps (on the supply and control lines)

The power supply I used was a 4A 12v supply, but I probably need less than 100ma.

look at: http://home.cogeco.ca/~rpaisley4/LM555.html#3 (astable oscillator)

There is a calculator for resistor/capacitor values and circuit details.

I'm probably going to add a power switch, some pots to adjust the on/off time and a button to force it to on. I would also like to add a TTL input so I can enable it from Mach3.

I attached a photo and (hopefully) a movie of the "Intermistant" in action.

Al Z.

[SpeedsCustom]

Cool, I'll probably build a nice little timer as well.! But first need too make my enclosure.

-Jason

[Swisha_House]

Thank your for posting! Genius idea, great compromise between wasted coolant in a constant feed system, or losing a hand to a spray bottle.

Inspired me I must say, just placed a order for a circuit over AE (AllElectronics) last night.

Just in case any body is wondering the values I'll list 'em real fast:
5VDC Power supply
100K Pots proceeded by 10K resistors
555 (duh!)
33uF Caps
5V relay
And some diodes

You can see the attached schematic below. Again, thank you for posting!

(Note - I figure the pots will allow me to vary the the on-and-off periods from .5 to 5 seconds)

[pdxalz]

That's pretty much the same circuit I used. I used a 12 volt source though, which allowed me to drive the solenoid valve directly from the 555 timer.

What are you connecting the relay to and which relay did you get from allelectronics.com?

Now that the concept is proven I'm planning on ordering some parts from them too for an adjustable version. I was thinking of using a relay on the 12v. supply to allow Mach3 to turn the coolant on.

Al Z.