Author Topic: Adding a cooling mister to a Denford Novamill  (Read 5084 times)

mc

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Adding a cooling mister to a Denford Novamill
« on: August 01, 2015, 01:03:22 PM »
My little Denford Novamill has proven to be quite a handy little machine to have, and has even made me some money, however the continual need to babysit it when machining to keep chips clear and apply some lubricant is, to be polite, a pain.

Now given this mill came running Denford's VR Milling 5 software, I was under the impression that if something never came fitted at the factory, then I wouldn't be able to add it, unless I carried out a retrofit. However after a bit playing in the VR software, I discovered you could access the machine settings, and change them, at which point several ideas opened up.
The first of which was some form of coolant.
After studying the Novamill wiring diagrams (available over the denfordata forum - www.denfordata.com), I found a mister was a factory option, and that the relevant coolant relay (COR) is controlled via output 2 on the control board, so after enabling the M8 and M9 functions in VR Milling, output 2 was eventually located on the controller. Off course, once it was located using trial and error, I discovered all the terminal numbers can be seen if you unplug the terminal blocks  ::)


Connector Details

So pin located, a spare opto-isolator from my Cyclone retrofit was added along with a couple wires, and I now have an opto-isoltaed output ready for connection to a coolant solenoid -


Opto-Isolators
(I'll get around to changing the label to COR at some point, instead of TSSR)

At the moment I still need to build the mister, and add the pipework along with a control solenoid, but I now know it's going to be doable without carrying a retrofit.

mc

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Re: Adding a cooling mister to a Denford Novamill
« Reply #1 on: August 14, 2015, 11:49:58 PM »

Mister Kit by mc_mtb, on Flickr
This collection of bits got delivered from various places this week, so building the mister can commence.

I'm going to base my mister of Karl Townsend's plans, which can be found at http://www.machinistblog.com/zero-fog-mister/ however I'm altering things a bit, to either simplify construction and/or use more common parts.
For the resevoir, I'm using a 10" water filter housing, which just so happened to have a pressure releif connections on the top, which got me thinking about a neater method of getting a pick-up line in. The photos and diagrams I found while searching for plans, all used a mix of connectors to get a pipe in via one of the main ports, however after a bit sketching and checking of dimensions, I came up with a design to use the pressure releif port as the pick-up port.

So after a bit maching, I ended up with the following assembly-

Tank pick-up assembles by mc_mtb, on Flickr

And dismantled-

Tank connector bits by mc_mtb, on Flickr

The purpose of the ball bearing, is to provide a crude one way valve to reduce how quickly the oil can drain back into the reservoir. The pick-up pipe is a bit of 4mm inside/6mm outside diameter polyurethane tubing, which is what I'll be using for the entire system. The polyurethane tubing is softer and more flexible than nylon tubing.

I'll hopefully get the misting head build over the next couple of days, and find something suitable to mount the reservoir and regulators on.

mc

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Re: Adding a cooling mister to a Denford Novamill
« Reply #2 on: August 15, 2015, 06:08:44 PM »
Managed to get the misting head made, and the reservoir/regulators plumbed up today.

After much moving bits around on the bench, and trying to find a suitable mounting board for all the individual bits, a light bulb lit up and I ended up with the following-

Plumbed up by mc_mtb, on Flickr

The pressure regulator for the oil is mounted via a 1/4" male to male nipple, and the regulator for the air is simply mounted to the filter housing mounting bracket. The whole lot is then hung via a couple screws underneath the bench the mill is sitting on.

It was then onto the misting head, and I've so far ended up with this-

Mister Head Assembly by mc_mtb, on Flickr

I'm not sure how well it's going to work, but the basic sizes are a 2.5mm drill all the way through for the air, with the outlet side drilled and tapped for a 4x0.7mm thread, with a 1.5mm hole drilled at 90 degreees for the oil connection. The blow pipe is a bit of 4mm outside diameter copper pipe, which I threaded the end of, and the two inlet connections are G1/8. The regulator is a basic needle valve without any bypass valve. I suspect I'll need to add a nozzle to the end of the pipe, but I want to try it as is first.
It's certainly not going to win any competitions for looks as it's just a bit rough sawn aluminium from the scrap box, but I'm not going to waste time making it look nice, when I'm not even sure it's going to work!

I had it connected up to the compressor earlier, and I get air where I expect air. I still need to order some suitable mister fluid, and the control solenoid probably won't be here for another week or so, as I opted for a cheap one from China.

mc

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Re: Adding a cooling mister to a Denford Novamill
« Reply #3 on: August 25, 2015, 10:37:41 PM »
It works!
Well, it blows air, and leaves a fairly consistent droplet pattern on some blue paper.


New Nozzle by mc_mtb, on Flickr

Initial testing with just the 4mm copper pipe, led to the coolant gathering into a drop at the end, before eventually being blown off, leading to spurts of droplets. The force of air coming out was also pretty poor unless I turned the air pressure up, so it was obvious a nozzle was needed. So an offcut of round bar was put in the lathe tonight, with a 4mm thread on one end to mount onto the copper pipe, and a 2mm hole to create a jet on the other end. Testing with the regulator only opened slightly, resulted in the pattern you can see on the blue paper in the above picture after about 30 seconds of flow. The air force is also more than strong enough to blow chips around, so I'll call it a success.
I may make another nozzle with a slightly smaller hole, however I'm wanting to run some parts to see how well this nozzle works first, and how much air it's actually using.

For a temporary mount, I used a magnetic base coolant hose I had lying around, removed the excess segments, and cable tied it on. It's a bit crude, but it'll be sturdy enough for testing.


Makeshift Mount by mc_mtb, on Flickr


As for the actual coolant. After a fair bit time spent googling and browsing various websites, the only reasonably priced minimal quantity lubricant I could find in small quantities was from John Neale - http://www.johnnealeltd.co.uk/minimallubricants.html
Everything else either involved large quantities (25 litre) or expensive prices.

mc

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Re: Adding a cooling mister to a Denford Novamill
« Reply #4 on: August 28, 2015, 06:36:35 PM »
It works!

What a revelation. No more continual chip clearing/coolant applying is needed. Just connect up the airline, hit cycle start, and walk away.
Chips get blown out the way, and just enough coolant gets applied to avoid any sticking issues.

The solenoid for the coolant control has also arrived, well 2 actually, one 110VAC and one 24VDC. I ordered two because Denford used 110VAC for all the solenoids, however I'm likely going to use 24VDC (or it may end up on the Shizzy). Still not decided on where I'm going to mount the solenoid, as I've got another expansion plan for this mill which will require a couple more solenoids, so I don't want to have to re-plumb/move things again.