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Post by craigbru on Mar 30, 2010 18:07:09 GMT -5
Hello all! I'm a brand new recipient of a HS-1, and have been working on getting it set up in the past week or so. I'm a computer modder (losias.net), and have big plans for this machine. While I'm anxiously waiting to get the CNC running, I needed to take care of a few small details first. One of those details involved a custom misting solution for cutting aluminum. Why mist? Well, for the work I have to do it can be just as effective as flood, yet it's so much easier. I should say it's easier, only if you can find a workable and convenient way to implement it. I have been doing some research into CNC misting techniques, and most of the options are geared towards commercial applications, and are quite expensive. I wasn't really willing to spend $300 on something I was convinced I could do myself. Since I'm a modder, it only made sense to mod a homebrew solution. Many hours were spent Googling anything that misted, before I came across the mention of using an airbrush as an option. I tried to find where someone had actually followed through using this method, and came up with nothing. So, I figured I might as well be the first. Even if I'm not, I'm hoping my methods and documentation will make it easier for others to find and implement themselves. Now, before any fabrication could begin, I needed an airbrush and dedicated on-demand compressor. Amazon came through with this nicely outfitted kit.    Okay, well, now that I've got the airbrush, I need to find a way to get it mounted to the Romaxx machine. Since the mister needs to follow the mill bits as they cut through the material, it was obvious that it needed to be attached to some location near the spindle. It just so happens that there were some unused spindle mounting locations that would be perfect. So, I just needed to come up with a workable bracket of some kind. Not only did the bracket have to hold the airbrush securely, but it couldn't interfere with any machine operation whatsoever. I needed full X, Y, and Z operation with no limits or restrictions. I broke out the cardboard and started experimenting. This got me in the ballpark...  Since I was satisfied I had a workable idea, I committed it to metal...  I love bending things, so the newly cut bracket received some attention.  With the cutting of a few well placed slots, and the help of some rubber o-rings, the brush and it's coolant reservoir were attached to the bracket. I used a simple mounting method for two reasons. Ease of maintenance, the ability to have flexible mount points should some unforeseen interference occur.  So, let's get this bracket mounted! You can see how cleanly it sits in it's location. It's also easily adjustable for height.   There is plenty of room for travel with no interference.  Now finally, here are a few pics of the machine as assembled and ready to run.    All that I've got left to do is make sure I'm set for live streaming on my website, and I'm ready to cut. If I can find a good material hold down solution, I'll give it a go tonight. (Yes, I'll likely be getting the aluminum top w/ mounting holes soon.) ;D |
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Post by georgemyers on Mar 31, 2010 0:01:57 GMT -5
Nice solation.
With the electronics under the table are you taking any precautions to insure they do not get wet or metal chips causing a short?
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Post by craigbru on Mar 31, 2010 0:10:21 GMT -5
Thanks George!
I'll be using denatured alcohol as a coolant, and only when cutting aluminum. Due to it's quick evaporation, and the fact that it will be applied in a mist, I'm not expecting anything to truly ever get wet. In my testing it would lightly dampen my fingers or a paper towel in just a few seconds, but had evaporated in about 20. Since the coolant will hit right at the mill bit, it should provide enough lubrication without lingering. I'll definitely do more testing once I get a handle on the machine and Mach3.
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Post by romaxxcnc on Mar 31, 2010 9:34:20 GMT -5
Hi Craig, A few things to consider are that alcohol is very flammable, If the bit were to overheat on clogged flutes, the temperature can rise rapidly, turn red and be at a sufficient temperature to provide ignition. The arcing of the brushes in the router itself would provide ignition as well. Also, the application of alcohol though mist and heating it on the cutter will be atomizing it into a gas, which could become explosive in the proper air mixture. I wouldn't suggest trying anything like this, and would not even attempt it. cameochemicals.noaa.gov/chemical/11065""Fire Hazard HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion and poison hazard indoors, outdoors or in sewers. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water. (ERG, 2008)"" A good way to machine aluminum is use a good 2 or 4 flute carbide endmill. Use a paint brush and cover the cutting path with a coat of Tapmatic or similar cutting oil. Take light passes like .050" and multiple iterations of the cut at 10 -20 ipm. Be careful, Ron |
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Post by craigbru on Mar 31, 2010 11:32:10 GMT -5
Thanks for the words of warning Ron. I'm aware of the potential risk, but was relying on the advice of others who are using this method on their own machines (although with commercial misters). That said, I've got no desire to blow myself up. I'm not going to make any cuts without taking the proper precautions, and would prefer to use another liquid for the mister if appropriate. I'll do some more research...
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Post by craigbru on Mar 31, 2010 12:00:49 GMT -5
After doing a little more research, I may try an isopropyl alcohol and water mix. It would lower the flammability factor quite a bit. I'd be open to other fluid suggestions as well. I'd really like the keep the option of misting though. Even if there isn't any fluid in the reservoir when the brush is on, it is still blowing a nice stream of air at the mill bit that should help with debris and chip removal.
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Post by romaxxcnc on Mar 31, 2010 18:46:56 GMT -5
The only types of coolant I'm familiar with are the water soluble oil based and organic based Kool-mist coolants. I'm not sure if they would be thin enough to go through the airbrush. They may be though. That is is what I would try first. Kool-mist also has a rust inhibitor. For ultimate cutter cooling you're heading in the right direction, the wetting of the surfaces greatly enhance heat dissipation. If you look at the table of the machine, a watertight tub could be made out of lexan, with sides about 4" tall. Then just use a standard air mister, but again, they don't do good things to the air. I've worked in small shops, where the air was like a swamp, very foggy. Need plenty of ventilation.
With a tank like that, you could probably use a small flood coolant set up with a drain on the tank, back to a sump. Flood coolant is the best. The cutter would sling coolant in one plane, but with the high sides of an enclosure would capture. Then you can use oil based water solubles, they are the best coolants.
Ron
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Post by mattgatten on Apr 2, 2010 9:25:26 GMT -5
Yeah, I would stay away from metal on metal with misting alcohol, myself. Mist is a lot more explosive than the liquids. Google fuel air bombs. Devastating. There has to be some type of liquid that can suffice. I think you're safe by protecting the components, losing the MDF table, and going from there.
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Post by craigbru on Apr 5, 2010 23:54:19 GMT -5
Well, I did some experimenting over the weekend. With the appropriate safety precautions, I did tests with both a denatured alcohol, and an isopropyl alcohol. I started with a cap full of each as out of the bottle and applied direct flame. The denatured alcohol did burn, which I expected, as it has a high concentration of alcohol in it. The isopropyl would not however, no matter how I tried (with 3 different bottles), I couldn't get it to ignite as a liquid. So, I thought I had my starting point...
I found an old spray bottle, and tried to get the isopropyl to ignite as mist from it... no luck. Now, I should mention it did seem to burn slightly when forced, but nothing I would call combustible, and there was no flashback.
So, I moved on to the last step. I removed the airbrush from the machine, and got an empty five gallon bucket. I also grabbed my model rocket launcher and some igniters. I headed to the back yard. My goal was to see if I could come up with an explosive combination. I proceeded to spray the mist continuously into a small hole in the bucket and dropped the igniter through at 1, 5, 10, and 15 minute intervals. Nothing... I then decided to try 30 minutes, and then one hour. I went through 6 igniters and there was no combustion. Now, I should note that this doesn't necessarily meant there is no danger, it just means that I could not get combustion under these circumstances.
I do know several things. Isopropyl has a lower alcohol content than denatured. It has added water that reduces the flammability. I also noticed that while the mist is very thorough on the airbrush, it is a very low volume. There aren't many CC's that actually move through it while on. Couple this with the fact that I personally know someone that has been using denatured alcohol with a similar setup, and not blown up, and it makes me think I might be okay with isopropyl. Just to be even safer, I'm going to make sure the electrics are sufficiently protected, and add a little more water to the mix. I should still have decent evaporation, and minimal mess.
One more thing, while I might be comfortable with the above solution, I'll also still likely look at even safer alternatives.
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Post by craigbru on Apr 9, 2010 21:52:08 GMT -5
Okay guys, since I have a habit of never being satisfied... I made a few changes to my CNC router. Since I plan on live streaming all the machine work I do for my next project, I needed to get webcams set up, which I did last weekend. However, after a dry run with picture in picture webcams, I started thinking about how cool it would be to add one of the cameras near the spindle itself. I thought it could capture the mill bit working as I machined. Well, in order to make this happen, I went ahead and got a $10 camera from newegg, and set out to find it a home. I knew I had to get it as close to the spindle as possible, yet there could be no interference in the machine operation or safety. This was a must. The machine comes first, and these little extras second. So, as I was poking around with the cam, one thing became clear. My new mister bracket wasn't going to cooperate. I could either ditch the idea of a camera, or redesign the bracket. Well, I chose to make a new bracket. It is greatly simplified over the other one, but required the flexible metal shaft from a donor lighter. This shaft was the key to making everything work, as only this, a piece aluminum angle were going to be used in the new design. After a short while, the new bracket was in place, and I could move on the mounting the camera. This was even easier. I just needed a small aluminum triangle and a rubber washer... I removed the camera's original mount, and attached the aluminum. I then bolted the bracket to a free hole behind the spindle, and I was in business. So, shall we get on to a few pics? Here you can see an overall pic of the machine. The new mister bracket, and the webcam behind the spindle are visible.  A little closer...   A few more closeups...     As you can see, there are no clearance issues of any kind. The machine is still just as easy to maintain, and I don't foresee any issues. Now all I need to do is get something cut! |
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Post by craigbru on May 3, 2010 11:27:39 GMT -5
I finally got around to using the mister with actual parts cutting this last weekend, and I must say that it has surpassed my expectations. After seeing it being used, I'm no longer that concerned about flammability either. It was providing a nice heavy mist/borderline spray, to the aluminum I was cutting, and there was a noticeable difference between using it and not. There was also no mess afterwards, which was even better.
That said, I'm not entirely happy with end mills I was using. I've got carbide 2-flute .125 mills, and I didn't feel they were cutting as well as they should. I started with 15 IPM, at .05 per pass and it was way too slow. I got some melting of the aluminum. I did some testing and found about 45 IPM, to be a good balance. I've since ordered some mills from Onsrud that should be even better in aluminum.
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Post by fr0stbyte on Oct 15, 2014 19:27:53 GMT -5
Its a dual action airbrush...so turning the screw will regulate the paint flow...
but i see no clamp holding the air piston down.
so how do you get the air to flow.
and another question is if the paint jar is removed. and a larger container is above the airbrush with the paintflow trigger open [trough the screw] doesnt gravity make the lubricant drip out of the nozzle?
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