|
|
I've grown tired of hand-squirting cutting oil into my milling machine and am trying to build an automatic lubrication system. I've run into a set-back and would like the advice of anyone that has:a) built one beforeb) an engineerc) knows something about hydraulics or pneumaticsd) anyone that knows SOMETHING more than the little that I currently do. My first thought was to use compressed air and draw the lubricating fluid up through a Venturi effect (Bernoulli Principle). As the compressed air passes through a smaller opening (I forgot to draw that in my diagram, so picture it at the base of the smallest blue arrow) it speeds up, causing a lower pressure on the other side. This lower pressure causes a vacuum that pulls the liquid up the tube. See "Venturi Effect" diagram below. In the next picture (the one with my right hand holding the blue air line) you'll see the contraption I rigged up. The Venturi chamber is at the very left side with clear plastic tubing coming out the bottom. It is just a right-angle fitting in which I drilled a small (3 millimeter) hole, then welded a 1/4" fitting onto. So when the valve is opened, the air passes through the 1/4" tubing, through the 3mm hole (chamfered) and then out into the bigger chamber (which happens to have an inlet at the bottom. This bottom inlet is connected with plastic tubing to the lubrication bottle. I tested it, and it worked like a charm. I set the pressure to 50 psi and was able to raise the liquid up about 3 feet high, and it pumped out the outlet very nicely. In fact, too well, because before I knew it, I had pumped lube all over the place. (No jokes here, guys). So then I hooked this up to the flexible outlet tube that I had mounted to my mill (the next photo shows it- blue with an orange tip). I expected great things when I hooked it up for the inaugural run except the moment I hit the air, an explosion of lube covered me (again, no jokes ) and everything around. What had happened was that the back-pressure from the small outlet tube defeated the great suction I had with NO TUBE connected. So instead of vacuum, the pressure fed downward into the lube bottle, which bubbled out explosively. So, after some cleaning up and further experimenting, I can't seem to find a way to use the orange and blue outlet tube and still get a vacuum back at the "T"/venturi chamber. Any thoughts on how to make this work??? Lower/Higher pressure? Larger outlet and smaller vacuum tube or vice-versa? Without an easy solution to this, I first wanted to abandon the whole thing and just hook up a little electric pump, but i'm determined (read: stubborn) and want to make it work. Next, I thought, if a Venturri-vacuum doesn't work, perhaps I can try using the air pressure to PUSH the fluid, rather than SUCK it. So I came up with the final idea (see diagram of square aluminum tank). This latter idea is just concept right now- I've worked nothing out in terms of what size aluminum to hold a certain pressure, or even if it would work. But it might be my only option if compressed air is the power and the Venturi thing is a no-go. So, back to my questions... is this (the Venturi idea) do-able? Or should I go with the latter forced oil option, or just scrap the whole air-pressure idea and get an electric pump? Thoughts? Attached ImagesLincoln AC225 & MigPak 140, Lincoln Magnum SpoolGun, Miller Spectrum 375-X Plasma, Syncrowave 200 TIG, Millermatic 252 MIG, Miller Digital Elite, General 7x12" horiz/vert bandsaw, 3' box/pan brake, 20 ton press, milling machine, 12x28 lathe, etc.
Reply:I only fit criteria B, C &D, and I damn sure ain't an engineer because they are worthless creatures.Let me begin by thanking you for the laughs and memoried. NOPE, you weren't the first to make any of those screwups. You also overlooked a lot of available options probably sitting in the it might come in handy some day pile under the bench.Where are yo trying to get? If you want to mist or spray the simplest thing would be to follow the paint sprayer model.If you just want to drip oil onto the cutter the easiest thing to do is siphone it from a supply located higher than the cutter with a fine adjustment valve to controll flow. If your goal is another oil bath definitely go with the pressurized tank method.
Reply:Not an engineer and I saw your other post when you welded the fitting up and wondered what you would use it for. Your drawing shows air entering from left to right with a straight run over the hole where it would suck the oil from. In your drawing to my eyes it shows your air coming in through large hole going over small hole and the exiting through large hole. We built a venturi type chamber for a small sandblasting cabinet the same way. However your manufactured item has the air coming in through small hole and going over large hole before exiting through large hole. I think if your fitting followed the diagram it might work as you expected. the air "rushing" straight past or over the smaller hole would create a vacuum in the tube attached to the smaller hole and suck the oil up into the airstream going through. Kinda similar to my pressure washer in the way it sucks up the soap. However like I said I'm not an engineer but that's the way I'd attempt it. Another thought might be if you want to use air is to have "T" fitting mounted roughly level with the workplace. Assume the "T" goes left to right and the third inlet is on the top. Push air in from the left and it would go straight through to the right and then into the flexible tube pointed at your workpiece. Have a resevour mounted vertically above the "T" attached to that third inlet with a valve. Once the valve is open and air is running out to the work piece open the valve on the oil resevour slowly until you reach the desired amount you want mixed in with your air flow. That might work as well. Good luck and keep us postedLast edited by haroldmulder; 05-01-2010 at 10:15 PM.Harold MulderMiller 211 AutosetHTP 201 Invertig with water coolerHardinge Cataract Quick Change Lathe
Reply:Three comments:1) put a needle valve in the pickup line from the reservoir to control flow. The continual blow of air helps a lot with cooling. You adjust the needle until you get the correct fluid volume, which is usually less than you would use pouring it on.2) Don't use oil or other hydrocarbon/flammable or toxic fluid. The setup is essentially a carburetor. Use water based fluids. There are a lot of mixes on the market, and a good general purpose mix can be made with water, dish detergent and vegetable oil. Not much detergent or oil.3) Now you know why mill tables have troughs with NPT plugs. Best place for the reservoir on this kind of setup is under the drain on one end of the table, with a screen to filter the juice that drips back in. Get a lot of use from the juice this way.
Reply:Aquafire,You correctly identified the cause in your 5th paragraph with haroldmulder and enlpck describing the solution in their posts.What you experienced is what happens when you subject an eductor (that's what you built) to excessive back pressure. What I suggest trying is use a standard tee (all female threads) and use a male thread fitting for the air inlet and solder in a length of small copper tubing (smaller ID than the flex tube - very important) to reduce the amount of air entering the suction chamber. Don't worry about trying to size an orifice for the required lube flow. Use a needle valve as enlpck suggested as it will provide you with variable control. You would be wise to put a control valve on the air inlet to contol air flow as well so you can fine tune the entire system.MM200 w/Spoolmatic 1Syncrowave 180SDBobcat 225G Plus - LP/NGMUTT Suitcase WirefeederWC-1S/Spoolmatic 1HF-251D-1PakMaster 100XL '68 Red Face Code #6633 projectStar Jet 21-110Save Second Base!
Reply:Oil sucks as a cutting tool lubricant. Doesn't dissipate heat like water. And it's a mess to deal with. Think I'm wrong.........just look at the steam coming off a tool if you're using water based coolant, and you're running a little too hot. The steam is converting heat efficiently.Mist coolant sucks too, unless you like the shop to be covered in gunk.Go with flood water based coolant and don't look back.IMHO"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Go on eBay and look for a Bijur cooling system, there are plenty of them for sale. That's what I use on my mill, they work great!an examplehttp://cgi.ebay.com/BIJUR-Spraymist-...item1c121e758bSynchowave 180SD Bernard 3500SS water coolerMillermatic 200Parker Plasma Tec 40dvOperating Engineers Local 12
Reply:Originally Posted by farmersammMist coolant sucks too, unless you like the shop to be covered in gunk.Go with flood water based coolant and don't look back.IMHO
Reply:In one shop I worked in with large band saws that ran all day, we used 5 gal buckets of methanol to cool the blades. Compressed air was ran into the bucket lid and a siphon tube was ran down to the bottom of the bucket. The siphon tube was ran up the blade and a mist of methanol was sprayed on the blade. Worked good.In another shop, we used water to cool double miter saw blades that ran all day. We used the same bucket idea, except we used adjustable venturi valves instead of just running the air down into the buckets so we could adjust how much water was being sprayed onto the blades. Later, we added a lubricant to the water that helped keep the water from rusting the blades and lubed them better, but made the aluminum welds black if too much lube was used in the mix since we didnt clean the cuts before welding.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:I have just joined the forum. I have been reading the posts for quite a while and just had to reply on this one. I fit into category (d) with 30+ years experience as a machinist/toolmaker in the aircraft industry. So you want a cutting fluid and not a lubricant for moving parts. As stated earlier flood coolant is great for an enclosed cabinet. But it could be used as just a gravity drip. Mist is pretty good but, you must watch out for breathing the particles. There are specific coolants designed for mist application. The best tool I have found to apply mist is the Bijur as stated earlier. I would never try to build a mister as they are just too cheap to buy. There is also the cold air tool. http://www.vortec.nl/fileadmin/Image...r_Guns_eur.pdfSo, flood, mist, and air. what ever you use must remove the heat, could also provide some lubrication, and have rust inhibiters to prevent you parts and machine from rusting.Russell
Reply:Thanks for the advice guys.... I have a bit more to think about before my next step. As for the cutting fluid/lubricant... I was using the terms kind of loosely- the actual stuff I'm using is called "A-10 Cool Lube". I buy it in gallon jugs and mix it 10:1 with water. If I can't make this work, I'll go with the gravity feed option as it's just easy to do. Thanks again for the great tips- as I expected, many people here really know this stuff. Lincoln AC225 & MigPak 140, Lincoln Magnum SpoolGun, Miller Spectrum 375-X Plasma, Syncrowave 200 TIG, Millermatic 252 MIG, Miller Digital Elite, General 7x12" horiz/vert bandsaw, 3' box/pan brake, 20 ton press, milling machine, 12x28 lathe, etc.
Reply:Like the above posts, I gotta go with the Bijur system if you can find one (they can be cashy). If you want easy portability Cedarberg makes good misters. If you want cutteing edge Trico makes the micro lube system that runs near dry and the coolant is not mixed (gallon lasts forever).The Bijur, Cedarberg and other better units can be set to "spit" very small droplets at low pressure settings and don't send a fine mist and fog into the shop air. They can get very good milage with the coolant when set right.The Trico micro drop starts at close to $600.00 for a single nozzle system but runs about 40 hours on 4 ounces of coolant (coolant is vegetable oil based and expensive too).If you build your own duaneb55 hit it on the head, a high pressure jet from the smaller supply opening creates a vacuum as it moves to the larger outlet.MattMatt
Reply:OK, now that we have exhausted the Buy it on Ebay and how to change the Chinese lightbulb requirement, and still don't know what the OP desires to accomplish, lets get to business.First, get rid of that lovely blue poppitbead contraption, and give it to some girl for a bracelet because there is no way in hell mist will flow thru it properly.This representation is a small diameter liquid handling eductor. Pay close attention to the coaxiality of the outlet opening and the injecting needle carrying the air. Also note the cone at the tip of the injector. The front to back position of the injector relative to the cone will be adjusted to accomodate the viscoscity of the liquid being moved. Also note the discharge portion of the device is tapered. Also note the injector is well past the liquid intake port, which generally prevents backpressuring the liquid.This device will need to be mounted as close to the cutter as is possible and be the discharge end of the system. Since you're going to spend a lot of money on compressed air employing this method, you might as well slip a secondary tandem barrel onto the eductor and gain additional air directed at the cutter at no additional cost.On the off chance you just want to spray liquid coolant at the cutter and not listen to the air compressor consume dollars all day you can make a nice sprayer using the nozzle from a gun type oil burner connected to a scrap 20# propane tank containing the liquid. Attached Images |
|
发表于 2021-8-31 22:39:27