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Homemade cutting oil pump for the lathe

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  • Homemade cutting oil pump for the lathe

    I’ve had this idea for a while & decided to make it happen. I like a small amount of cutting oil dribbling on parts in the lathe. Just enough to keep the work & tool shiny wet without making a huge mess like flood coolant does.

    I used a Mikuni 2-stroke dirt bike oil injection pump driven by an old 7.2vdc model airplane motor. I bought a few of the “Leisure 05” motors back in the 80’s when electric airplanes were 1st becoming popular. They have dual ball bearings, replaceable brushes, well-built cases & endbells and the timing is easily adjustable. It’s pretty relaxed running on 5v and should last a long time.

    I made a housing to hook the pump & motor together from aluminum scraps and made a coupler from acetal rod. The thing is a teeny bit noisy so I’m using a rubber stud mount to isolate it from the lathe enclosure.

    On the bike, the pump had had a cable operated variable displacement cam to vary the oil output from idle to full throttle. I removed the return spring so now it’s easy to make manual flow rate adjustments. It works great and I just need to get some tubing, a reservoir and a relay board to get it buttoned up. Mach3 will turn a relay on & off in response to M-codes when lube is needed.

    I plan to mount the pump & reservoir on the back of the lathe close to the height of the tool and hope it won’t drip forever without a check valve after it’s shut off. The “applicator” will be plastic carb cleaner straw adjusted against the work in front of the tool tip with spring tension so it follows the work as it is turned smaller. If that doesn’t work I’ll make a hollow stem brush to apply the oil.







    I partially dis-assembled the pump to clean it but couldn’t quite figure out how it works. Here’s a pic I pinched on the web if any of you engineering type want to take a stab at it.

    It puts out little single pulses of oil similar to a tiny hand pump oil can but never seems to get tired.

    Milton

    "Accuracy is the sum total of your compensating mistakes."

    "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

  • #2
    I went to a home center where they sell water fountins bought a fountin pump for $14.00 it works great and so far the pump bean lasting for 1 1/2 years. Had to put a shut of valve in the end of the coolant line to regulate the coolant. In your tank put a baffel in it about 3" high and put your return line in that part.
    The baffel will trap shavings and junk and keep the junk away from your pump

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    • #3
      I wonder how one of those electric drill water pumps would work with it's own motor?
      Jim
      So much to learn, so little time

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      • #4
        Originally posted by outback View Post
        I wonder how one of those electric drill water pumps would work with it's own motor?
        Jim
        Probably great for the large quantities of low viscosity water soluble coolant needed in a flood system.

        I wanted an adjustable, very small quantity of neat cutting oil applied in front of the cutting point so I'd get smoke and some drips, not the torrent of fluid to deal with in a flood setup. I've been using a small squeeze bottle for years but wanted to automate the process for the Orac.
        Milton

        "Accuracy is the sum total of your compensating mistakes."

        "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

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        • #5
          I have a honing tank. I went through several motor/pump combinations; ten or twelve hours and the motor would burn up. It turned out the power rating on the pumps was "free flow", and by throttling the exit I was increasing the load on the electric motor, which probably wasn't rated for continuous duty anyway.

          I put a tee in the output line, and moved the valve to the new leg on the tee. Instead of throttling the output, I bypassed excess oil back to the tank. 15 years later, still using the same motor...

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          • #6
            I did this to my lathe many years ago. I made a drawer that slides under the bed and mad a hole (indented) so coolant could flow into the drawer. Used a fountain pump and also a tee so as I closed the shut off valve it would just direct more back to the drawer. Drawer had 3 sections, the left two had spill over plates with small holes in them to allow coolant to pass. The first section (where the coolant came down from the lathe holds a mesh type coffee filter, which catches most of the swarf. I mounted the regulating valve and on/off switch to a small box which is attacked to a magnetic base, then use a flexible goose-neck to deliver the coolant (goose-neck from a HF parts washer). Works really well with the water based coolant concentrate I got (had to buy a 10 gal pail when I got the Way lube, also 10 gal. Should last me forever),

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            • #7
              Upon further review...

              After running it for about 10 minutes last night, the whole thing got much hotter than expected. The adapter housing made a good heat sink but way more motor heat was being created than necessary.

              An ammeter showed the motor was pulling a hair over 7 amps! The airplane motor is wound pretty hot and designed to run 3 or 4 minute bursts at high amperage. Bad choice on my part!

              Motor iteration #2 is a Buehler 13v motor off an auto power sunroof gear drive unit. Had to modify the mounting plate a bit and make another acetal coupler but this version purrs happily along pumping a bit faster than the other one and draws only .9A @ 12V. I have plenty of 12V power available so it's no sweat going to 12V from 5. This one is way smoother & quieter than the other one too. I think I got it where it needs to be now.

              Milton

              "Accuracy is the sum total of your compensating mistakes."

              "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

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              • #8
                Has anyone ever tried using a fruit tree sprayer as a dispenser for cutting oil/coolant? It seems that they are inexpensive and could easily be adapted as a reservoir and supply oil/coolant via the pressurized tank. If there are concerns about having to continually pump it up one could supply regulated compressed air by drilling a hole and installing a quick coupler fitting. A small ball or gate valve could be installed in line to regulate flow. As inexpensive as the sprayers are these days one could own two, one to receive screened oil/coolant while the other supplies it. When the first is empty it would be a simple task to switch tanks and continue working.

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