2-stage Magnetically Coupled Gear Pump

thingiverse

Higher Pressure, Higher Volume than the Original + Minor Fixes. Grease the Outer Gears on This One. Differences: Uses 1 1/4" Dowel Pins Instead of 1". https://www.grainger.com/product/GRAINGER-APPROVED-Stainless-Steel-Dowel-Pin-1NU35 Need Two More Bearings, Any R188 Will Work Since These Can Be Lubed. Tips and Tricks: Pump Designed with 0.2mm Clearance, So Sand Off Any Blobs Your Printer Leaves First. Press Magnets Flush with the Surface of All Four Gears, If Loose, Add Glue, but They Should Be a Tight Press Fit. I Found the Best Way to Ream Out Holes in 3D Prints Is to Use a Drill Bit *Backwards*. The Friction Melts the Plastic and Pushes It into the Infill, Adding a Little Friction Welding There Too for a Stronger Seamless Wall. Stop the Drill in the Hole, Allow to Cool, and Spin It Slowly to Pull Out. It Also Shrinks a Tiny Bit on Cooling That Makes Perfect Press Fits. Press Bearings into Both Sides of the Pump Gears, Flush Is Fine for Now. These Should Go in No Problem. Place a 0.1mm Metal Shim (I Have Spot Weld Tabs for Making Battery Packs That Worked Perfectly) in the Housing Under the Pump Gears, Press the Gears and Dowel Pin All the Way into the Housing (the Ones I Spec Are a 0.001" Interference Fit on the Bearings). Remove Your Shims. Now Everything Is a Tight Fit and the Pump Gear Has 0.1mm Clearance from the Housing (and 0.1 from the Cover). Attach the Covers. Use X60 Filament as a Gasket, Cut Slightly Long So the Ends Press Together and Seal. Take One of the Drive Gears, Stick It on the Back of the Pump by the Magnets, and See If It Spins (Roughly at First) If Not, You May Have Issues with Dimensional Accuracy. Either Way, This Trick Should Free It and Smooth It Out. The Ports Are Meant to Be Tapped for 3/8 NPT. Find Some Fittings, and Hook It to a Garden Hose. It's Now Basically a Hydraulic Motor. Turn On the Water and Use It to Wash Your Car or Something. All the While, the Gears Are Wearing into Each Other and the Housing, the Pump Should Loosen Up and Spin Freely. If Its Still Binding, Add Some Abrasive Media, Run It for a While Again, and Then Disassemble and Clean **All** of It Out. Very Little to None Should Be Able to Get Between the Gear Faces to the Bearings if Your Z Dimension Is Accurate, but Flush Them Well Too and Check There's None Embedded into the Gears or Housing. Insert Two Long (So You Can Reach Them Later) M3 Screws into the Shaft Holders on the Motor Housing. Press Bearings into the Gears. (and Make Sure Your Magnets Are Flush with *This Surface*.) Now You Want to Run the Motor for a While, Add Abrasive If Necessary but Make Sure Not Get Any into the Motor and Get It All Out After. Put a Dab of Lube on the Faces of the Drive Gears (in Case They Ever Rub) and the Teeth. I Used Superlube That I Had for My 3D Printer. Assemble the Motor Housing to the Pump Body, and There You Have It. A Functional Twin Stage, Shaft-Less Gear Pump; Go Watch It in Action If You Did the Polycarbonate Top Covers. If Printed in Nylon as Suggested, Its Compatible with All Kinds of Fluids. The Pins and Bearings Should Retain All the Gears at Their Perfect (Minimal) Clearance, So the Only Wear Parts Should Be the Gear Teeth Unless You're Using It for Something Really Unusual. Automotive Fluids Would Probably Make It Happier than Water. Enjoy Your New Long Life Gear Pump Until the Output Drops (Might Be Years) and Just Print a New Set of Pump Gears When the Time Comes If It Slips, There Is a Few Percent More Coupling to Be Gained by Adding Another Layer of Magnets in the Drive Gears, but It's Not Very Much. There's Enough Clearance if Your Pin Press Fit in Tightly and Didn't Need the Locking Screws. I Found Some Smaller 1/8 Magnets and Might Be Able to Add a Row or 2 into Gear Faces..A Halbach Array Could Be Another Option, but Finding Magnets in the Right Form Factor and Fitting Them Will Be a Challenge. Self-Priming, Pressure and Volume Tests Coming After I Get a Few More Bits and Pieces in the Mail. Might Be a While Because the Last Print Adhered So Well to My Garolite Bed That I Broke the Glass Backing Removing It.