Intro: A Citrus Juice Press With Mortise and Tenon Joints
The goals of this project are two-fold:
- Make an awesome and beautiful citrus juicer
- Create a mechanical/metal project that someone can build with almost no tooling of their own, as a means of learning more about outsourcing manufacturing steps.
The result is this juicer constructed of waterjet-cut mild steel plate, using wedged mortise and tenon joints, as well as some commercially available hardware. This is not a cheap project by any means, but produces an absolutely beautiful piece that works well.
What you'll need:
- Tools as shown in the image above
- Hardware as shown in the image above or similar (Parts list shown below as well).
- Most of the hardware can be substituted if something is easier to get (for example, you don't need brass acorn nuts; any nuts will do fine; I just like brass)
- The DXF for this pattern will only work with the juicer parts shown. If you get different parts you will have to alter the DXF.
- Use the attached DXF and get your parts cut at a shop of your choice
- See my tutorial on getting parts cut for help with this.
- Parts must be 3/16" unless you alter the pattern to work with a different thickness.
--NB: I'm including Mcmaster #s for all hardware, but many of them are sold in packs of 25 any you only need 1 or 2; check your local store first unless you are a hardware horder like me :)
- McMaster #6679K17 Bronze Bearing, for 12 mm Shaft Diameter, 20 mm Length QTY: 2
- McMaster #5544T352 12L14 Carbon Steel Metric High-Tolerance Rod, 14MM Diameter, 1' Length QTY:1
- McMaster #6050K16 Threaded Oval Knob, 1-1/8" Diameter, 3/8"-16 Thread 2Each
- McMaster #91125A240 Female Threaded Round Standoff, 1/4" OD, 1-1/2" Length, 10-32 Screw Size QTY:4
- McMaster #98750A056 Alloy Steel Fully Thread Stud, Plain Finish, 3/8"-16 Thread, 1-1/4" Length QTY:1
- McMaster #2938T7 Bronze Flanged-Sleeve Bearing, for 3/8" Shaft Diameter, 1/2" OD X1/2" L QTY:2
- McMaster #91259A634 Alloy Steel Shoulder Screw, 3/8" Diameter X 2-1/2" LG Shoulder, 5/16"-18 Thread QTY:1
- McMaster #92415A250 Unthreaded Round Spacer, 1/2" OD, 13/16" Length, 1/4" Screw Size QTY:4
- McMaster #92916A405 Brass Flat Washer, 3/8" Screw Size, 7/8" OD, .05"-.08" Thick, QTY: 2
- McMaster #92716A610 Brass Acorn Nut, 5/16"-18 Thread Size, 9/16" Width, 7/16" Height, QTY: 1
- McMaster #93131A530 Metric Clevis Pin, M12 Diameter, 60 mm Length, 53 mm Usable Length QTY: 1
- McMaster #92716A519 Brass Acorn Nut, 1/4"-20 Thread Size, 7/16" Width, 3/8" Height, QTY: 2
- McMaster #8510K19 Rubber Edge Trim, 3/16" Inside Width, 7/16" Inside Height, QTY: about 20"
- McMaster #91259A615 Alloy Steel Shoulder Screw, 3/8" Diameter X 1/4" LG Shoulder, 5/16"-18 Thread QTY: 2
- McMaster #91251A345 Black-Oxide Alloy Steel Socket Head Cap Screw, 10-32 Thread, 3/4" Length, QTY: 8
- McMaster #91124A062 Shim for Shortening Screw Shoulders, Spring Steel, .010" Thick, 3/8" Diameter, QTY: 10
- McMaster #8457K53 Multipurpose 304 Stainless Steel Tube, 1/4" OD, 0.1940" ID, QTY: about 2"
- McMaster #90575A361 Type 316 Stainless Steel Fully Threaded Stud, 10-24 thread, 2-1/2 length, QTY: 1
- McMaster #92716A011 Brass Acorn Nut, 10-24 Thread Size, 3/8" Width, 11/32" Height, QTY: 2
- McMaster #98335A054 Reusable Cotter Pin, Fits 5/16"-3/8" Pin Diameter, 1-1/2" Length, QTY: 1
- KaTom Product Code: 268-17443 Strainer Cone, For All Juicers, Stainless Steel
- KaTom Product Code: 268-17448 Funnel Cup, Stainless Steel, For All Juicers
- KaTom Product Code: 268-17550 Aluminum Cone, For Olympus And Jupiter Juicers
Step 1: Ouch, That's Sharp!
Fresh off the waterjet table, parts tend to have pretty sharp edges. This makes for an uncomfortable user experience unless the edges are softened somehow.
- Tumble the parts (some shops will do this for you if you ask, otherwise you might find someone else with a parts tumbler)
- Sand/grind the edges with an angle grinder
- File/sand the edges by hand (a great way to do it would be with soft sanding bricks you can buy from the hardware store, applied flat to the faces of the parts just to 'break' the edge)
I was fortunate to have access to a parts tumbler, so you can see the softened edges I got in the picture above.
Step 2: Test Fit the Body
- The mortise and tenon joints can be test-assembled without any tools at all.
- Do not pound the wedges into the tenons during test-assembly.
- Each side of the machine (left and right) should be assembled entirely before joining together with the threaded spacers and central plate.
Follow the steps as shown in the photographs above.
Step 3: Test Fit the Handle
Follow the pictures to test-assemble the handle.
Step 4: Finishing the Test Assembly
Follow the instructions shown in the photographs to finish the test-assembly.
Step 5: Finishing
You have many options for finishing this piece:
- Leave it rusty. Always an option. You might get rusty drips on your countertop.
- Just clean the parts, wax them, and reassemble. The parts will look like raw metal, and it's easy.
- Paint or powdercoat. Disassemble, clean, and paint on your own or take them to a powdercoat shop. The powder finish may be so thick the mortise and tenon joints will no longer fit together. Beware.
- Electroplate. A nickel plate or "black zinc" (actually zinc with a black chromate finish) would look spectacular on this piece, and probably cost about $90.
- Patina. You can look at options at Sculpt Nouveau and Jax.
I decided to patina mine with BST4 Presto Black from Sculpt Nouveau. I like the lustre of the finish, but I will warn you that patina like this is finicky, and especially with all the piercings, waxing the pieces afterwards was a pain. See the pictures above for an explanation of the steps.
Step 6: Final Assembly
Reassemble, this time pounding in wedges.
Add rubber stripping to the base.
Brush of any stray bits of steel wool and paper towel.