Fun Wire Bender for the Classroom

Quick Introduction: If you want to help a group of students make automatons or Stirling Engines -- anything with a wire crankshaft -- then this Instructable is for you. For a super-quick look at the project, here's a 40 second YouTube short (but if you have time, the video above is more informative).

The Fuller Story: This Instructable is a spinoff of an ongoing Stirling Engine project that I've been developing for years. When I first had my students try to make Stirling Engines, the most serious roadblock was making crankshafts -- making them, installing them, attaching things to them -- it was too much frustration for most students. This Instructable is the fruition of years spent trying turn a major obstacle (dealing with crankshafts) into something easier, or possibly even something fun. I imagined how nice it would be to have a fun wire bender, an easy wire straightener, and an easy and satisfying way to attach and adjust the rods, strings, and flywheel that attach to the crankshaft. I imagined the process being so much fun that I would have to limit kids' time at the wire bender and remind them to move on. I imagined more energy remaining for testing and iterating and less energy expended on frustration. I think this process and these tools and accessories finally come close to my vision.

The 16 gauge wire that fits in this bender is inexpensive in bulk, and it's easy to work with. It is strong enough for small Stirling Engines, and it also works well for making automatons. It's also recyclable; I put the unusable bits in the scrap metal bin at our local trash drop-off. I don't see any reason why the bender could not be scaled up to bend heavier gauge wire. At some point, the 3-D printed PLA parts of the bender mechanism would need to be replaced with something more robust.

[At some point in the future I plan to share my Stirling Engine project. It's getting better, but it's not ready yet. :-)]

1. For the bending process:
2. 16 Gauge Steel Wire (for bending)
3. Wire cutters
4. two pairs of locking pliers
5. Bender Parts and Assembly:
6. 3-D Printer (I used PLA)
7. Laser Cutter (I used an Epilog Zing 50W)
8. Approximately 0.2" thick plywood -- approximately 1'x2'
9. Screws --
10. #8 (3/4") -- about 14 of them
11. #6 (5/8") -- about 4 of them
12. 1 1/4" drywall -- 2 of them.
13. Screwdriver
14. 1/4" hex bolt -- 1 1/2" long
15. 1/4" washers -- 2
16. 1/4" nut or wingut -- 1
17. "Straightening Station" parts:
18. approximately 3' long, sturdy board
19. Drill and small bit (1/8" or 3/16")
20. 2 metal washers
21. Glue (hot glue or super glue with accelerant)

The three parts are attached. I used PLA.

The two attached files are:

1. The "raster" file is the scale that is etched onto the surface of the bender. I am calling it the "raster" file here, but I like to use vector cutting at high speed and low power.
2. The "vector" cutting file is for cutting all of the wooden parts from 0.2" (5mm) plywood.

I made my bender from Revolutionply that I bought at Lowes. The thickness is nominally 1/4", but I see that they give a more specific thickness of 5mm. For my designs with this wood, I usually work in inches and use a thickness of 0.2". So, if you're going to use these files, you're going to need to use the same thickness -- somewhere around 0.2" or 5mm.

I think this is best explained in a video.

This could be done in a lot of different ways. My method is described below and shown in the video.

1. Get a sturdy piece of wood (e.g. a 2x4) that is about 3 feet long.
2. Securely clamp it onto a table with a foot or so hanging off.
3. Near the end of the board that is hanging off, drill a small horizontal hole, just big enough to be able to easily pass the wire through the hole.
4. Glue a washer on each side of the board, so that the drilled hole is in the center of the washer. You really only need a washer on the side of the board where you're spinning the locking pliers. But it's easier for lefties on one side, and easier for righties on the other.
5. You're done!

See video. :-)

These are some accessories that I have made to use with 16 gauge wire crankshafts. I print them all on "Fast" with no support and no bed adhesion. This works great on my Ultimaker 3, with the bed covered in blue painter's tape. When I try to print things at school with no adhesion, they sometimes come loose, so apparently results vary.

1. Crankshaft-Rod Connector
2. Rod-String Connector
3. Rod-Surface Connector (for attaching a connector rod to a membrane)
4. Universal Joint (Rod-Rod)
5. Crankshaft-Flywheel Connector
6. Wire rod-membrane connectors (for connection to Stirling Engine Membranes) -- screw together
7. Crankshaft-Flywheel connectors (crankshaft passes through flywheel and is held firmly by set screw -- also has a built-in small pulley)
8. Clips to support crankshaft ends (clip onto 0.2" plywood)