Ultimate 3D Printed Wire Twister

Update 3/20/22

You can now find this design at the Wago Creators web site: https://wago-creators.com/design/185

"Let's Do The Twist"

When you're wiring things like 3D printers, sand tables, model train layouts, and almost anything else, you often need to use wires to connect things that are separated anywhere from a few cm to a few meters. If you want to do it neatly, you want the wires twisted together, especially if they carry motor or bed heater currents. Twisting wires carrying high currents helps prevent them from inducing currents in adjacent wires.

A few years ago I designed a wire twister and posted it on Youmagine.com. It was a simple, two-part 3D printed tool. The spinning part had screw clamps to hold two wires and a hex shaft to fit in an electric drill/screwdriver. The fixed part was intended to be held in a bench vise. The wire clamps in both parts used screws to hold the wire tightly, so you had to use a screw driver to secure each end of each wire, creating four opportunities to stab yourself with a screwdriver in the process. Operation was simple- just pull the wires tight and pull the trigger on the drill. Bob's yer uncle, instant twisted wire pair!

First generation wire twister. A similar piece held the wires in a bench vise. The screws proved hazardous.

A few days ago, I got an email notice that my old wire twister design was added to someone's collection at Youmagine.com. That same day I had demonstrated Wago lever nuts to my boss who is getting into model train layouts. And then, just like this old commercial...

...something clicked and I realized I could redesign the wire twister to use Wago lever nuts so all you'd have to do is lift the levers, shove the wires into the holes, snap the levers down and spin. No more screwdriver, no more risk of stab wounds! Wagos and 3D printing are the greatest combo since peanut butter and chocolate! The Wago 221-412 lever nuts are good for 24-12 gauge wire, solid or stranded, so they're good for almost any wires you'll ever need to twist.

The New Spinning Clamp Design

I previously designed some printable screw-down mounts for the Wago lever nuts and they worked very well. The lever nuts snap into the mounts so securely you have to use a screw driver to pry them back out. This is the basic unit I started with for the screw-down mounts, and for the new wire twister design:

I grabbed the design for the Wago holder above and reworked it to include a hex shaft to go into a drill:

The model for the Wago lever nut came from partcommunity.com and is supposed to be accessible from inside Fusion360 (Insert>Insert a manufacturer part). It refused my login name/password when I tried to insert the part that way, so I just logged into the site in a web browser, downloaded the .stp file, then "uploaded" it to Fusion360. The model isn't very detailed, and doesn't include the concavity on the sides of the part that allow it to be held in place by the bumps inside my holder design. This is why it is sometimes better to make your own models or at least to measure the parts you want to use in CAD.

The New Fixed Clamp Design

My initial design was for a fixed clamp that you'd use with a C-clamp to hold it on the edge of a table or shelf, or in a bench vise. Then I decided it would be better if the fixed wire clamp actually was a C-clamp so you wouldn't need another tool. Here's what it looks like:

The fixed wire clamp is a clamp! Printed in 3 parts, the thumbwheel, the end cap, and the clamp body.

You can still use a vise to hold the C-clamp, if you prefer, or skip printing the fixed clamp and just hold a Wago in a bench vise.

The hardware consists of a 5/16"-18 bolt, 3-4" long, two nuts, and a washer. Those of you who live in the civilized world (you know, metric) may have to edit/scale the design file a little to use 8mm hardware. Assembly is obvious.

Printing

I used PETG filament for this one because it's pretty tough stuff and can take a lot of abuse. I arranged the parts on the print bed like this:

I have a 1mm nozzle on UMMD and the print came out OK, but I recommend you use a smaller nozzle and print in 0.2 mm layers. The extra cylinder is there to help the hex shaft of the spinning clamp print nicely. You could just print 2 or 3 of the spinning clamps (your friends are going to want one of these tools when they see it) instead.

I printed a bright color so I'd be able to find the thing in the bottom of a bag or toolbox.

The Result

The clamps were printed in 0.2 mm layers. I used contact cement to glue a piece of rubber to the fixed clamp to keep it from slipping when you pull the wires tight. I also used a drop of hot melt glue under each Wago to ensure they'd stay put. Shown here in "storage" mode- a piece of wire will keep the two parts together in your tool box so they don't get lost/separated. 

The Wago lever nuts snap into the tool, but dimensions are critical for retention and depend on your printer settings, so you may find that they will pop out of one or both clamps when you twist thick wires. The solution is as easy as a single drop of glue on the bottom of each Wago when you assemble the clamps. If you use ABS to print, superglue will work. You might want to use other glue depending on the plastic you use to print the clamps. Hot melt glue seems to work well on the Wagos.

It's a good idea to glue a little piece of rubber to the fixed clamp so it's less likely to slip when you clamp it to a smooth table top and start pulling on the wires.

The CAD File

You can download the .stp file here and open it in almost any CAD program you like.

Video, or it didn't happen!

How to Use It

In case it isn't obvious from the video above, just cut two wires to equal lengths, strip the ends, and insert them into the Wagos, and snap the levers down. Put the spinning clamp in the chuck of your drill/screwdriver, clamp the fixed clamp to a table or or shelf or put it in a vise, pull the wires tight, and pull the trigger. Keep tension on the wires as they twist, and when you feel you have enough twists in the wires, let go of the trigger. Give the drill a tug to "set" the twist and then release the wires from the Wagos.

3D Printable Wago 221 Lever Nut Mounting Blocks

I like to use Wago 221 lever nuts in place of screw terminals and have started replacing screw terminals in my 3D printers with them.  To that end I designed a few printable mounting blocks to hold single and multiple lever nuts.

The Wagos come in 2, 3, and 5 wire parts (221-412, 221-413, and 221-415), handle 24-12 gauge wire, handle 32A up to 450V, and have multiple safety certifications (unlike the much cheaper Chinese made knock-offs).  Full specs are available here.  When I first got them I inserted some wires and then pulled at them and was unable to pull any of the wires out. They really hang on tightly to solid and stranded wires.  All the wires will connect together in each block.  The 5 wire blocks are great for making DC power distribution blocks in a 3D printer, as I did in UMMD.

I have printed the 2x2 and the 221-415 mounting blocks using ABS.  The other blocks are based on the same dimensions so they should work fine.  You insert the back end of the lever nut as far as it will go into the mounting block, then press down hard on the open end and it will snap into place.  They fit and hang on tightly so there's little danger of the lever nuts coming out of the blocks, and even if they do, the bare wires are entirely enclosed within the lever nuts, so nothing is going to short.

Here's the 1x5 mounting block with a 221-415 block installed.

Yes, they're pretty small.

Here's the 2x2 mounting block.  It uses 2 screws to mount on a flat surface or t-nuts to mount on t-slot.

Here are two vertical mounting blocks that hold 4 of the 221-412 lever nuts.  The one on the left has an 8 mm tang that prevents rotation in a t-slot (so you need to use bed-only support material when printing) and uses a single t-nut to hold it in place.  I used that one to make bed heater and thermistor connections in UMMD.  The one on the right is intended for mounting on a flat surface.

The CAD file is easy to edit for any combo of lever nuts you want to make.  You can DL the Fusion360 CAD file for the mounting blocks here.