We just got these solder sleeves in, and they are fantastic. They solder and heat shrink wires together all in one go!
http://3.bp.blogspot.com/-qiIuSp5WjCs/VUuXFsTZwbI/AAAAAAAABwE/JT7A3iC7_9w/s640/Soldersleeve1.gif
Check out this blog post for the details: http://blog.inventables.com/2015/05/new-product-solder-sleeves.html
As a professional aviation wire monkey, I can attest to the wonderfulness of this type of solder sleeve. We use an unfathomable amount of them when doing avionics system installations and upgrades. The only real difference I can see between these and the ones that we use, is that ours come with an FAA certification and cost five times as much. 
That’s really cool, I didn’t know these were used in that industry. Someone asked me if these would be good for automotive wiring, I assume so?
The mind-blowing selling point for me was the fact you can make it work with a cigarette lighter, which means you can just throw some in your pocket and work on wire installations anywhere and not have to worry about soldering.
These look fantastic, I can think of all sorts of uses…
Michael, what size would be appropriate for extending the wiring on the X-Carve ?
They’re great for automotive wiring too. It’s what’s also called an “environmental splice” - those little globs of softer plastic in either end of the shrink tube should form a water-tight seal when properly heated, protecting the solder joint from moisture intrusion and preventing corrosion. They’re brilliant little widgets!
Depends on what size wire you’re using, but if you’re using a gauge similar to the wires already attached to the stepper motor, but the 22-18awg Red ones are probably the best bet.
I was introduced to solder-sleeves in the telecom industry, where they’re used to fix the occasional “oops” on twisted-pair wiring from 19AWG to 26AWG. I gather that a larger version is used for terminating coax shields, largely in aviation, and these seem to often have a drain wire preinstalled as part of the sleeve assembly.
They seem to be available in quite a range of sizes and styles, though they’re such a niche product it’s hard to find a comprehensive list anywhere.
Air Force avionic tech here, we use those for doing shield splices and stuff. But for joining 2 wires together, we use a crimp splice with an environmental sleeve over the top. Solder joins like that can become brittle in a vibration enviroment.
