Envious of those cool-touch espresso machine steam wands? It's easy conceptually - just run a PTFE tube down the center. However, getting everything the correct dimensions to make it work and fitting things together is a bit of a challenge. As usual, when you have a 3D printer the answer is… 3D printing :)

Remember, “cool-touch” doesn't mean the outside will stay cool forever - the longer you steam the warmer the outside will get, and it'll typically be at least the temp of the milk you're steaming. However, it won't shoot up to 100 C in a few seconds, keeps milk from burning on for a long time, and shouldn't immediately give you a burn if you contact it by accident.

Parts:

• Gaggia Classic Pro/Eco/Evo steam wand
• Vise
• Power drill
• 4 mm drill bit
• 4 mm OD, 3 mm ID PTFE tube, 200+ mm length
• 6 mm OD, 4 mm ID PTFE tube, 100+ mm length
• razor or utility knife blade

Printing:

Tested with PETG, 0.1 mm layer height (or 0.2 mm with adaptive layers) for the holding jig, 0.4 mm nozzle and line width, 20% gyroid infill. Print one holding jig and one pusher.

Holding jig may be compromised after the clamping and drilling. I recommend printing multiple jigs if you're converting multiple steam tips.

Steam Tip Modification:

WARNING: YOU NEED TO HAVE COMMON SENSE AND SOME EXPERIENCE WITH BASIC POWER TOOLS. THERE IS SOME RISK OF BREAKING YOUR STEAM TIP. That being said, this worked for me first try :)

Remove the steam wand and steam wand tip from the espresso machine.

Cut a 25 mm length of 6x4 mm PTFE tube and press it into the top of the holding jig until flush.

Screw the steam wand tip into the threads on the holding jig (between the clamping arms). When screwed in you should be able to see straight down the center of the steam tip, with everything lined up. Shades of Coffee's “The One” steam tip is shown, though this mod was tested with the stock 2-hole tip as well.

Insert the 4 mm drill bit into the drill and tighten. Then, line up the drill bit with the holding jig, measure how much length is needed to reach within 1-2 mm of the end, and then cut that length from the 6x4 mm PTFE tubing and insert it onto the drill bit as a drill depth-stop.

Clamp in a vise at the clamp feet as shown, drill. Make sure to peck drill (short plunges with raises to clear chips) and stop to let things cool if they get too hot. You can use a thin cutting fluid if desired, though it's not needed.

When you're done you should have a steam tip with a 4 mm hole in it, ready to fit the 4x3 mm PTFE tubing.

Cool Touch Steam Wand Assembly:

Thread the 4x3 mm PTFE tubing through the steam wand, starting at the top

Insert the steam tip fully onto the end of the tubing. You may need to use rubber gloves for extra grip on the PTFE tubing.

Screw on the steam tip

Cut a 15 mm length of 6x4 mm PTFE tubing and then cut a small chamfer on one end to aid insertion into the top of the steam wand.

Use the pusher to press the 6x4 mm tubing section (around the 4x3 mm tubing) into the top of the steam wand. It should go in 8-10 mm.

Cut the tubing flush with the top of the wand

Reinstall the wand into your espresso machine and you're done!

Side Note:
This general method will work with basically any steam wand that can be drilled to match PTFE tube sizes.
For example, the Rancilio Silvia steam wand can be drilled to 3 mm in the threaded tip and 4 mm at the tube top. This allows a 3 mm OD, 2 mm ID tube to be routed through, and the top plugged with a 4 mm OD, 3 mm ID tube.