INDX Nozzle seal - injection mold for silicone sleeve

The INDX FE and Prusa Edition each have got a nozzle seal per tool made from flat spring steel and a silicone sleeve.

The spring can be ground out of 0,3mm flat spring steel. A width of 8mm is ideal; 10mm stock can be easily ground down to fit. Use a dremel with a metal cutting disk, a diamond bit for the 3mm screw hole and a grinding stone/diamond bit for deburring. Watch out, spring steel can get really sharp! Ask me how I know.

The silicone I used is casting silicone for tin figurines. Heat-resistant up to 450°C, so I don't expect any heat issues. Durability still needs to be tested, though.
https://trollfactory.de/Produkte/Silikon-Kautschuk/Verarbeitungszeit/sehr-schnell-5-Min/TFC4020/TFC-Troll-Factory-Silikon-Kautschuk-Typ-3-HB-Zinnguss-hitzebestaendig-RTV-1-1-Groesse-500g-2x250g
or
https://www.amazon.de/dp/B01MZ7EO1V

Use this mold to cast the silicone sleeve around your handcrafted springs.

Preparation:

1. Print both halves of the mold.
   If you got Ironing dialed in for your setup, go for it, the surface improves noticeable.

2. If necessary, smooth out minor print lines or blobs on the mating surfaces with a small file or sandpaper.

3. If the rounded part at the end of the top mold has any print defects, carefully scrape or smooth it with the tip of a utility knife.

Casting instructions:

1. Put the spring into the bottom part and align the screw hole.

2. Check the flatness of the steel against the mold. It may have bent slightly during grinding; try to bend it back so it fits as evenly as possible, visually.

3. Put the top mold on and use one M3 screw in the single screw hole at one end to lock the mold and spring together. Optionally, use two more M3 screws or a large paper clip at the other end to further secure the mold.

4. Place the mold on a suitable work surface that can get a bit dirty. The silicone is fairly easy to remove, but you never know.

5. Mix up some silicone — I load 2-3ml into the syringe, so mixing about 4ml is enough.

6. Use a standard syringe to load about 2-3ml of silicone. Try to get the air out like Dr. House.

7. Press the silicone SLOWLY into the mold. It will eventually ooze out a bit on all four sides, but don't worry, those thin parts are easy to trim afterwards.

8. Once there's squeeze-out on all four sides, there shouldn't be any air pockets left.

9. Leave the mold to cure for 1-2h.

10. Remove clips/screws and carefully open the mold. I use a small flat screwdriver or knife edge for leverage at 1-2 corners, until the halves separate. Trim off the excess with a pair of scissors, a sharp knife, or even better, a flush cutter.

Versions:

• v1: initial trial

• v2: smoothed out some corners, removed ineffective vents, and slightly enlarged others to improve flow and reduce air pockets during casting.