For a long time i am experimenting with different silicones which are very usable at different points of a 3D Printer. U can use them for dampening the print bed or insulating the heating block. Another good working solution is to use silicone as a compensation for a regular spring in your extruder.
Don´t be irritated by the title of my instructable it will be solved...
Step 1: Choose the Right Extruder
At first you have to choose the extruder you want to use with the "silcone spring". There are many differnt on the web. I choose this one http://www.thingiverse.com/thing:1230975 designed by loco.
I choose it, because there it is easy to substitute the regular spring with the silicone one you will see later on. The exact file is for me the mirrored one. With that i am able to use it perfectly with my DELTA 3D printer.
Step 2: Print Extruder and Idler
Next step is to print the extruder parts of loco´s "MK8 Remix". It is very important that your printer is calibrated well, otherwise the bearing in front of the extruder won´t fit.
Step 3: Get the 'HEAVY METAL' Except the Springs ;-)
(1x) NEMA17 stepper motor
(1x) MK8 drive gear
(1x) 608 Bearing
(1x) MR105 Bearig
(1x) R1/8" push-fit connector
(2x) Spring (ID >= 3mm) YOU DON´T NEED THAT ANYMORE!
(2x) M3x30mm or longer, depending on your springs
(2x) M3 nut
(2x) M4 T-nut
(4x) M3 washers
Step 4: Print the Silicon Mold and Cast the 'spring'
Now you have to print the mold for the silicone. The .stl is made for locos extruder, but maybe it will fit for others.
If the printing is done use dental rubber or something similar (maybe heat resitastant rubber for casting) to cast the 'spring'. I used this.
Step 5: The 1 Cent Upgrade
Grab a cent and drill two 3.2 mm holes in it with a distance of around 9mm. Then you can substitute two of washers of Step 3 with one good looking washer, which is cheaper than the two ones before....
Step 6: Assembly
Now you put all the parts together and got you Extruder ready.
Step 7: Credits
Thanks to loco for his perfect design of the extruder.
If you want top read more about silicones/rubber in 3D printing you can give this topic of the Reprap forum a try. Sorry that it is in german.
If you have any questions of the used rubber and so on don´t hesitate to ask or give a comment.