Extruder Tension Setting Gauge by davidhbrown

Last crawled date: 3 years ago

Edit/update: Thanks to everyone who has added it to additional groups/collections. I have reprinted it in blue so as to take a photograph with better contrast than the original red on orange.
While learning to print with flexible filament on my Prusa i3 Mk2s, I wanted to be able to quickly and repeatably set the spring tension on the extruder feed bearing. This gauge will probably be usable on many other models of printer with a similar tension mechanism. (springs on M3 screws).
Loose and tight versions
Both versions of the gauge include 12.0mm and 12.5mm settings. As a longer tool is awkward to position, I created two shorter tools, one for looser tension settings and one to go tighter.
The Loose version includes larger sizes up to 16mm at which point my printer does not compress the spring at all until filament is loaded. This is the version you'd want for printing flexible filament that wants a very low tension.
The tight version extends down to 9.5mm at which point my springs have completely compressed; this is probably uselessly tight. I don't have any filaments that require more tension than standard, so I've included this just for the sake of completeness. (I'm curious if there are materials which require a lot of tension?)
Using the gauge
loosen each bolt a bit looser than you want
place the section of the tool marked with the desired width over the spring
tighten the bolt until both washers make gentle contact with the gauge.
The total distance between the extruder housing and the head of the bolt will be a bit greater (the thickness of two washers), so I have been using the 12.0mm or 12.5mm marks as "normal" for the recommended 13mm.
I usually try to get the flat edge of the gauge against the extruder housing to help ensure the gauge isn't skewed.