In order to catch up to all of the latest features/bugfixes in Marlin but retain the Felix settings, I thought I'd make a fork of the official Marlin source available via Github. I will continue to keep it up to date with ongoing Marlin development. It can be found at https://github.com/andrewsil1/FelixMarlin.
All you need to do is use Github to download a ZIP of the whole repository, and then compile/upload using the Arduino IDE exactly as you would with either the Repetier or Marlin firmware provided here. The only source changes are in the main config files (configuration.h, configuration_adv.h, language.h, and pins.h.) Mostly I've just moved things around and updated values to keep in sync with changes in Marlin, but the important settings, such as steps/mm and the various speed limits, limit switches, etc., are essentially identical to the original Felix versions. There are a few features I have enabled that aren't part of the original Felix firmware:
- PID control is enabled for the Felix 3.0 "sandwich" heated bed, optimized for a target temp of 55C. It may work just fine at higher temps, but I haven't tried it. This has resulted in major print quality improvements for me, since "bang-bang" bed heater mode causes enough expansion/contraction in the bed to result in layer height differences which show up as a very visible "Z-ribbing." Enabling PID for more accurate temp control eliminated this problem.
- Z-"babystepping" is enabled in the menu during a print in case you want to make fine adjustments to the initial layer height. Now that I have my bed levelling dialed in well I rarely need this, but it doesn't hurt to have it available.
- SD card detection sensing polarity is fixed relative to the Felix version, where cards are not detected on insertion, and vice versa. It now behaves as expected.
- Other very minor tweaks here and there to allow some optional features to be used (e.g. automatic firmware-based retraction settings) but these are not enabled by default during printing, so no differences should be noted unless used deliberately.
I use this firmware daily and have not encountered any problems, so you shouldn't encounter any significant issues. Feel free to contact me if you try it and run into anything unexpected.