Buy a new printer or fix my old printer? Reprap prusa mendel

[Stu FL]

My 3D printer is a total basket case. My question is, can I rebuild it into a reasonably decent functional machine, or am I better off buying a whole new machine? Would this machine be on par with newer machines if fixed up properly? If I can fix it up, what parts do I need to replace, and with what should I replace them? My goal is that I want to be able to print random replacement parts for stuff (brackets, gears), mainly centering around my vintage computer collection and other hobby projects. Biggest "accuracy" issue for me is that I will need to create housings for small projects, and I'll need screw holes in the housing to line up with the mounting holes in the PCB. I'll need to make boxes and lids, and the lip of the lid will need to line up with the box so it can be screwed together nicely.

The printer is a RepRap Prusa/Mendel V2/V3. It has a horizontal carriage assembly. Originally designed for the filament feed motor to be mounted directly on the carriage, however has been modified with a bowden type remote extruder. Hot end is some no-name off of ebay, held in place by a piece of paint-stirring stick (because the bracket was made for a direct drive not bowden. It's got a genuine arduino mega 2560, and RAMSP 1.4A board. Yes, it says "RAMSP" not "RAMPS" Heated bed, all steppers are "Kysan 1124090". Frame is thick acrylic, plexiglass, or similar. "Geeetech" LCD display with rotary encoder, speaker, and momentary switch.

What are the problems:

- Weak gear in servo motor ocassionally causes arm to partially extend for z-axis autolevel switch, causing hot end to ram into and shatter glass bed. (I think some sort of fixed-mount optical sensor would be better.)

- Z-axis motors make "jamming" sound, even with threaded rods disconnected from motor. I've tried adjusting the little driver boards on the RAMSP. It works more reliably at extremely slow speeds, although never 100% reliable.

- Intermittent yet frequent random heater error messages (thermal runaway, etc...) causing print job to halt.

- Filiment jams up inside of hot end causing print job to be ruined.

- After completing a layer, the printer does not correctly increment the carriage up "one notch" (z-axis) causes filament to be dispensed too far above the object being printed. By about a quarter inch worth of layers, the item being printed is a mess and ruined.


I would imagine the thing to do is replace the carriage assembly with one made for a bowden filiment feed, and perhaps replace the arduino/ramsp board with something newer. Replacing the carriage could include an optical Z sensor, and proper cooling for the cold end.

So, is this machine worth putting a few $$ into? Do newer machines spin circles around it? Time to toss it?

Thanks!