Hints and tips to cure faults and keep prints consistent

Hi All.
There are quite a few threads on here regarding upgrading your CTC printer, but not so many about curing faults and compensating for inherent weaknesses in the design. Here's my ideas, but feel free to add.

Firmware:
Creator 1.0 that the majority of these machines ship with is fine for 90% of users. Loading Sailfish will cure very few faults or problems and is really only a worthwhile upgrade for fiddlers and tweakers looking to squeeze the last ounce out of their machines. If you have a fault that is developing, it is unlikely to be the firmware causing it or that installing Sailfish will fix a poorly performing printer.

Chassis:
The wooden chassis is held together with a nut and bolt system that works loose over time. Often on arrival from China, you might find that some of these connectors have fallen out and are rattling around in the bottom of the box! To ensure accurate assembly, place the printer on a dead flat surface - a large mirror is good, then tighten up all the connectors ensuring the chassis remains square and is not lifting up a corner. If you have a set square, this is also useful to check the corners stay square. Do not over-tighten. You will simply distort the wood.

Filament Feeder Tubes & Support
Quite why they don't ship the printers with filament feed tubes is a mystery! 2mm tubing is cheap enough and combined with a new combined filament and cable strain relief - http://www.thingiverse.com/thing:340031 you get a much more robust system. The other mystery is why you only get one spool holder. Yes, you can just about squeeze 2 smaller reels on there, but a second one makes things easier. Easy print here: http://www.thingiverse.com/thing:295102 If you are mounting the reels onto the back of the printer, then this: http://www.thingiverse.com/thing:409297 gives you a neat way of finishing off the feed tubing.

Extruder and Hotend:
The current extruder and hotend is actually pretty good. The major weak point is the extruder feeder, as the wheel which presses the filament onto the hobbed gear is not sprung loaded and is set to a fixed distance. Soft filaments - PLA and Ninjaflex in particular, can easily jam, usually causing a build up of debris on the hobbed gear, making things even worse. One of the few upgrades I would recommend is changing the feeders for a sprung type. Less than £10 for the plastic ones or £30 for nice looking aluminium ones. You can of course print your own, but use ABS, as PLA is too soft to last very long and will distort.

The PTFE liner needs replacing every 200 - 400 hours. If you are getting repeated filament jams, then it is possible that the tubing has softened and has either kinked or thickened at the end, causing a restriction. The actual cause is often that the extruder temperature is too high, allowing heat creep back up the past the heat sink.

The thermocouples are mounted directly to the heater block, so must be insulated. Many aftermarket units are not insulated and simply won't give correct readings, as the junction is crimped into the ring. You need to modify these to fully insulate the junction. Unless they have failed, there is little point to changing them, as the original ones are fine.

The supplied nozzles are OK, but better quality ones will give slightly more consistent results. If you have been overheating the filament, have had contamination or notice the extrusion is not consistent, either clean or change the nozzle. I bought a set of mini drills for £1 and find these are excellent for clearing out the crud. I use them by hand, so I don't have enough force to damage the brass, but I can get out the burnt debris. If you change the nozzle, change the PTFE liner at the same time - it saves a lot of grief! When re-mounting a nozzle, tighten it by hand while the block is cold, then heat it to 200C and then use a pair of spanners - one on the block and one for the nozzle to nip it up. It does not need a huge amount of torque, just enough to prevent it coming lose.

Build Platform:
For whatever reason, many of these printers are shipped with the wrong thermister on the heated bed, so the temperature reads incorrectly. Easy check, from cold, put the printer into monitor mode and see if the bed and heater temperatures match to within a couple of degrees. If not, you can either swap out the thermister - easy job with a soldering iron, or simply compensate in your settings. It's normally about 10C low, so just add 10C to your bed temperature.

To get good adhesion, you need to select the right solution for your material. I print 90% ABS - as it is easier to sand and shape after printing, so I use a textured Buildtak sheet and then a quick spray of hairspray every few prints. Getting the bed at the correct height is critical to good adhesion. As well as the usual method using a piece of thin paper, do a quick test laying down circles of increasing diameters across the whole plate. Check the same level of "squish" is present and adjust the screws a quarter turn or so until the filament is adhering well but is not being prevented from flowing. For PLA, painter's tape is normally fine, but I find the extra expense of Buildtak worth it, as it works with most materials without issue. I get - 40 -50 prints from each sheet if I am careful removing the parts! An old credit card is good for this.

Platform Wobble
The build plate could be more stable, but fortunately, the fix is usually quite simple. The wobble is normally caused by movement in the vertical slide bars, as the holes in the mounts are a little too large. It's a simple job to undo them one at a time a put a turn of electrical tape around the rod at each end and reassembling. This is a simple fix and reduces the wobble massively.

Printer Failing on Prints or Reseting
This one took me a while to figure out! Every so often, but increasingly so, my printer would issue a grating noise and the print would fail. Restart it and it would usually be OK for a few more hours. The cause was actually a failing stepper motor cable, which was internally arcing and creating enough interference on the power supply line to reset the printer! I replaced the cable (The X Axis drive on mine), normal service was resumed. Probably worth re-routing the cables at the same time to reduce the bending at the same point. Mine now come directly up from the base of the machine instead of being fed from above.

Noisy Cooling Fans
The fan that keeps the stepper motor drives cool was very unbalanced and the method of mounting made the vibrations even worse. Easy fix is to replace the fan, but I also wired in a voltage regulator to reduce the fan speed. I also used some sticky pads to cushion the fan. It's so much quieter now!

Enclosing the Printer
I simply bought some sheets of perspex - 4mm thick, and had it cut to size. I made the front as a "door", with hinges to the top and then a "greenhouse" for the top, with a large slot for the cables and filament feed. Happy to share the info if anyone is interested.

I also added LED lighting - a kit with 4 50cm lengths and a transformer was very cheap and makes things much more attractive. Easy to fit, just stick the lengths right up inside the case and use the supplied jumper cables around the corners.

I think that's about it for now. Feel free to add to the thread :)