Hi Bang,
I changed the original filament drive gear to one with fewer, more defined, teeth. That improved things a little but the tension spring was still not strong enough to pull filament smoothly off the spool and push it through the hot end.
In the end I changed the whole filament feeder for an aluminium one with a screw adjustment on the tension spring.
I also bought some PEI heat film for the glass sheet and supported the bed from underneath with some 18mm mdf to try and even out a dip in the middle which has worked wonders for getting prints started. So far I've successfully printed calibration pieces, a cover and brackets for the PSU. I'm currently printing a pair of anti z wobble brackets to see how they improve the layer lines on printed objects.
So, along the way I've cooked a USB port on my laptop and the FTDI chip on the Sanguinololu when the PSU spiked (when I dropped an allen key which rattled into it); changed the filament feeder completely; rigged up a Pi3 with camera running Octopi. I've bought a temporary Sanguinololu to get things running again and ordered a GT2560 controller and an autolevel sensor to make bed levelling quicker between prints. I've redrawn [ur=
http://www.thingiverse.com/thing:2178701l]the touch sensor mounting[/url] in Sketchup with a rectangular base so it can be printed upright (rather than rotated 90 degrees as the curved one on Thingiverse is) so it has fewer z layer wobbles.
I've dismantled and reassembled the extruder/hot end so many times I've invested in a second complete hot end with stepper and everything so I can at least print whilst I'm fiddling with it. I've also managed to cook some of the A983 Pololu modules so I replaced the lot with DRV8825 boards and set the Y axis and Extruder drivers to a vref of 0.75 volts which gives them a max current of 1.5 amps.
Everywhere you look the advice with the Sanguinololu is to cut the 5volt line on the FTDI to USB port link which I think this is something that Geeetech should adapt with header pins and a jumper. I now only have the left side usb ports on my laptop and have ordered some of
these USB to USB isolaters to prevent this kind of clumsy mishap destroying my computer in the future!
It's taken a little while to get there but I am having a lot of fun - my friend bought a genuine Prusa I3 MK2 with the MK42 heat bed and auto level/axis calibration which is undoubtedly 3 times better at 3 times the price, with the drivers pre-calibrated and every wire exactly the right length. I've learnt much more about the nuts and bolts of 3D printing with this, if I was to be buying now I'd definitely go for the external control box and screen to avoid the risk and potential problems of having exposed mains connections again.
Regards
David
