Printing wierdness

Using Marlin V1.0 RC3
RAMPS 1.2 with onboard MAX6675
Slic3R V0.93
Nozzle 0.4mm dia
Filament 2.9mm dia
Layer height 0.3mm

I have two problems, that I hope someone could possibly enlighten me on please.

When doing a print, PronterFace shows this as feedback part way through the print

Marlin 1.0.0
echo: Last Updated: 2012-05-02 | Author: erik
echo: Free Memory: 5580  PlannerBufferBytes: 1232
echo:Using Default settings:
Setting hotend temperature to 160.000000 degrees Celsius.
Print Started at: 17:57:46
Error:checksum mismatch, Last Line:144
Resend:145
Error:checksum mismatch, Last Line:228
Resend:229
Error:Line Number is not Last Line Number+1, Last Line:239
Resend:240
Error:checksum mismatch, Last Line:258
Resend:259
Error:No Checksum with line number, Last Line:270
Resend:271
Error:No Checksum with line number, Last Line:341
Resend:342
Error:No Checksum with line number, Last Line:392
Resend:393
Error:checksum mismatch, Last Line:437
Resend:438
Error:checksum mismatch, Last Line:460
Resend:461
Error:No Checksum with line number, Last Line:613
Resend:614
Error:No Checksum with line number, Last Line:790
Resend:791
Error:Line Number is not Last Line Number+1, Last Line:821
Resend:822
Error:checksum mismatch, Last Line:1118
Resend:1119
Error:Line Number is not Last Line Number+1, Last Line:1229
Resend:1230

Or the print stops mid way through and the MEGA becomes unresponsive until a Power On Reset.


The other problem, believe it or not, the Z height travel and feedrate are set for my machine (Sells Mendel)
3360 Steps per mm Z (1/8th step, 8 tooth driven, 21 tooth pulley to threaded rods)
Feedrate 80 for Z
I have reduced the acceleration of Z to 50

X and Y axes are good as is E.

Giving a result of a layer height of ~100um (pretty hard to tell exactly without verniers)
Or to give a better idea, the height of the object is suppose to be 5mm, what is printed is 2mm high

Any ideas

Edited 1 time(s). Last edit at 10/12/2012 04:41AM by Grogyan.

if your temp is at 160, you are below the extrusion cut off point by default. probably wires are loose and moving around your thermistor. easy fix just zip tie it down within a few inches of extruder.

I think what is happening is if extruder is below 160, or above 260 firmware goes into dwell state. commands are rejected until it is reset. it is a way to prevent serious damage to your machine.

loose wiring of thermistor can provide for false readings and rapid temp changes that are false.

double check wiring, make sure there is no loose connection or short for thermistor, and like i said zip tie the wire so they do not move in the region of 3 inches around the hot end and extruder. there is a lot ofe pulling and jerking from the wires. it does not take much to work a loose connection.

Edited 1 time(s). Last edit at 10/12/2012 06:38AM by jamesdanielv.

There is no loose connections.
I use a Thermocouple instead of a thermistor.

The cold extrusion cut off has been reduced to 150C to enable me to print at a decent quality, without a fan. Normally it is 170C, which leaves a glob that resembles a print and not much else.

can you list the first 200 lines of gcode, just copy it into a text editor save the file and upload it. for some reason your firmware is getting something it does not like. if there is something there then some one here can diagnose it for you.

also it does still sound like a thermal sensor issue. when temp is raised to 170 on your machine does the print go past the above lines? even though there are print issues, does the job complete in pronterface? this helps troubleshoot further.

I was plagued by an intermittent "Error:Line Number is not Last Line Number+1" error a few months ago on two separate printers (both with RAMPS 1.4, an older non-gen6 version of Marlin, and two different versions of pronterface). Sometimes I could print again after unplugging the USB cable and plugging it back in, but sometimes it would require a firmware reinstall to get things working again. The error would occur more frequently when I tried to print models with a higher polygon count so I chalked it up to a serial communication error between the laptop and the Arduino Mega.

To make a long, frustrating story much shorter, I switched to Repetier Host and Repetier firmware and then everything suddenly started working as desired on both printers! I followed the instructions for the Repetier firmware installation and replaced the Arduino serial communication code with the version bundled with the Repetier firmware prior to compiling and uploading the firmware. I can't say for certain if it was this change to the Arduino serial communication code or the fact that Repetier uses a more efficient binary encoding to send gcode between the host and the printer that fixed the issue. But I can say the issue is most definitely fixed!

Here is a clip of the gcode.

Go into config or config_adv in marlin firmware; look at line that indicates buffers. What is it set at? Or better yet, also paste your config and adv config.

There seems to be nothing that stands out with the gcode, at least that I can see at a quick glance. It may also be that your buffers are set to high and the arduino is losing the last part of a line of data, and therefore generating a false checksum.

I managed to fix the Z height problem, had to reduce the feedrate, homing feedrate and acceleration. Just the buffer to sort out now.

Config and Advanced Config files attached